Multivariable controller design evaluating closed-loop interaction by iterative LMI optimization using frequency response data

This paper proposes a multivariable controller design method using frequency response data. The proposed method evaluates a diagonal dominance in a closed-loop manner by using a singular value and designs a controller by solving an optimization problem that involves nonconvex quadratic matrix inequalities. This optimization problem is rewritten as linear matrix inequalities (LMI) by introducing iterative LMI constrains. The controller achieving highly diagonal dominance is designed by repeating an update of the optimization problem and the convex optimization. This optimization algorithm guarantees monotonically convergence of an evaluation value in terms of the iteration. The experimental results show the effectiveness of the proposed method in comparison with the conventional method.