AUTOMATIC GUIDANCE OF AGRICULTURAL VEHICLES AT HIGH FIELD SPEEDS

Abstract

An automatic steering controller was installed on a Case-IH Model 7220 tractor. The primary posture sensor was a kinematic differential GPS. Open loop and closed loop frequency response tests were conducted to evaluate the steering controller dynamics. A double integrator transfer function adequately related vehicle lateral deviation to steering angle within the frequency range of 0.04 Hz to 0.5 Hz. Forward placement of the posture sensor was critical to reducing the phase lag, allowing the use of a simplified guidance controller design.