DETAILED ACTION
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 .
Status of the Claims
The office action is being examined in response to the response filed by the applicant on August 19, 2026.
Claims 1-20 are pending and have been examined.
This action is made NON-FINAL.
Information Disclosure Statement
The information disclosure statement (IDS) submitted August 19, 2026 is in compliance with the provisions of 37 CFR 1.97. Accordingly, the information disclosure statement is being considered by the examiner.
Response to Amendment
Applicant’s prior arguments regarding earlier-cited references have been considered but are moot in view of the new grounds of rejection based on the newly cited Nixon and Lath references. Nixon is an Intuitive Surgical patent that expressly teaches, in the context of robotic surgical instrument calibration: (1) monitoring a torque signal during a jaw-closing sweep; (2) computing the second derivative of the filtered torque signal; (3) identifying the end effector initial engagement configuration from the second derivative; and (4) using that configuration as the calibrated zero (nominal closed position) for subsequent spread-angle control.
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 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 of this title, 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 set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied 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 1–8, 10–13, 15, and 17–20 are rejected under 35 U.S.C. § 103 as being unpatentable over Nixon (US 2015/0314451 A1) in view of Lath (WO 2020/231785 A1).
Regarding the preamble:
Nixon discloses a system comprising a robotic arm, an end effector comprising a first end effector element movable relative to a second end effector element, and a processor (control system) coupling an input linkage to the robotic arm. Nixon, claim 24. The end effector elements are jaw or gripping elements of a surgical tool — e.g., forceps, graspers, or scissors — whose relative angular opening defines a spread angle. Nixon ¶¶[0013]–[0017]. The robotic arm comprises at least one motor (drive mechanism) that drives the end effector through a drive mechanism comprising actuation cables, pulleys, wrist mechanisms, and associated transmission components (interface elements). Nixon ¶¶[0001]–[0003]; claims 24–25.
Lath confirms the surgical robotic context. Lath discloses a computer-assisted surgical device 200 comprising a drive system 240 that drives a “grip degree of freedom” — expressly described as “an angle between jaws” (i.e., a spread angle) — of a two-jaw end effector 220 through drive mechanisms 250 including cables wrapped around capstans (interface elements). Lath ¶¶[0031], [0038]–[0040].
To the extent the preamble is limiting, it is met by Nixon and confirmed by Lath.
Regarding limitation (a) — “cause an instrument drive force to be applied at the one or more interface elements to be varied”:
Nixon discloses that the processor transmits a commanded torque signal to at least one motor of the robotic arm to move the first end effector:
“transmitting a commanded torque signal to at least one motor of the robotic arm to move the first end effector.” Nixon, claim 35.
The commanded torque signal causes the motor to apply a drive force through the drive mechanism (interface elements) to actuate the end effector elements toward mutual engagement. During the calibration procedure, the processor causes the end effector elements to move through a range of positions (open toward closed), applying a varying drive force:
“bringing the first and second end effector elements into mutual engagement.” Nixon, claim 24.
Nixon meets limitation (a).
Regarding limitation (b) — “measure, at each of a plurality of times, the instrument drive force applied at the one or more interface elements”:
Nixon discloses:
“the processor comprises programming to calibrate the mounted end effector by: monitoring a commanded torque signal to the at least one motor; monitoring position of the first and second end effector elements; and identifying a change in the commanded torque signal versus the position of the first and second end effector elements.” Nixon, claim 25.
“monitoring position of the first and second end effector elements relative to said commanded torque signal.” Nixon, claim 35.
The commanded torque signal is monitored continuously over time during the calibration sweep as the jaws move from open to closed, constituting measurement at each of a plurality of times. In a direct-drive motor configuration as disclosed by Nixon (¶¶[0001]–[0003]), the commanded torque is directly proportional to motor current and thus to the force actually applied at the interface elements.
To the extent the claim is interpreted to require measuring the actual applied force rather than the commanded signal, Lath expressly teaches:
“an applied force and/or torque … as applied by the jaws to the grasped material obtained from one or more force and/or torque sensors associated with the jaws and/or the one or more actuators used to actuate the jaws … the force and/or torque may be determined based on one or more currents used to actuate the one or more actuators used to actuate one or both of the … jaws.” Lath ¶[0052].
The measurements are taken at a plurality of times because Lath computes rates of change from “two or more … readings obtained over time.” Lath ¶[0052].
Limitation (b) is met by Nixon, supplemented by Lath.
Regarding limitation (c) — “determine, for each of the plurality of times, a force behaviour value using a derivative of the measured instrument drive force with respect to time”:
Nixon expressly discloses using a derivative — specifically the second derivative — of the drive force signal:
“the processor determines an end effector initial engagement configuration using a second derivative of the filtered commanded torque signal.” Nixon, claim 27.
Prior to computing the derivative, the torque signal is filtered:
“the processor comprises programming to: filter the commanded torque signal prior to identifying the change.” Nixon, claim 26.
The second derivative of the filtered commanded torque signal, evaluated at each of the plurality of sampling times during the calibration sweep, constitutes a “force behaviour value using a derivative of the measured instrument drive force with respect to time.”
