Direct Sliding-Mode Controller Design for a 6DOF Stewart Manipulator

The focus is on direct sliding-mode control design for tracking and regulation of a Stewart platform without any apriori knowledge of the system´s mass properties in presence of nonlinearities. The position and velocities are the major inputs to the controller. The appropriately chosen sliding surfaces isin R⁶, composed of system states vectors, proper choice of reachability gains drive the system to stable manifold and then slide it to an equilibrium point. It leads us to a control law which clearly deals with nominal performance and robust stability. The resulting dynamic feedback is shown to provide chatter-free control. The controller is based on generalized Lyapunov approach and guarantees global asymptotic and exponential convergence. The control performance of the proposed algorithm is verified by computer simulations. These simulations show that system follows the desired trajectory and errors efficiently converged to zero.