Heading Error Removal System for Tracking Devices
First Claim
1. A method for removing drift error from a tracking device having a sensor assembly to measure rate of rotation and heading for the tracking device, the method comprising:
- removing static drift error from the measured rate of rotation to produce a normalized rate of rotation, wherein the normalized rate of rotation includes a drift error component that varies during operation of the tracking device;
applying the normalized rate of rotation to a closed loop feedback control that includes an accumulator for accumulating error values corresponding to a difference between the normalized rate of rotation and a baseline rate of rotation;
the closed loop feedback control producing an integrator signal that counteracts the effects of the drift error component of the normalized rate of rotation; and
correcting the normalized rate of rotation by applying the integrator signal to the normalized rate of rotation signal to produce a corrected rate of rotation signal.
1 Assignment
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Accused Products
Abstract
Systems are able to reduce or remove slowly-varying drift errors, such as heading errors and rate of rotation errors, to correct the measurements from tracking devices. The systems may be used to remove the slow varying drift errors for gyroscopic tracking device sensors, or other types of sensors used for determining heading, rates of rotation, or position. The systems may be employed in personal dead reckoning systems, or other personnel tracking device, as well as in vehicle tracking devices. The system uses heuristic assumptions to correct for these drift errors, via a feedback loop control having an accumulator responsive to changes in output signals. The accumulator is able to produce a signal that over time compensates for the inherent drift errors on those output signals. In some examples, that feedback loop control can be adjusted to compensate from deviations from those heuristic assumptions, such as swaying, curving, or turning.
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Citations
48 Claims
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1. A method for removing drift error from a tracking device having a sensor assembly to measure rate of rotation and heading for the tracking device, the method comprising:
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removing static drift error from the measured rate of rotation to produce a normalized rate of rotation, wherein the normalized rate of rotation includes a drift error component that varies during operation of the tracking device; applying the normalized rate of rotation to a closed loop feedback control that includes an accumulator for accumulating error values corresponding to a difference between the normalized rate of rotation and a baseline rate of rotation; the closed loop feedback control producing an integrator signal that counteracts the effects of the drift error component of the normalized rate of rotation; and correcting the normalized rate of rotation by applying the integrator signal to the normalized rate of rotation signal to produce a corrected rate of rotation signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for removing drift error from a tracking device having a sensor assembly to measure rate of rotation and heading for the tracking device, the method comprising:
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removing static drift error from the measured rate of rotation to produce a normalized rate of rotation, wherein the normalized rate of rotation includes a drift error component that varies during operation of the tracking device; integrating the normalized rate of rotation to produce a feedback heading; supplying the feedback heading to a closed loop feedback control that is to perform a low pass filtering on the feedback heading and that is to map the feedback heading onto one of a plurality of dominant directions to form a mapped feedback heading; an accumulator within the closed loop feedback control accumulating error values corresponding to a difference between the mapped feedback heading and a baseline heading; the closed loop feedback control producing an integrator signal that counteracts the effects of the drift error component of the normalized rate of rotation; correcting the normalized rate of rotation by applying the integrator signal to the normalized rate of rotation signal to produce a corrected rate of rotation signal; and integrating the corrected rate of rotation to produce a corrected heading. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A tracking device comprising:
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a sensor assembly to measure rate of rotation and heading for the tracking device; a memory for storing measured rate of rotation and heading data; and a controller to execute computer-executable instructions for, removing static drift error from the measured rate of rotation to produce a normalized rate of rotation, wherein the normalized rate of rotation includes a drift error component that varies during operation of the tracking device; integrating the normalized rate of rotation to produce a feedback heading; supplying the feedback heading to a closed loop feedback control that is to perform a low pass filtering on the feedback heading and that is to map the feedback heading onto one of a plurality of dominant directions to form a mapped feedback heading; an accumulator within the closed loop feedback control accumulating error values corresponding to a difference between the mapped feedback heading and a baseline heading; the closed loop feedback control producing an integrator signal that counteracts the effects of the drift error component of the normalized rate of rotation; correcting the normalized rate of rotation by applying the integrator signal to the normalized rate of rotation signal to produce a corrected rate of rotation signal; and integrating the corrected rate of rotation to produce a corrected heading. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. A tracking device comprising:
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a sensor assembly to measure rate of rotation and heading for the tracking device; a memory for storing measured rate of rotation and heading data; and a controller to execute computer-executable instructions for, removing static drift error from the measured rate of rotation to produce a normalized rate of rotation, wherein the normalized rate of rotation includes a drift error component that varies during operation of the tracking device; applying the normalized rate of rotation to a closed loop feedback control that includes an accumulator for accumulating error values corresponding to a difference between the normalized rate of rotation and a baseline rate of rotation; the closed loop feedback control producing an integrator signal that counteracts the effects of the drift error component of the normalized rate of rotation; and correcting the normalized rate of rotation by applying the integrator signal to the normalized rate of rotation signal to produce a corrected rate of rotation signal. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification