Robust motion and force control of robot manipulators in the presence of environmental constraint uncertainties

Due to task kinematic modeling inaccuracy, the constraint function imposed on robot manipulators may not be known exactly. A variable structure control (VSC) method is developed for robust motion and constrained force control of robot manipulators in the presence of parameter uncertainties, external disturbances, and constraint function uncertainties. The method is based on the particular structure of the constrained robot, in which motion control and force control are treated together. The proposed VSC controller can also provide the sliding mode and the reaching transient response with prescribed qualities. A sufficient condition to guarantee that the robot does not lose contact with the constraint surface is given. Detailed simulation results illustrate the proposed method