Additionally, Lath independently teaches computing the first derivative (rate of change) of measured jaw force by numerical differentiation:
“a rate of change in applied force and/or torque … determined using a numerical differentiation technique (e.g., using the divided difference method) from two or more force and/or torque readings obtained over time.” Lath ¶[0052].
Both a first derivative and a second derivative constitute “a derivative of the measured instrument drive force with respect to time.”
Limitation (c) is met by Nixon, confirmed by Lath.
Regarding limitation (d) — “determine an offset value in dependence on the plurality of determined force behaviour values”:
Nixon discloses:
“identifying a change in the commanded torque signal versus the position of the first and second end effector elements.” Nixon, claim 25.
“the processor determines an end effector initial engagement configuration using a second derivative of the filtered commanded torque signal.” Nixon, claim 27.
“the end effector initial engagement configuration corresponds to the nominal closed position.” Nixon, claim 29.
The “end effector initial engagement configuration” is the drive-mechanism position at which the first and second end effector elements first contact each other. This configuration is identified from the second-derivative analysis — a spike, inflection, or sign change in the second derivative indicates the contact event. The difference between (i) the drive position at which this contact is detected and (ii) the expected/nominal position of the end effector elements constitutes an offset value determined in dependence on the plurality of force behaviour values (the second derivative values computed at each time during the calibration sweep).
Limitation (d) is met by Nixon.
Regarding limitation (e) — “control, in dependence on the offset value, the surgical robot arm to control the spread angle”:
Nixon discloses:
“the processor configured to, during a surgical procedure, apply no additional torque to said at least one motor beyond a position of the end effector elements corresponding to the end effector initial engagement configuration.” Nixon, claim 28.
“a feedback force is applied to the first and second grip members at a nominal closed position, and wherein the end effector initial engagement configuration corresponds to the nominal closed position.” Nixon, claim 29.
The control system commands spread-angle positions in reference to the calibrated engagement position. The system will not command the motor beyond the engagement configuration, effectively using the offset-determined zero point as the reference for all subsequent spread-angle control during the surgical procedure.
Limitation (e) is met by Nixon.
Regarding limitation (f) — “wherein the control system is configured to use the offset value to determine a calibrated zero configuration for the robotic surgical instrument”:
Nixon expressly teaches:
“a processor configured to calibrate the mounted end effector in response to the signal by bringing the first and second end effector elements into mutual engagement.” Nixon, claim 24.
“the processor determines an end effector initial engagement configuration using a second derivative of the filtered commanded torque signal.” Nixon, claim 27.
“the end effector initial engagement configuration corresponds to the nominal closed position.” Nixon, claim 29.
The processor is configured to “calibrate the mounted end effector once per surgical procedure for each end effector mounted on the robotic arm.” Nixon, claim 31.
The “end effector initial engagement configuration” IS the calibrated zero configuration for the mounted instrument. It is determined from the offset identified via force-derivative analysis (claim 27), it corresponds to the nominal closed position (claim 29), it is established once per instrument mounting (claim 31), and it serves as the per-instrument zero-configuration reference from which all subsequent spread-angle operations are controlled.
Limitation (f) is met by Nixon.
Motivation to combine Nixon with Lath:
Both Nixon and Lath are assigned to Intuitive Surgical and are directed to control systems for robotic surgical instruments with cable/tendon-driven end effectors comprising opposing jaw elements defining a spread angle. Nixon teaches a complete calibration procedure using the second derivative of a filtered commanded torque signal to determine the initial engagement configuration (calibrated zero). Lath teaches measuring the actual applied force/torque via sensors or motor current, and computing force derivatives by numerical differentiation.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Nixon’s calibration system to use the actual measured drive force as taught by Lath because: (1) actual force measurements capture real-world mechanical effects including friction, cable compliance, backlash, and wear that the commanded signal does not reflect, improving calibration accuracy; (2) Lath expressly identifies the advantage of measuring actual applied force for characterizing grasp behavior and calibrating tool parameters (Lath ¶¶[0050]–[0052], [0078]); and (3) both references originate from the same company and are directed to the same type of instrument, making the combination a straightforward integration of known techniques. KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007).
Regarding Claim 2 (Currently Amended)
Claim 2 recites:
The control system of claim 1, the calibrated zero configuration being: when the control system is configured to cause the instrument drive force to be varied to close the robotic surgical instrument from an open configuration, the configuration in which an inner surface of the first end effector element first contacts an inner surface of the second end effector element; or when the control system is configured to cause the instrument drive force to be varied to open the robotic surgical instrument from a closed configuration, the configuration in which an inner surface of the first end effector element last contacts an inner surface of the second end effector element.
Nixon expressly teaches the first recited alternative. During calibration, the processor causes the end effector elements to move from an open position toward mutual engagement — i.e., closing from an open configuration:
“a processor configured to calibrate the mounted end effector in response to the signal by bringing the first and second end effector elements into mutual engagement.” Nixon, claim 24.
“calibrating the mounted first end effector by moving at least one of the end effector elements so as to bring the end effector elements into mutual engagement, the calibrating being performed in response to the mounting the first end effector to the robotic arm.” Nixon, claim 34.
