초록 ▼

The improved vehicle navigation system and method uses information from a Global Positioning System (GPS) to obtain velocity vectors, which include speed and heading components, for "dead reckoning" the vehicle position from a previous position. If information from the GPS is not available, then the

The improved vehicle navigation system and method uses information from a Global Positioning System (GPS) to obtain velocity vectors, which include speed and heading components, for "dead reckoning" the vehicle position from a previous position. If information from the GPS is not available, then the improved vehicle navigation system uses information from an orthogonal axes accelerometer, such as two or three orthogonally positioned accelerometers, to propagate vehicle position. Because the GPS information should almost always be available, the improved vehicle navigation system relies less on its accelerometers, thereby allowing the use of less expensive accelerometers. The improved vehicle navigation system retains the accuracy of the accelerometers by repeatedly calibrating them with the velocity data obtained from the GPS information. The improved vehicle navigation system calibrates the sensors whenever GPS data is available (for example, once a second at relatively high speeds). Furthermore, the improved vehicle navigation system does not need to rely on map matching to calibrate sensors. System flexibility is improved because map matching is oblivious to the hardware, and the system hardware can be updated without affecting map matching or a change in the map database.

대표청구항 ▼

[ We claim:] [12.] An improved vehicle navigation system, comprising:a GPS receiver which provides GPS velocity information, said vehicle navigation system uses said GPS velocity information to propagate a previous position to a current position;an orthogonal axes accelerometer provides motion signa

[ We claim:] [12.] An improved vehicle navigation system, comprising:a GPS receiver which provides GPS velocity information, said vehicle navigation system uses said GPS velocity information to propagate a previous position to a current position;an orthogonal axes accelerometer provides motion signals having longitudinal and lateral acceleration information and zero offsets, including longitudinal and lateral acceleration information, said vehicle navigation system determines heading change using said lateral acceleration information and longitudinal speed; said vehicle navigation system uses said heading change to propagate a previous position to a current position if said GPS velocity information is not used, said vehicle navigation system comparing said motion signals with a threshold to determine a zero motion state, and said vehicle navigation system locks heading changes and calibrates said zero offsets of said orthogonal axes accelerometer if said vehicle navigation system is in said zero motion state;an odometer provides displacement information, said vehicle navigation system determines displacement using at least one of said longitudinal acceleration information and said displacement information, said vehicle navigation system determines heading change from said lateral acceleration information, said vehicle navigation system determines odometer calibration information from said GPS velocity information if said GPS velocity information is used, said vehicle navigation system uses said heading change and said displacement to propagate a previous position to a current position if said GPS velocity information is not used; anda map database which stores map information, said vehicle navigation system determines a heading from said map information, said vehicle navigation system updates said GPS velocity information with said heading before propagating said previous position to a current position.