Disturbance-Observer-Based Backstepping Controller for Position Tracking Error Constrained Electro-pneumatic Servo Systems

In this paper, a disturbance observer based backstepping controller is developed for the electro-pneumatic servo systems with single-rod cylinder. A disturbance observer that does not require the state derivatives is firstly constructed, and based on which a nonlinear control law is then synthesized by adopting the backstepping method. By utilizing the Barrier Lyapunov Function in the controller design, a prescribed tolerance of position tracking error can be guaranteed theoretically. The stability of the closed-loop system is proven by the means of Lyapunov theory. Experimental results are presented to demonstrate the effectiveness of the proposed controller.