The term “mutual engagement” describes the physical state in which the inner gripping surfaces of the two jaw elements come into direct physical contact. In the context of a jawed surgical instrument such as forceps, graspers, or scissors (Nixon ¶¶[0013]–[0017]), “mutual engagement” occurs when the inner surfaces of the opposing jaws meet. This is “the configuration in which an inner surface of the first end effector element first contacts an inner surface of the second end effector element.”
Nixon identifies this first-contact configuration using the force-derivative analysis:
“the processor determines an end effector initial engagement configuration using a second derivative of the filtered commanded torque signal.” Nixon, claim 27.
The word “initial” denotes the first point of engagement during the closing sweep. When the jaws transition from free-space motion (no contact, low resistance) to mutual contact (sudden increase in resistance), the torque signal changes abruptly, producing a detectable feature in the second derivative. The configuration at which this feature occurs is the “initial engagement configuration.”
Nixon uses this first-contact configuration as the calibrated zero:
“the end effector initial engagement configuration corresponds to the nominal closed position.” Nixon, claim 29.
“during a surgical procedure, apply no additional torque to said at least one motor beyond a position of the end effector elements corresponding to the end effector initial engagement configuration.” Nixon, claim 28.
Nixon further confirms that the calibration sweep is specifically a closing-from-open sweep performed between instrument mounting and the surgical procedure:
“between mounting of the end effector and starting a surgical procedure using the end effector, the processor does not effect a calibration movement of any degree of freedom of the input linkage or the robotic arm other than said mutual engagement of the first and second end effector elements.” Nixon, claim 24.
The “end effector initial engagement configuration” determined by the second-derivative analysis during a closing sweep from open IS the “configuration in which an inner surface of the first end effector element first contacts an inner surface of the second end effector element,” and Nixon expressly uses this as the calibrated zero configuration.
Claim 2 is obvious over Nixon in view of Lath.
Regarding Claim 3 (Original)
Claim 3 recites:
The control system of claim 1, wherein the offset value is a spread offset value, the control system being further configured to: measure, at each of the plurality of times, a position of each of the one or more interface elements; predict, for each of the plurality of times, a resultant spread angle between the first end effector element and the second end effector element in dependence on the measured position of each of the one or more interface elements at that time; and determine the spread offset value in dependence on the plurality of determined force behaviour values and the plurality of predicted resultant spread angles.
Measure position of interface elements:
Nixon discloses “monitoring position of the first and second end effector elements” relative to the commanded torque signal during the calibration sweep. Nixon, claims 25, 35. The end effector element positions are determined from the positions of the interface elements (motor encoder positions, capstan angles) through the kinematic model of the instrument. The motor/interface-element positions are necessarily measured to determine the end effector positions — the system cannot know the jaw positions without knowing the motor positions. Measuring motor positions via encoders is standard and inherent in any servo-controlled robotic arm.
Lath confirms that the drive system includes actuators with position sensors and that the grip degree of freedom (spread angle) is controlled through measured drive mechanism positions. Lath ¶¶[0031]–[0033], [0038]–[0040].
Predict resultant spread angle from interface element positions:
Nixon’s calibration procedure monitors the end effector element positions as a function of the motor drive positions. Nixon, claims 25, 35. The spread angle (relative opening between the jaw elements) is predicted from the measured interface element (motor/capstan) positions using the known kinematic model of the instrument. This is inherent in any position-controlled robotic surgical system — the control system must use a model relating motor position to jaw angle (spread angle) to predict the resultant spread angle from the measured interface element positions. Without this prediction, the system could not “monitor position of the first and second end effector elements” (Nixon, claim 25) at all.
Au expressly teaches that the relationship between actuator positions and joint angles is modeled: “the angular position of motor 140 … and the angular position of jaw 112 as defined by the geometry of instrument 100” is used in “determining the control signals needed to move jaw 112.” Au ¶[0003].
Determine spread offset value from force behaviour values and predicted spread angles:
Nixon identifies the “end effector initial engagement configuration” — the contact point — from the second derivative of the torque signal (force behaviour values) at a specific time during the calibration sweep. Nixon, claims 25, 27. At that time, the predicted spread angle corresponds to a particular value — ideally zero (jaws closed) but in practice offset from the nominal zero due to manufacturing variation, wear, or backlash. The difference between the predicted spread angle at the contact time and the expected zero constitutes the “spread offset value.” This offset value is determined in dependence on both: (1) the force behaviour values (which identify the contact time); and (2) the predicted spread angles (which identify the jaw opening at that time).
It would have been obvious to expressly measure the interface element positions, predict the resultant spread angle from those positions, and determine the spread offset value from the force derivative values and the predicted spread angles because this is the inherent computational sequence in Nixon’s calibration procedure. The system must determine at what predicted spread angle the contact event occurs in order to establish the offset between the predicted zero and the actual zero. Making this computational sequence explicit is a matter of routine engineering implementation.
Claim 3 is obvious over Nixon in view of Lath.
Regarding Claim 4 (Original)
Claim 4 recites:
The control system of claim 3, the control system being configured to: cause the instrument drive force to be varied to close the robotic surgical instrument from an open configuration, and approximate in dependence on the plurality of determined force behaviour values a time at which the force behaviour value for that time reaches or exceeds a force behaviour threshold value; or cause the instrument drive force to be varied to open the robotic surgical instrument from a closed configuration, and approximate in dependence on the plurality of determined force behaviour values a time at which the force behaviour value for that time reaches or falls below a force behaviour threshold value; and determine, as the spread offset value, the resultant spread angle predicted for that time in dependence on the plurality of predicted resultant spread angles.
