Automatic velocity control of a self-propelled windrower

A velocity control methodology is presented for an agricultural vehicle with a hydrostatic drive-train. A cascade control design incorporating a current control, cylinder position control and velocity control is proposed. The cylinder position controller uses a set of gain scheduled lag compensators in series with a sequence of segmented deadzone inversions. The deadzone inversions compensate for nonlinear valve dynamics. The velocity controller consists of a digital feedback control. A stability analysis of the closed loop system is performed. Experimental results from a self-propelled windrower are used to demonstrate the effectiveness of the control system.