A Plausible Approximation Method for Linear Systems and its Application for the Design of Low-Order Controllers

The contribution of this paper is twofold. First, a plausible method for the approximation of a system´s transfer function is introduced. Second, a procedure for designing a low-order controller based on this approximation method is presented. The method proposed in this paper performs an order-reduction while considering the properties of the closed loop system. This ensures that the reduced-order controller achieves a performance close to the one of a full-order controller. Roughly speaking, the proposed procedure computes the low-order controller by approximating an equivalent closed-loop state feedback system and then performing an inverse operation.