Adaptive sliding mode control of flexure jointed hexapods

This paper investigates the vibration isolation problem for a specific kind of Stewart Platform called flexure jointed hexapod (FJH). First, an existing dynamic model of the hexapod is re-formulated appropriately for control design. Second, an adaptive sliding mode controller is proposed for the FJH in the presence of disturbances. The asymptotic stability of the closed-loop system is proved based on Lyapunov's approach and sliding mode theory. In order to eliminate the chattering, a saturation function is used instead of the symbolic function in the adaptive control law, and it is proved that the ultimate boundedness of the closed-loop system can be guaranteed. Finally, numerical simulation results are provided to demonstrate the effectiveness of the proposed controller.