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 .
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-20 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
INDEPENDENT CLAIM 1 — UNCLEAR POSITIVE RECITATION OF THE SYSTEM
Claim 1 recites, “A system of auto-calibration is provided in a crossing gate mechanism, the crossing gate mechanism comprising,” followed by the recitation of a shaft, a gate arm, a gate-down buffer, a BLDC motor, a motor speed and position controller, an accelerometer, and a hall-sense position counter.
The claim is indefinite because it is unclear whether the claimed “system of auto-calibration” is the crossing gate mechanism itself, a subsystem within the crossing gate mechanism, or merely an intended function performed by the crossing gate mechanism. The preamble states that a system “is provided,” while the body recites that “the crossing gate mechanism” comprises the listed components. The claim does not clearly and positively recite what structural components constitute the claimed system, as distinguished from the crossing gate mechanism in which the system is allegedly provided.
Applicant may amend the claim to positively recite the claimed apparatus, for example, by stating that “a system for auto-calibration in a crossing gate mechanism comprises...” or that “a crossing gate mechanism comprising...” is configured to perform the claimed calibration operations.
INDEPENDENT CLAIM 1 — UNCLEAR FUNCTIONAL PHRASE “WHEREIN THE SYSTEM TO AUTO-CALIBRATE”
Claim 1 recites, “wherein the system to auto-calibrate the accelerometer and/or the hall-sense position counter when they are in disagreement due to temperature or due to some other phenomenon.”
The phrase is indefinite because it lacks a verb or other grammatical structure that clearly states a limitation. It is unclear whether the system is required to be configured to auto-calibrate, whether the system actually performs auto-calibration during operation, or whether the phrase merely states an intended purpose. Further, the phrase “they are in disagreement” lacks clear antecedent and comparison context because the immediately preceding objects are “the accelerometer and/or the hall-sense position counter.” An accelerometer is a physical sensor, whereas the hall-sense position counter produces or stores a counter value. The claim later compares a shaft angular position with a hall-sense position counter value, but the earlier phrase does not clearly identify which values are compared.
Applicant may amend the claim to recite, for example, “wherein the system is configured to compare a shaft angular position determined from the accelerometer with a hall-sense position counter value and, when the difference satisfies a re-homing threshold, re-home the gate arm...” with any appropriate threshold or detection condition supported by the specification.
INDEPENDENT CLAIM 1 — UNCLEAR PHRASE “DUE TO TEMPERATURE OR DUE TO SOME OTHER PHENOMENON”
Claim 1 recites that the accelerometer and/or hall-sense position counter are auto-calibrated “when they are in disagreement due to temperature or due to some other phenomenon.”
The phrase “some other phenomenon” renders the claim indefinite because it does not identify the type, source, or scope of the phenomenon that triggers the claimed auto-calibration. It is unclear whether the claim is limited to environmental drift, temperature drift, mechanical slippage, electrical noise, missed hall counts, accelerometer offset drift, shock, vibration, wear, or any other condition that could cause disagreement. The phrase therefore does not clearly inform one of ordinary skill in the art what conditions are within or outside the scope of the claimed triggering condition.
Applicant may amend the claim to recite the particular disagreement condition rather than an undefined cause, for example, by reciting that re-homing is triggered when a shaft angular position determined from the accelerometer differs from the hall-sense position counter value by a predetermined amount for a predetermined time period.
INDEPENDENT CLAIM 1 — UNCLEAR DETECTION OF THE GATE-DOWN BUFFER
Claim 1 recites that “the crossing gate mechanism lowers the gate arm until it detects the gate-down buffer,” and later recites that “the gate-down buffer is detected again to establish the home position.”
The claim is indefinite because it is unclear what structure performs the detecting, what signal or condition constitutes detection, and how a mechanical “gate-down buffer” is detected. The claim separately recites an accelerometer and a hall-sense position counter, but neither is expressly recited as detecting the gate-down buffer. The claim also does not recite a limit switch, current-sensing circuit, torque threshold, stall-detection operation, contact sensor, software condition, FPGA signal, or other mechanism for detecting the gate-down buffer. As a result, the metes and bounds of “detects the gate-down buffer” are unclear.
Applicant may amend the claim to identify the detecting structure and/or detection condition, for example, by reciting that the gate-down buffer is detected by contact, by motor stall, by a motor current threshold, by a gate-down signal, by a position tolerance signal, or by another expressly supported detection mechanism.
INDEPENDENT CLAIM 1 — UNCLEAR RE-HOMING CONDITION
Claim 1 recites, “if the shaft angular position disagrees substantially with a hall-sense position counter value, then it becomes necessary to re-establish the home position of the gate arm.”
The phrase “then it becomes necessary” does not positively recite what the system does. It is unclear whether the system automatically initiates re-homing, merely sets a re-home pending condition, stores a fault or flag, waits for a subsequent lowering operation, or only recognizes that re-homing should occur at some later time. The claim later recites that “when re-homing the gate arm, the next time the crossing gate mechanism lowers the gate arm,” the gate-down buffer is detected again, but the claim does not clearly recite the operative step or system configuration that transitions from detecting disagreement to performing re-homing.
Applicant may amend the claim to recite the operative control action, for example, by stating that the controller sets a re-home pending state when the disagreement satisfies a threshold and, during the next gate-lowering operation, detects the gate-down buffer and resets the shaft angular position and hall-sense position counter to zero.
INDEPENDENT CLAIM 11 — UNCLEAR METHOD RECITATION
Claim 11 recites, “A method of providing auto-calibration in a crossing gate mechanism, wherein the method comprising,” followed by steps of providing a shaft, providing a gate arm, providing a gate-down buffer, providing a BLDC motor, providing a motor speed and position controller, providing an accelerometer, and providing a hall-sense position counter.
The claim is indefinite because the phrase “wherein the method comprising” is grammatically incomplete, and the claim initially recites only steps of providing hardware components. It is unclear whether the claimed method is limited to providing the components, operating the crossing gate mechanism, lowering the gate arm, detecting the gate-down buffer, comparing the shaft angular position with the hall-sense position counter value, setting a re-home condition, and recalibrating values to zero, or some subset of those actions.
Applicant may amend the claim to positively recite the method steps that constitute the auto-calibration method, for example, “lowering,” “detecting,” “establishing,” “comparing,” “determining,” “setting a re-home condition,” and “resetting” or “calibrating” the relevant values.
