Switching on the derivative of control to reduce chatter

When applying a classical sliding-mode control based on variable structure systems, a high-frequency chatter appears. This phenomenon, caused by discontinuous control, is usually undesirable for most practical applications. The paper proposes a robust control law for decreasing the chatter based on a generalised sliding-mode control that switches on the derivative of control instead of the control input itself. This new robust control algorithm is applied on a SCARA type manipulator arm with three degrees of freedom, in the case of trajectory tracking mode, to show the reduced chatter and its robustness against manipulated payload variation and external disturbance. Experimental results demonstrating the advantages and superiority of the generalised variable structure controller over the classical variable structure controller are presented