Positioning of vehicle on undulating ground using GPS and dead reckoning

A method of positioning vehicles on undulating ground is proposed. This method uses GPS data and internal sensor data (fiber optic gyro, roll pitch sensor, and wheel encoders) and improves the positioning accuracy by compensating the error of each sensor data. A prototype of autonomous mower using this positioning method was developed and its positioning performance was evaluated. The experimental results show that the fusion system is more accurate than using only the GPS or internal sensor system. When the accuracy of the GPS is 1 m, the accuracy of the fusion system is 0.2 m; this accuracy is enough to control the vehicles. We expect that the positioning system for vehicle control can be realized using a differential GPS with accuracy of 1 m instead of an expensive kinematic GPS.