Weighting function selection in the H∞ design process

Abstract The theory of H∞-norm optimisation is well known, and the technique has been applied to numerous design examples. Although simple rules exist for the selection of weighting functions used in the controller synthesis, the process is still subjective in nature. This paper is concerned with two aspects of the determination of weighting functions: firstly, guidelines for the initial selection of weighting functions and secondly tuning the performance weighting function to achieve the required closed-loop performance. The theory is illustrated with reference to the design of a do servo system controller.