Claim 11 is further indefinite for the same reasons discussed above with respect to claim 1 because claim 11 includes substantially the same unclear phrases: “wherein the method to auto-calibrate,” “they are in disagreement,” “due to some other phenomenon,” “detects the gate-down buffer,” “disagrees substantially,” and “then it becomes necessary to re-establish the home position.”
Dependent claims 2-10 depend from claim 1 and are indefinite at least because they incorporate the indefinite limitations of claim 1. Dependent claims 12-20 depend from claim 11 and are indefinite at least because they incorporate the indefinite limitations of claim 11.
Claim 2 recites, “wherein there is no need for a rotary encoder attached to the shaft, or for cam lobes to provide an electro-mechanical position of the shaft.”
Claim 12 recites the same limitation in method form.
The phrase “there is no need for” renders the claims indefinite because it is unclear whether the claims affirmatively exclude a rotary encoder and cam lobes, or merely state an intended advantage that such components are unnecessary. If the phrase is intended as a negative limitation, the claims should positively recite that the crossing gate mechanism lacks, excludes, or is without a rotary encoder and cam lobes. If the phrase is merely an advantage or intended result, it does not clearly limit the claimed system or method.
Applicant may amend the claims to clarify the intended scope, for example, by reciting “wherein the crossing gate mechanism does not include a rotary encoder attached to the shaft and does not include cam lobes configured to provide an electro-mechanical position of the shaft,” if supported and intended.
Claim 6 recites that “the accelerometer measures its own angular orientation in X, Y and Z angle values” and further recites that the accelerometer “reports changes in its angular orientation in X, Y and Z angle values.”
Claim 16 recites the same limitation in method form.
The phrase “X, Y and Z angle values” renders the claims indefinite because it is unclear whether the X, Y, and Z values are raw accelerometer-axis outputs, gravity-component readings, calculated orientation angles, or another type of value. The claim language states that the accelerometer measures “angular orientation” in X, Y, and Z “angle values,” while dependent claims 7 and 17 recite that a shaft angular position calculator converts the X, Y, and Z angle values into a single shaft angular position. If the X, Y, and Z values are already angular-orientation angle values, it is unclear what additional conversion is required. If they are raw accelerometer readings or gravity-component values, the claims should not identify them as “angle values” without clarification.
Claims 7 and 17 are indefinite because they depend from claims 6 and 16, respectively, and further rely on the unclear “X, Y and Z angle values” for conversion into a single shaft angular position.
Applicant may amend the claims to clarify whether the accelerometer outputs raw X, Y, and Z acceleration or gravity-component readings, and whether the CPU or shaft angular position calculator derives angular orientation or shaft angular position from those readings.
Claim 6 recites that “the accelerometer measures its own angular orientation in X, Y and Z angle values” and further recites that the accelerometer “reports changes in its angular orientation in X, Y and Z angle values.”
Claim 16 recites the same limitation in method form.
The phrase “X, Y and Z angle values” renders the claims indefinite because it is unclear whether the X, Y, and Z values are raw accelerometer-axis outputs, gravity-component readings, calculated orientation angles, or another type of value. The claim language states that the accelerometer measures “angular orientation” in X, Y, and Z “angle values,” while dependent claims 7 and 17 recite that a shaft angular position calculator converts the X, Y, and Z angle values into a single shaft angular position. If the X, Y, and Z values are already angular-orientation angle values, it is unclear what additional conversion is required. If they are raw accelerometer readings or gravity-component values, the claims should not identify them as “angle values” without clarification.
Claims 7 and 17 are indefinite because they depend from claims 6 and 16, respectively, and further rely on the unclear “X, Y and Z angle values” for conversion into a single shaft angular position.
Applicant may amend the claims to clarify whether the accelerometer outputs raw X, Y, and Z acceleration or gravity-component readings, and whether the CPU or shaft angular position calculator derives angular orientation or shaft angular position from those readings.
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph:
Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claims 2 and 12 are rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends.
Claims 2 and 12 recite that “there is no need for a rotary encoder attached to the shaft, or for cam lobes to provide an electro-mechanical position of the shaft.” This language, as presently drafted, states an intended advantage or lack of necessity rather than a structural or method limitation. Because the phrase does not clearly require the absence of a rotary encoder or cam lobes and does not otherwise specify a further limitation of the system of claim 1 or the method of claim 11, claims 2 and 12 fail to further limit the subject matter of the claims upon which they depend.
Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
REFERENCES USED
Reference 1: U.S. Patent Application Publication No. US 2024/0034370 A1.
Reference 2: U.S. Patent No. US 8,505,359 B2.
Reference 3: U.S. Patent Application Publication No. US 2014/0312178 A1.
Reference 4: U.S. Patent No. US 9,636,823 B2.
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.
Claims 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Reference 1 in view of Reference 2, Reference 3, and Reference 4.
Reference 1 is relied upon as the primary reference because Reference 1 is directed to a railroad crossing gate mechanism having a BLDC motor, Hall UVW signals, a Hall state encoder, a Hall-state-based position estimator/counter, a motor controller, and commutation of motor phases A, B, and C. Reference 2 is relied upon for an accelerometer or direction-sensitive sensor mounted on or coupled to a barrier arm or drive shaft to determine gate position and establish calibrated open/closed reference positions. Reference 3 is relied upon for a railroad crossing gate mechanism having a main shaft, gate arm, gate-down or horizontal buffer, and detection of the horizontal gate-down condition. Reference 4 is relied upon for the general motion-control teaching of comparing position values from multiple rotation/angle detectors and updating or recalibrating stored position information based on disagreement between the detector values.
The combination applies to the system claims 1-10 and the method claims 11-20 because the method claims substantially correspond to operation of the same structure recited in the system claims.
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Claim 1
A system of auto-calibration is provided in a crossing gate mechanism, the crossing gate mechanism comprising:
a shaft;
a gate arm;
a gate-down buffer;
a brushless DC (BLDC) motor;
a motor speed and position controller;
an accelerometer; and
a hall-sense position counter,
wherein the system to auto-calibrate the accelerometer and/or the hall-sense position counter when they are in disagreement due to temperature or due to some other phenomenon,
wherein after powering up, the crossing gate mechanism lowers the gate arm until it detects the gate-down buffer, which establishes a home position of the gate arm thus calibrating a shaft angular position to 0 degrees and the hall-sense position counter to 0 degrees,
wherein when the gate arm is raised to a “gate up” position, or lowered back to a “gate down” position, if the shaft angular position disagrees substantially with a hall-sense position counter value, then it becomes necessary to re-establish the home position of the gate arm, also called “re-homing” the gate arm, and
wherein when re-homing the gate arm, the next time the crossing gate mechanism lowers the gate arm, the gate-down buffer is detected again to establish the home position of the gate arm thus auto-calibrating the shaft angular position back to 0 degrees and the hall-sense position counter back to 0 degrees.
