METERING SYSTEM FOR AN AGRICULTURAL PLANTER ROW UNIT

Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claims 1–4, 7–11, 14, and 16–18 are rejected under 35 U.S.C. 103 as being unpatentable over Connors et al. (US 2016/0135362 A1) in view of Czapka et al. (US 2018/0208058 A1) and Schoeny et al. (US 2021/0007271 A1). Claims 5–6, 12–13, and 19–20 are rejected under 35 U.S.C. 103 as being unpatentable over Connors in view of Czapka, Schoeny, and Rains et al. (US 2017/0094893 A1). Claim 15 is rejected under 35 U.S.C. 103 as being unpatentable over Connors in view of Czapka, Schoeny, and Wang (US 2019/0387663 A1). Claim 1 Regarding Claim 1, Disclosure by Connors Connors discloses: A metering system for an agricultural planter row unit, comprising: See at least: “To facilitate depositing seeds, the row unit 20 includes a furrow opener disc 24, an opener shoe 26, a closing disc 28, a seed hopper 30, a seed meter 32, a seed tube 34, a press wheel 36, and an auxiliary hopper 38.” ([0027]) Rationale: Connors expressly discloses seed meter 32 carried on row unit 20 of planting implement 10. The seed meter, together with its direct vacuum source 68 and control unit 42, is a metering system for an agricultural planter row unit. a controller comprising a memory and a processor, See at least: “The operation of the seed meter 32, and particularly the vacuum source 40, is controlled by a control unit 42. As depicted, the control unit 42 includes a processor 44 and memory 46.” ([0030]) Rationale: Control unit 42 with processor 44 and memory 46 is expressly a controller comprising a memory and a processor. wherein the controller is configured to: See at least: “In some embodiments, process 74 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as memory 46, and executable by processing circuitry, such as processor 44.” ([0050]) Rationale: Control unit 42 is programmed by stored instructions to perform the operations of process 74, so it is expressly configured to perform the operations that follow. iteratively perform a first set of operations, comprising: See at least: “Generally the process 74 includes operating the seed meter (process block 76), determining whether a skip is detected (decision block 78), when a skip is detected, increasing vacuum pressure (process block 80) …” ([0050]); “In either case, the seed meter 32 may continue operation with the increased vacuum pressure (arrow 86).” ([0056]) Rationale: The sensing, skip-determination and vacuum-increase operations of process 74 (blocks 76, 78, 80) form a first set of operations. Arrow 86 returns the process to block 76 after each pass, so the set is expressly performed iteratively. receiving a sensor signal indicative of an agricultural product flow rate through the agricultural planter row unit; See at least: “the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: Seeds are agricultural product, and the sensor sits “in the singulator 54 or in the seed tube” ([0053]), i.e., in the product path through the row unit. A signal indicating the number of seeds output, received each time a seed is expected, indicates seeds per unit time, which is a flow rate. Connors itself frames meter output as a rate: “the desired seed output rate” ([0047]). The limitation is therefore disclosed, or at minimum implicit to a PHOSITA reading Connors. after receiving the sensor signal indicative of the agricultural product flow rate through the agricultural planter row unit; See at least: “a sensor, located in the singulator 54 or in the seed tube, may communicate with the control unit 42 when seeds are output from the seed meter 32. Additionally, the control unit 42 may determine when a seed is expected to be output by the seed meter 32.” ([0053]) Rationale: Control unit 42 evaluates meter output (skip or not) only after the sensor reports what was output. The evaluation therefore expressly occurs after the sensor signal is received. returning to receiving the sensor signal indicative of the agricultural product flow rate See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: Control unit 42 polls the sensor again for every expected seed. When neither a skip nor a multiple is found, process 74 returns to operating the meter and polling the sensor (FIG. 5, blocks 76–82). Connors therefore expressly returns to receiving the sensor signal. comparing a fluid pressure differential between opposite sides of a metering device of the metering system See at least: “As used herein, ‘vacuum pressure’ is intended to describe a pressure differential from atmospheric pressure and not necessarily a true vacuum.” ([0020]); “the seed disc 48 may divide the seed meter between a seed chamber 62 and a vacuum chamber 64.” ([0031]); “when skips continue to occur even after the vacuum pressure is increased above a threshold amount, which may be a predetermined vacuum pressure that is sufficient to attach a certain seed type to the seed disc openings 66 …” ([0065]) Rationale: Seed disc 48 is a metering device, and it separates seed chamber 62 from vacuum chamber 64. The vacuum pressure, which Connors defines as a pressure differential, is applied to the vacuum-chamber side while the seed side is fed from the hopper. Connors' vacuum pressure is therefore a fluid pressure differential between opposite sides of the metering device. Connors also determines whether that vacuum pressure has been “increased above a threshold amount,” which is a comparison of the differential against a stored value. The comparison step is expressly disclosed; the identity of the threshold as a maximum is addressed below. increasing the fluid pressure differential, See at least: “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: Increasing the supplied vacuum pressure expressly increases the fluid pressure differential across seed disc 48. via an electrically-driven fluid pump of the metering system, See at least: “Thus, any suitable type of fan 72 that can generate vacuum pressure may be utilized, such as an electric fan, a gear drive fan, a hydraulic fan, or the like.” ([0046]); “to increase the vacuum pressure, the speed of the fan 72 may be increased” ([0043]) Rationale: Fan 72 moves air to create the pressure differential and is therefore a fluid pump. An electric fan is an electrically-driven fluid pump. Fan 72 is part of direct vacuum source 68 mounted on the meter's vacuum port ([0038]), so it is a pump of the metering system. Selecting the expressly listed electric fan from Connors' short list is an express teaching of the claimed pump (MPEP 2123). iteratively perform a second set of operations, See at least: “determining whether a multiple is detected (decision block 82), and when a multiple is detected, decreasing vacuum pressure (process block 84).” ([0050]); “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Blocks 82 and 84 are a second set of operations, which arrow 86 repeats on every pass. Connors expressly discloses performing it iteratively. separate from the first set of operations, See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82).” ([0057]) Rationale: The multiple branch (blocks 82–84) is a distinct decision path from the skip branch (blocks 78–80), entered only on a different condition. The second set is therefore expressly separate from the first. wherein the second set of operations comprises: See at least: “Similar to increasing the vacuum pressure, the control unit 42 may instruct the fan 72 to make an incremental decrease in vacuum pressure, which may be predefined and stored in the memory 46.” ([0059]) Rationale: Connors expressly identifies the operations that make up its decrease branch, namely the incremental decreases mapped below. decreasing the fluid pressure differential, See at least: “When a multiple is detected, the control unit 42 may instruct the direct vacuum source 68 to decrease the supplied vacuum pressure (process block 84).” ([0058]) Rationale: Decreasing the supplied vacuum pressure expressly decreases the fluid pressure differential across seed disc 48. via the electrically-driven fluid pump of the metering system, See at least: “to decrease the vacuum pressure, the speed of the fan 72 may be decreased.” ([0043]) Rationale: The decrease is made by the same fan 72, which may be the electric fan of [0046]. The same electrically-driven fluid pump of the metering system therefore expressly performs the decrease. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: comparing the agricultural product flow rate to a target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; to a maximum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka discloses: comparing the agricultural product flow rate to a target agricultural product flow rate range See at least: “if the operating parameter(s) corresponds to a seed-related parameter and the threshold value(s) corresponds to a desired seed population range for the various active row units 28, the planter controller 104 may be configured to monitor the current seed distribution for the relevant row unit(s) 28 (e.g., via the seed sensor(s) 84) and compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: Czapka expressly compares sensed seed output to a range bounded by maximum and minimum values. Its seed sensor 84 provides “an indication of the output rate of the seed meter 78” ([0048]), and ground speed is sent to the planter controller ([0044]). Seed population is that output rate divided by ground speed and row spacing, so a population range at the travel speed is an output-rate range. A PHOSITA would recognize that comparing population to a desired range is comparing the agricultural product flow rate to a target range. The teaching is express as to the range comparison and PHOSITA-obvious as to expressing it in flow-rate units. in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]); “The control algorithm 400 may then return back to flow step 412 shown in FIG. 8.” ([0071]) Rationale: When output meets its target, Czapka makes no vacuum adjustment and returns to step 412, which checks seed discharges “via the associated seed sensors 84” ([0066]). Read with Czapka's target expressed as a range ([0054], [0065]), this expressly teaches returning to sensing in response to the output being within the target range. to a maximum threshold fluid pressure differential See at least: “suitable operator inputs may include, but are not limited to, … maximum and minimum vacuum pressures for the seed meter 78 …” ([0045]) Rationale: Czapka expressly provides a maximum vacuum pressure for the seed meter. Because vacuum pressure in the seed meter is the differential across the seed disc (see Connors [0020]), Czapka's maximum vacuum pressure is a maximum threshold fluid pressure differential. Substituting it for Connors' unlabeled “threshold amount” ([0065]) supplies the claimed comparison target. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Czapka expressly enters its vacuum-adjustment logic (steps 420–424) only when output is off target. Czapka does not state how its operator-set maximum vacuum ([0045]) is observed, and a limit could be observed in other ways (for example, by saturating the command). Implementing that limit by comparing the current vacuum to the maximum when, and because, an out-of-range output calls for a vacuum change would have been an obvious controller design. Czapka shows the general practice of comparing a row-unit actuator setting to threshold values before adjusting it: at step 450 it checks whether down force “is greater than a minimum down force threshold” and at step 454 whether it “is less than a maximum down force threshold” ([0072]). Czapka applies those comparisons to down force, so it is relied on for the threshold-comparison practice, not for the identical conditional relationship claimed. in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and See at least: “Similarly, if the current seed population is too low, the planter controller 104 may, at (424), increase the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Czapka increases vacuum to correct output, subject to a maximum vacuum pressure for the meter ([0045]). Czapka does not expressly condition the increase on a comparison. Conditioning it on the differential being less than the maximum would have been an obvious way to observe Czapka's maximum, applying Czapka's threshold-comparison approach ([0072]) to the vacuum setting. The comparison is a known, predictable choice among ways to observe a limit. comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28.” ([0072]) Rationale: Czapka supplies a minimum vacuum pressure for the meter ([0045]) and shows its controller comparing a row-unit actuator setting against a minimum threshold ([0072]). Czapka uses that comparison to decide whether to increase down force; the claimed comparison decides whether to permit a further decrease in vacuum. Czapka is therefore relied on for the general practice of threshold-based actuator control, not the identical conditional relationship. Applying that comparison to Czapka's minimum vacuum pressure is a predictable use of Czapka's own approach. It is PHOSITA-obvious. in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. See at least: “If the current seed population is too high, the planter controller 104 may, at (422), reduce the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Czapka reduces vacuum to correct output, subject to a minimum vacuum pressure ([0045]). Czapka does not expressly condition the decrease on a comparison. Applying Czapka's threshold-comparison approach ([0072]) to its disclosed minimum vacuum setting would permit the controller to continue reducing vacuum while the differential remains above the minimum and to inhibit further reduction at that minimum. Connors gives the technical reason for doing so: “skips may occur more frequently when the vacuum pressure is lower because the vacuum pressure may be insufficient to secure a single seed” (Connors [0035]). Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to modify Connors' control unit 42 to compare the sensed seed output rate to a target range with maximum and minimum values and to bound its fan-driven vacuum adjustments between maximum and minimum vacuum pressures, as taught by Czapka. Both references control a row-unit vacuum source from a seed sensor to reduce skips and multiples. Czapka controls vacuum “to regulate the rate at which the seeds are expelled from the meter 78 into the seed tube 82” (Czapka [0046]). Judging output against a tolerance range, rather than reacting to every single deviation, gives more stable control. Bounding the vacuum keeps the meter inside an operating window: Connors explains that excess vacuum causes multiples and insufficient vacuum causes skips (Connors [0035]). Applying a known control technique (range-based feedback with actuator limits) to a similar device ready for improvement yields predictable results (KSR; MPEP 2143(I)(C), (D)). Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly disclosed: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, When Czapka's vacuum adjustment fails to restore output, Czapka resets the vacuum and slows the tractor ([0068]); it does not switch to the decreasing operations upon reaching the maximum. Disclosure by Schoeny Schoeny discloses: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, See at least: “in the case of a reverse vacuum calibration cycle following the determination of the maximum acceptable vacuum pressure (e.g., at 320), the controller 202 may increase the vacuum pressure by a given margin (e.g., 10% over the previously determined maximum acceptable vacuum pressure) and then iteratively decrease the vacuum pressure of the vacuum source 70 until it is detected that the number of multiples is less than the predetermined allowable multiples threshold …” ([0079]) Rationale: Schoeny steps vacuum upward to a maximum acceptable value and then, in a separate reverse calibration cycle, raises vacuum above that previously determined maximum (for example, 10% over it) and iteratively decreases it while re-assessing meter performance ([0075]–[0079]). Schoeny thus teaches an up-then-down sequence in which the descending routine begins above a previously determined maximum acceptable vacuum pressure. Schoeny does not expressly disclose three features of the claim: (1) it performs the sequence as a calibration routine, not as an in-operation branch entered from an out-of-range flow rate; (2) it does not compare the current differential to a maximum threshold as the trigger for the descending routine; and (3) its experimentally determined “maximum acceptable” value is not identical to Czapka's operator-selected maximum (Czapka [0045]). Configuring the combined controller to begin the descending operations upon determining that the current differential has reached or exceeded the established maximum threshold, and using that sequence during operation, is the modification explained in the motivation below. