Adaptive Integral Sliding Mode Force Control of Robotic Manipulators with Parametric Uncertainties and Time-Varying Loads

In order to overcome the problem of unmodeled dynamics, design of accurate control strategies for trajectory tracking or force control is necessary. Starting from the mathematical modeling stage, it's necessary to select, design and implement robust control strategies to eliminate this problem. On the other side, for different kinds of applications, time varying loads are important to be considered because of different applications of robotics in industry and other fields. For these reasons, in this study, the design of an adaptive integral sliding mode force controller for robotic manipulators is proposed. An adaptive control law is designed by selecting an integral sliding surface and by using a Lyapunov function. The respective adaptive gains are obtained taking into account the parametric uncertainties that represent the unmodeled system's dynamics which are found in the inertia, mass and center of mass terms of the robot. Taking into account the robustness of the adaptive sliding mode force control, the time varying loads or external disturbances that can be found in the end effector and on the robot structure that can occur in a specific task are suppressed satisfactorily. The simulation results demonstrated that the adaptive integral sliding mode controller ensures the closed loop stability of the system while following the end effector time varying profile.