Analysis
Reference 1 discloses a railroad crossing gate mechanism 200 for controlling a crossing gate arm in a railroad crossing system 100. Reference 1’s crossing gate mechanism 200 includes an enclosure 210, gearing 212, electric motor 214, control unit 216, and printed circuit board 218. Reference 1 further discloses a motor controller 300 that controls the electric motor 214 to raise and lower crossing gate arms 132 and 142. Reference 1 therefore provides the primary crossing gate mechanism and control environment corresponding to the claimed crossing gate mechanism.
With respect to the claimed shaft, Reference 1 discloses that the motor in the gate control mechanism drives gearing connected to shafts that are connected to support arms for the gate arms. Reference 3 further expressly discloses a railroad crossing gate mechanism 150 having a main shaft 152 and a second shaft 154 connected through gearing 156 for raising and lowering gate arms 132 and 142. Reference 3’s main shaft 152 is the claimed shaft.
With respect to the claimed gate arm, Reference 1 discloses roadway gate arm 132 and pedestrian gate arm 142, each raised and lowered by the crossing gate mechanism 200. Reference 3 similarly discloses roadway gate arm 132 and pedestrian gate arm 142. Either Reference 1’s gate arm 132 or Reference 3’s gate arm 132 corresponds to the claimed gate arm.
With respect to the claimed gate-down buffer, Reference 3 discloses an adjustable spring buffer 166 that sets the final horizontal position of the gate arms. In the context of the claim, the gate-down position corresponds to the horizontal lowered position of the gate arm. Reference 3’s adjustable spring buffer 166 functions as a mechanical buffer/stop at the final lowered horizontal gate position and therefore corresponds to the claimed gate-down buffer.
With respect to the claimed brushless DC (BLDC) motor, Reference 1 discloses that electric motor 214 is a brushless DC motor and that the BLDC motor includes Hall effect sensors. Reference 1’s BLDC motor 214 corresponds to the claimed BLDC motor.
With respect to the claimed motor speed and position controller, Reference 1 discloses motor controller 300 including Gate Control State Machine 316, Position PID Controller 318, Speed PID Controller 320, Scale Desired Speed logic 322, and Commutator 324. Position PID Controller 318 uses the actual position from Position Estimator 308, Speed PID Controller 320 controls desired speed, and Commutator 324 controls the phases of the BLDC motor. Reference 1’s motor controller 300 therefore corresponds to the claimed motor speed and position controller.
With respect to the claimed accelerometer, Reference 2 discloses a position-determining sensor for a movable barrier or gate, including accelerometer-based sensing to determine the gate position or tilt of the barrier. Reference 2 teaches that an accelerometer or direction-sensitive sensor may be mounted relative to the movable barrier, including on the barrier arm or on a drive shaft directly connected to the barrier arm, such that movement of the barrier or shaft is translated into sensed position or angular displacement. Reference 2’s accelerometer-based gate-position sensing corresponds to the claimed accelerometer.
With respect to the claimed hall-sense position counter, Reference 1 discloses Hall UVW input signals 302 from the BLDC motor, Hall UVW Debounce 304, Hall State Encoder 306, and Position Estimator 308. Reference 1’s Position Estimator 308 counts Hall states and increments or decrements the actual gate-arm position depending on the detected Hall-state sequence and motor direction. Reference 1’s Hall State Encoder 306 and Position Estimator 308 together correspond to the claimed hall-sense position counter because they receive Hall sensor information and maintain a counted position value for the gate arm.
With respect to the limitation that the system auto-calibrates the accelerometer and/or the hall-sense position counter when they are in disagreement due to temperature or some other phenomenon, Reference 1 teaches that the actual position determined from Hall states is reset to avoid accumulating positional error. Reference 2 teaches using an independent accelerometer or direction-sensitive gate-position sensor to determine gate position and to calibrate reference open and closed positions. Reference 4 teaches a motion-control arrangement having plural rotation-angle detectors, including a first detector and a second detector, and a control unit that compares detected angle values and updates stored position information based on the relationship between the detected values. In the combined system, the accelerometer-derived shaft angular position from Reference 2 is an independent position value, and Reference 1’s Hall-state Position Estimator 308 provides a Hall-derived counter value. Reference 4 provides the teaching of comparing multiple detector-derived angle or position values and updating or recalibrating stored position information when the values indicate disagreement. Accordingly, it would have been obvious to configure Reference 1’s motor controller 300 to compare the accelerometer-derived shaft angular position with the Hall-derived position counter value and, when the values disagree beyond an acceptable tolerance, initiate re-homing and recalibration.
With respect to the limitation that, after powering up, the crossing gate mechanism lowers the gate arm until it detects the gate-down buffer, thereby establishing a home position and calibrating the shaft angular position and hall-sense counter to zero degrees, Reference 1 teaches resetting actual position information to avoid accumulating positional error, and Reference 2 teaches that gate-position systems may require reference open or closed positions because position information can be lost or require calibration after power interruption. Reference 3 teaches that horizontal buffer 166 establishes the final horizontal position of the gate arm and that the horizontal gate condition may be detected using a gate tip sensor 180 or horizontal detector 520. In the combined system, after power-up, the controller lowers the gate arm toward the known gate-down position, detects that the gate arm has reached the buffered horizontal gate-down position established by buffer 166, and uses that known physical end position as the home position. Reference 2’s lower closed position is a zero-degree reference, and Reference 1’s Position Estimator 308 may be reset at such reference position. The combination therefore teaches or renders obvious calibrating the shaft angular position to 0 degrees and resetting the Hall-derived counter value to 0 degrees at the detected home position.
With respect to the limitation that, when the gate arm is raised to a gate-up position or lowered to a gate-down position, if the shaft angular position disagrees substantially with the hall-sense position counter value, it becomes necessary to re-establish the home position, Reference 1 teaches raising and lowering the crossing gate arm and maintaining an actual gate position by counting Hall states. Reference 2 teaches an independent gate position/tilt measurement. Reference 4 teaches comparison of multiple detected angle values and position updating based on detected differences. A person of ordinary skill in the art would have understood that if Reference 1’s Hall-state Position Estimator 308 no longer agrees with the independent accelerometer-derived shaft angular position, the Hall count, accelerometer calibration, or both may be unreliable. The predictable correction is to re-establish the known physical home position at the next available gate-down movement and reset the stored values.