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to configure the combined controller to respond to an out-of-range flow rate with a bounded search of the vacuum window. In that search the controller increases the differential while it is below the maximum threshold and, upon determining that the differential has reached or exceeded the maximum, switches to iteratively decreasing it while it remains above the minimum threshold, rather than choosing a single direction from the type of error. The rationale addresses three separate questions. Motivation for the modification. Connors and Czapka choose the direction of correction from the type of error: they raise vacuum for skips or low output and lower it for multiples or high output (Connors [0054], [0058]; Czapka [0067]). The claimed flow rate, however, is an aggregate measure. An off-target rate shows that output is wrong, but it does not by itself show which direction of vacuum change will correct it. Connors recognizes that output may contain “a mixture of multiples and skips” (Connors [0065]). Connors attributes that condition to seed clumping and handles it with a separate response; it does not itself suggest a pressure search, and it is cited here only to show that aggregate output can combine both error types. Schoeny supplies the reason to search. It explains that the appropriate vacuum for a given meter and seed lot is not known in advance, because recommended ranges “may not be ideal” (Schoeny [0003]), and it addresses that uncertainty by stepping vacuum through a bounded range upward and then downward, re-assessing performance at each step (Schoeny [0075]–[0081]). A person of ordinary skill seeking to restore an off-target flow rate without knowing which side of an acceptable setting the current vacuum lies on would have had reason to adapt Schoeny's bounded up-then-down search for use in place of a single direction-selected correction. Schoeny's search was known as a calibration routine; its operating trigger (an out-of-range flow rate), its transition upon determining that the differential has reached an established maximum threshold, and its operator-selected bounds are the modifications identified above. The complete operational strategy is therefore not asserted to have been known in that precise form. Substituting the adapted search for the direction-selected correction yields predictable results (KSR; MPEP 2143(I)(B), (G)). The search trades some speed of correction for a result that does not depend on first diagnosing the direction of the error. Reasonable expectation of success. Where the deviation can be corrected by vacuum, a stepped search that runs from the current setting up to the maximum and then down toward the minimum traverses the selected window, and would be expected to reach an acceptable setting within that window at the resolution of its steps. Schoeny shows that a stepped search of this kind, with performance re-assessed at each step, is used to identify an acceptable vacuum setting (Schoeny [0079]–[0081]). Where the deviation cannot be corrected by vacuum, such as the clumping or obstructions Connors describes (Connors [0065]–[0066]), Connors teaches escalation after unsuccessful attempts, including operator notification, rather than further pressure adjustment (Connors [0069], [0073]; see Claims 5–6). The rationale therefore does not depend on the search succeeding in every circumstance. Feasibility. The modification uses hardware Connors already discloses: the seed sensor, control unit 42, and the variable-speed electric fan (Connors [0043], [0046], [0053]–[0058]). Connors' repeated sensing after pressure adjustments (Connors [0056], [0060]) and Czapka's target-based feedback (Czapka [0067]–[0068]) support retaining output monitoring during the search. This shows that the search could be implemented; it is not relied on as the motivation for the search. Claim 2 Regarding Claim 2, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 1, which is the basis for Claim 2. Disclosure by Connors Connors discloses: wherein the second set of operations comprises receiving the sensor signal indicative of the agricultural product flow rate through the agricultural planter row unit See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: Polling the seed sensor is part of the multiple-detection branch (decision block 82) that leads to the decrease at block 84. Receiving the sensor signal is therefore expressly an operation of Connors' second set. after decreasing the fluid pressure differential. See at least: “In other words, the control unit 42 may instruct the direct vacuum source 68 to decrease vacuum pressure after each detected multiple or alternatively after a given period of operation. In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: After each decrease, arrow 86 returns the process to operating the meter and polling the sensor at the new, lower vacuum. Connors therefore expressly receives the sensor signal after decreasing the differential. In the combination of claim 1, the same post-decrease sensing occurs within the bounded descent taught by Schoeny, which likewise re-assesses meter performance after each iterative change (Schoeny [0070]). Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to receive the flow-rate sensor signal after each decrease of the differential within the combined controller's second set of operations, for the reasons given for Claim 1. Sensing after each adjustment is the only way the controller can learn whether that adjustment corrected the output. Connors does so after every vacuum change (Connors [0060]). Schoeny waits after each step so that the meter “reaches a steady state condition” before re-assessing (Schoeny [0070]). Retaining that feedback in the combined loop improves control accuracy predictably (KSR; MPEP 2143(I)(A)). Claim 3 Regarding Claim 3, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 2, which is the basis for Claim 3. Disclosure by Connors Connors discloses: after receiving the sensor signal indicative of the agricultural product flow rate of the second set of operations; See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82). More specifically, as discussed above, the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: Within the multiple branch, control unit 42 evaluates output only after receiving the sensor signal. Evaluation following receipt of the second set's sensor signal is expressly disclosed. returning to receiving the sensor signal indicative of the agricultural product flow rate of the second set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Arrow 86 returns the process to operating the meter and polling the sensor after the decrease branch. Connors expressly returns to receiving the sensor signal. Arrow 86 returns through Connors' general skip/multiple decision sequence, so Connors alone does not retain the descending mode while sensing; that arrangement is addressed by the combination below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: The metering system of claim 2, wherein the second set of operations comprises: (as to the target range and minimum-threshold operations below) comparing the agricultural product flow rate to the target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. Disclosure by Czapka Czapka discloses: The metering system of claim 2, wherein the second set of operations comprises: See at least: “Following the increase or reduction in the vacuum pressure, the planter controller 104 may, at (426), determine whether the pressure adjustment resulted in an improvement to the monitored seed population.” ([0068]) Rationale: Czapka expressly re-evaluates output after a vacuum reduction as part of the same adjustment routine. The post-reduction operations below therefore belong to the decreasing set of operations. comparing the agricultural product flow rate to the target agricultural product flow rate range See at least: “compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: As explained for Claim 1, Czapka's comparison of sensed output to a population range is a comparison of the product flow rate to a target range. After a reduction, Czapka re-checks output against that target ([0068], returning to step 418). in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]) Rationale: When the re-checked output meets its target, Czapka makes no further vacuum change and returns to sensing at step 412 ([0071]). This expressly teaches returning to receiving the sensor signal in response to the output being within the target. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Czapka expressly evaluates output after each adjustment ([0068]). If the adjustment improved the seed population, Czapka returns to step 418 (“the control algorithm 400 may return back to flow step 418”); if it did not, Czapka reduces ground speed and may “re-set the vacuum pressure for the seed meter 78 to its previous pressure setting” ([0068]). Czapka therefore does not continue vacuum adjustment in every off-target case. Continuing the descending vacuum search whenever output remains outside the target range, including when the preceding adjustment produced no improvement, is the proposed modification using Schoeny's reverse search, explained in the motivation below. Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to re-evaluate the sensed output rate against the target range after each decrease in Connors' second set of operations and to continue monitoring output while it remains within range, as Czapka evaluates output after each vacuum change and returns to sensing when output meets its target (Czapka [0067]–[0068], [0071]). Checking each adjustment against the target prevents both over-correction and needless further change, improving control accuracy predictably (KSR; MPEP 2143(I)(C)). Czapka does not continue vacuum adjustment in every off-target case; continuing the descending search whenever output remains out of range is addressed with Schoeny below. Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly disclosed: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential Disclosure by Schoeny Schoeny discloses: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential See at least: “Thereafter, the controller 202 may further iteratively decrease the vacuum pressure of the vacuum source 70 until the number of skips is greater than the predetermined allowable skips threshold and record the previous vacuum pressure of the vacuum source 70 (e.g., the vacuum pressure before the allowable skips threshold was exceeded) as a second minimum acceptable vacuum pressure.” ([0079]) Rationale: In its descending routine, Schoeny takes repeated downward steps and evaluates performance after each, first until multiples become acceptable and then onward, through acceptable performance, to locate the lower bound at which skips become excessive ([0079]). Schoeny therefore supplies iterative downward adjustment with performance evaluation, but not the claimed stopping condition; in the combined controller, Czapka's target-range evaluation governs whether adjustment continues or the controller returns to sensing without further adjustment. Schoeny evaluates performance at each step to find the lower acceptable bound; it does not compare the current vacuum to an already established minimum. In the combination, the minimum is Czapka's minimum vacuum pressure, enforced by the comparison adapted in Claim 1, and returning to that comparison after an out-of-range result is how the combined controller continues Schoeny's repeated descent. The teaching is express as to the repeated descent and PHOSITA-obvious as to the comparison against the stored minimum. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return to the minimum-threshold comparison whenever the re-checked output remains out of range, so that the controller keeps stepping the vacuum down only while it stays above the minimum. The modified controller also retains its current search direction while it monitors acceptable output: when the re-checked rate is within the target range, it keeps receiving the sensor signal within the second set without further adjustment, and when the rate later falls outside the range, it resumes the descent at the minimum-threshold comparison rather than re-entering a direction-selected correction. This arrangement is attributed to the combination, not to Connors' return arrow alone. Schoeny continues its descending pass, re-assessing performance at each step, rather than reversing direction partway through (Schoeny [0079]), and Czapka supplies the target-range check that decides whether adjustment is needed (Czapka [0067]–[0068]). Continuing the descent when the preceding adjustment produced no improvement, rather than following Czapka's ground-speed reduction, is part of the same modification; it keeps the vacuum search within the bounded window, with persistent failure handled by escalation (see Claims 5–6). Schoeny teaches repeating downward steps until a performance limit is reached (Schoeny [0079]). Czapka supplies the minimum vacuum that bounds those steps (Czapka [0045]). Connors explains why the floor matters: too little vacuum causes skips (Connors [0035]). The combination yields a predictable bounded search (KSR; MPEP 2143(I)(A)). Claim 4 Regarding Claim 4, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 1, which is the basis for Claim 4. Disclosure by Connors Connors discloses: wherein the second set of operations comprises returning to increasing the fluid pressure differential of the first set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]); “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: After the decrease branch, arrow 86 returns process 74 to the skip branch, where vacuum is increased at block 80. Connors therefore expressly returns from the decreasing operations to the increasing operation of the first set. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitation: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka discloses: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28. If the down force is not greater than the minimum down force threshold, the planter controller 104 may, at (452), be configured to increase the current down force (e.g., by controlling the operation of the down force actuator 126).” ([0072]) Rationale: Czapka's controller increases a row-unit actuator setting in response to determining that the setting is not greater than (i.e., is less than or equal to) its minimum threshold. Czapka also supplies a minimum vacuum pressure for the meter ([0045]). Applying the same not-greater-than-minimum test to the vacuum, and responding by increasing it, is a PHOSITA-obvious use of Czapka's own control logic on the same row unit. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return from the decreasing operations to the increasing operations when the differential reaches or falls below the minimum threshold. Connors teaches that vacuum below the needed level causes skips (Connors [0035]), so at the floor the only remaining vacuum correction is to raise it again. Czapka teaches responding to an at-or-below-minimum actuator setting by increasing it (Czapka [0072]). Schoeny teaches repeating its up and down vacuum cycles “any number of times to determine more accurate ranges” (Schoeny [0030]). Restarting the upward phase at the lower bound keeps the controller searching within the bounded window instead of stalling at a limit, a predictable result (KSR; MPEP 2143(I)(A)). Claim 5 Regarding Claim 5, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 1, which is the basis for Claim 5. Disclosure by Connors Connors discloses: The metering system of claim 1, wherein the controller is configured to: See at least: “In some embodiments, the process 88 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as the memory 46, and executable by processing circuitry, such as the processor 44.” ([0062]) Rationale: Control unit 42 is expressly programmed to perform fault-handling operations of the kind mapped below. in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential; See at least: “when skips continue to occur even after the vacuum pressure is increased above a threshold amount, which may be a predetermined vacuum pressure that is sufficient to attach a certain seed type to the seed disc openings 66, the control unit 42 may determine that seed clumping is occurring in the seed chamber 62 and/or the seed input port 60.” ([0065]) Rationale: Connors treats vacuum having been raised past a threshold while skips persist as a checkpoint for further fault handling, and it monitors failed correction attempts ([0067], [0069]). Connors' threshold is a pressure sufficient to attach seeds, not the combined controller's maximum operating limit. Using the combined controller's determination that the differential is at or above the maximum as the checkpoint that triggers the counter operations is the proposed modification explained in the motivation below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: compare a maximum pressure differential counter value to a maximum pressure differential counter threshold increase the maximum pressure differential counter value by one in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations after increasing the maximum pressure differential counter value. Connors acts “after a specific number of failed attempts” ([0069]) but does not expressly describe comparing a stored counter to a threshold, incrementing it, or the order of those steps. Disclosure by Rains Rains discloses: compare a maximum pressure differential counter value to a maximum pressure differential counter threshold See at least: “Retry component 226 may, for instance, include a retry counter” … “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: Rains' controller for a seed-metering drive ([0031]) compares a retry counter to a predetermined number of attempts each time a fault persists. This expressly discloses comparing a counter value to a counter threshold. In the combination, the counted event is the maximum-pressure checkpoint identified above, which makes the counter a maximum pressure differential counter. increase the maximum pressure differential counter value by one See at least: “If retry component 226 determines that the momentary motor reversal should be tried, then it increments the retry counter” ([0040]) Rationale: Rains