VARIABLE-STRUCTURE ADAPTIVE MOTION AND FORCE CONTROL OF ROBOT MANIPULATORS

A variable structure adaptive method is developed for robust motion and force tracking control of robot manipulators in the presence of uncertainties in parameters of robot dynamics, contact surface, and external disturbances. The method takes advantages of both variable structure control (VSC) and adaptive control which results in a two-loop controller structure. VSC utilized in the inner-loop drives the system to reach and be maintained on a dynamic sliding mode which is provided by the outer-loop design. Adaptive control is used in the outer-loop to estimate contact surface parameters for ensuring the system with force tracking property. Overall stability of the two-loop system is established and simulation results are presented.