Tightly coupled GPS and dead-reckoning vehicle navigation
First Claim
1. An improved vehicle location system, comprising:
- a GPS receiver carried aboard a vehicle and subject to interruptions of signal transmissions from orbiting navigation satellites;
a DR-computer coupled to the GPS receiver and providing for range and heading information computed by dead-reckoning during periods of said signal interruptions, and such that vehicle location solutions are provided to a user;
wheel-tick sensors coupled to the DR-computer and providing for rotational data related to the rotation of individual wheels that carry said vehicle;
wherein, one or more parameters estimated to account for true radii of said individual wheels are combined with said rotational data from the wheel-tick sensors to generate delta-range information indicative of change in range, and delta-heading information indicative of change in heading, related to movements of said vehicle;
wherein, said delta-range and delta-heading information are propagated by the DR-computer from absolute position information periodically obtained from the GPS receiver, with dead-reckoning location alone sometimes being output as a vehicle location solution; and
wherein, said vehicle location solutions are derived solely from the GPS receiver, solely by the DR-computer, or from a mix provided by the GPS receiver and the DR-computer.
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Accused Products
Abstract
A tightly coupled GPS and dead-reckoning system collects wheel speed transducer data over a vehicle'"'"'s network to compute vehicle range and direction. The dead-reckoning bridges over gaps in navigation solutions that would otherwise occur when GPS signal transmission is lost in tunnels, parking garages, and other common situations. Continual calibration of the wheel radii and compensation for speed effects are calculated from GPS position fixes, and such improves the performance and accuracy of dead-reckoning during long outages of GPS signal reception. When the GPS signals are restored, the dead-reckoning solutions provide a high quality starting place for the GPS receiver to search around.
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Citations
10 Claims
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1. An improved vehicle location system, comprising:
- a GPS receiver carried aboard a vehicle and subject to interruptions of signal transmissions from orbiting navigation satellites;
a DR-computer coupled to the GPS receiver and providing for range and heading information computed by dead-reckoning during periods of said signal interruptions, and such that vehicle location solutions are provided to a user;
wheel-tick sensors coupled to the DR-computer and providing for rotational data related to the rotation of individual wheels that carry said vehicle;
wherein, one or more parameters estimated to account for true radii of said individual wheels are combined with said rotational data from the wheel-tick sensors to generate delta-range information indicative of change in range, and delta-heading information indicative of change in heading, related to movements of said vehicle;
wherein, said delta-range and delta-heading information are propagated by the DR-computer from absolute position information periodically obtained from the GPS receiver, with dead-reckoning location alone sometimes being output as a vehicle location solution; and
wherein, said vehicle location solutions are derived solely from the GPS receiver, solely by the DR-computer, or from a mix provided by the GPS receiver and the DR-computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- a GPS receiver carried aboard a vehicle and subject to interruptions of signal transmissions from orbiting navigation satellites;
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9. A GPS, dead-reckoning, and map matching location software application program for execution as a GPS application in a host computer, comprising:
- an input process for collecting time, fix trigger, Doppler, and pseudorange reports from a GPS measurement platform (MP) device mounted aboard a vehicle with wheels;
a GPS-time to host computer time offset calculation process for aligning otherwise asynchronous data generated by said vehicle to GPS time;
a least squares snapshot estimator for position (P), velocity (V), calibration parameters for the wheel radii and ratio (B), delta-heading and delta-range (D), and time based on each new position fix and GPS system time;
a Kalman Filter configured for position (P), velocity (V), calibration parameters for the wheel radii and ratio (B), delta-heading and delta-range (D), and time, and for processing dead-reckoning delta-range, delta-heading, mixed modes, and propagation;
a continuous mode selection process for operating in a GPS only mode, dead-reckoning only mode, or a mixed mode of both GPS and dead-reckoning, depending on an availability of GPS solutions and wheel data calibrations;
a new fix computation process for computing hardware preposition data and adjusting a GPS millisecond timer connected to the time offset calculation process;
a buffer process for collecting time-stamped CANbus data related to wheel rotation ticks measured by a vehicle'"'"'s wheel transducers;
a dead-reckoning calibration Kalman filter for processing AL and AR calibration parameters for delta-heading/tick difference for left and right wheels, and BL, and BR calibration parameters for delta-range/tick for left and right wheels, and a heading-offset calibration parameter that translates a sum delta-heading to a known heading reference;
a dead-reckoning data process for converting data from the buffer process into delta-range, delta-heading, and delta-heading sum information for subsequent processing by the Kalman Filter, and including a dead-reckoning error model; and
an applications programming interface (API) for outputting new location fixes. - View Dependent Claims (10)
- an input process for collecting time, fix trigger, Doppler, and pseudorange reports from a GPS measurement platform (MP) device mounted aboard a vehicle with wheels;
Specification