expressly discloses incrementing a retry counter for each permitted attempt. A skilled person would understand this attempt-counting implementation to add one per attempt; at minimum, adding one per counted event is a straightforward implementation. in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and See at least: “it is only desirable to attempt to automatically resolve the jam a pre-determined number of times” ([0040]) Rationale: Rains increments the counter and retries only when the counter has not yet reached the predetermined number, i.e., in response to the counter being below the threshold. Expressly disclosed. after increasing the maximum pressure differential counter value. See at least: “and then again attempts to drive it in the forward direction, and processing reverts to block 242.” ([0041]) Rationale: Rains increments the counter at block 258 and then performs the corrective retry, after which processing returns to receiving sensor signals (block 242) for re-evaluation of whether a jam exists (block 252) ([0040]–[0041]). Rains thus expressly discloses performing the next corrective attempt after increasing the counter. In the combination, that corrective attempt is the return to the descending operations addressed below. Motivation to Combine Connors and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Rains before them, to implement Connors' failed-attempt monitoring with Rains' retry counter (compare the stored count to a predetermined number of attempts, increment it when below that number, then retry) and to apply that counter to the combined controller's maximum-pressure checkpoint. Both references address automatic recovery of a seed-metering system that is not metering correctly, and both limit automatic recovery to a set number of attempts before involving the operator (Connors [0069]; Rains [0040], [0043]–[0044]). Rains explains that “it is only desirable to attempt to automatically resolve the jam a pre-determined number of times” (Rains [0040]). The maximum-pressure encounter is a natural checkpoint for that count: finding the differential at or above the maximum while the flow rate remains out of range means the upward correction available at that limit has not restored the target, whether the controller stepped up to the maximum or was already there. Counting those encounters with Rains' counter, and retrying while below the limit, limits how many further descending attempts the combined controller makes before escalating. Using Rains' known retry-management technique in Connors' similar seed-meter controller yields predictable results (KSR; MPEP 2143(I)(C), (D)). Selecting the maximum-pressure encounter as the counted event is the identified adaptation; neither reference expressly names it. The count is of maximum-pressure determinations, each authorizing another descending attempt, not necessarily of completed unsuccessful search cycles. Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Rains After combining the teachings of Connors and Rains, the following claim limitation is not explicitly disclosed: return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations Disclosure by Schoeny Schoeny discloses: return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations See at least: “In some embodiments, the controller may repeat the calibration cycles any number of times to determine more accurate ranges. Additionally or alternatively, in some embodiments, the controller may perform one or more reverse calibration cycles to better account for hysteresis effects in which the controller may iteratively decrease the vacuum pressure and/or aggressiveness of the singulator.” ([0030]) Rationale: Schoeny repeats its reverse cycle, which begins above the previously determined maximum acceptable vacuum and descends toward the minimum ([0030], [0079]). Schoeny thus expressly teaches repeating the descending cycle with performance evaluation. Schoeny's descent evaluates performance to find the lower bound; it does not compare the current vacuum to an established minimum. That comparison is Czapka's minimum vacuum pressure, observed as adapted in Claim 1, and returning to it after the counter operation is an operation of the combined controller. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to return the combined controller, after updating the counter, to the minimum-bounded descending operations of Claim 1. Rains performs the corrective action after incrementing its counter (Rains [0041]). In the combined controller, the corrective action available at the maximum is Schoeny's reverse, descending search (Schoeny [0030], [0079]) bounded by Czapka's minimum vacuum (Czapka [0045]). Updating the counter before returning preserves the count for the next maximum-threshold comparison and permits escalation when that comparison finds the counter equal to its threshold. The result is predictable (KSR; MPEP 2143(I)(A)). Claim 6 Regarding Claim 6, The combination of Connors, Czapka, Schoeny, and Rains establishes the system of Claim 5, which is the basis for Claim 6. Disclosure by Connors Connors discloses: is configured to perform a third set of operations, comprising: See at least: “Accordingly, the control unit 42 may notify the operator using an auditory alarm, an indicator light, a displayed message, or the like.” ([0073]) Rationale: Operator notification is a set of operations distinct from vacuum adjustment, and control unit 42 is expressly configured to perform it. outputting a signal to a user interface indicative of instructions to correct the agricultural product flow rate; See at least: “For example, if several attempts are made to alleviate the abnormal operation by supplying opposite vacuum pressure, the control unit 42 may determine that operator maintenance is desired.” ([0073]) Rationale: A displayed message that meter maintenance is desired is a signal to a user interface instructing the operator to act on the meter so as to restore correct seed output. Express as to the signal and interface; PHOSITA-obvious as to stating the corrective instruction. Performing it in response to the claimed counter condition is addressed below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: wherein the controller, in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, terminating operation of the metering system; or a combination thereof. Connors stops seed output while supplying opposite pressure ([0070]) and notifies the operator after several attempts ([0073]), but not in response to the Claim 5 counter. Disclosure by Rains Rains discloses: wherein the controller, in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, See at least: “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: When the fault persists, Rains returns to this check ([0041], “processing will continue to block 258”). When no further retry is permitted under the predetermined number, Rains stops retrying and shuts down and notifies instead ([0043]–[0044]). A skilled person would understand that condition to be met when the count reaches the predetermined number, i.e., equals the counter threshold. Applied to the Claim 5 counter, the combination establishes the claimed trigger. terminating operation of the metering system; See at least: “motor controller 224 can shut down the motor driving the jammed system. This can be done in an attempt to avoid damaging the motor or other equipment in the jammed system.” ([0043]) Rationale: Rains' motor drives the seed-metering system ([0031], “the motor that drives rotation of the metering system 114”), so shutting it down terminates operation of the metering system. Expressly disclosed. or a combination thereof. See at least: “motor controller 224 can shut down the motor driving the jammed system.” ([0043]) Rationale: Rains supplies the termination alternative. Because the operations are recited disjunctively, that alternative is sufficient once the inherited counter trigger is established through the combination. The hopper-level alternative is not relied on, and the user-interface alternative mapped to Connors above is an additional basis only; Rains' generic notification is not relied on as a corrective instruction. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to shut down the metering system and/or display a corrective message to the operator when the Claim 5 counter equals its threshold, as Rains does when its retry counter reaches the predetermined number. Rains shuts down the motor “in an attempt to avoid damaging the motor or other equipment” and notifies the operator so that the operator can “take any desired corrective action” (Rains [0043]–[0044]). Connors likewise escalates to the operator after a set number of failed attempts (Connors [0069], [0073]). Stopping a meter that automatic correction cannot bring back to target, and telling the operator, predictably improves safety and reliability (KSR; MPEP 2143(I)(A)). Claim 7 Regarding Claim 7, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 1, which is the basis for Claim 7. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: wherein the controller is configured to determine the maximum threshold fluid pressure differential, the minimum threshold fluid pressure differential, or a combination thereof, via machine learning. Czapka's maximum and minimum vacuum pressures are operator inputs (Czapka [0045]), so Czapka does not supply these limitations either. Disclosure by Schoeny Schoeny discloses: wherein the controller is configured to determine the maximum threshold fluid pressure differential, the minimum threshold fluid pressure differential, or a combination thereof, See at least: “As a result of the above-described calibration routine 300, the controller 202 may define a target range of vacuum pressures, from the minimum acceptable vacuum pressure to the maximum acceptable vacuum pressure, in which the number of skips and multiples are within expectations.” ([0081]) Rationale: Schoeny's controller determines a minimum acceptable vacuum pressure and a maximum acceptable vacuum pressure for the meter from sensed performance. For this dependent claim, the combined controller's operating thresholds would be determined from Schoeny's performance-based range, using the modeling adaptation explained below, rather than relying solely on the operator-selected values (Czapka [0045]) discussed for Claim 1. Schoeny expressly discloses a controller that determines minimum and maximum vacuum values; the machine-learning determination is addressed below. via machine learning. See at least: “For example, the controller 202 may generate a mathematical relationship between the vacuum pressure and singulator aggressiveness setting using one or more techniques, such as linear regression, polynomial regression, logistic regression, Bayesian inference, K-nearest neighbor, fuzzy classification, and/or the like. Thereafter, in some embodiments, the controller 202 may display, such as via the user interface 220, the determined relationship(s) and/or one or more acceptable combinations of vacuum pressure and singulator aggressiveness corresponding to the determined relationship(s) to an operator.” ([0152]) Rationale: Schoeny fits models (for example, Bayesian inference, K-nearest neighbor and logistic regression) to recorded skip and multiple data, which a PHOSITA would recognize as machine learning under the broadest reasonable interpretation. Schoeny directs that modeling to the relationship between vacuum and singulator settings and to identifying acceptable combinations, not to the operating thresholds themselves. Separately, Schoeny uses its categorized results to “suggest, for the seed type, … a target range for the vacuum pressure” ([0151]), whose endpoints correspond to minimum and maximum vacuum thresholds. Using the acceptable settings identified by the [0152] models to set the [0151] range, and then using that range's endpoints as the controller's thresholds, would have been obvious to a PHOSITA. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to have the combined controller determine its maximum and/or minimum threshold differentials from sensed performance data using machine-learning techniques such as regression, Bayesian inference or K-nearest neighbor, as taught by Schoeny, rather than relying solely on operator-entered values as in Czapka. Schoeny explains that recommended vacuum ranges “may not be ideal” because of “slight variations between seed meters of the same model or variations in seed lots” (Schoeny [0003]). Data-derived thresholds fit to the actual meter and seed improve metering accuracy and reduce skips and multiples, a predictable improvement from applying known analysis techniques to the same data (KSR; MPEP 2143(I)(C), (D)). Claim 8 Regarding Claim 8, Disclosure by Connors Connors discloses: A metering system for an agricultural planter row unit, comprising: See at least: “To facilitate depositing seeds, the row unit 20 includes a furrow opener disc 24, an opener shoe 26, a closing disc 28, a seed hopper 30, a seed meter 32, a seed tube 34, a press wheel 36, and an auxiliary hopper 38.” ([0027]) Rationale: Seed meter 32, its direct vacuum source 68 and control unit 42 together form a metering system for row unit 20 of a planter. The limitation is expressly disclosed. a metering device configured to meter agricultural product through the agricultural planter row unit; See at least: “Generally, seed meters utilize vacuum pressure to attach seeds to a rotating seed disc, which controls the rate at which seeds are output by the seed meter.” ([0020]) Rationale: Seed disc 48 controls the rate at which seeds, an agricultural product, are output to seed tube 34 and the furrow. It is expressly a metering device that meters agricultural product through the row unit. a housing containing the metering device; See at least: “As depicted, the seed meter 32 includes a housing 46, a seed disc 48, an agitator 50, a seed baffle 52, a singulator 54, a vacuum port 56, a seed output port 58, and a seed input port 60. More specifically, the seed disc 48 may divide the seed meter between a seed chamber 62 and a vacuum chamber 64.” ([0031]) Rationale: Housing 46 encloses seed disc 48, which divides the housing interior into chambers 62 and 64. The housing expressly contains the metering device. an electrically-driven fluid pump See at least: “Thus, any suitable type of fan 72 that can generate vacuum pressure may be utilized, such as an electric fan, a gear drive fan, a hydraulic fan, or the like.” ([0046]) Rationale: Fan 72 moves air to generate a pressure differential, so it is a fluid pump. The expressly listed electric fan is an electrically-driven fluid pump (MPEP 2123). fluidly coupled to the housing See at least: “As depicted in FIG. 4A, the direct vacuum source 68A includes a housing 70 and a fan 72. In the depicted embodiment, the housing 70 is coaxial with and extends outwardly from the vacuum port 56. Thus, in some embodiments, the housing 70 may be molded with the seed meter housing 46.” ([0038]) Rationale: Fan 72 sits in housing 70 on the meter's vacuum port 56, so air flows directly between the fan and meter housing 46. The pump is expressly fluidly coupled to the housing. and configured to establish a fluid pressure differential between opposite sides of the metering device; See at least: “More specifically, the fan 72 may create a negative pressure in the vacuum chamber 64 by blowing air out of the seed meter 32 and a positive pressure in the vacuum chamber 64 by drawing air into the seed meter 32.” ([0042]) Rationale: Vacuum chamber 64 lies on one side of seed disc 48 and seed chamber 62 on the other ([0031]). By lowering pressure in chamber 64, fan 72 establishes a pressure differential across the disc. Connors defines its vacuum pressure as such a differential ([0020]). The limitation is expressly disclosed. a flow sensor configured to output a sensor signal indicative of an agricultural product flow rate through the agricultural planter row unit; and See at least: “As such, in some embodiments, a sensor may be included in the singulator 54 or in the seed tube 34 to determine when a seed is being output and/or the number of seeds being out.” ([0034]) Rationale: The sensor detects seeds passing through the singulator or seed tube and “may output a signal indicative of the number of seeds output from the seed meter 32” ([0057]). A count of seeds output per expected seed interval indicates seeds per unit time, i.e., a flow rate, and Connors frames meter output as “the desired seed output rate” ([0047]). The sensor is therefore a flow sensor outputting a signal indicative of product flow rate, expressly or at minimum implicitly. a controller communicatively coupled to the electrically-driven fluid pump and to the flow sensor, See at least: “More specifically, the operation (e.g., speed, blade pitch and/or direction) of the fan 72 may be controlled by the control unit 42.” ([0045]); “a sensor, located in the singulator 54 or in the seed tube, may communicate with the control unit 42 when seeds are output from the seed meter 32.” ([0053]) Rationale: Control unit 42 commands fan 72 and receives communications from the seed sensor. It is expressly communicatively coupled to both the pump and the flow sensor. wherein the controller comprises a memory and a processor, See at least: “As depicted, the control unit 42 includes a processor 44 and memory 46.” ([0030]) Rationale: Expressly disclosed. and the controller is configured to: See at least: “In some embodiments, process 74 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as memory 46, and executable by processing circuitry, such as processor 44.” ([0050]) Rationale: