Dynamic output feedback sliding mode control for uncertain mechanical systems without velocity measurements

For MIMO mechanical systems using position measurements only, this paper presents a dynamic output feedback sliding mode control algorithm in which an additional dynamics is introduced into the design of the sliding surface. Although the system has the mismatched uncertainty and external disturbance, once the system is in the sliding mode, the proposed method can guarantee robust stabilization and sustain the nature of performing disturbance attenuation through utilizing H_∞ control analytical technique. A controller is then designed to drive the system to the sliding surface in a finite time and stay on it thereafter. Finally, a numerical example is explained for demonstrating the applicability of the proposed scheme.