<i>Development of an electric automatic steering system for agricultural vehicles</i>

Abstract

Abstract. Automatic steering contributes as a prerequisite technique in automatic navigation of agricultural vehicles that need to be modified with regard to their steering mechanism, hydraulic system and electrical system on currently commercialized products. It will benefit farmers more to cost less in routine maintenance in use of an aftermarket automatic steering system. The objective of this research was to develop an electric automatic steering system that was compact in its structure and integrated into the original steering mechanism in a simply and convenient way. A brushless motor and reducer assembly was utilized to provide the steering torque instead of manual maneuver. A rapid assembling approach was proposed by passing the steering shaft through the hollow output shaft. A digital PID algorithm was implemented to calculate the rotation speed and direction by comparing the desired angle from other devices and the actual angle feedback by a rotary position sensor, which was realized in a printed circuit board with a MCU and interface chips. A wheeled tractor was used as the test platform to integrate the newly developed automatic steering system. And experiments were conducted to evaluate its performance in terms of both stability and responsibility. For the validation, an autonomous navigation system guided the tractor along target paths in the field by sending steering commands to the automatic steering system. Results showed that the lateral errors was no more than 5 cm in terms of following straight paths. And headland turns were robustly executed according to the required pattern.