Control unit 42 is expressly programmed to perform the operations of process 74. iteratively perform a first set of operations, comprising: See at least: “In either case, the seed meter 32 may continue operation with the increased vacuum pressure (arrow 86).” ([0056]) Rationale: Blocks 76–80 of process 74 (operate, detect skip, increase vacuum) form a first set of operations, which arrow 86 repeats. They are expressly performed iteratively. receiving the sensor signal from the flow sensor; See at least: “More specifically, as discussed above, the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: Control unit 42 expressly receives the flow sensor's signal. after receiving the sensor signal; See at least: “Additionally, the control unit 42 may determine when a seed is expected to be output by the seed meter 32.” ([0053]) Rationale: Control unit 42 evaluates actual output against expected output once the sensor has reported. Evaluation after receiving the signal is expressly disclosed. returning to receiving the sensor signal See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: The sensor is polled again for each expected seed, so process 74 expressly returns to receiving the signal. comparing the fluid pressure differential See at least: “when skips continue to occur even after the vacuum pressure is increased above a threshold amount, which may be a predetermined vacuum pressure that is sufficient to attach a certain seed type to the seed disc openings 66 …” ([0065]) Rationale: Determining whether the vacuum pressure has been increased above a threshold amount is a comparison of the fluid pressure differential against a stored value. The comparison is expressly disclosed; the threshold's identity as a maximum is addressed below. increasing the fluid pressure differential, See at least: “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: Expressly disclosed. via the electrically-driven fluid pump, See at least: “For example, to increase the vacuum pressure, the speed of the fan 72 may be increased, and to decrease the vacuum pressure, the speed of the fan 72 may be decreased.” ([0043]) Rationale: The increase is made by fan 72, the electric fan of [0046]. Expressly disclosed. iteratively perform a second set of operations, See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Blocks 82–84 (detect multiple, decrease vacuum) form a second set, which arrow 86 repeats. They are expressly performed iteratively. separate from the first set of operations, See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82).” ([0057]) Rationale: The multiple branch is a distinct decision path from the skip branch. Expressly separate. wherein the second set of operations comprises: See at least: “Similar to increasing the vacuum pressure, the control unit 42 may instruct the fan 72 to make an incremental decrease in vacuum pressure, which may be predefined and stored in the memory 46.” ([0059]) Rationale: Connors expressly identifies the operations of its decrease branch. decreasing the fluid pressure differential, See at least: “When a multiple is detected, the control unit 42 may instruct the direct vacuum source 68 to decrease the supplied vacuum pressure (process block 84).” ([0058]) Rationale: Expressly disclosed. via the electrically-driven fluid pump, See at least: “More specifically, the control unit 42 may instruct the fan 72 to displace a smaller volume of air, for example, by rotating at a lower speed and/or changing fan blade pitch.” ([0058]) Rationale: The decrease is made by the same electric fan 72. Expressly disclosed. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: comparing the agricultural product flow rate to a target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; to a maximum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka discloses: comparing the agricultural product flow rate to a target agricultural product flow rate range See at least: “the planter controller 104 may be configured to monitor the current seed distribution for the relevant row unit(s) 28 (e.g., via the seed sensor(s) 84) and compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: Czapka's seed sensor gives “an indication of the output rate of the seed meter 78” ([0048]), and ground speed is sent to the planter controller ([0044]). A population range at the travel speed corresponds to an output-rate range, so comparing population to its range is comparing the product flow rate to a target range. The range comparison is express; the flow-rate framing is PHOSITA-obvious. in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]) Rationale: When output meets its target, Czapka makes no vacuum change and returns to sensing at step 412 ([0071]). Expressly taught. to a maximum threshold fluid pressure differential See at least: “suitable operator inputs may include, but are not limited to, … maximum and minimum vacuum pressures for the seed meter 78 …” ([0045]) Rationale: Czapka's maximum vacuum pressure for the seed meter is a maximum threshold fluid pressure differential. Expressly disclosed. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Czapka enters its vacuum-adjustment logic only when output is off target. Implementing its maximum vacuum ([0045]) by comparing the current vacuum to that maximum when an off-target output calls for a change would have been an obvious controller design, applying the general threshold-comparison practice Czapka uses for down force ([0072]). Czapka is not relied on for the identical conditional relationship claimed. in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and See at least: “Similarly, if the current seed population is too low, the planter controller 104 may, at (424), increase the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Conditioning the increase on the differential being below the maximum would have been an obvious way to observe Czapka's maximum ([0045]), applying Czapka's threshold-comparison approach ([0072]) to the vacuum setting. comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28.” ([0072]) Rationale: Czapka compares a row-unit actuator setting to its minimum threshold to decide whether to increase it ([0072]), and supplies a minimum vacuum pressure ([0045]). Applying that threshold-comparison approach to the vacuum, here to decide whether to permit a further decrease, is PHOSITA-obvious. Czapka is relied on for the general practice, not the identical conditional relationship. in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. See at least: “If the current seed population is too high, the planter controller 104 may, at (422), reduce the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Applying Czapka's threshold-comparison approach to its minimum vacuum setting ([0045], [0072]) would permit the controller to continue reducing vacuum while the differential exceeds the minimum and to inhibit further reduction at the minimum. Connors explains that too little vacuum causes skips (Connors [0035]). Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to modify Connors' control unit 42 to compare the sensed seed output rate to a target range and to bound its fan-driven vacuum adjustments between maximum and minimum vacuum pressures, as taught by Czapka. Both references control a row-unit vacuum source from a seed sensor to reduce skips and multiples, and Czapka controls vacuum “to regulate the rate at which the seeds are expelled from the meter 78 into the seed tube 82” (Czapka [0046]). Range-based feedback stabilizes control. Vacuum bounds keep the meter within the window between skips and multiples that Connors describes (Connors [0035]). Applying this known technique to Connors' similar device yields predictable results (KSR; MPEP 2143(I)(C), (D)). Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly disclosed: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, Disclosure by Schoeny Schoeny discloses: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, See at least: “in the case of a reverse vacuum calibration cycle following the determination of the maximum acceptable vacuum pressure (e.g., at 320), the controller 202 may increase the vacuum pressure by a given margin (e.g., 10% over the previously determined maximum acceptable vacuum pressure) and then iteratively decrease the vacuum pressure of the vacuum source 70 …” ([0079]) Rationale: Schoeny steps vacuum up to a maximum acceptable value and then, in a reverse calibration cycle beginning above that previously determined maximum, iteratively decreases it while re-assessing performance ([0075]–[0079]). Schoeny does not expressly disclose using this sequence during operation in response to an out-of-range flow rate, comparing the current differential to a maximum threshold as the trigger for the descent, or using Czapka's operator-selected maximum (Czapka [0045]) in place of its experimentally determined “maximum acceptable” value. Configuring the combined controller to begin the descending operations upon determining that the differential has reached or exceeded the established maximum threshold, and using that sequence during operation, is the modification explained in the motivation below. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to configure the combined controller to respond to an out-of-range flow rate with a bounded search of the vacuum window. In that search the controller increases the differential while it is below the maximum threshold and, upon determining that the differential has reached or exceeded the maximum, switches to iteratively decreasing it while it remains above the minimum threshold, rather than choosing a single direction from the type of error. Motivation for the modification. Connors and Czapka choose the direction of correction from the type of error (Connors [0054], [0058]; Czapka [0067]). An off-target flow rate, however, is an aggregate measure that does not by itself show which direction of vacuum change will correct it. Connors recognizes output containing “a mixture of multiples and skips” (Connors [0065]); Connors attributes that condition to clumping and does not itself suggest a pressure search, so it is cited only to show that aggregate output can combine both error types. Schoeny supplies the reason to search: recommended vacuum ranges “may not be ideal” (Schoeny [0003]), and Schoeny locates an acceptable setting by stepping through the bounded range upward and then downward, re-assessing performance at each step (Schoeny [0075]–[0081]). Adapting that search for use in place of the direction-selected correction, when the needed direction is uncertain, yields predictable results (KSR; MPEP 2143(I)(B), (G)). Schoeny's search was known as a calibration routine; its operating trigger, its transition at an established maximum threshold, and its operator-selected bounds are the modifications identified above, so the complete operational strategy is not asserted to have been known in that precise form. It trades some speed of correction for a result that does not depend on first diagnosing the direction of the error. Reasonable expectation of success. Where the deviation can be corrected by vacuum, a stepped search from the current setting up to the maximum and then down toward the minimum traverses the selected window and would be expected to reach an acceptable setting at the resolution of its steps, as Schoeny's stepped search does (Schoeny [0079]–[0081]). Causes outside the vacuum, such as clumping or obstructions (Connors [0065]–[0066]), are handled by Connors' escalation after unsuccessful attempts (Connors [0069], [0073]; see Claims 12–13), so the rationale does not depend on the search succeeding in every circumstance. Feasibility. The modification uses Connors' existing seed sensor, control unit 42, and variable-speed electric fan (Connors [0043], [0046], [0053]–[0058]). Connors' repeated sensing after pressure adjustments (Connors [0056], [0060]) and Czapka's target-based feedback (Czapka [0067]–[0068]) support retaining output monitoring during the search. This shows that the search could be implemented; it is not relied on as the motivation for the search. Claim 9 Regarding Claim 9, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 8, which is the basis for Claim 9. Disclosure by Connors Connors discloses: wherein the second set of operations comprises receiving the sensor signal from the flow sensor See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: Polling the seed sensor is part of the multiple-detection branch (decision block 82) leading to the decrease at block 84. Receiving the flow sensor's signal is expressly an operation of Connors' second set. after decreasing the fluid pressure differential. See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: After each decrease, arrow 86 returns process 74 to operating the meter and polling the sensor at the lower vacuum. Receiving the signal after decreasing is expressly disclosed, and Schoeny likewise re-assesses after each iterative change (Schoeny [0070]). Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to receive the flow sensor signal after each decrease within the combined controller's second set of operations, for the reasons given for Claim 8. Sensing after each adjustment is how the controller learns whether the adjustment worked. Connors does so after every vacuum change (Connors [0060]), and Schoeny waits for the meter to reach “a steady state condition” before re-assessing (Schoeny [0070]). This predictably improves control accuracy (KSR; MPEP 2143(I)(A)). Claim 10 Regarding Claim 10, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 9, which is the basis for Claim 10. Disclosure by Connors Connors discloses: after receiving the sensor signal of the second set of operations; See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82). More specifically, as discussed above, the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: Within the multiple branch, control unit 42 evaluates output only after receiving the sensor signal. Expressly disclosed. returning to receiving the sensor signal of the second set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Arrow 86 returns the process to operating the meter and polling the sensor, through Connors' general skip/multiple decision sequence. Expressly disclosed as to returning to sensing; retaining the descending mode is addressed by the combination below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: The metering system of claim 9, wherein the second set of operations comprises: (as to the target range and minimum-threshold operations below) comparing the agricultural product flow rate to the target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. Disclosure by Czapka Czapka discloses: The metering system of claim 9, wherein the second set of operations comprises: See at least: “Following the increase or reduction in the vacuum pressure, the planter controller 104 may, at (426), determine whether the pressure adjustment resulted in an improvement to the monitored seed population.” ([0068]) Rationale: Czapka re-evaluates output after a vacuum reduction within the same adjustment routine, so the post-reduction operations belong to the decreasing set. Expressly disclosed. comparing the agricultural product flow rate to the target agricultural product flow rate range See at least: “compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: As explained for Claim 8, this is a comparison of the product flow rate to a target range. After a reduction, Czapka re-checks output against its target ([0068]). in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]) Rationale: When the re-checked output meets its target, Czapka returns to sensing at step 412 ([0071]). Expressly taught. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Czapka expressly evaluates output after each adjustment and returns to its population check if the adjustment improved the population; if not, it reduces ground speed and may restore the previous vacuum setting ([0068]). Continuing the descending vacuum search whenever output remains outside the target range, including when the preceding adjustment produced no improvement, is the proposed modification using Schoeny's reverse search, explained in the motivation below. Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to re-evaluate the sensed output rate against the target range after each decrease in Connors' second set of operations and to continue monitoring output while it remains within range, as Czapka evaluates output after each vacuum change and returns to sensing when output meets its target (Czapka [0067]–[0068], [0071]). Checking each adjustment against the target prevents over-correction and needless change, predictably improving control accuracy (KSR; MPEP 2143(I)(C)). Czapka does not continue vacuum adjustment in every off-target case; continuing the descending search whenever output remains out of range is addressed with Schoeny below. Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly disclosed: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential Disclosure by Schoeny Schoeny discloses: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential See at least: “Thereafter, the controller 202 may further iteratively decrease the vacuum pressure of the vacuum source 70 until the number of skips is greater than the predetermined allowable skips threshold and record the previous vacuum pressure of the vacuum source 70 (e.g., the vacuum pressure before the allowable skips threshold was exceeded) as a second minimum acceptable vacuum pressure.” ([0079]) Rationale: Schoeny takes repeated downward steps with performance evaluation after each, continuing through acceptable performance to locate the lower bound at which skips become excessive ([0079]), rather than comparing against an established minimum. Schoeny supplies the iterative downward adjustment; in the combined controller, Czapka's target-range evaluation governs whether adjustment continues or the controller returns to sensing without further adjustment. In the combination, the minimum is Czapka's minimum vacuum pressure, enforced by the comparison adapted in Claim 8, and returning to that comparison after an out-of-range result is how the combined controller continues Schoeny's repeated descent. Express as to the repeated descent; PHOSITA-obvious as to the stored minimum. