An Approach to Design Controllers for MIMO Fractional Order System Based on RFN Method

Abstract

Fractional calculus has attracted more and more attention and is applied in different fields. However the controller design techniques for fractional order systems mostly focus on single input single output (SISO) ones. This paper deals with the design of controllers for multiple inputs multiple outputs (MIMO) fractional order systems. A method to synthetize controller based on the eigenvalue function and singular value decomposition (SVD) is proposed with aid of fractional order transfer function (FOTF) MATLAB toolbox for the computation and fitting. Instead of setting specification to the controller, the method proposed aiming at achieving the target closed-loop control effect of the system as a whole. Several models evolved from fractional-order Proportional-Integral-Derivative (fPID) controller are selected to form the designed multivariable controller. The effectiveness and robustness of the proposed method are illustrated by an example via simulation.