Sliding modes in motion control systems

In this paper we discuss the realization of motion control systems in the sliding mode control (SMC) framework. Any motion control system design should take into account the unconstrained motion (generally perceived as a trajectory tracking) and motion of the system in contact with unknown environment (perceived as force control and/or compliance control.) In the SMC framework control is selected to enforce certain preselected dependence among system coordinates, what is interpreted as forcing the system state to stay in selected manifold in state space. In this paper it has been shown that such a formulation allows a unified treatment of the both unconstrained and constrained motion control and, due to the Lyapunov based design, it guaranty the stability of the motion. Moreover control design in this framework allows extension of the solution to control design in interconnected dynamical systems (like mobile robots or bilateral systems).