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return to the minimum-threshold comparison whenever the re-checked output remains out of range, so the controller keeps stepping vacuum down only while it stays above the minimum. The modified controller retains its current search direction while it monitors acceptable output: within range, it keeps receiving the sensor signal within the second set without further adjustment; when the rate later falls outside the range, it resumes the descent at the minimum-threshold comparison rather than re-entering a direction-selected correction. This arrangement is attributed to the combination, not to Connors' return arrow alone: Schoeny continues its descending pass rather than reversing partway through (Schoeny [0079]), and Czapka supplies the target-range check (Czapka [0067]–[0068]). Continuing the descent when an adjustment produced no improvement, rather than following Czapka's ground-speed reduction, is part of the same modification, with persistent failure handled by escalation (see Claims 12–13). Schoeny teaches repeating downward steps until a performance limit is reached (Schoeny [0079]). Czapka supplies the minimum vacuum that bounds them (Czapka [0045]), and Connors explains that too little vacuum causes skips (Connors [0035]). The result is a predictable bounded search (KSR; MPEP 2143(I)(A)). Claim 11 Regarding Claim 11, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 8, which is the basis for Claim 11. Disclosure by Connors Connors discloses: wherein the second set of operations comprises returning to increasing the fluid pressure differential of the first set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]); “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: After the decrease branch, arrow 86 returns process 74 to the skip branch, where vacuum is increased at block 80. Expressly disclosed. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitation: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka discloses: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28. If the down force is not greater than the minimum down force threshold, the planter controller 104 may, at (452), be configured to increase the current down force (e.g., by controlling the operation of the down force actuator 126).” ([0072]) Rationale: Czapka increases a row-unit actuator setting in response to determining it is not greater than (i.e., is less than or equal to) its minimum threshold, and supplies a minimum vacuum pressure ([0045]). Applying the same test to the vacuum and responding by increasing it is a PHOSITA-obvious use of Czapka's own control logic. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return from the decreasing operations to the increasing operations when the differential reaches or falls below the minimum threshold. Connors teaches that insufficient vacuum causes skips (Connors [0035]), so at the floor the remaining vacuum correction is to raise it. Czapka teaches increasing an at-or-below-minimum actuator setting (Czapka [0072]). Schoeny repeats its vacuum cycles “any number of times” (Schoeny [0030]). Restarting the upward phase at the lower bound keeps the controller searching within the window, a predictable result (KSR; MPEP 2143(I)(A)). Claim 12 Regarding Claim 12, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 8, which is the basis for Claim 12. Disclosure by Connors Connors discloses: The metering system of claim 8, wherein the controller is configured to: See at least: “In some embodiments, the process 88 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as the memory 46, and executable by processing circuitry, such as the processor 44.” ([0062]) Rationale: Control unit 42 is expressly programmed to perform fault-handling operations of the kind mapped below. in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential; See at least: “when skips continue to occur even after the vacuum pressure is increased above a threshold amount, which may be a predetermined vacuum pressure that is sufficient to attach a certain seed type to the seed disc openings 66, the control unit 42 may determine that seed clumping is occurring in the seed chamber 62 and/or the seed input port 60.” ([0065]) Rationale: Connors treats vacuum having been raised past a threshold while skips persist as a checkpoint for further fault handling, and it monitors failed correction attempts ([0067], [0069]). Connors' threshold is a pressure sufficient to attach seeds, not the combined controller's maximum operating limit. Using the combined controller's at-or-above-maximum determination as the checkpoint that triggers the counter operations is the proposed modification explained in the motivation below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: compare a maximum pressure differential counter value to a maximum pressure differential counter threshold increase the maximum pressure differential counter value by one in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations after increasing the maximum pressure differential counter value. Disclosure by Rains Rains discloses: compare a maximum pressure differential counter value to a maximum pressure differential counter threshold See at least: “Retry component 226 may, for instance, include a retry counter” … “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: Rains' controller for a seed-metering drive ([0031]) compares a retry counter to a predetermined number of attempts each time a fault persists. Expressly disclosed; in the combination the counted event is the maximum-pressure checkpoint identified above. increase the maximum pressure differential counter value by one See at least: “If retry component 226 determines that the momentary motor reversal should be tried, then it increments the retry counter” ([0040]) Rationale: Rains expressly discloses incrementing a retry counter for each permitted attempt. A skilled person would understand this to add one per attempt; at minimum, adding one per counted event is a straightforward implementation. in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and See at least: “it is only desirable to attempt to automatically resolve the jam a pre-determined number of times” ([0040]) Rationale: Rains increments and retries only while the counter is below the predetermined number. Expressly disclosed. after increasing the maximum pressure differential counter value. See at least: “and then again attempts to drive it in the forward direction, and processing reverts to block 242.” ([0041]) Rationale: Rains performs the corrective retry after incrementing the counter, then returns to receiving sensor signals (block 242) for re-evaluation of whether a jam exists (block 252) ([0040]–[0041]). In the combination, that corrective attempt is the return to the descending operations addressed below. Motivation to Combine Connors and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Rains before them, to implement Connors' failed-attempt monitoring with Rains' retry counter and to apply that counter to the combined controller's maximum-pressure checkpoint. Both references address automatic recovery of a seed-metering system and limit it to a set number of attempts before involving the operator (Connors [0069]; Rains [0040], [0043]–[0044]), and Rains explains that “it is only desirable to attempt to automatically resolve the jam a pre-determined number of times” (Rains [0040]). Finding the differential at or above the maximum while the flow rate remains out of range means the upward correction available at that limit has not restored the target, which makes it a natural checkpoint to count. Counting those encounters and retrying while below the limit limits how many further descending attempts the controller makes before escalating at the limit, a predictable result (KSR; MPEP 2143(I)(C), (D)). Selecting the maximum-pressure encounter as the counted event is the identified adaptation; neither reference expressly names it. The count is of maximum-pressure determinations, each authorizing another descending attempt, not necessarily of completed unsuccessful search cycles. Claim Limitations Not Explicitly Disclosed by the Combination of Connors and Rains After combining the teachings of Connors and Rains, the following claim limitation is not explicitly disclosed: return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations Disclosure by Schoeny Schoeny discloses: return to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations See at least: “In some embodiments, the controller may repeat the calibration cycles any number of times to determine more accurate ranges. Additionally or alternatively, in some embodiments, the controller may perform one or more reverse calibration cycles to better account for hysteresis effects in which the controller may iteratively decrease the vacuum pressure and/or aggressiveness of the singulator.” ([0030]) Rationale: Schoeny expressly teaches repeating the descending cycle with performance evaluation ([0079]), but not a comparison of current vacuum to an established minimum. That comparison is Czapka's minimum vacuum pressure enforced as adapted in Claim 8, and returning to it after the counter operation is an operation of the combined controller. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to return the combined controller, after updating the counter, to the minimum-bounded descending operations of Claim 8. Rains performs the corrective action after incrementing its counter (Rains [0041]); in the combined controller that action is Schoeny's reverse, descending search (Schoeny [0030], [0079]) bounded by Czapka's minimum vacuum (Czapka [0045]). Updating the counter before returning preserves the count for the next maximum-threshold comparison and permits escalation when that comparison finds the counter equal to its threshold (KSR; MPEP 2143(I)(A)). Claim 13 Regarding Claim 13, The combination of Connors, Czapka, Schoeny, and Rains establishes the system of Claim 12, which is the basis for Claim 13. Disclosure by Connors Connors discloses: is configured to perform a third set of operations, comprising: See at least: “Accordingly, the control unit 42 may notify the operator using an auditory alarm, an indicator light, a displayed message, or the like.” ([0073]) Rationale: Operator notification is a set of operations distinct from vacuum adjustment. Expressly disclosed. outputting a signal to a user interface indicative of instructions to correct the agricultural product flow rate; See at least: “For example, if several attempts are made to alleviate the abnormal operation by supplying opposite vacuum pressure, the control unit 42 may determine that operator maintenance is desired.” ([0073]) Rationale: A displayed message that meter maintenance is desired instructs the operator to act on the meter to restore correct seed output. Express as to the signal and interface; PHOSITA-obvious as to the corrective instruction. The claimed counter trigger is addressed below. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: wherein the controller, in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, terminating operation of the metering system; or a combination thereof. Disclosure by Rains Rains discloses: wherein the controller, in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, See at least: “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: When the fault persists, Rains returns to this check ([0041]); when no further retry is permitted, it shuts down and notifies instead of retrying ([0043]–[0044]). A skilled person would understand that condition to be met when the count equals the predetermined number. Applied to the Claim 12 counter, the combination establishes the claimed trigger. terminating operation of the metering system; See at least: “motor controller 224 can shut down the motor driving the jammed system. This can be done in an attempt to avoid damaging the motor or other equipment in the jammed system.” ([0043]) Rationale: The motor drives the seed-metering system ([0031]), so shutting it down terminates operation of the metering system. Expressly disclosed. or a combination thereof. See at least: “motor controller 224 can shut down the motor driving the jammed system.” ([0043]) Rationale: Rains supplies the termination alternative. Because the operations are recited disjunctively, that alternative is sufficient once the inherited counter trigger is established through the combination. The hopper-level alternative is not relied on, and the user-interface alternative mapped to Connors above is an additional basis only. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to shut down the metering system and/or display a corrective message when the Claim 12 counter equals its threshold, as Rains does when its retry counter reaches the predetermined number “in an attempt to avoid damaging the motor or other equipment” and so the operator can “take any desired corrective action” (Rains [0043]–[0044]). Connors likewise escalates to the operator after a set number of failed attempts (Connors [0069], [0073]). This predictably improves safety and reliability (KSR; MPEP 2143(I)(A)). Claim 14 Regarding Claim 14, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 8, which is the basis for Claim 14. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: wherein the controller is configured to determine the maximum threshold fluid pressure differential, the minimum threshold fluid pressure differential, or a combination thereof, via machine learning. Czapka's maximum and minimum vacuum pressures are operator inputs (Czapka [0045]), so Czapka does not supply these limitations either. Disclosure by Schoeny Schoeny discloses: wherein the controller is configured to determine the maximum threshold fluid pressure differential, the minimum threshold fluid pressure differential, or a combination thereof, See at least: “As a result of the above-described calibration routine 300, the controller 202 may define a target range of vacuum pressures, from the minimum acceptable vacuum pressure to the maximum acceptable vacuum pressure, in which the number of skips and multiples are within expectations.” ([0081]) Rationale: Schoeny's controller determines minimum and maximum acceptable vacuum pressures from sensed performance. For this dependent claim, the combined controller's operating thresholds would be determined from Schoeny's performance-based range, using the modeling adaptation explained below, rather than relying solely on the operator-selected values (Czapka [0045]) discussed for Claim 8. Schoeny expressly discloses a controller that determines minimum and maximum vacuum values; the machine-learning determination is addressed below. via machine learning. See at least: “For example, the controller 202 may generate a mathematical relationship between the vacuum pressure and singulator aggressiveness setting using one or more techniques, such as linear regression, polynomial regression, logistic regression, Bayesian inference, K-nearest neighbor, fuzzy classification, and/or the like.” ([0152]) Rationale: Schoeny fits models (e.g., Bayesian inference, K-nearest neighbor, logistic regression) to recorded skip/multiple data, which a PHOSITA would recognize as machine learning under the broadest reasonable interpretation. The models address the vacuum/singulator relationship rather than the thresholds themselves. Schoeny also suggests “a target range for the vacuum pressure” from its results ([0151]); using the model-identified acceptable settings to set that range, and its endpoints as the thresholds, would have been obvious to a PHOSITA. