SELF-TUNING CONTROLLER FOR FARM TRACTOR GUIDANCE

Automatic guidance of farm tractors would improve productivity of many field operations by reducing operator fatigue and improving machine p erformance. A self-tuning steering controller, which can be used for a ll noncontact types of positioning systems, was designed for tractor g uidance. A simple two degrees-of-freedom model was chosen with which t o develop a prediction model used in recursive least-squares parameter estimation. A variable forgetting factor was implemented and its algo rithm modified to cope with time-varying nonlinear systems. The self-t uning steering controller based upon minimum variance control was test ed and verified with a tractor dynamic simulator. Circular, lane chang e, and sinusoidal paths were used. A model tractor was also used to ve rify controller performance for straight-line and sinusoidal paths.