Robust stability and performance

Abstract

This chapter is devoted to the important subject of robust stability and robust performance analysis using MATLAB®. First we show how to implement functions from Robust Control Toolbox® to analyze the robust stability of systems with unstructured, structured, and mixed uncertainty. Then we consider the implementation of the function robustperf to analyze the robust performance of closed-loop systems and show how to interpret the results obtained by this function. Similarly to robust stability margin, we use the notion of performance margin that shows the uncertainty level, up to which the system possesses specified performance. Finally, we consider how to determine the so called worst-case gain, which is determined as the largest value of the frequency response maximum for the allowed uncertainty.