With respect to the limitation that, when re-homing the gate arm, the next time the crossing gate mechanism lowers the gate arm, the gate-down buffer is detected again to establish the home position, thereby auto-calibrating the shaft angular position and hall-sense position counter back to zero degrees, Reference 1 teaches that the position estimate may be reset at the bottom position to avoid accumulated error. Reference 3 teaches that buffer 166 establishes the final horizontal gate-down position and that the horizontal gate condition may be detected by gate tip sensor 180 or horizontal detector 520. Reference 2 teaches use of calibrated reference positions, including the lower closed position as a reference. Reference 4 teaches updating stored angle/position information based on comparison of multiple detector values. Thus, in the combined system, when a discrepancy is detected, the controller waits for or uses the next lowering operation, detects the gate-down physical reference established by buffer 166, and resets both the accelerometer-derived shaft angle reference and Reference 1’s Hall-state Position Estimator 308 counter value to zero.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious every limitation of claim 1.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to modify Reference 1’s BLDC Hall-state crossing gate mechanism 200, 214, 300, 302, 306, and 308 to include Reference 2’s accelerometer-based gate-position sensing because Reference 1 already maintains gate position from Hall states and Reference 2 teaches an independent way to determine gate position or shaft/barrier angular displacement. The modification would provide redundant and independent gate-position verification without requiring a separate rotary encoder, thereby improving reliability in a safety-critical railroad crossing gate environment.
It would have been further obvious to use Reference 3’s horizontal buffer 166 and horizontal detection arrangement, such as gate tip sensor 180 or horizontal detector 520, as the physical home reference because Reference 1 resets position information to avoid accumulated error, and Reference 3 provides a repeatable railroad crossing gate-down mechanical reference. Using the known gate-down mechanical stop as a zero-degree reference is a predictable control technique for eliminating accumulated Hall-count or sensor-position drift.
It would have been further obvious to apply Reference 4’s teaching of comparing multiple angle detector values and updating stored position information when the values indicate disagreement because the combined Reference 1/Reference 2 system includes two independently obtained position values: a Hall-count-derived value from Reference 1’s Position Estimator 308 and an accelerometer-derived gate/shaft angle from Reference 2. Comparing the two values and re-homing when they diverge would predictably improve positional accuracy and fault tolerance.
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Claim 2
The system of claim 1, wherein there is no need for a rotary encoder attached to the shaft, or for cam lobes to provide an electro-mechanical position of the shaft.
Analysis
Reference 1 discloses determining gate-arm position using the BLDC motor’s Hall UVW signals 302, Hall State Encoder 306, and Position Estimator 308. Reference 1’s Position Estimator 308 counts Hall states to determine actual gate position, thereby avoiding the need for a separate rotary encoder attached to the shaft.
Reference 1 also teaches digital BLDC control using Hall signals and control logic rather than conventional mechanical cam-based arrangements. Reference 2 likewise teaches accelerometer-based or direction-sensitive gate-position sensing, which provides position information without requiring cam lobes to provide an electro-mechanical shaft position. In the combined system, the Hall-state Position Estimator 308 and Reference 2’s accelerometer-derived shaft angular position provide position information electronically, and Reference 3’s gate-down buffer 166 provides a physical home reference. The system therefore does not require a rotary encoder attached to the shaft or cam lobes to provide an electro-mechanical shaft position.
To the extent Reference 3 discloses cam 164 and contact 162 as one possible horizontal detector, Reference 3 also discloses gate tip sensor 180 and horizontal detector 520 for detecting the horizontal gate condition. For claim 2, the combination relies on Reference 1’s Hall-state counting and Reference 2’s accelerometer-based sensing for shaft/gate position, and on Reference 3’s buffer 166 as the mechanical home reference, without requiring cam lobes to provide electro-mechanical shaft position.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 2.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to implement the combined system without a rotary encoder or cam lobes for electro-mechanical shaft-position determination because Reference 1’s Hall UVW signals 302, Hall State Encoder 306, and Position Estimator 308 already provide motor/gate position information, and Reference 2’s accelerometer-based sensing provides independent gate-position information. Eliminating separate encoders and cam-based position mechanisms would reduce mechanical wear, simplify installation, reduce maintenance, and improve reliability while retaining position feedback.
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Claim 3
The system of claim 1, wherein the gate arm is lowered by the crossing gate mechanism as a barrier to track-crossing traffic when a train is either approaching or passing.
Analysis
Reference 1 discloses railroad crossing gate system 100, including crossing gate arms 132 and 142 controlled by crossing gate mechanism 200. Reference 1 teaches that the crossing gate mechanism lowers the gate arms to restrict roadway and pedestrian traffic when a train is approaching or passing and raises the arms after the train has passed.
Reference 3 similarly discloses railroad crossing gate mechanism 150 that lowers gate arms 132 and 142 to restrict traffic and pedestrians at a railroad crossing. Therefore, the combined system teaches the gate arm being lowered by the crossing gate mechanism as a barrier to track-crossing traffic when a train is approaching or passing.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 3.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use Reference 1’s crossing gate mechanism 200 to lower the gate arm as a barrier to track-crossing traffic because that is the intended and expressly taught function of a railroad crossing gate mechanism. Applying the auto-calibration arrangement to that conventional crossing-gate operation would ensure that the safety barrier reaches and is accurately detected at its intended gate-down and gate-up positions during train approach and passage events.
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Claim 4
The system of claim 1, wherein the gate-down buffer is installed as a mechanical stop within the crossing gate mechanism to establish a 0-degree “gate down” position for the gate arm.
Analysis
Reference 3 discloses adjustable spring buffer 166 within railroad crossing gate mechanism 150. Buffer 166 sets the final horizontal position of gate arms 132 and 142. The horizontal lowered position of a crossing gate arm corresponds to the gate-down position.
