Fixed-Order Robust H∞ Controller Design With Regional Pole Assignment

In this paper, the problem of designing fixed-order robustH∞ controllers is considered for linear systems affected by polytopic uncertainty. A polynomial method is employed to design a fixed-order controller that guarantees that all the closed-loop poles reside within a given region of the complex plane. In order to utilise the freedom of the controller design, an H∞ performance specification is also enforced by using the equivalence between robust stability and H∞ norm constraint. The design problem is formulated as a Linear Matrix Inequality (LMI) constraint whose decision variables are controller parameters. An illustrative example demonstrate the feasibility of the proposed design methods.