Simulation Study and Experimental Position Control of Pneumatic Cylinder Using Sliding Mode Control with on/off Control Valves

Simulation and experimental studies of pneumatic cylinder position control are introduced. High speed on-off solenoid air valve is used instead of the proportional control valve. Sliding mode control with error modification, SMCE, is proposed to drive the air valves with pulse width modulation (PWM) technique. Comparison of the performance of the closed loop position control using SMCE with the traditional PID is held. The simulation model is used to optimize the SMC and PID controller parameters to start the experimental test as a first trial. The experimental results for square and sinusoidal position reference show superiority of the SMCE over the PID in terms of lower steady state errors, faster settling time, and less overshoot. The root mean square error for a sinusoidal input of 0.1 Hz, is 0.22 mm for SMCE and 0.69 mm for PID controller. The maximum absolute errors are 0.66 mm and 1.46 mm for SMCE and PID respectively.