Reference 2 teaches that the lower closed position of a barrier can be used as a zero-degree reference, with the upper open position being approximately ninety degrees. Reference 1 teaches that actual position information may be reset to avoid accumulated positional error. In the combined system, Reference 3’s buffer 166 is installed as the mechanical stop establishing the repeatable gate-down physical reference, and Reference 2’s zero-degree lower closed reference is applied to that buffered gate-down position. Reference 1’s Position Estimator 308 is then reset at that known reference.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 4.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use Reference 3’s buffer 166 as the mechanical stop establishing the zero-degree gate-down position because a physical stop provides a repeatable reference position for calibration. Using a fixed gate-down mechanical reference would predictably improve the reliability of Reference 1’s Hall-state position estimate and Reference 2’s accelerometer-derived angle reference by anchoring both to the same physical end position.
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Claim 5
The system of claim 1, wherein the shaft is within the crossing gate mechanism and holds the gate arm at one end.
Analysis
Reference 1 discloses that the gate control mechanism drives gearing connected to shafts connected to support arms for gate arms 132 and 142. The gate arms are raised and lowered by the crossing gate mechanism through the shaft/support-arm drive arrangement.
Reference 3 more expressly discloses main shaft 152 within gate mechanism 150, with gearing 156 and support arms 134 and 144 coupled to gate arms 132 and 142. Main shaft 152 transmits motion to the gate arm through the support arm at one end of the gate arm. Thus, Reference 3’s main shaft 152 within the crossing gate mechanism corresponds to the claimed shaft that holds the gate arm at one end.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 5.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use a shaft within the crossing gate mechanism to support and rotate the gate arm at one end because both Reference 1 and Reference 3 use shaft-driven support arms to raise and lower railroad crossing gate arms. This arrangement is a conventional and predictable way to transmit torque from the motor and gearing to the gate arm.
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Claim 6
The system of claim 1, wherein the accelerometer measures its own angular orientation in X, Y and Z angle values such that the accelerometer is mounted on the shaft so that when the shaft rotates to raise or lower the gate arm, the accelerometer also moves and reports changes in its angular orientation in X, Y and Z angle values.
Analysis
Reference 2 discloses a direction-sensitive or accelerometer-based position sensor for determining the position of a movable barrier or gate. Reference 2 teaches that sensor output may be used to determine the tilt or angular displacement of the gate and that accelerometers may provide multi-axis data. Reference 2 also teaches that the sensor may be mounted on the barrier arm or on a drive shaft directly connected to the barrier arm.
In the combined system, Reference 2’s accelerometer is mounted on Reference 3’s main shaft 152 or on the shaft/support-arm structure driven by Reference 1’s gate mechanism. When Reference 1’s BLDC motor 214 rotates the shaft to raise or lower gate arm 132, the accelerometer mounted on the shaft rotates with the shaft. As the accelerometer rotates, it senses changes in its orientation relative to gravity or other sensed axes and provides multi-axis orientation-related values. These sensed values correspond to the claimed X, Y, and Z angle values under the broadest reasonable interpretation of the claim.
Reference 1 supplies the BLDC-driven shaft movement and motor controller 300, Reference 3 supplies the explicit railroad crossing gate shaft 152 and gate arm 132, and Reference 2 supplies the accelerometer mounted on the barrier arm or drive shaft for determining angular position. The combined system therefore teaches the accelerometer mounted on the shaft such that shaft rotation causes the accelerometer to move and report changes in angular orientation.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 6.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to mount Reference 2’s accelerometer-based position sensor on the shaft of the Reference 1/Reference 3 crossing gate mechanism because the shaft rotates with the gate arm and therefore provides a direct measurement location for determining gate-arm angular position. Mounting the sensor on the rotating shaft would reduce indirect measurement error, provide a compact installation inside the mechanism, and allow the controller to compare shaft-angle data with Reference 1’s Hall-state position estimate.
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Claim 7
The system of claim 6, wherein a shaft angular position calculator is software run by a Central Processing Unit (CPU) that converts the X, Y and Z angle values into a single shaft angular position.
Analysis
Reference 1 discloses motor controller 300, which may be implemented using programmable digital control hardware, including a CPU or comparable processing logic. Reference 1’s controller 300 processes Hall UVW signals 302, determines motor direction through Hall State Encoder 306, maintains position using Position Estimator 308, and controls motor operation through Position PID Controller 318, Speed PID Controller 320, and Commutator 324.
Reference 2 teaches that accelerometer or direction-sensitive sensor output is provided to a controller or microcontroller to determine the gate position or tilt of the gate. The accelerometer-derived multi-axis values are processed to determine a single gate position or angular displacement.
In the combined system, the CPU or processor of Reference 1’s motor controller 300 executes software that receives Reference 2’s X, Y, and Z orientation-related accelerometer values and converts those values into a single shaft angular position. That software function corresponds to the claimed shaft angular position calculator. The single shaft angular position is then available for comparison with Reference 1’s Hall-state Position Estimator 308 counter value and for recalibration at the zero-degree home position.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 7.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to implement the shaft angular position calculator in software executed by a CPU because Reference 1’s motor controller 300 already performs digital signal processing and motor-control functions, and Reference 2’s accelerometer output requires processing to determine gate position. Software implementation would allow calibration constants, tolerance thresholds, filtering, and re-homing logic to be updated without changing mechanical hardware.
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Claim 8
The system of claim 1, wherein the brushless DC motor is a driving force that rotates the shaft and thereby raises or lowers the gate arm.
Analysis
Reference 1 discloses electric motor 214 as a BLDC motor used in crossing gate mechanism 200. Reference 1’s BLDC motor drives gearing 212 to move the crossing gate arm between raised and lowered positions. Reference 1 therefore teaches the BLDC motor as the driving force for raising and lowering the gate arm.
Reference 3 discloses motor/braking assembly 158 and gearing 156 coupled to main shaft 152 to rotate the shaft and move gate arms 132 and 142. In the combined system, Reference 1’s BLDC motor 214 is used as the motor within Reference 3’s shaft-driven gate mechanism 150, thereby rotating shaft 152 and raising or lowering gate arm 132.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 8.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use Reference 1’s BLDC motor 214 as the driving force for rotating the gate shaft because Reference 1 expressly teaches BLDC control for raising and lowering railroad crossing gates, and Reference 3’s shaft-and-gearing structure provides the ordinary mechanical path between the motor and gate arm. The combination predictably provides controlled gate movement with reduced mechanical wear relative to older drive arrangements.
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Claim 9
The system of claim 1, wherein the brushless DC motor sends U, V and W hall sense input signals to the hall-sense position counter to increment or decrement that counter when the gate arm is raised or lowered by the brushless DC motor.
