Position and heading error-correction method and apparatus for vehicle navigation systems
First Claim
1. A navigational system for a vehicle having built-in error correction comprising:
- (a) a heading sensor having a bias that drifts over time and capable of measuring heading data;
(b) a temperature sensor capable of measuring temperature data;
(c) a dead reckoning component having a heading sensor interface and a temperature sensor interface, wherein the dead reckoning component receives the heading data from the heading sensor and the temperature data from the temperature sensor;
(d) a first computational means for determining whether the vehicle is at a stationary point;
(e) if the vehicle is at the stationary point, a second computational means for generating a temperature-based calibration curve for an estimated bias drift rate, the estimated bias drift rate at the stationary point being a ratio of a change in bias between the stationary point and a prior stationary point by a change in temperature between the stationary point and the prior stationary point, the calibration curve being modeled by an expression as a function of a plurality of coefficients calculated by a filter, a current temperature measured at the stationary point, and a prior temperature measured at the prior stationary point;
(f) a third computational means for calculating a corrected vehicle heading using the temperature-based calibration curve for the estimated bias drift rate to compensate for vehicle heading errors induced by heading sensor bias drift; and
(g) a fourth computational means for calculating a corrected vehicle position using at least the corrected vehicle heading to compensate for vehicle position errors induced by heading sensor bias drift.
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Abstract
The present invention solves the problems of the prior art by providing methods for compensating for temperature-dependent drift of bias in a vehicle heading sensor of a dead reckoning vehicle positioning system. Specifically, the invention uses a Kalman filter to generate a calibration curve for the rate of heading sensor bias drift with temperature change. The Kalman filter calculates coefficients for a model of heading sensor bias drift rate versus temperature at each point where the vehicle is stationary. The bias drift rate calibration curve is then used to estimate a heading sensor bias periodically while the vehicle is moving. The invention further provides a method for using an aging time for temperature sensor bias drift rate to force convergence of the error variance matrix of the Kalman filter. The invention further provides vehicle navigational systems that utilize the methods of the present invention.
214 Citations
29 Claims
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1. A navigational system for a vehicle having built-in error correction comprising:
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(a) a heading sensor having a bias that drifts over time and capable of measuring heading data;
(b) a temperature sensor capable of measuring temperature data;
(c) a dead reckoning component having a heading sensor interface and a temperature sensor interface, wherein the dead reckoning component receives the heading data from the heading sensor and the temperature data from the temperature sensor;
(d) a first computational means for determining whether the vehicle is at a stationary point;
(e) if the vehicle is at the stationary point, a second computational means for generating a temperature-based calibration curve for an estimated bias drift rate, the estimated bias drift rate at the stationary point being a ratio of a change in bias between the stationary point and a prior stationary point by a change in temperature between the stationary point and the prior stationary point, the calibration curve being modeled by an expression as a function of a plurality of coefficients calculated by a filter, a current temperature measured at the stationary point, and a prior temperature measured at the prior stationary point;
(f) a third computational means for calculating a corrected vehicle heading using the temperature-based calibration curve for the estimated bias drift rate to compensate for vehicle heading errors induced by heading sensor bias drift; and
(g) a fourth computational means for calculating a corrected vehicle position using at least the corrected vehicle heading to compensate for vehicle position errors induced by heading sensor bias drift. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for correcting temperature-dependent sensor bias drift in a navigational system for a vehicle comprising a heading sensor, a temperature sensor, and a dead reckoning component, comprising the steps of:
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(a) transmitting heading data from the heading sensor to the dead reckoning component and storing the heading data in the dead reckoning component;
(b) transmitting temperature data from the temperature sensor to the dead reckoning component and storing the temperature data in the dead reckoning component;
(c) determining whether the vehicle is at a stationary point;
(d) if the vehicle is at the stationary point, generating a temperature-based calibration curve for an estimated bias drift rate, the estimated bias drift rate at the stationary point being a ratio of a change in bias between the stationary point and a prior stationary point by a change in temperature between the stationary point and the prior stationary point, the calibration curve being modeled by an expression as a function of a plurality of coefficients calculated by a filter, a current temperature measured at the stationary point, and a prior temperature measured at the prior stationary point. - View Dependent Claims (21, 22, 23, 24, 25)
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26. A method for correcting heading and position error induced by temperature-dependent heading sensor bias drift in a navigational system for a vehicle comprising a heading sensor, a temperature sensor, and a dead reckoning component, comprising the steps of:
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(a) transmitting heading data from the heading sensor to the dead reckoning component and storing the heading data in the dead reckoning component;
(b) transmitting temperature data from the temperature sensor to the dead reckoning component and storing the temperature data in the dead reckoning component;
(c) determining whether the vehicle is at a stationary point;
(d) if the vehicle is at the stationary point, generating a temperature-based calibration curve for an estimated bias drift rate, the estimated bias drift rate at the stationary point being a ratio of a change in bias between the stationary point and a prior stationary point by a change in temperature between the stationary point and the prior stationary point, the calibration curve being modeled by an expression as a function of a plurality of coefficients calculated by a filter, a current temperature measured at the stationary point, and a prior temperature measured at the prior stationary point;
(e) estimating a corrected vehicle heading using at least the temperature-based calibration curve for the estimated bias drift rate;
(f) estimating a corrected vehicle position using at least the corrected vehicle heading. - View Dependent Claims (27)
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28. A method for correcting heading and position error induced by temperature-dependent heading sensor bias drift in a navigational system for a vehicle comprising a heading sensor, a temperature sensor, a global positioning system, and a dead reckoning component, comprising the steps of:
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(a) transmitting heading data from the heading sensor to the dead reckoning component and storing the heading data in the dead reckoning component;
(b) transmitting temperature data from the temperature sensor to the dead reckoning component and storing the temperature data in the dead reckoning component;
(c) transmitting global positioning data from the global positioning system to the dead reckoning component and storing the global positioning data in the dead reckoning component;
(d) determining whether the vehicle is at a stationary point;
(e) if the vehicle is at a stationary point, generating a temperature-based calibration curve for an estimated bias drift rate, the estimated bias drift rate at the stationary point being a ratio of a change in bias between the stationary point and a prior stationary point by a change in temperature between the stationary point and the prior stationary point, the calibration curve being modeled by an expression as a function of a plurality of coefficients calculated by a filter, a current temperature measured at the stationary point, and a prior temperature measured at the prior stationary point;
(f) estimating a corrected vehicle heading using at least the temperature-based calibration curve for the estimated bias drift rate;
(g) estimating a corrected vehicle position using at least the corrected vehicle heading;
(h) calculating an integrated vehicle heading using at least the corrected vehicle heading and the global positioning data transmitted from the global positioning system; and
(i) calculating an integrated vehicle position using at least the corrected vehicle position and the global positioning data transmitted from the global positioning system. - View Dependent Claims (29)
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Specification