Mechanical resonance suppression in servo system based on the fractional order low-pass filter

The conventional filter method could effectively suppress resonance in servo system without backlash. But when the system contains backlash, the methods may fail. In this paper, a fractional order low-pass filter substitutes the integer order low-pass in a dual-inertia servo system with backlash to solve the problem. Fractional algorithm provides greater flexibility for robust control design, because it makes the order of the low-pass filter from integer domain to real-number domain. Fractional order low-pass filter can achieve a better tradeoff between robustness and resonance suppression by selecting the appropriate order. For implementation of the fractional order, Oustaloup recursive approximation method is introduced. Experimental results show that fractional-order low-pass filter can improve robustness while suppressing system resonance.