Analysis
Reference 1 discloses Hall UVW input signals 302 from the BLDC motor 214. Reference 1’s Hall UVW signals 302 are debounced by Hall UVW Debounce 304 and processed by Hall State Encoder 306. Reference 1’s Position Estimator 308 counts Hall states to determine actual gate-arm position.
Reference 1 further teaches that the Position Estimator 308 increments or decrements the position count depending on the detected Hall-state sequence and direction of motion. When the gate arm is moving up, the position count changes in one direction; when the gate arm is moving down, the count changes in the opposite direction. Thus, Reference 1’s BLDC motor 214 sends U, V, and W Hall sense input signals 302 to Hall State Encoder 306 and Position Estimator 308, which together form the hall-sense position counter that increments or decrements when the gate arm is raised or lowered.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 9.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use the BLDC motor’s U, V, and W Hall sense input signals to increment or decrement the position counter because Reference 1’s motor already includes Hall sensors used for commutation and direction detection. Reusing those same Hall signals for position counting reduces the need for separate sensors while providing a direct measure of motor rotation associated with gate-arm movement.
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Claim 10
The system of claim 9, wherein the motor speed and position controller uses a counter value from the hall-sense position counter to drive the A, B and C winding output signals to rotate the brushless DC motor.
Analysis
Reference 1 discloses that Position Estimator 308 provides an actual position value based on counted Hall states. Reference 1’s Position PID Controller 318 compares the actual position from Position Estimator 308 with a desired position, and Speed PID Controller 320 controls motor speed. Reference 1’s Commutator 324 uses Hall-state information to activate phase outputs to the BLDC motor.
Reference 1 further discloses commutation of motor phases A, B, and C based on the Hall-state sequence and controller output. The Hall-state-derived position counter value from Position Estimator 308 is used in the position-control loop to determine how the motor should be driven, and the commutator 324 drives the motor phases A, B, and C to rotate BLDC motor 214. Thus, Reference 1 teaches the motor speed and position controller using the Hall-derived counter value to drive A, B, and C winding output signals to rotate the BLDC motor.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 10.
Motivation
It would have been obvious for the controller to use the Hall-derived position counter value in driving the A, B, and C windings because Reference 1’s BLDC controller 300 already uses Hall state and position information in the position and speed control loops and then commutates the motor phases. This is the predictable control architecture for a BLDC motor in which Hall feedback supports both position tracking and proper phase energization.
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Claim 11
A method of providing auto-calibration in a crossing gate mechanism, wherein the method comprising:
providing a shaft;
providing a gate arm;
providing a gate-down buffer;
providing a brushless DC (BLDC) motor;
providing a motor speed and position controller;
providing an accelerometer; and
providing a hall-sense position counter,
wherein the method to auto-calibrate the accelerometer and/or the hall-sense position counter when they are in disagreement due to temperature or due to some other phenomenon,
wherein after powering up, the crossing gate mechanism lowers the gate arm until it detects the gate-down buffer, which establishes a home position of the gate arm thus calibrating a shaft angular position to 0 degrees and the hall-sense position counter to 0 degrees,
wherein when the gate arm is raised to a “gate up” position, or lowered back to a “gate down” position, if the shaft angular position disagrees substantially with a hall-sense position counter value, then it becomes necessary to re-establish the home position of the gate arm, also called “re-homing” the gate arm, and
wherein when re-homing the gate arm, the next time the crossing gate mechanism lowers the gate arm, the gate-down buffer is detected again to establish the home position of the gate arm thus auto-calibrating the shaft angular position back to 0 degrees and the hall-sense position counter back to 0 degrees.
Analysis
Reference 1 discloses operating a railroad crossing gate mechanism 200 by controlling BLDC motor 214 with motor controller 300 to raise and lower gate arms 132 and 142. Reference 1’s method includes receiving Hall UVW signals 302, determining Hall state and direction using Hall State Encoder 306, counting position using Position Estimator 308, controlling speed and position using Position PID Controller 318 and Speed PID Controller 320, and commutating the motor phases through Commutator 324.
With respect to providing a shaft, Reference 1 discloses shafts connected through gearing to gate support arms, and Reference 3 expressly discloses main shaft 152 within crossing gate mechanism 150.
With respect to providing a gate arm, Reference 1 discloses gate arms 132 and 142, and Reference 3 likewise discloses gate arms 132 and 142.
With respect to providing a gate-down buffer, Reference 3 discloses adjustable spring buffer 166, which sets the final horizontal gate-down position of the gate arms.
With respect to providing a BLDC motor, Reference 1 discloses BLDC motor 214.
With respect to providing a motor speed and position controller, Reference 1 discloses motor controller 300, including Gate Control State Machine 316, Position PID Controller 318, Speed PID Controller 320, Scale Desired Speed logic 322, and Commutator 324.
With respect to providing an accelerometer, Reference 2 discloses an accelerometer-based or direction-sensitive gate-position sensor mounted on or coupled to the movable barrier or drive shaft for determining gate position or tilt.
With respect to providing a hall-sense position counter, Reference 1 discloses Hall UVW input signals 302, Hall State Encoder 306, and Position Estimator 308, wherein Position Estimator 308 counts Hall states and increments or decrements gate-arm position based on motion direction.
With respect to the method auto-calibrating the accelerometer and/or hall-sense position counter when they are in disagreement due to temperature or some other phenomenon, the combined method uses Reference 2’s accelerometer-derived shaft or gate angular position as an independent position measurement and Reference 1’s Hall-state Position Estimator 308 as a Hall-derived counter value. Reference 4 teaches comparing position values from multiple detectors and updating stored position information based on disagreement between detected values. Reference 1 further teaches resetting actual position information to avoid accumulated error. Thus, the combined method compares the accelerometer-derived shaft angular position with the Hall-derived counter value and re-homes when the values disagree beyond an acceptable threshold.
With respect to the step in which, after powering up, the crossing gate mechanism lowers the gate arm until it detects the gate-down buffer, Reference 1 teaches lowering the gate arm using BLDC motor 214 and controller 300, and Reference 2 teaches the need to establish calibrated reference positions after position uncertainty or power interruption. Reference 3 teaches the horizontal gate-down physical reference established by buffer 166 and detection of the horizontal gate condition using gate tip sensor 180 or horizontal detector 520. In the combined method, after power-up the controller lowers the gate arm to the gate-down buffered position, detects the known gate-down condition associated with buffer 166, and sets the accelerometer-derived shaft angular position and Reference 1’s Hall-state Position Estimator 308 counter value to zero.
