Robust control method for industrial servo systems based on approximation of fractional order integral

A novel robust control method for industrial servo systems is proposed. The method is aimed at improving robustness as much as possible without using detailed information on the linearized plant model such as mechanical resonance. The proposed method is equipped with a filter which is approximated to the fractional order integral. The parameters for the filter are determined automatically by taking into account robustness in the collocation condition. The method is especially efficient when the load inertia ratio is large and the linearity of the plant is deteriorated, such as in the belt drive or gear drive machines. Robustness for servo systems is discussed and the principle and construction of the proposed method are described. Experimental results with a simple tuning method proved the efficiency of the proposed method.