The development of electrohydraulic steering control system for off-road vehicle automatic guidance

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The researches in this thesis focus on the development of computer controlled electrohydraulic steering control system for off-road vehicle automatic guidance. The system developed in this research includes steering control computer, data acquisition pad, PWM driver, electrohydraulic proportional valve, hydraulic steering cylinder and vehicle steer angle sensor. Electrohydraulic proportional valve in the system has inherent dead-band and saturation. Dead-band influences steering accuracy very much. To remove it, a nonlinear compensation algorithm is developed and implemented in this research. The developed electrohydraulic steering control system is installed on a John Deere 8200 tractor. It receives steering command signal from a machine vision system. It also can receive steering command signal (sine wave, triangle wave and step signal) generated by computer. The test road conditions include paved cement road and farm field. The test results indicated that the developed electrohydraulic steering control system can implement steering control command successfully.