Abstract
Influence of the vehicle pitch angle was reduced by mounting two velocity sensors-one each on the front and back of the vehicle-thereby improving the accuracy of travel speed control of a crawler vehicle with an autonomous running function, On sloping grassland of about 11°, the vehicle travel speed was detected to within a 0.2% error margin. A digital PI control without differential action was effective to control the travel speed on sloping grassland. Small overshoots were apparent, but it was possible to maintain control at slightly excess speeds. Travel at the set speed was possible regardless of the slope direction.
