Automatic Tractor Steering System for Forage Harvesting

Abstract

An automatic tractor steering system was developed to save labors in farm operations of forage harvesting. A piezoelectric vibratory gyroscope and an ultrasonic Doppler speed sensor were used in the system to estimate the position and direction of the tractor. The voltage output of each sensor was converted into a pulse train by a V/F converter, and the sensor output was integrated easily by counting the number of pulses. The steering was controlled by a personal computer under the combination of on-off and proportional control methods. The results of experiments on farm showed the tractor was controlled well. In 100m of straight driving tests at the speed of 0.8m/s or 1.8m/s, the maximum displacement was less than 0.2m. In the case of 25m square driving at the speed of 0.8m/s, the final displacement was less than 0.5m.