1998 Volume 60 Issue 2 Pages 59-66
An autonomous tractor was developed for the purpose of saving labors in forage production. Precise recognition of the position and direction of the vehicle is required for autonomous driving. In this system, two internal sensors (a fiber optic gyroscope and an ultrasonic Doppler velocimeter) were mounted on the tractor to detect the yaw angular velocity and the running speed. The tractor position was calculated by integrating those outputs. The steering was operated by a personal computer under the combination of on-off and proportional control methods. The results of 50m straight running tests on a flat field at the speed of 4 steps from 0.7m/s to 1.8m/s showed that the maximum lateral displacement from the reference line was less than 10cm. In the case of 400m running at the speed of 1.2m/s for straight running and 0.8m/s for turning, whitch was carried out to demonstrate the practical application, the maximum displacement from the predetermined path was about 1.5m.