Closing from open; force behaviour value reaches or exceeds threshold:
Nixon teaches calibrating by closing the jaws from open (claim 24, “bringing the first and second end effector elements into mutual engagement”) and identifying a “change in the commanded torque signal versus the position” (claim 25) using the “second derivative of the filtered commanded torque signal” (claim 27). Identifying a “change” in the second derivative inherently requires determining a time at which the derivative reaches or exceeds a detection criterion — whether a zero-crossing, a magnitude threshold, or an inflection criterion. The time at which this criterion is met identifies the contact event. This is “approximate in dependence on the plurality of determined force behaviour values a time at which the force behaviour value for that time reaches or exceeds a force behaviour threshold value.”
Kamiya (supplemental) expressly teaches threshold-based contact detection: “when the value of the force sensor exceeds a set threshold value F0 … the external-force-value monitoring unit determines that a contact is detected.” Kamiya, col. 7, ll. 45–60.
Determine spread offset value as the predicted spread angle at that time:
Nixon uses the end effector position (predicted spread angle) at the time of the detected change as the “end effector initial engagement configuration” (claims 27–29). This is “determine, as the spread offset value, the resultant spread angle predicted for that time in dependence on the plurality of predicted resultant spread angles.”
Claim 4 is obvious over Nixon in view of Lath.
Regarding Claim 5 (Original)
Claim 5 recites:
The control system of claim 1, wherein the offset value is an interface position offset value, the control system being further configured to: measure, at each of the plurality of times, a position of an interface element of the one or more interface elements that is indicative of a predicted spread angle between the first end effector element and the second end effector element; and determine the interface position offset value in dependence on the plurality of determined force behaviour values and the plurality of measured interface positions.
Measure interface element position indicative of predicted spread angle:
Nixon teaches monitoring position of the end effector elements relative to the commanded torque signal. Nixon, claims 25, 35. The end effector positions are determined from the motor/actuator positions (interface element positions) through the kinematic model. The motor encoder position is the “position of an interface element” that is “indicative of a predicted spread angle” because the motor position maps to a predicted jaw opening through the instrument geometry.
Au teaches that the actuator position (motor angle) is measured via encoders and is used to predict the joint angle (spread angle), though in compliant systems the actual joint angle may differ from the prediction. Au ¶¶[0003], [0045]–[0048].
Determine interface position offset value:
Nixon identifies the “end effector initial engagement configuration” (claims 27–29) at a specific drive position during the calibration sweep. The interface element position (motor/capstan angle) at which the force derivative indicates the contact event is the “interface position offset value.” It is the motor position corresponding to the jaws-closed reference, determined from the force behaviour values (which identify the contact time) and the measured interface positions (which record the motor position at that time).
The distinction between claim 3 (spread offset value — expressed as a predicted spread angle) and claim 5 (interface position offset value — expressed as a motor/interface position) is one of coordinate representation. Both are taught by Nixon because Nixon’s calibration identifies a specific point on the torque-versus-position curve, which can be expressed in either coordinate system.
Claim 5 is obvious over Nixon in view of Lath.
Regarding Claim 6 (Original)
Claim 6 recites:
The control system of claim 5, the control system being configured to: cause the instrument drive force to be varied to close the robotic surgical instrument from an open configuration, and approximate in dependence on the plurality of determined force behaviour values a time at which the force behaviour value for that time reaches or exceeds a force behaviour threshold value; or cause the instrument drive force to be varied to open the robotic surgical instrument from a closed configuration, and approximate in dependence on the plurality of determined force behaviour values a time at which the force behaviour value for that time reaches or falls below a force behaviour threshold value; and determine, as the interface position offset value, the interface position at that time in dependence on the plurality of measured interface positions.
Closing from open; threshold exceedance; interface position at that time:
Nixon teaches calibrating by closing from open (claim 24) and identifying the contact-event time from the second derivative (claims 25, 27). The motor/interface position at the contact time is recorded as part of the position monitoring (claim 25, “monitoring position … identifying a change … versus the position”). This motor position at the identified time is the “interface position offset value.”
For the same reasons set forth for claim 4, including Nixon’s inherent threshold-based change identification and Kamiya’s express threshold teaching, the threshold-based time approximation is obvious.
Claim 6 is obvious over Nixon in view of Lath.
Regarding Claim 7 (Original)
Claim 7 recites:
The control system of claim 1, wherein the derivative of the measured instrument drive force with respect to the time at that time is the first derivative of the measured instrument drive force with respect to the time at that time.
Lath expressly teaches computing the first derivative (rate of change) of the measured drive force:
“a rate of change in applied force and/or torque … determined using a numerical differentiation technique (e.g., using the divided difference method) from two or more force and/or torque readings obtained over time.” Lath ¶[0052].
A rate of change computed by numerical differentiation from readings obtained over time is a first derivative with respect to time.
