Low order robust controller design for preserving Hinfinity performance: genetic algorithm approach

This paper investigates the design of low order robust controllers based on an Hinfinity performance index using a real-code genetic algorithm. In Hinfinity controller design, the major disadvantage of the existing methods is that they lead to high-order controllers. This is the gap between theory and practice. Therefore the purpose of this paper is to design a low order controller with similar performance to the Hinfinity optimal controllers, which can find sufficiently wide use in engineering practice. We first design the Hinfinity optimal controller using Glover and Doyle's results, and obtain the corresponding performance index gamma. Second, the desired low order controller with several parameters is chosen, e.g., a first-order controller, or a PID controller. Finally, we use the real-code genetic algorithm to find the optimal controller parameters that preserve the performance index y. Computational simulations illustrate the effectiveness of the proposed approach.