A Novel PID Controller for Pneumatic Proportional Valves with Hysteresis

A novel Modified PID (MPID) controller is developed to control and minimize the effect of hysteresis in Pneumatic proportional valves. It consists of four parts: a Proportional-Integral-Derivative (PID) controller, a Feedforward term, an Anti-Windup mechanism, and a Bang-Bang controller. The result is a unique Modified PID (MPID) control scheme that demonstrates better command following and disturbance rejection qualities than a Conventional PID (PID + Feedforward + Antiwindup) scheme. The control scheme is simulated based on an empirical model derived from actual valve measurement data. The results show that the proposed MPID controller provides better step response, command following, and greater bandwidth than conventional methods. Furthermore, it is demonstrated that the robust control is achieved in the presence of significant dynamic variations in the valve. In particular, it is shown that satisfactory performance can be maintained when the valve hysteresis characteristics are varied by as much as 30%.