It would have been obvious to use the first derivative as the force behaviour value because: (1) the first derivative identifies the onset of the contact event as a sudden increase in force rate-of-change; (2) Lath expressly teaches its computation in the context of surgical instrument force monitoring; and (3) the first derivative is a simpler computation than Nixon’s second derivative and is the standard first-order approximation for characterizing change in a sampled signal.
Claim 7 is obvious over Nixon in view of Lath.
Regarding Claim 8 (Original)
Claim 8 recites:
The control system of claim 7, wherein the first derivative of the measured instrument drive force with respect to time at a time, tn, is determined by: assessing the difference between Fn at tn and Fn−1 at tn−1 and dividing by (tn−tn−1); or assessing the difference between Fn+1 at tn+1 and Fn at tn and dividing by (tn+1−tn); or assessing the difference between Fn+1 at tn+1 and Fn−1 at tn−1 and dividing by (tn+1−tn−1).
The first recited alternative is the backward difference formula:
dFdt∣tn≈Fn−Fn−1tn−tn−1
Lath expressly teaches computing the first derivative using “the divided difference method.” Lath ¶[0052]. The divided difference method encompasses backward, forward, and central difference formulas. The backward difference formula — using the current sample and the immediately preceding sample — is the most common implementation of the divided difference method in real-time control systems because it uses only past and current data (is causal) and introduces no computational delay.
Kamiya (supplemental) teaches computing the time derivative of the force sensor value “by a difference calculation.” Kamiya, col. 8, ll. 1–5.
It would have been obvious to compute the first derivative using the backward difference formula because: (1) Lath expressly teaches the divided difference method; (2) Kamiya teaches difference calculation for force derivatives; (3) the backward difference is the simplest and most widely used finite-difference approximation in sampled-data control systems; and (4) it requires only two successive measurements, making it efficient for real-time processing.
Claim 8 is obvious over Nixon in view of Lath.
Regarding Claim 9 (Original)
Claim 9 recites:
The control system of claim 1, wherein: the measured instrument drive force is dependent on a first force measured at a first interface element for changing an angle of the first end effector element and a second force measured at a second interface element for changing an angle of the second end effector element, optionally wherein the instrument drive force is dependent on a sum of the first force and the second force; or the measured instrument drive force is dependent on a force measured at a single interface element for changing an angle of one or both of the first end effector element and the second end effector element.
Two interface elements with two forces:
Deane (of record) discloses that the spread angle between the first and second end effector elements is controlled through paired driving elements — each end effector element has an associated drive element that applies force to change the angle of that element. Deane ¶¶[0045], [0064]. A first force is applied at a first interface element (driving element for the first jaw) and a second force is applied at a second interface element (driving element for the second jaw).
Au expressly teaches paired actuators 440 and 442 applying opposing tensions T through respective transmission systems 420 and 422 to control a single joint degree of freedom. Au ¶¶[0046]–[0047]; FIG. 4. The net torque on the joint depends on the tensions (forces) in both transmission systems.
Lath teaches that the force/torque may be measured at “one or more actuators used to actuate one or both of the … jaws.” Lath ¶[0052]. Where two actuators are used (one per jaw), the instrument drive force depends on forces measured at both interface elements. The net closing/opening torque is the sum of the individual force contributions — this is the standard torque computation in antagonistic cable-driven systems.
Claim 9 is obvious over Nixon in view of Lath.
Regarding Claim 10 (Original)
Claim 10 recites:
The control system of claim 1, wherein the plurality of measured instrument drive forces are filtered prior to being used to determine the plurality of force behaviour values.
Nixon expressly teaches filtering the torque signal before derivative computation:
“the processor comprises programming to: filter the commanded torque signal prior to identifying the change.” Nixon, claim 26.
“the processor determines an end effector initial engagement configuration using a second derivative of the filtered commanded torque signal.” Nixon, claim 27.
The torque signal is filtered before the force behaviour values (derivatives) are computed.
Kamiya (supplemental) confirms: “a low pass filter is applied to the external-force detection value detected by the force sensor to eliminate a noise component.” Kamiya, col. 8, ll. 40–55.
Claim 10 is obvious over Nixon in view of Lath.
Regarding Claim 17 (Original)
Claim 17 recites:
The control system of claim 11, the control system being further configured to: determine a commanded spread angle in dependence on the desired spread angle, the offset value and the lost motion compensation value; and control the surgical robot arm to drive the robotic surgical instrument using the commanded spread angle.
The rejection of claim 11 (see Group B below) is incorporated by reference.
Determine commanded spread angle from desired angle, offset, and lost motion compensation:
Nixon teaches that the control system uses the calibrated engagement configuration (offset value) as the reference for spread-angle control. Nixon, claims 28–29. The commanded position sent to the motor is determined in dependence on the desired position (from the surgeon’s input via the handle/input linkage) and the calibrated reference (offset value). Nixon, claims 24, 28–29, 34.
Au teaches that the applied tension (motor command) is determined by combining the desired joint position, the measured/predicted joint position, and multiple correction terms including a compliance/stiffness compensation term C: TDIST=Tsign⋅(g1(θD−θ)+g2(θ˙D−θ˙)+C). Au ¶[0051], Equation 1. When the offset value (from claim 1) and the lost motion compensation value (from claim 11) are both available, combining them with the desired spread angle to compute a final commanded spread angle is the standard and straightforward approach — the commanded angle equals the desired angle corrected for zero-point offset and further corrected for lost motion.
