Sliding Mode Control for a Hybrid Force Control Scheme of a Robot Manipulator Under Uncertain Dynamics

This paper presents the sliding mode control method for separate position and force control of a hybrid force control scheme in robot manipulation. Integral sliding mode control (ISMC) functions are defined and applied to both position and force controlled direction separately to improve the control performances by minimizing the ill effect of uncertain dynamics. Stability of integral sliding mode control for both position and force-controlled direction is analyzed in a Lyapunov sense under the decomposed sub-dynamics configurations based on the independent axis control. The sliding mode force control scheme was expected to show the better tracking performance by taking care of not only external disturbance but also internal uncertainties of a robot manipulator. Force control tasks of a three-link robot manipulator are tested with nonmodel dynamics under unknown uncertainties and their performances are compared.