Force/motion control of constrained robots using sliding mode

A sliding mode control algorithm is presented for trajectory tracking of an end-effector on a constrained surface with specified constraint forces by using the theory of variable structure systems. The development of the algorithm is based on a new formulation of the dynamic model and the expansion of sliding surfaces to include the constraint force error. The proposed sliding controller is explicit, which ensures the occurrence of the sliding mode on the intersection of the surfaces. A detailed numerical example is presented to illustrate the method