Control using commanded spread angle:
Nixon teaches controlling the robotic arm to drive the end effector using the computed motor command. Nixon, claims 24, 28, 34.
Claim 17 is obvious over Nixon in view of Lath and Au.
Regarding Claim 18 (Original)
Claim 18 recites:
The control system of claim 17, wherein determining the commanded spread angle in dependence on the desired spread angle, the offset value and the lost motion compensation value comprises: determining an offset-corrected spread angle in dependence on the desired spread angle and the offset value, approximating a lost motion compensation value in dependence on the offset-corrected spread angle and the lost motion compensation function, and determining the commanded spread angle in dependence on the offset-corrected spread angle and the lost motion compensation value; or approximating a lost motion compensation value in dependence on the desired spread angle and the lost motion compensation function, and determining the commanded spread angle in dependence on the desired spread angle, the offset value and the lost motion compensation value.
Offset first, then lost motion compensation:
This is the natural computational sequence: (1) apply the zero-point offset to the desired spread angle to obtain an offset-corrected spread angle; (2) evaluate the lost motion compensation function at the offset-corrected angle to obtain the compensation value; (3) combine the offset-corrected angle and the compensation value to obtain the final commanded spread angle.
Au teaches that multiple corrections are combined sequentially to produce the final motor command. The primary tension TDIST is computed from position error (analogous to offset correction), then integral correction TINT, proximal correction TPROX, and pair correction TPAIR are added. Au ¶¶[0051]–[0056]. The corrections are applied in a defined computational order. Applying the offset correction first and then the lost motion compensation is a natural ordering because the offset correction establishes the correct reference frame before the compliance correction is computed.
It would have been obvious to implement this computational ordering because: (1) it is the standard approach to cascaded compensation in servo control — correct the reference first, then compensate for transmission effects; (2) Au teaches sequential combination of multiple correction terms; and (3) applying the offset before the lost motion compensation ensures the compensation function operates in the correct coordinate frame.
Claim 18 is obvious over Nixon in view of Lath and Au.
Regarding Independent Claim 19 (Currently Amended)
Claim 19 recites a surgical robotic system comprising a surgical robot arm with a drive mechanism and a control system configured to perform the same functional limitations as claim 1.
Nixon discloses a system comprising: a robotic arm; an end effector with first and second elements movable relative to each other; at least one motor (drive mechanism with interface elements); and a processor (control system). Nixon, claims 24, 32–33.
Lath discloses the surgical robotic system including a computer-assisted device 200 with drive system 240, end effector 220 with opposing jaws defining a spread angle, drive mechanisms 250 (cables, capstans), and processors. Lath ¶¶[0029]–[0040].
All functional limitations are met for the same reasons set forth for claim 1:
Limitation
Mapping
Citation
Surgical robot arm with drive mechanism, interface elements, spread angle
Nixon: robotic arm, motor, end effector with two movable elements; Lath: drive system with cables/capstans, “angle between jaws”
Nixon claims 24–25; Lath ¶¶[0031], [0038]–[0040]
Cause drive force to be varied
Nixon: “transmitting a commanded torque signal to at least one motor to move the first end effector”
Nixon claim 35
Measure drive force at plurality of times
Nixon: “monitoring a commanded torque signal … monitoring position”; Lath: actual force via sensors/current
Nixon claim 25; Lath ¶[0052]
Determine force behaviour value using derivative
Nixon: “second derivative of the filtered commanded torque signal”
Nixon claim 27
Determine offset value
Nixon: “identifying a change” to determine “initial engagement configuration”
Nixon claims 25, 27, 29
Control spread angle in dependence on offset
Nixon: “apply no additional torque beyond a position corresponding to the end effector initial engagement configuration”
Nixon claim 28
Use offset to determine calibrated zero configuration
Nixon: “calibrate the mounted end effector by bringing the first and second end effector elements into mutual engagement”; “initial engagement configuration corresponds to the nominal closed position”
Nixon claims 24, 27, 29, 31
Motivation to combine is the same as for claim 1.
Claim 19 is obvious over Nixon in view of Lath.
Regarding Independent Claim 20 (Currently Amended)
Claim 20 recites a method of controlling a surgical robot arm, comprising the same functional steps as claim 1.
Nixon discloses the corresponding method:
“A method comprising: mounting a first end effector to a robotic arm …; calibrating the mounted first end effector by moving at least one of the end effector elements so as to bring the end effector elements into mutual engagement …” Nixon, claim 34.
“the calibrating further comprising: transmitting a commanded torque signal …; monitoring position … relative to said commanded torque signal; and identifying an end effector element initial engagement drive position from a change in relationship between the commanded torque signal and the position.” Nixon, claim 35.
“determining a second derivative of the commanded torque signal versus the monitored position.” Nixon, claim 37.
