A model reference robust multiple-surfaces design for tracking control of radial pneumatic motion systems

A robust model reference backstepping (multiple-surfaces) controller is proposed for radial pneumatic motor motion systems with variable inlet pressure and mismatched uncertainties (time-varying payload). A radial pneumatic motor is first modeled by a non-autonomous equation with consideration of a ball screw table. A practical integral action and robust action are included in the backstepping design to compensate for the disturbance, mismatched uncertainty, and to eliminate the steady state error. The motion system is proved to have asymptotically stable performance and the experimental results show that the proposed controller is able to track the reference model output signal and maintain steady-state error.