A review of μ and its applications

Several applications of structured singular value analysis (μ-analysis) are described. Structured singular value analysis is an extremely powerful multivariable technique which has been applied to many problems in the aerospace and process industries , mainly in the USA. It takes into account perturbation structure in performance and robustness analysis. It is explained why μ is useful in robust stability analysis, and then the discussion is extended to embrace performance in the face of model perturbations. Different types of perturbation (complex, real etc.) are considered. It is then described how the analysis approach can be extended to cope with quite complex problems. Finally it is considered how μ may be used for the design of control systems which can guarantee specified levels of performance robustness, in the procedure known as μ-synthesis