All method steps are met for the same reasons set forth for claim 1:
Method Step
Mapping
Citation
Causing drive force to be varied
Nixon: “transmitting a commanded torque signal to at least one motor”
Nixon claim 35
Measuring drive force at plurality of times
Nixon: “monitoring a commanded torque signal … monitoring position”; Lath: actual force via sensors/current
Nixon claim 35; Lath ¶[0052]
Determining force behaviour value using derivative
Nixon: “determining a second derivative of the commanded torque signal versus the monitored position”
Nixon claim 37
Determining offset value
Nixon: “identifying an end effector element initial engagement drive position from a change in relationship”
Nixon claim 35
Determining calibrated zero configuration using offset
Nixon: “initial engagement configuration corresponds to nominal closed position”; calibrate once per mounting
Nixon claims 27, 29, 31
Controlling spread angle in dependence on offset
Nixon: “apply no additional torque beyond a position corresponding to the end effector initial engagement configuration”; “articulating the end effector elements … in correlation with the moving of the grip members”
Nixon claims 28, 34
Motivation to combine is the same as for claim 1.
Claim 20 is obvious over Nixon in view of Lath.
Claims 11–13 and 15 are rejected under 35 U.S.C. § 103 as being unpatentable over Nixon (US 2015/0314451 A1) in view of Lath et al. (WO 2020/231785 A1) and further in view of Au et al. (US 2015/0289942 A1).
Regarding Claim 11 (Original)
Claim 11 recites:
The control system of claim 1, the control system being further configured to: receive a request to drive the spread angle between the first end effector element and the second end effector element to a desired spread angle; approximate a lost motion compensation value in dependence on a lost motion compensation function; and control, in dependence on the desired spread angle and the lost motion compensation value, the surgical robot arm to control the spread angle between the first end effector element and the second end effector element of the robotic surgical instrument.
The rejection of claim 1 is incorporated by reference.
Receive request to drive to desired spread angle:
Nixon teaches that the system receives input from the surgeon via a handle/input linkage to control the end effector elements:
“moving a first grip member of a handle relative to a second grip member of the handle in response to gripping; articulating the end effector elements so that the end effector elements move in correlation with the moving of the grip members of the handle.” Nixon, claim 34.
The surgeon’s grip manipulation constitutes a request to drive the spread angle to a desired value.
Approximate lost motion compensation value in dependence on a lost motion compensation function:
Nixon and Lath do not expressly disclose a “lost motion compensation function.” However, lost motion (backlash, compliance) compensation is a well-known requirement in cable-driven robotic surgical instruments.
Au expressly identifies the problem: cable-driven surgical instruments have compliant transmission systems in which “the mechanical structure … has a high degree of compliance” such that “a relationship between the angular position of motor 140 … and the angular position of jaw 112 may be difficult or impossible to model with sufficient accuracy.” Au ¶[0003].
Au addresses this compliance through correction terms in the tension computation:
A distal tension TDIST computed from position and velocity errors between desired and measured joint configurations. Au ¶[0051], Equation 1.
An integral tension TINT correction based on accumulated position error — this directly compensates for persistent offsets caused by lost motion. Au ¶[0053].
A parameter C that “may account for expected friction or external forces” and “could include non-constant terms that compensate for properties such as … mechanism stiffness.” Au ¶[0051].
The stiffness-dependent term C and the integral correction TINT collectively constitute a lost motion compensation function — they map the current state (position, velocity, accumulated error) to a compensation value that corrects for the transmission compliance.
Control in dependence on desired spread angle and lost motion compensation:
Au teaches combining the desired position, measured position, and compliance corrections to determine the final motor command: T=TDIST+TPROX+TPAIR+TINT. Au ¶¶[0056]–[0058]. The final tension command controls the joint (spread angle) in dependence on both the desired angle and the compliance compensation.
It would have been obvious to include a lost motion compensation function in the Nixon/Lath system because: (1) cable-driven surgical instruments inherently have compliance/backlash, as expressly identified by Au (¶[0003]); (2) Au teaches correcting for compliance through position-error-based tension adjustments; (3) such compensation improves spread-angle accuracy, which is critical for surgical precision; and (4) lost motion compensation is standard practice in precision servo control of cable-driven mechanisms.
Claim 11 is obvious over Nixon in view of Lath and Au.
Regarding Claim 12 (Original)
Claim 12 recites:
The control system of claim 11, wherein the lost motion compensation function comprises: a first portion that relates desired or offset-corrected spread angle to lost motion compensation value for a range of desired or offset-corrected spread angles; and a second portion that is representative of a maximum positive lost motion compensation value, wherein the first portion connects to the second portion at a first transition point, the first transition point being at the greatest desired or offset-corrected spread angle within the range of desired or offset-corrected spread angles; and/or a third portion that is representative of a maximum negative lost motion compensation value, wherein the first portion connects to the third portion at a second transition point, the second transition point being at the smallest desired or offset-corrected spread angle within the range of desired or offset-corrected spread angles.
Claim 12 describes a piecewise compensation function with:
A first (middle) portion: a function relating spread angle to compensation value over a range.
A second (upper) portion: a constant maximum positive compensation at angles above the range.
A third (lower) portion: a constant maximum negative compensation at angles below the range.
This is a saturating piecewise compensation function — variable compensation in the middle range, clamped at maximum positive and maximum negative values at the extremes.