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to have the combined controller determine its maximum and/or minimum threshold differentials from sensed performance data using regression, Bayesian inference or K-nearest neighbor, as taught by Schoeny, rather than relying solely on operator-entered values as in Czapka. Schoeny explains that recommended vacuum ranges “may not be ideal” because of “slight variations between seed meters of the same model or variations in seed lots” (Schoeny [0003]). Data-derived thresholds fit the actual meter and seed and predictably improve metering accuracy (KSR; MPEP 2143(I)(C), (D)). Claim 15 Regarding Claim 15, The combination of Connors, Czapka, and Schoeny establishes the system of Claim 8, which is the basis for Claim 15. Claim Limitations Not Explicitly Disclosed by Connors Connors does not explicitly disclose the following claim limitations: a pressure sensor fluidly coupled to the housing and communicatively coupled to the controller, wherein the pressure sensor is configured to output a third sensor signal indicative of the fluid pressure differential. Czapka's pressure sensors 128 monitor down-force actuator fluid (Czapka [0047]), and Schoeny shows no pressure sensor on the meter; neither supplies these limitations. Disclosure by Wang Wang discloses: a pressure sensor See at least: “The vacuum sensor 86 can be any desired pressure differential sensor, such as a pressure transducer.” ([0027]) Rationale: Vacuum sensor 86, a pressure differential sensor or pressure transducer, is expressly a pressure sensor. fluidly coupled to the housing See at least: “In a further embodiment, the seed metering system 50 may also include a vacuum sensor 86 which is fluidly coupled to the vacuum port 80 of the seed meter 58, by way of the vacuum duct 82.” ([0027]) Rationale: Vacuum port 80 is part of seed meter 58, which includes “a housing 76, a seed disc with perforations … pressure and vacuum chambers on a respective side of the seed disc … and a vacuum port 80 fluidly coupled to the vacuum chamber” ([0025]). A sensor fluidly coupled to that port is expressly fluidly coupled to the meter housing. and communicatively coupled to the controller, See at least: “The seed metering system 50 may further include a control unit 88 operably coupled to the vacuum fan 60 and to the vacuum sensor 86.” ([0028]) Rationale: Control unit 88 is coupled to sensor 86 and acts on “a pressure signal from the vacuum sensor 86” ([0028]), so the sensor is expressly communicatively coupled to the controller. wherein the pressure sensor is configured to output a third sensor signal indicative of the fluid pressure differential. See at least: “The control unit 88 may shut off or turn on the vacuum fan(s) 60, increase or decrease the speed of the vacuum fan(s) 60, alter the pitch of the fan blades, and/or change the direction of rotation of the vacuum fan(s) 60 based upon preprogramed software, a GPS signal, an operator command, and/or a pressure signal from the vacuum sensor 86.” ([0028]) Rationale: Sensor 86 outputs a pressure signal from the meter's vacuum chamber, and it may be a “pressure differential sensor” ([0027]). Placed on Connors' meter, whose seed chamber is fed from the hopper and whose “vacuum pressure” is defined as “a pressure differential from atmospheric pressure” (Connors [0020]), that signal indicates the differential across seed disc 48. Identified by its source and informational content, that pressure signal corresponds to the claimed signal designated “third.” Expressly disclosed as to the pressure signal, and PHOSITA-obvious as to its indicating the differential across the metering device in Connors' meter. Motivation to Combine Connors, Czapka, Schoeny, and Wang Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Wang before them, to add Wang's vacuum sensor 86, fluidly coupled to the meter's vacuum port and communicatively coupled to the controller, to the combined metering system so that the controller measures the actual differential it compares to the maximum and minimum thresholds. The combined controller of Claim 8 must know the current differential to perform those comparisons, and Wang teaches obtaining it from a sensor on the meter's vacuum port and controlling a per-row fan from “a pressure signal from the vacuum sensor 86” (Wang [0028]). Like Connors, Wang gives each row its own fan so that “the vacuum pressure for each seed meter can be individually controlled” (Wang [0009]). Closed-loop measurement predictably improves the accuracy of the threshold comparisons over relying on commanded fan speed alone (KSR; MPEP 2143(I)(A), (C)). Claim 16 Regarding Claim 16, Disclosure by Connors Connors teaches: A method for operating a metering system of an agricultural planter row unit, comprising: See at least: “Generally the process 74 includes operating the seed meter (process block 76), determining whether a skip is detected (decision block 78), when a skip is detected, increasing vacuum pressure (process block 80), determining whether a multiple is detected (decision block 82), and when a multiple is detected, decreasing vacuum pressure (process block 84).” ([0050]) Rationale: Process 74 is a method of operating seed meter 32 of row unit 20, together with its direct vacuum source and control unit. It is expressly a method for operating a metering system of an agricultural planter row unit. iteratively performing a first set of operations See at least: “In either case, the seed meter 32 may continue operation with the increased vacuum pressure (arrow 86).” ([0056]) Rationale: Blocks 76–80 form a first set of operations, which arrow 86 repeats. Expressly taught. via a controller comprising a memory and a processor, comprising: See at least: “In some embodiments, process 74 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as memory 46, and executable by processing circuitry, such as processor 44.” ([0050]) Rationale: Process 74 is performed by control unit 42, which includes processor 44 and memory 46 ([0030]). Expressly taught. receiving a sensor signal indicative of an agricultural product flow rate through the agricultural planter row unit; See at least: “the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: The sensor sits in the singulator or seed tube ([0053]) and signals the number of seeds output per expected seed interval, i.e., seeds per unit time. That is a flow rate of agricultural product through the row unit; Connors itself refers to “the desired seed output rate” ([0047]). Expressly, or at minimum implicitly, taught. after receiving the sensor signal indicative of the agricultural product flow rate through the agricultural planter row unit; See at least: “a sensor, located in the singulator 54 or in the seed tube, may communicate with the control unit 42 when seeds are output from the seed meter 32. Additionally, the control unit 42 may determine when a seed is expected to be output by the seed meter 32.” ([0053]) Rationale: Control unit 42 evaluates output after the sensor reports. Expressly taught. returning to receiving the sensor signal indicative of the agricultural product flow rate See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: The sensor is polled again for every expected seed, so the method returns to receiving the signal. Expressly taught. comparing a fluid pressure differential between opposite sides of a metering device of the metering system See at least: “As used herein, ‘vacuum pressure’ is intended to describe a pressure differential from atmospheric pressure and not necessarily a true vacuum.” ([0020]); “when skips continue to occur even after the vacuum pressure is increased above a threshold amount …” ([0065]) Rationale: Seed disc 48 separates seed chamber 62 from vacuum chamber 64 ([0031]). Connors' vacuum pressure is the differential across it, and Connors determines whether that pressure has been increased above a threshold amount. The comparison is expressly taught; the threshold's identity as a maximum is addressed below. increasing the fluid pressure differential, See at least: “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: Expressly taught. via an electrically-driven fluid pump of the metering system, See at least: “Thus, any suitable type of fan 72 that can generate vacuum pressure may be utilized, such as an electric fan, a gear drive fan, a hydraulic fan, or the like.” ([0046]) Rationale: Fan 72 of the meter's direct vacuum source is a fluid pump; the expressly listed electric fan is electrically driven, and its speed is raised to increase vacuum ([0043]). Expressly taught (MPEP 2123). iteratively performing a second set of operations, See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Blocks 82–84 form a second set, which arrow 86 repeats. Expressly taught. separate from the first set of operations, See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82).” ([0057]) Rationale: The multiple branch is a distinct decision path. Expressly separate. via the controller, See at least: “When a multiple is detected, the control unit 42 may instruct the direct vacuum source 68 to decrease the supplied vacuum pressure (process block 84).” ([0058]) Rationale: Control unit 42 performs the second set. Expressly taught. wherein the second set of operations comprises: See at least: “Similar to increasing the vacuum pressure, the control unit 42 may instruct the fan 72 to make an incremental decrease in vacuum pressure, which may be predefined and stored in the memory 46.” ([0059]) Rationale: Connors expressly identifies the operations of its decrease branch. decreasing the fluid pressure differential, See at least: “More specifically, the control unit 42 may instruct the fan 72 to displace a smaller volume of air, for example, by rotating at a lower speed and/or changing fan blade pitch.” ([0058]) Rationale: Displacing less air lowers the vacuum, i.e., the differential. Expressly taught. via the electrically-driven fluid pump of the metering system, See at least: “to decrease the vacuum pressure, the speed of the fan 72 may be decreased.” ([0043]) Rationale: The same electric fan 72 performs the decrease. Expressly taught. Claim Limitations Not Explicitly Taught by Connors Connors does not explicitly teach the following claim limitations: comparing the agricultural product flow rate to a target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; to a maximum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka teaches: comparing the agricultural product flow rate to a target agricultural product flow rate range See at least: “the planter controller 104 may be configured to monitor the current seed distribution for the relevant row unit(s) 28 (e.g., via the seed sensor(s) 84) and compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: Czapka's seed sensor gives “an indication of the output rate of the seed meter 78” ([0048]) and ground speed reaches the planter controller ([0044]). A population range at the travel speed is an output-rate range. Express as to the range comparison; PHOSITA-obvious as to flow-rate units. in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]) Rationale: On-target output leads, without vacuum change, back to sensing at step 412 ([0071]). Expressly taught. to a maximum threshold fluid pressure differential See at least: “suitable operator inputs may include, but are not limited to, … maximum and minimum vacuum pressures for the seed meter 78 …” ([0045]) Rationale: The maximum vacuum pressure for the seed meter is a maximum threshold fluid pressure differential. Expressly taught. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range; and See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Off-target output triggers Czapka's vacuum logic. Implementing the maximum vacuum ([0045]) by checking the vacuum against it before raising it would have been an obvious controller design, applying the general threshold-comparison practice Czapka uses for down force ([0072]). Czapka is not relied on for the identical conditional relationship claimed. in response to determining the fluid pressure differential is less than the maximum threshold fluid pressure differential; and See at least: “Similarly, if the current seed population is too low, the planter controller 104 may, at (424), increase the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Conditioning the increase on the vacuum being below the maximum would have been an obvious way to observe Czapka's maximum ([0045]), applying its threshold-comparison approach ([0072]) to the vacuum setting. comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28.” ([0072]) Rationale: Applying Czapka's threshold-comparison approach ([0072]) to its minimum vacuum pressure ([0045]), here to decide whether to permit a further decrease rather than, as in Czapka, whether to increase down force, is PHOSITA-obvious. in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential. See at least: “If the current seed population is too high, the planter controller 104 may, at (422), reduce the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” ([0067]) Rationale: Applying Czapka's threshold-comparison approach to its minimum vacuum setting ([0045], [0072]) would permit the controller to continue reducing vacuum while it is above the minimum and to inhibit further reduction at the minimum. Connors explains that too little vacuum causes skips (Connors [0035]). Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to modify Connors' method so that control unit 42 compares the sensed seed output rate to a target range and bounds its fan-driven vacuum adjustments between maximum and minimum vacuum pressures, as taught by Czapka. Both references control a row-unit vacuum source from a seed sensor to reduce skips and multiples, and Czapka controls vacuum “to regulate the rate at which the seeds are expelled from the meter 78 into the seed tube 82” (Czapka [0046]). Range-based feedback stabilizes control. Vacuum bounds keep the meter within the window between skips and multiples (Connors [0035]). The result is predictable (KSR; MPEP 2143(I)(C), (D)). Claim Limitations Not Explicitly Taught by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly taught: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, Disclosure by Schoeny Schoeny teaches: in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, See at least: “in the case of a reverse vacuum calibration cycle following the determination of the maximum acceptable vacuum pressure (e.g., at 320), the controller 202 may increase the vacuum pressure by a given margin (e.g., 10% over the previously determined maximum acceptable vacuum pressure) and then iteratively decrease the vacuum pressure of the vacuum source 70 …” ([0079]) Rationale: Schoeny steps vacuum up to a maximum acceptable value and then, in a reverse calibration cycle beginning above that previously determined maximum, iteratively decreases it while re-assessing performance ([0075]–[0079]). Schoeny does not expressly disclose using this sequence during operation in response to an out-of-range flow rate, comparing the current differential to a maximum threshold as the trigger for the descent, or using Czapka's operator-selected maximum (Czapka [0045]) in place of its experimentally determined “maximum acceptable” value. Performing the descending steps of the combined method upon determining that the differential has reached or exceeded the established maximum threshold, and using that sequence during operation, is the modification explained in the motivation below. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to perform the combined method so that the controller responds to an out-of-range flow rate with a bounded search of the vacuum window. In that search the controller increases the differential while it is below the maximum threshold and, upon determining that the differential has reached or exceeded the maximum, switches to iteratively decreasing it while it remains above the minimum threshold, rather than choosing a single direction from the type of error. Motivation for the modification. Connors and Czapka choose the direction of correction from the type of error (Connors [0054], [0058]; Czapka [0067]). An off-target flow rate, however, is an aggregate measure that does not by itself show which direction of vacuum change will correct it. Connors recognizes output containing “a mixture of multiples and skips” (Connors [0065]); Connors attributes that condition to clumping and does not itself suggest a pressure search, so it is cited only to show that aggregate output can combine both error types. Schoeny supplies the reason to search: recommended vacuum ranges “may not be ideal” (Schoeny [0003]), and Schoeny locates an acceptable setting by stepping through the bounded range upward and then downward, re-assessing performance at each step (Schoeny [0075]–[0081]). Adapting that search for use in place of the direction-selected correction, when the needed direction is uncertain, yields predictable results (KSR; MPEP 2143(I)(B), (G)). Schoeny's search was known as a calibration routine; its operating trigger, its transition at an established maximum threshold, and its operator-selected bounds are the modifications identified above, so the complete operational strategy is not asserted to have been known in that precise form. It trades some speed of correction for a result that does not depend on first diagnosing the direction of the error. Reasonable expectation of success. Where the deviation can be corrected by vacuum, a stepped search from the current setting up to the maximum and then down toward the minimum traverses the selected window and would be expected to reach an acceptable setting at the resolution of its steps, as Schoeny's stepped search does (Schoeny [0079]–[0081]). Causes outside the vacuum, such as clumping or obstructions (Connors [0065]–[0066]), are handled by Connors' escalation after unsuccessful attempts (Connors [0069], [0073]; see Claims 19–20), so the rationale does not depend on the search succeeding in every circumstance. Feasibility. The method uses Connors' existing seed sensor, control unit 42, and variable-speed electric fan (Connors [0043], [0046], [0053]–[0058]). Connors' repeated sensing after pressure adjustments (Connors [0056], [0060]) and Czapka's target-based feedback (Czapka [0067]–[0068]) support retaining output monitoring during the search. This shows that the search could be implemented; it is not relied on as the motivation for the search. Claim 17 Regarding Claim 17, The combination of Connors, Czapka, and Schoeny establishes the method of Claim 16, which is the basis for Claim 17. Disclosure by Connors Connors teaches: receiving the sensor signal indicative of the agricultural product flow rate through the agricultural planter row unit See at least: “As such, each time a seed is expected to be output, the control unit 42 may poll the sensor to determine the number of seeds that are actually output.” ([0057]) Rationale: Polling the seed sensor is part of the