The Application of Fractional Order Control to Backlash Vibration Suppression

This paper applies fractional order PID controller to torsional system’s backlash vibration suppression control, in which the order k of D controller can not only be integer but also be any real number. In order to improve control system’s robustness against backlash non-linearity, several methods have been proposed. However their design processes are very complicated. In this paper, a clear and straightforward design is achieved by adjusting the D controller’s order k directly. An approximation method based on sampling time scaling property is also introduced to realize the discrete D controller. Design process and experimental results demonstrate straightforward robust control design through the novel Fractional Order Control (FOC) approach, the PID control system’s robustness against backlash non-linearity and good approximation of the realization method.