Sliding-mode observer as a time-variant estimator for control of pneumatic systems

The force and position of pneumatic actuators are difficult to control, since their nonlinear model includes unknown variables such as temperature and the discharge coefficient. This paper presents a specific sliding-mode observer to estimate these unknown time-variant quantities. The stability of the estimation error is studied, and real-time results show that the proposed approach combined with a feedback linearization controller performs better than a standard sliding-mode controller