With respect to the step in which disagreement between the shaft angular position and hall-sense position counter value makes it necessary to re-home the gate arm, Reference 1 provides the Hall-state counter value, Reference 2 provides the shaft angular position from the accelerometer, and Reference 4 teaches detecting disagreement between detector-derived position values and updating stored position information. Thus, when the accelerometer-derived shaft angular position and Reference 1’s Hall-state Position Estimator 308 disagree substantially, the combined method determines that the home reference should be re-established.
With respect to the step in which, when re-homing the gate arm, the next lowering of the gate arm detects the gate-down buffer again and recalibrates both values to zero, Reference 1 teaches resetting the actual position to avoid accumulated positional error, Reference 3 teaches the repeatable horizontal buffer 166 and detection of the horizontal gate condition, and Reference 2 teaches use of the lower closed position as a zero-degree reference. Therefore, the combined method performs re-homing by again detecting the buffered gate-down position and resetting the shaft angular position and Hall-derived counter to zero.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious every limitation of claim 11.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to operate Reference 1’s BLDC Hall-state crossing gate mechanism according to Reference 2’s accelerometer-based gate-position sensing, Reference 3’s buffered gate-down reference, and Reference 4’s detector-comparison/update technique because the combined method uses known and complementary position-sensing techniques to solve the predictable problem of accumulated position error. Reference 1 already counts Hall states and resets position to avoid error, Reference 2 provides independent gate-position feedback, Reference 3 provides a repeatable gate-down physical reference, and Reference 4 teaches comparing multiple detector values and updating stored position information. The result would be a predictable method of re-homing a railroad crossing gate at a known physical zero-degree position when redundant position values disagree.
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Claim 12
The method of claim 11, wherein there is no need for a rotary encoder attached to the shaft, or for cam lobes to provide an electro-mechanical position of the shaft.
Analysis
Reference 1’s method determines gate-arm position from Hall UVW signals 302 using Hall State Encoder 306 and Position Estimator 308. The Position Estimator 308 counts Hall states to track gate-arm position, eliminating the need for a separate rotary encoder attached to the shaft.
Reference 2’s method uses accelerometer-based or direction-sensitive sensing to determine gate position or tilt, also avoiding the need for cam lobes to provide electro-mechanical shaft position. In the combined method, shaft position is obtained from the Hall-state counter and accelerometer-derived angular position, while Reference 3’s buffer 166 supplies the physical gate-down home reference. Therefore, the method does not require a rotary encoder attached to the shaft or cam lobes to provide an electro-mechanical position of the shaft.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 12.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to perform the method without a shaft-mounted rotary encoder or cam-lobe electro-mechanical shaft-position system because Reference 1’s Hall-state Position Estimator 308 and Reference 2’s accelerometer-based position sensing already provide position information. Avoiding encoders and cam-lobe position mechanisms would simplify the crossing gate mechanism and reduce wear-prone mechanical parts while preserving position feedback and calibration capability.
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Claim 13
The method of claim 11, wherein the gate arm is lowered by the crossing gate mechanism as a barrier to track-crossing traffic when a train is either approaching or passing.
Analysis
Reference 1 discloses operating crossing gate mechanism 200 to lower gate arms 132 and 142 as barriers to roadway and pedestrian traffic when a train approaches or passes. Reference 3 likewise discloses railroad crossing gate mechanism 150 lowering gate arms 132 and 142 to restrict traffic until the train has passed.
The combined method therefore includes lowering the gate arm by the crossing gate mechanism as a barrier to track-crossing traffic when a train is approaching or passing.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 13.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to apply the auto-calibration method during ordinary train-approach and train-passage gate operation because Reference 1 and Reference 3 are directed to railroad crossing gates whose fundamental safety function is to lower the gate arm as a traffic barrier. Accurate re-homing and position calibration would improve confidence that the gate arm has reached the intended safe barrier position.
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Claim 14
The method of claim 11, wherein the gate-down buffer is installed as a mechanical stop within the crossing gate mechanism to establish a 0-degree “gate down” position for the gate arm.
Analysis
Reference 3 discloses adjustable spring buffer 166 within crossing gate mechanism 150. Buffer 166 sets the final horizontal position of the gate arms, which corresponds to the gate-down position. Reference 2 teaches using the lower closed position as a zero-degree reference for gate position, and Reference 1 teaches resetting position information to avoid accumulated positional error.
In the combined method, Reference 3’s buffer 166 is installed as the mechanical stop defining the gate-down home position. When the gate arm reaches the buffered horizontal position, the method establishes that position as zero degrees and resets the shaft angular position and Hall-state counter to zero.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 14.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use Reference 3’s buffer 166 as the zero-degree gate-down mechanical stop because a repeatable mechanical end position provides a reliable physical calibration reference. This would allow Reference 1’s Hall-state counter and Reference 2’s accelerometer-derived angular position to be reset to a common known position each time re-homing occurs.
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Claim 15
The method of claim 11, wherein the shaft is within the crossing gate mechanism and holds the gate arm at one end.
Analysis
Reference 1 discloses operating a gate mechanism in which a motor drives gearing connected to shafts and support arms for the gate arms. Reference 3 expressly discloses main shaft 152 within crossing gate mechanism 150, with support arms 134 and 144 connected to gate arms 132 and 142. The shaft/support-arm arrangement supports and rotates the gate arm at one end.
The combined method therefore provides and uses a shaft within the crossing gate mechanism that holds and rotates the gate arm at one end.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 15.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to provide the shaft within the crossing gate mechanism and hold the gate arm at one end because that arrangement is the conventional mechanical configuration used by Reference 1 and Reference 3 to transmit motor torque to a crossing gate arm. The shaft location also provides a practical mounting point for Reference 2’s accelerometer when shaft angular position is to be measured.
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Claim 16
The method of claim 11, wherein the accelerometer measures its own angular orientation in X, Y and Z angle values such that the accelerometer is mounted on the shaft so that when the shaft rotates to raise or lower the gate arm, the accelerometer also moves and reports changes in its angular orientation in X, Y and Z angle values.
Analysis
Reference 2 teaches using an accelerometer-based or direction-sensitive sensor to determine gate position or tilt. Reference 2 further teaches that the sensor may be mounted on the barrier arm or on a drive shaft directly connected to the barrier arm. Such mounting causes the sensor to move as the barrier or shaft moves.
