Low-order H∞ controller design on the frequency domain by partial optimization

摘要

In this paper, an optimization method of low-order multivariable controllers for H∞ control is proposed. Starting from a low-order stabilizing controller, our method gives a sequence of controllers for which the H∞ norm performance index is monotonically non-increasing by tuning the numerator coefficient matrices of the low-order controller. This controller class includes multivariable PID controllers. The proposed method is a descent method where the feasible direction is calculated by solving a linear matrix inequality that represents a sufficient condition for the H∞ criterion for each frequency. Usefulness is shown by two numerical examples.