Improving robust controller performance via multi-objective fixed-structure controller design

In this paper we explore the performance improvements that can be achieved by using multi-objective optimization. Specifically, we optimize a convex combination of a guaranteed cost bound and the nominal H₂ cost to improve performance over standard robust control designs. In those standard designs, performance degrades as robustness levels are increased. However, once we have designed a controller with a desired robustness level, applying the multi-objective optimization can enhance performance levels while still maintaining the original guaranteed robustness level. This procedure is demonstrated on several numerical examples.