Explicit Model Predictive Control of an electropneumatic clutch actuator using on/off valves and pulse-width modulation

This paper considers the optimal reference tracking control of an electropneumatic clutch actuator. To control both supply to and exhaust from the clutch actuator chamber, one pair of on/off valves is used. The on/off valves are controlled by pulse-width modulation. The fast dynamics of the clutch actuator and the presence of both state and input constraints makes it appropriate to design an explicit Model Predictive Controller (MPC), where the only computation performed on-line would be a piecewise linear function evaluation. A multi-parametric Nonlinear Programming approach is applied to design the explicit MPC. In order to reduce the computational burden, the design of the explicit controller is based on a simplified 3-rd order model of the clutch actuator. The controller performance is verified by simulating with the full 5-th order model of the actuator dynamics. Also, the closed-loop response is compared to that of an explicit MPC controller without pulse-width modulation, where the valves are directly commanded fully open or fully closed.