Dynamic compensation for the deadzone of the electrohydraulic proportional position servo control system

The valve-controlled motor eletrohydraulic proportional servo system driving static load torque has severe time-varying deadzone and gain nonlinearities in the presence of the load torque variations. An experimental comparison study was made between several control methods. Experimental results show that the high gain control causes instability; the integral control aggravates stick slip and introduces hunting; the fixed deadzone compensation greatly reduces the positioning error when the load torque is a constant, but it causes poor positioning accuracy when the load torque varies greatly. The dynamic deadzone compensation based on the error e(t) and error-in-change Δe(t) can significantly improve the positioning precision over a wide range of load torque.