| 摘要 |
A turn detection algorithm is used by a navigation system for determining position and heading of a vehicle relative to a road network represented by a geographic database used by the navigation system. A dead-reckoned position and heading are determined along a plurality of road segments in the road network using sensor measurements of a distance traveled by the vehicle and a change in heading of the vehicle. A vehicle trajectory history is formed and then continuously updated. The vehicle trajectory history includes sensor-derived data representing the vehicle trajectory over a relatively small, chosen distance. The sensor-derived data in the vehicle trajectory history include total turn (i.e., heading change of the vehicle), vehicle state (e.g., travelling straight, turning or reversing in turn direction within a specified small distance) and type of vehicle maneuver. These data represent the trajectory of the vehicle for that distance and are kept in a memory. Corresponding data for the same distance interval are also obtained from GPS measurements and the geographic database. Using the data in the vehicle trajectory history and the corresponding data from the GPS and geographic database, a corrected dead-reckoned position and heading are determined. In addition, using the data in the vehicle trajectory history and the corresponding data from the GPS and geographic database, bias and scale factor correction parameters for the sensors are also obtained.
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