Au expressly teaches that the applied tension is limited to saturate at maximum and minimum values:
“function f3 limits the maximum and minimum values of tension T. Maximum tension TMAX and minimum tension TMIN can be set in the programming of control system 450.” Au ¶[0056].
Au further teaches that the tension computation produces values that vary with the position/velocity error (the first portion), but these values are clamped between TMIN and TMAX (the second and third portions). Au ¶[0056]; FIG. 5D. The transition from the variable region to the saturated region occurs at the position/velocity error values that produce TMAX (first transition point) and TMIN (second transition point).
This is the same piecewise structure recited in claim 12: a variable first portion connecting to a saturated second portion at a first transition point and to a saturated third portion at a second transition point.
It would have been obvious to implement the lost motion compensation function as a saturating piecewise function because: (1) Au expressly teaches clamping the computed tension between maximum and minimum values (¶[0056]); (2) saturation limits prevent damage to the instrument from excessive forces (Au ¶[0056]: “maximum tension TMAX should be set to avoid damage to the instrument”); (3) minimum tension limits prevent cable slack (Au ¶[0056]: “tension TMIN should be set to ensure that tendons … do not slack”); and (4) piecewise functions with saturation limits are the standard implementation of bounded compensation in servo control systems.
Claim 12 is obvious over Nixon in view of Lath and Au.
Regarding Claim 13 (Original)
Claim 13 recites:
The control system of claim 12, the control system being configured to: receive a request to increase the spread angle from a desired or offset-corrected spread angle within the range of desired or offset-corrected spread angles to an increased desired or offset-corrected spread angle within the range of desired or offset-corrected spread angles; approximate a lost motion compensation value for the increased desired or offset-corrected spread angle using the first portion of the lost motion compensation function; subsequently, receive a request to decrease the spread angle from the increased desired or offset-corrected spread angle to a decreased desired or offset-corrected spread angle within the range of desired or offset-corrected spread angles; and approximate a lost motion compensation value for the decreased desired or offset-corrected spread angle using the first portion of the lost motion compensation function.
Claim 13 describes operating within the variable (first) portion of the piecewise function: the surgeon requests an increase in spread angle (opening the jaws), the system computes compensation from the first portion; the surgeon then requests a decrease (closing the jaws), and the system again computes compensation from the first portion. Both requests remain within the range of the first portion — neither exceeds the saturation limits.
Au teaches that the tension computation is performed at each control cycle (250 Hz or more) in response to the continuously changing desired position from the surgeon’s input. Au ¶[0057]. During normal operation where the desired angle changes remain within the operating range, the computed tensions remain within the TMIN to TMAX bounds, and the variable first portion of the function is used for both increasing and decreasing angle commands. The system recalculates the compensation at each cycle regardless of direction.
It would have been obvious to use the first portion of the compensation function for both increasing and decreasing spread-angle requests within the operating range because: (1) within the unsaturated range, the variable compensation function applies by definition; (2) Au computes a new tension at every control cycle based on the current error, regardless of direction (¶[0057]); and (3) this is the standard behavior of a bounded linear compensation system operating within its unsaturated region.
Claim 13 is obvious over Nixon in view of Lath and Au.
Regarding Claim 15 (Original)
Claim 15 recites:
The control system of claim 12, wherein the lost motion compensation function is a piecewise function, in which: the first portion of the lost motion compensation function is a first sub-function of the piecewise function that relates desired or offset-corrected spread angle to lost motion compensation value for the range of desired or offset-corrected spread angles; the second portion of the lost motion compensation function is a second sub-function of the piecewise function that is representative of the maximum positive lost motion compensation value; and the first transition point of the lost motion compensation function is a first endpoint of the first sub-function that connects the first sub-function and the second sub-function.
Claim 15 further specifies that the compensation function is expressly a piecewise function with named sub-functions and a defined endpoint connecting them.
Au teaches the equivalent structure. The tension computation produces a variable value based on position/velocity error (the first sub-function), which is clamped at TMAX (the second sub-function representing the maximum positive value). The point at which the variable computation equals TMAX is the first endpoint connecting the two sub-functions. Au ¶[0056]; FIG. 5D.
This is precisely the piecewise function structure recited in claim 15, expressed in Au’s tension-control terminology.
It would have been obvious to implement the compensation as an explicit piecewise function with defined sub-functions and transition endpoints because: (1) Au teaches precisely this structure (variable computation clamped at maximum and minimum values); (2) piecewise functions are the standard mathematical implementation of bounded compensation in control systems; and (3) defining the transition endpoint
Examiner Note
V. ALLOWABLE SUBJECT MATTER
Claims 14 and 16 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter:
The prior art of record, taken alone or in combination, does not teach or suggest the specific additional limitations recited in claims 14 and 16 in combination with all limitations of their respective base claims. The closest prior art (Nixon, Lath, Au, Kamiya, Deane, Noonan) does not disclose or render obvious [the specific limitations of claims 14 and 16 — Examiner note: insert the specific distinguishing features of these claims when the exact text is confirmed].
CONCLUSION
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Mike Anderson
Supervisor Patent Examiner
Art Unit 3693
/Mike Anderson/Supervisory Patent Examiner, Art Unit 3693
