AN EFICIENT CONTROL ALGORITHM FOR CONTROLLING A PNEUMATIC SYSTEM

Position control of pneumatic systems is a challenging task because of their nonlinear properties and difficulties in acquiring system parameters. Designing a suitable controller in such situation is very important. The designed control scheme must operate properly to deal with the nonlinear characteristics and lack of system parameter information.Variable structure based sliding mode control (SMC) is proposed as a control algorithm that matches with nonlinear systems because of its robustness and insensitivity to system uncertainties. However, due to nonzero tracking error inside boundary layer, SMC should be combined with another control action to gain good performances.In this paper, a flexible controller which is a combination between SMC and PID controller called multimode PID-SMC is addressed to pneumatic system control problem. This proposed control scheme extracts advantages of both SMC and PID controller. The control quality of multimode SMC-PID is acceptable in some specific cases where the required accuracy is not so high.