Robust nonlinear nominal-model following control to overcome deadzone nonlinearities

A robust nonlinear nominal-model following control is proposed to overcome deadzone nonlinearities which are unavoidable in many physical systems due to the imperfections of system components. First, an ideal linear nominal m odel of the plant and a model controller are employed to generate an ideal reference output. Then, a nonlinear robust loop controller is added to forc e the actual output to follow the ideal reference output, The robust loop c ontroller contains an ordinary proportional-integral-derivative controller combined with a deadband relay. The added deadband relay has the capability of reducing nonlinear effects of the plant. A systematic design methodolog y is established and it is linked to the conventional control system design . The proposed scheme is practically applied to the control of a de motor p osition servo system containing a severe deadzone nonlinearity, Both simula tion and experimental results have illustrated the effectiveness and robust ness of the proposed technique.