Sliding mode control of an electrically powered industrial robot

The paper considers the multivariable control of anthropomorphic robot manipulators, and its objective is to develop a control technique which exploits the full potential of the performance of robot arms. In its ideal form, the computed torque technique achieves the desired performance in nonlinear time-varying systems. However, its stability cannot be guaranteed, and its performance deteriorates rapidly with the presence of disturbances and parametric uncertainties. The variable structure control strategy which can guarantee stability, given bounded parametric uncertainty, is used as an additional input to rectify the uncertainties in the estimated control model of the computed torque technique. The benefits of the combined computed torque/variable structure controller are demonstrated practically on an electrically powered industrial robot, and the performance of the proposed controller is compared to that of the computed torque technique.