Robust sliding mode based impedance control

Industrial robots are confronted with performing tasks where a contact with their environment occurs. Therefore, a need for control algorithms with position tracking performance and force control ability appears. Many algorithms have been proposed which deal with robot motion and force control. They could be mainly separated into two classes, namely: hybrid control, where constrained and unconstrained DOFs of the robot are observed separately based on the principle of the orthogonality; and impedance control where the robot should adopt some physical properties such as mass, damping and stiffness in order to assure stable dynamic interaction with the environment. In this paper the robust impedance control law based on the attractive theory of sliding mode is proposed. The control law guarantees a robot predefined impedance and therefore force regulation based on impedance properties is discussed. Experimental results on a simple 1 DOF mechanism is shown to verify theoretical statements.