The application backlash of fractional order control to vibration suppression

This paper applies fractional order PID/sup k/ 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. 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/sup k/ controller. Design process and experimental results demonstrate straightforward robust control design through the novel fractional order control (FOC) approach, the PID/sup k/ control system´s robustness against backlash non-linearity and good approximation of the realization method.