multiple-detection branch leading to the decrease. Expressly taught as an operation of the second set. after decreasing the fluid pressure differential; See at least: “In other words, the control unit 42 may instruct the direct vacuum source 68 to decrease vacuum pressure after each detected multiple or alternatively after a given period of operation. In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: After each decrease, arrow 86 returns the method to operating the meter and polling the sensor. Expressly taught. after receiving the sensor signal indicative of the agricultural product flow rate of the second set of operations; See at least: “On the other hand, when no skip is detected, the control unit 42 may detect whether multiple seeds are being output when a single seed is expected (e.g., a multiple) (decision block 82). More specifically, as discussed above, the sensor may output a signal indicative of the number of seeds output from the seed meter 32 to the control unit 42.” ([0057]) Rationale: Evaluation within the multiple branch follows receipt of the signal. Expressly taught. returning to receiving the sensor signal indicative of the agricultural product flow rate of the second set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]) Rationale: Arrow 86 returns the method to polling the sensor, through Connors' general skip/multiple decision sequence. Expressly taught as to returning to sensing; retaining the descending mode is addressed by the combination below. Claim Limitations Not Explicitly Taught by Connors Connors does not explicitly teach the following claim limitations: The method of claim 16, wherein the second set of operations comprises: (as to the target range and minimum-threshold operations below) comparing the agricultural product flow rate to the target agricultural product flow rate range in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. Disclosure by Czapka Czapka teaches: The method of claim 16, wherein the second set of operations comprises: See at least: “Following the increase or reduction in the vacuum pressure, the planter controller 104 may, at (426), determine whether the pressure adjustment resulted in an improvement to the monitored seed population.” ([0068]) Rationale: Czapka re-evaluates output after a reduction within the same adjustment routine. Expressly taught. comparing the agricultural product flow rate to the target agricultural product flow rate range See at least: “compare the monitored seed distribution value to the maximum and minimum values associated with the seed population range.” ([0054]) Rationale: As explained for Claim 16, this is a comparison of product flow rate to a target range, repeated after each adjustment ([0068]). in response to determining the agricultural product flow rate is within the target agricultural product flow rate range; and See at least: “If the current seed population is equal to the desired seed population target, the control algorithm 400 may move to flow step 442 shown in FIG. 11.” ([0067]) Rationale: On-target output returns the method to sensing at step 412 ([0071]). Expressly taught. in response to determining the agricultural product flow rate is outside of the target agricultural product flow rate range. See at least: “However, if the current seed population is not equal to the desired seed population target, the planter controller 104 may, at (420), determine whether the current seed population is higher or lower than the desired seed population target.” ([0067]) Rationale: Czapka expressly evaluates output after each adjustment and returns to its population check if the adjustment improved the population; if not, it reduces ground speed and may restore the previous vacuum setting ([0068]). Continuing the descending vacuum search whenever output remains outside the target range, including when the preceding adjustment produced no improvement, is the proposed modification using Schoeny's reverse search, explained in the motivation below. Motivation to Combine Connors and Czapka Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Czapka before them, to re-evaluate the sensed output rate against the target range after each decrease in Connors' method and to continue monitoring output while it remains within range, as Czapka evaluates output after each vacuum change and returns to sensing when output meets its target (Czapka [0067]–[0068], [0071]). This prevents over-correction and needless change, predictably improving control accuracy (KSR; MPEP 2143(I)(C)). Czapka does not continue vacuum adjustment in every off-target case; continuing the descending search whenever output remains out of range is addressed with Schoeny below. Claim Limitations Not Explicitly Taught by the Combination of Connors and Czapka After combining the teachings of Connors and Czapka, the following claim limitation is not explicitly taught: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential Disclosure by Schoeny Schoeny teaches: returning to comparing the fluid pressure differential to the minimum threshold fluid pressure differential See at least: “Thereafter, the controller 202 may further iteratively decrease the vacuum pressure of the vacuum source 70 until the number of skips is greater than the predetermined allowable skips threshold and record the previous vacuum pressure of the vacuum source 70 (e.g., the vacuum pressure before the allowable skips threshold was exceeded) as a second minimum acceptable vacuum pressure.” ([0079]) Rationale: Schoeny takes repeated downward steps with performance evaluation after each, continuing through acceptable performance to locate the lower bound at which skips become excessive ([0079]), rather than comparing against an established minimum. Schoeny supplies the iterative downward adjustment; in the combined method, Czapka's target-range evaluation governs whether adjustment continues or the controller returns to sensing without further adjustment. With Czapka's minimum vacuum enforced by the comparison adapted in Claim 16, returning to that comparison after an out-of-range result is how the combined method continues the repeated descent. Express as to the descent; PHOSITA-obvious as to the stored minimum. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return to the minimum-threshold comparison whenever the re-checked output remains out of range, so that vacuum keeps stepping down only while above the minimum. In the combined method the controller retains its current search direction while it monitors acceptable output: within range, it keeps receiving the sensor signal within the second set without further adjustment; when the rate later falls outside the range, it resumes the descent at the minimum-threshold comparison rather than re-entering a direction-selected correction. This arrangement is attributed to the combination, not to Connors' return arrow alone: Schoeny continues its descending pass rather than reversing partway through (Schoeny [0079]), and Czapka supplies the target-range check (Czapka [0067]–[0068]). Continuing the descent when an adjustment produced no improvement, rather than following Czapka's ground-speed reduction, is part of the same modification, with persistent failure handled by escalation (see Claims 19–20). Schoeny teaches repeated downward steps to a performance limit (Schoeny [0079]), Czapka supplies the minimum vacuum (Czapka [0045]), and Connors explains that too little vacuum causes skips (Connors [0035]). The result is a predictable bounded search (KSR; MPEP 2143(I)(A)). Claim 18 Regarding Claim 18, The combination of Connors, Czapka, and Schoeny establishes the method of Claim 16, which is the basis for Claim 18. Disclosure by Connors Connors teaches: wherein the second set of operations comprises returning to increasing the fluid pressure differential of the first set of operations See at least: “In either case, the seed meter 32 may continue operation with the decreased vacuum pressure (arrow 86).” ([0060]); “When a skip is detected, the control unit 42 may instruct the direct vacuum source 68 to increase the supplied vacuum pressure (process block 80).” ([0054]) Rationale: After the decrease branch, arrow 86 returns the method to the skip branch, where vacuum is increased. Expressly taught. Claim Limitations Not Explicitly Taught by Connors Connors does not explicitly teach the following claim limitation: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. Disclosure by Czapka Czapka teaches: in response to determining the fluid pressure differential is less than or equal to the minimum threshold fluid pressure differential. See at least: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28. If the down force is not greater than the minimum down force threshold, the planter controller 104 may, at (452), be configured to increase the current down force (e.g., by controlling the operation of the down force actuator 126).” ([0072]) Rationale: Czapka increases an actuator setting in response to its being not greater than (i.e., at or below) the minimum threshold, and supplies a minimum vacuum pressure ([0045]). Applying the same test to vacuum is PHOSITA-obvious. Motivation to Combine Connors, Czapka, and Schoeny Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, and Schoeny before them, to return from the decreasing operations to the increasing operations when the differential reaches or falls below the minimum threshold. Insufficient vacuum causes skips (Connors [0035]), so at the floor the remaining vacuum correction is to raise it. Czapka increases an at-or-below-minimum actuator setting (Czapka [0072]), and Schoeny repeats its vacuum cycles “any number of times” (Schoeny [0030]). The result is a predictable bounded search (KSR; MPEP 2143(I)(A)). Claim 19 Regarding Claim 19, The combination of Connors, Czapka, and Schoeny establishes the method of Claim 16, which is the basis for Claim 19. Disclosure by Connors Connors teaches: The method of claim 16, comprising: See at least: “In some embodiments, the process 88 may be implemented by instructions stored on a tangible, non-transitory, computer readable medium, such as the memory 46, and executable by processing circuitry, such as the processor 44.” ([0062]) Rationale: Connors expressly teaches fault-handling steps performed by control unit 42 as part of its method. in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential; See at least: “when skips continue to occur even after the vacuum pressure is increased above a threshold amount, which may be a predetermined vacuum pressure that is sufficient to attach a certain seed type to the seed disc openings 66, the control unit 42 may determine that seed clumping is occurring in the seed chamber 62 and/or the seed input port 60.” ([0065]) Rationale: Connors treats vacuum raised past a threshold while skips persist as a checkpoint for further fault handling and monitors failed attempts ([0067], [0069]). Connors' threshold is a pressure sufficient to attach seeds, not the combined method's maximum limit; using the at-or-above-maximum determination as the checkpoint is the proposed modification explained in the motivation below. Claim Limitations Not Explicitly Taught by Connors Connors does not explicitly teach the following claim limitations: comparing, via the controller, a maximum pressure differential counter value to a maximum pressure differential counter threshold increasing, via the controller, the maximum pressure differential counter value by one in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and returning, via the controller, to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations after increasing the maximum pressure differential counter value. Disclosure by Rains Rains teaches: comparing, via the controller, a maximum pressure differential counter value to a maximum pressure differential counter threshold See at least: “Retry component 226 may, for instance, include a retry counter” … “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: Rains' controller for a seed-metering drive ([0031]) compares a retry counter to a predetermined number of attempts. Expressly taught; in the combination the counted event is the maximum-pressure checkpoint. increasing, via the controller, the maximum pressure differential counter value by one See at least: “If retry component 226 determines that the momentary motor reversal should be tried, then it increments the retry counter” ([0040]) Rationale: Rains expressly teaches incrementing a retry counter for each permitted attempt. A skilled person would understand this to add one per attempt; at minimum, adding one per counted event is a straightforward implementation. in response to determining the maximum pressure differential counter value is less than the maximum pressure differential counter threshold; and See at least: “it is only desirable to attempt to automatically resolve the jam a pre-determined number of times” ([0040]) Rationale: Rains increments and retries only while the counter is below the predetermined number. Expressly taught. after increasing the maximum pressure differential counter value. See at least: “and then again attempts to drive it in the forward direction, and processing reverts to block 242.” ([0041]) Rationale: Rains performs the corrective retry after incrementing, then returns to receiving sensor signals (block 242) for re-evaluation of whether a jam exists (block 252) ([0040]–[0041]). In the combination, that retry is the return to the descending operations addressed below. Motivation to Combine Connors and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors and Rains before them, to perform Connors' failed-attempt monitoring with Rains' retry counter, via the controller, and to apply that counter to the combined method's maximum-pressure checkpoint. Both references limit automatic recovery of a seed-metering system to a set number of attempts before involving the operator (Connors [0069]; Rains [0040], [0043]–[0044]). Finding the differential at or above the maximum while the flow rate remains out of range means the upward correction available at that limit has not restored the target, making it a natural checkpoint to count. Counting and retrying while below the limit limits how many further descending attempts are made before escalating at the limit, a predictable result (KSR; MPEP 2143(I)(C), (D)). Selecting the maximum-pressure encounter as the counted event is the identified adaptation; neither reference expressly names it. The count is of maximum-pressure determinations, each authorizing another descending attempt, not necessarily of completed unsuccessful search cycles. Claim Limitations Not Explicitly Taught by the Combination of Connors and Rains After combining the teachings of Connors and Rains, the following claim limitation is not explicitly taught: returning, via the controller, to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations Disclosure by Schoeny Schoeny teaches: returning, via the controller, to comparing the fluid pressure differential to the minimum threshold fluid pressure differential of the second set of operations See at least: “In some embodiments, the controller may repeat the calibration cycles any number of times to determine more accurate ranges. Additionally or alternatively, in some embodiments, the controller may perform one or more reverse calibration cycles to better account for hysteresis effects in which the controller may iteratively decrease the vacuum pressure and/or aggressiveness of the singulator.” ([0030]) Rationale: Schoeny's controller expressly repeats the descending cycle with performance evaluation ([0079]), but does not compare current vacuum to an established minimum. That comparison is Czapka's minimum vacuum pressure enforced as adapted in Claim 16, and returning to it after the counter step is a step of the combined method. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to return, via the controller and after updating the counter, to the minimum-bounded descending operations of Claim 16. Rains performs the corrective action after incrementing (Rains [0041]); in the combined method that action is Schoeny's reverse, descending search (Schoeny [0030], [0079]) bounded by Czapka's minimum vacuum (Czapka [0045]). Updating the counter before returning preserves the count for the next maximum-threshold comparison and permits escalation when that comparison finds the counter equal to its threshold (KSR; MPEP 2143(I)(A)). Claim 20 Regarding Claim 20, The combination of Connors, Czapka, Schoeny, and Rains establishes the method of Claim 19, which is the basis for Claim 20. Disclosure by Connors Connors teaches: performing a third set of operations, via the controller, comprising: See at least: “Accordingly, the control unit 42 may notify the operator using an auditory alarm, an indicator light, a displayed message, or the like.” ([0073]) Rationale: Control unit 42 performs operator notification, a set of operations distinct from vacuum adjustment. Expressly taught. outputting a signal to a user interface indicative of instructions to correct the agricultural product flow rate; See at least: “For example, if several attempts are made to alleviate the abnormal operation by supplying opposite vacuum pressure, the control unit 42 may determine that operator maintenance is desired.” ([0073]) Rationale: A displayed message that meter maintenance is desired instructs the operator to act on the meter to restore correct seed output. Express as to signal and interface; PHOSITA-obvious as to the corrective instruction. The counter trigger is addressed below. Claim Limitations Not Explicitly Taught by Connors Connors does not explicitly teach the following claim limitations: in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, terminating operation of the metering system; or a combination thereof. Disclosure by Rains Rains teaches: in response to determining the maximum pressure differential counter value is equal to the maximum pressure differential counter threshold, See at least: “by determining whether it has already been tried, for this jam, a pre-determined number of times.” ([0040]) Rationale: When the fault persists, Rains returns to this check ([0041]); when no further retry is permitted, it shuts down and notifies instead of retrying ([0043]–[0044]). A skilled person would understand that condition to be met when the count equals the predetermined number. Applied to the Claim 19 counter, the combination establishes the claimed trigger. terminating operation of the metering system; See at least: “motor controller 224 can shut down the motor driving the jammed system. This can be done in an attempt to avoid damaging the motor or other equipment in the jammed system.” ([0043]) Rationale: The motor drives the seed-metering system ([0031]), so shutting it down terminates operation of the metering system. Expressly taught. or a combination thereof. See at least: “motor controller 224 can shut down the motor driving the jammed system.” ([0043]) Rationale: Rains supplies the termination alternative. Because the operations are recited disjunctively, that alternative is sufficient once the inherited counter trigger is established through the combination. The hopper-level alternative is not relied on, and the user-interface alternative mapped to Connors above is an additional basis only. Motivation to Combine Connors, Czapka, Schoeny, and Rains Therefore, given the teachings as a whole, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, having Connors, Czapka, Schoeny, and Rains before them, to shut down the metering system and/or display a corrective message, via the controller, when the Claim 19 counter equals its threshold, as Rains does when its retry counter reaches the predetermined number “in an attempt to avoid damaging the motor or other equipment” and so the operator can “take any desired corrective action” (Rains [0043]–[0044]). Connors likewise escalates to the operator after a set number of failed attempts (Connors [0069], [0073]). This predictably improves safety and reliability (KSR; MPEP 2143(I)(A)). Response to Arguments Applicant's arguments filed 08/14/2026 with respect to independent claims 1, 8, and 16, and the claims depending from them, have been fully considered. I. Withdrawal of the Prior Ground of Rejection Applicant's arguments are persuasive to the following extent: the previous rejection did not adequately establish why the combined controller would perform the claimed decrease, conditioned on the minimum threshold, after determining that the differential had reached the maximum threshold. Perain's thresholds command only stopping and starting the vacuum pump, and the previous rationale did not adequately explain how that stop/start regime would be reconciled with Connors' commanded fan-speed reduction. Accordingly, the rejection of claims 1–20 under 35 U.S.C. 103 as unpatentable over Connors in view of Prickel (US 2017/0000016 A1) and Perain et al. (US 2016/0264119 A1) is withdrawn. Upon further consideration, new grounds of rejection are made under 35 U.S.C. 103, as set forth above. They rely on different teachings and a new rationale for that sequence. Because the new grounds of rejection were not necessitated by Applicant's amendment, this action is non-final. See MPEP 706.07(a). II. Arguments Rendered Moot by the New Grounds of Rejection Applicant argues that Perain's upper and lower differential-pressure thresholds command only stopping and starting the vacuum pump; that combining Perain with Connors would render Connors unsuitable for its intended purpose, because Perain's start command could raise the differential regardless of whether a multiple is detected and a pump stopped by Perain could not carry out Connors' commanded decrease; and that Prickel does not cure these deficiencies. These arguments are directed solely to the teachings of Perain and Prickel and to the rationale for modifying Connors with Perain's stop/start pump control. The new grounds of rejection rely on neither Perain nor Prickel for any teaching and do not modify Connors with stop/start pump control. These arguments are therefore moot. The mootness finding is limited to those arguments. The disputed limitations, and Applicant's arguments concerning Connors, which remains applied, are addressed on the merits below. III. The Disputed Limitations Under the New Grounds of Rejection Applicant contends that the applied art does not teach or suggest the following recitation of claims 1 and 8, and the corresponding recitation of method claim 16: “iteratively perform a second set of operations, separate from the first set of operations, in response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential, wherein the second set of operations comprises: comparing the fluid pressure differential to a minimum threshold fluid pressure differential; and decreasing the fluid pressure differential, via the electrically-driven fluid pump . . . , in response to determining the fluid pressure differential is greater than the minimum threshold fluid pressure differential” The recitation is addressed under the new grounds as follows. A. Connors Applicant argues that Connors decreases vacuum pressure when a multiple is detected (Connors, [0058]), not in response to determining that the fluid pressure differential is greater than a minimum threshold. The examiner agrees that Connors, standing alone, does not condition its decrease on a comparison with a minimum threshold. The new grounds do not rely on Connors for that condition. Connors is relied upon for decreasing the differential (“When a multiple is detected, the control unit 42 may instruct the direct vacuum source 68 to decrease the supplied vacuum pressure (process block 84).” (Connors, [0058])), for doing so in repeated increments (“[T]he control unit 42 may instruct the fan 72 to make an incremental decrease in vacuum pressure, which may be predefined and stored in the memory 46.” (Connors, [0059])), and for doing so through an electrically-driven fluid pump (“[T]o decrease the vacuum pressure, the speed of the fan 72 may be decreased.” (Connors, [0043]); “any suitable type of fan 72 that can generate vacuum pressure may be utilized, such as an electric fan” (Connors, [0046])). Connors defines its vacuum pressure as “a pressure differential from atmospheric pressure” (Connors, [0020]), and its seed disc 48 divides the meter into a seed chamber 62 and a vacuum chamber 64 (Connors, [0031]). Reducing the speed of the electric fan therefore decreases the fluid pressure differential across opposite sides of the metering device. The transition at the maximum threshold and the minimum-threshold condition are addressed in Parts III.B and III.C. B. “[I]n response to determining the fluid pressure differential is greater than or equal to the maximum threshold fluid pressure differential” Czapka provides operator-selected “maximum and minimum vacuum pressures for the seed meter 78” (Czapka, [0045]). Czapka's maximum vacuum pressure is an established maximum threshold for the fluid pressure differential across the metering device. Schoeny teaches a descending vacuum sequence that begins above a previously determined maximum: “in the case of a reverse vacuum calibration cycle following the determination of the maximum acceptable vacuum pressure (e.g., at 320), the controller 202 may increase the vacuum pressure by a given margin (e.g., 10% over the previously determined maximum acceptable vacuum pressure) and then iteratively decrease the vacuum pressure of the vacuum source 70 until it is detected that the number of multiples is less than the predetermined allowable multiples threshold” (Schoeny, [0079]; see also [0075]–[0078]) The examiner acknowledges that Schoeny performs this sequence as a calibration routine rather than during field operation in response to an out-of-range flow rate; that Schoeny does not expressly disclose comparing the current differential to a maximum threshold as the trigger for the descending sequence; and that Schoeny's experimentally determined “maximum acceptable” value is not identical to Czapka's operator-selected maximum. The modification relied upon is therefore twofold: configuring the combined controller to begin the descending sequence upon determining that the current differential has reached or exceeded the established maximum threshold, and using that sequence during operation. The rationale for that modification is set forth in Part III.D. C. “[C]omparing the fluid pressure differential to a minimum threshold fluid pressure differential; and decreasing . . . in response to determining the fluid pressure differential is greater than the minimum threshold” Czapka teaches reducing meter vacuum to correct seed output: “If the current seed population is too high, the planter controller 104 may, at (422), reduce the vacuum pressure within the seed meter 78 (e.g., by adjusting the operation of the associated vacuum source 80).” (Czapka, [0067]). Czapka also provides a minimum vacuum pressure for that meter (Czapka, [0045]), but does not expressly state how the controller observes that minimum. Czapka shows its controller comparing a row-unit actuator setting against threshold values before adjusting that setting: “the planter controller 104 may, at (450), determine whether the current down pressure or force is greater than a minimum down force threshold set for the row units 28” (Czapka, [0072]). Czapka uses that comparison to decide whether to increase down force; the claimed comparison decides whether to permit a further decrease in vacuum. Czapka is therefore relied upon for the general practice of threshold-based actuator control, not for the identical conditional relationship. Applying Czapka's threshold-comparison approach to its disclosed minimum vacuum setting would permit the controller to continue reducing vacuum while the differential remains above the minimum and to inhibit further reduction at that minimum. Connors provides the technical reason for doing so: “skips may occur more frequently when the vacuum pressure is lower because the vacuum pressure may be insufficient to secure a single seed” (Connors, [0035]). See MPEP 2143(I)(C)–(D). D. Reason to arrange the operations in the claimed manner, and expectation of success Applicant correctly notes that the examiner must identify a reason that would have prompted a person of ordinary skill to combine the elements in the way claimed (citing KSR). The new grounds address three distinct questions: why a person of ordinary skill would have selected the claimed sequence, whether that person would have reasonably expected it to succeed, and whether existing hardware could implement it. Reason to select the sequence. Connors and Czapka each choose the direction of correction from the type of error, raising vacuum for skips or low output and lowering it for multiples or high output (Connors, [0054], [0058]; Czapka, [0067]). The claimed flow rate, however, is an aggregate measure. An off-target rate shows that output is wrong, but it does not by itself show which direction of vacuum change will correct it. Connors recognizes that output may contain “a mixture of multiples and skips” (Connors, [0065]). Connors attributes that condition to seed clumping and handles it by a separate response; it does not itself suggest a pressure search and is cited only to show that aggregate output can combine both error types. Schoeny supplies the reason to search. Schoeny explains that the appropriate vacuum for a given meter and seed lot is not known in advance, because recommended ranges “may not be ideal” (Schoeny, [0003]), and addresses that uncertainty by stepping vacuum through a bounded range, first upward and then downward, re-assessing meter performance at each step (Schoeny, [0075]–[0081]). A person of ordinary skill seeking to restore an off-target flow rate, without knowing which side of an acceptable setting the current vacuum lies on, would have had reason to adapt Schoeny's bounded up-then-down search for use in place of a single direction-selected correction. Schoeny's search was known as a calibration routine; its operating trigger, its transition upon determining that the differential has reached an established maximum threshold, and its operator-selected bounds are the modifications identified above. The complete operational strategy is therefore not asserted to have been known in that precise form. Substituting the adapted search for the direction-selected correction yields predictable results. See MPEP 2143(I)(B), (G). The search trades some speed of correction for a result that does not depend on first diagnosing the direction of the error. Reasonable expectation of success. Where the deviation can be corrected by vacuum, a stepped search that runs from the current setting up to the maximum, and then down toward the minimum, traverses the selected window and would be expected to reach an acceptable setting within that window at the resolution of its steps. Schoeny shows that a stepped search of this kind, with performance re-assessed at each step, is used to identify an acceptable vacuum setting (Schoeny, [0079]–[0081]). Where the deviation cannot be corrected by vacuum, such as the clumping or obstructions Connors describes (Connors, [0065]–[0066]), Connors teaches escalation after unsuccessful attempts, including operator notification, rather than further pressure adjustment (Connors, [0069], [0073]), as addressed in the rejection of claims 5–6, 12–13, and 19–20. The rationale does not depend on the search succeeding in every circumstance. Feasibility. The modification uses hardware Connors already discloses: a seed sensor, control unit 42, and a variable-speed electric fan (Connors, [0043], [0046], [0053]–[0058]). This shows that the search could be implemented; it is not relied upon as the motivation for the search. The rejection does not require that the claimed sequence appear expressly in a single reference. It relies on express teachings where they exist, and on articulated reasoning with rational underpinning where a limitation is reached through modification. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 418 (2007). E. Intended purpose Applicant's intended-purpose argument rested on Perain's stop/start control, which is no longer applied. During the descending correction routine, the proposed controller reduces fan output (Connors, [0043]) while maintaining operation of the vacuum source, continues to sense seed output, and adjusts the differential through the same fan to restore the target flow rate. The modification therefore preserves Connors' purpose of reducing skips and multiples by adjusting vacuum (Connors, [0035]), and it does not render Connors unsatisfactory for its intended purpose or change its principle of operation. See MPEP 2143.01(V)–(VI). F. Dependent claims Applicant does not separately argue the dependent claims. Their additional limitations are addressed individually in the claim-by-claim rejections set forth above. For at least these reasons, claims 1–20 stand rejected under 35 U.S.C. 103 as set forth in this action. G. Synthesis of the Combined Controller (Claims 1, 8 and 16) Read together, the references and the identified modification produce one controller, summarized here. Contribution Source or adaptation Electrically-driven fan on each meter, seed sensing, and fan-speed increase and decrease of the pressure differential Connors ([0030], [0043], [0046], [0053]–[0058]) Output tolerance range, and selected maximum and minimum vacuum limits Czapka ([0045], [0054], [0067]) Comparison of an actuator setting to minimum and maximum thresholds before adjusting it Czapka ([0072]), general threshold-comparison practice, applied to vacuum as an obvious implementation (not the identical conditional relationship) Upward search to a maximum acceptable value, then a reverse downward calibration search beginning above it Schoeny ([0075]–[0079]) Running that search during operation with the claimed conditional transitions (out of range → maximum comparison → increase while below the maximum → at the maximum, decrease while above the minimum) Identified modifications (use during operation; maximum-threshold comparison as the trigger), supported by the rationale above A skilled person would choose this arrangement over direct error-based correction when the needed direction is uncertain. Direct correction (raise vacuum for skips, lower it for multiples) is faster when the error type is clear. An off-target flow rate, however, does not by itself show the needed direction. Connors recognizes that output can mix skips and multiples (Connors [0065]), although Connors attributes that condition to clumping and does not itself suggest a pressure search. Schoeny supplies the reason to search: the right vacuum for a given meter and seed lot is not known in advance (Schoeny [0003]). The bounded search gives up some speed for a correction that does not depend on diagnosing the direction. It stays within selected limits, and it leaves causes outside the vacuum to escalation. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to OLUWABUSAYO ADEBANJO AWORUNSE whose telephone number is (571)272-4311. The examiner can normally be reached M - F (8:30AM - 5PM). 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