In the combined method, Reference 2’s accelerometer is mounted on Reference 3’s main shaft 152 or on the shaft driven by Reference 1’s BLDC crossing gate mechanism. When Reference 1’s BLDC motor 214 rotates the shaft to raise or lower the gate arm, the accelerometer rotates with the shaft and reports changes in its orientation. The multi-axis orientation-related values reported by the accelerometer correspond to the claimed X, Y, and Z angle values under the broadest reasonable interpretation of the claim.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 16.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to mount the accelerometer on the shaft so that it moves with shaft rotation because the shaft directly corresponds to the angular position of the gate arm. This placement would provide a direct and compact measurement of shaft/gate angular position for comparison against Reference 1’s Hall-state counter value.
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Claim 17
The method of claim 16, wherein a shaft angular position calculator is software run by a Central Processing Unit (CPU) that converts the X, Y and Z angle values into a single shaft angular position.
Analysis
Reference 1’s motor controller 300 may be implemented using programmable processing logic, including CPU-type control hardware, and performs digital position and speed control using Hall-derived position information. Reference 2 teaches providing accelerometer or direction-sensitive sensor output to control circuitry or a microcontroller to determine gate position or angular displacement.
In the combined method, software executed by the CPU or processor of Reference 1’s controller 300 receives the X, Y, and Z accelerometer orientation-related values from Reference 2’s sensor and converts those values into a single shaft angular position. This calculated shaft angular position is then compared with Reference 1’s Hall-state Position Estimator 308 counter value and is reset to zero during re-homing.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 17.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to perform the conversion in CPU-executed software because Reference 1’s controller 300 already processes digital feedback signals and controls motor operation, and Reference 2’s accelerometer-derived values require calculation to produce a usable gate or shaft angle. Software calculation would allow flexible calibration, filtering, tolerance checking, and re-homing logic without adding separate mechanical position hardware.
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Claim 18
The method of claim 11, wherein the brushless DC motor is a driving force that rotates the shaft and thereby raises or lowers the gate arm.
Analysis
Reference 1 discloses BLDC motor 214 as the motor used to raise and lower the crossing gate arm through the crossing gate mechanism 200. Reference 3 discloses motor/braking assembly 158 and gearing 156 that rotate main shaft 152 to raise and lower gate arms 132 and 142.
In the combined method, Reference 1’s BLDC motor 214 provides the driving force in Reference 3’s shaft-driven crossing gate mechanism, thereby rotating shaft 152 and raising or lowering the gate arm.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 18.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use the BLDC motor as the driving force for the shaft because Reference 1 expressly teaches a BLDC crossing gate motor and Reference 3 teaches a shaft-driven gate mechanism. The combination predictably provides controlled motorized rotation of the gate shaft and controlled raising/lowering of the gate arm.
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Claim 19
The method of claim 11, wherein the brushless DC motor sends U, V and W hall sense input signals to the hall-sense position counter to increment or decrement that counter when the gate arm is raised or lowered by the brushless DC motor.
Analysis
Reference 1 discloses that BLDC motor 214 sends Hall UVW input signals 302. The signals are processed by Hall UVW Debounce 304 and Hall State Encoder 306. Reference 1’s Position Estimator 308 counts Hall states to determine actual gate-arm position.
Reference 1 further teaches incrementing or decrementing the position count depending on the detected Hall-state order and the direction of gate-arm movement. Thus, when the BLDC motor raises or lowers the gate arm, the U, V, and W Hall signals are used by the Hall-state position counter to increment or decrement the counter.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 19.
Motivation
It would have been obvious to one of ordinary skill in the art, before the effective filling date of the claimed invention, to use U, V, and W Hall sense input signals to increment or decrement the position counter because those signals are already available in Reference 1’s BLDC motor control system and inherently indicate motor rotation state and direction. Using them for counting position would reduce additional sensing hardware and integrate naturally with BLDC commutation.
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Claim 20
The method of claim 19, wherein the motor speed and position controller uses a counter value from the hall-sense position counter to drive the A, B and C winding output signals to rotate the brushless DC motor.
Analysis
Reference 1 discloses that Position Estimator 308 supplies an actual position value derived from counted Hall states. Reference 1’s Position PID Controller 318 uses the position value in the position-control loop, and Speed PID Controller 320 controls motor speed. Reference 1’s Commutator 324 uses Hall-state information and controller output to energize the BLDC motor phases.
Reference 1 further discloses that the BLDC motor phases A, B, and C are driven according to the commutation sequence. Thus, Reference 1’s motor speed and position controller 300 uses the Hall-derived counter value in controlling motor operation and drives the A, B, and C winding outputs to rotate BLDC motor 214.
Accordingly, Reference 1 in view of Reference 2, Reference 3, and Reference 4 teaches or renders obvious the additional limitation of claim 20.
Motivation
It would have been obvious for the controller to use the Hall-derived counter value to drive the A, B, and C windings because Reference 1’s controller 300 already uses Hall state and position information for position and speed control and then commutates the BLDC phases. This is a predictable BLDC control arrangement in which the same Hall feedback supports both position tracking and motor phase energization.
CONCLUSION
Additional patent art located during searching was considered but not used in the rejection. Older grade-crossing gate patent publications were relevant because they disclose railroad crossing gates, motor-driven shafts, controllers, and Hall-type position sensing, but they were not used because Reference 1 is more directly aligned with the present claims by expressly disclosing a BLDC railroad crossing gate mechanism using Hall UVW signals 302, Hall State Encoder 306, Position Estimator 308, Position PID Controller 318, Speed PID Controller 320, and Commutator 324 for motor phases A, B, and C.
Older motor homing and stepper-gauge zeroing patent references were also not used. Although such references may disclose generic homing to a mechanical stop, they are less analogous than Reference 3 and Reference 2 because they are not directed to railroad crossing gate mechanisms or barrier-arm position calibration. Reference 3 provides the field-specific gate-down buffer 166 and horizontal gate detection, and Reference 2 provides the field-specific accelerometer-based gate-position sensing.
Newer crossing-gate patent publications located during the search were not used because their apparent filing or priority information did not provide a better prior-art posture for the present application, and Reference 1 provided the closest available patent disclosure for the BLDC Hall-sense crossing-gate architecture.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JASON C SMITH whose telephone number is (703)756-4641. The examiner can normally be reached Monday - Friday 8:30 AM - 5:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Joseph Morano can be reached at (571) 272-6684. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/Jason C Smith/ Primary Examiner, Art Unit 3615
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