AN EFICIENT CONTROL ALGORITHM FOR CONTROLLING A PNEUMATIC SYSTEM

Abstract

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.