Fit Synthesis for Robust Multiobjective Performance

Abstract

Earlier in the book we saw how a number of performance specifications can be expressed as bounds on a particular transfer function or a specific combina-tion of transfer functions. Asymptotic tracking places a bound on the weighted sensitivity, noise attenuation on the weighted complementary sensitivity. The requirement of robust asymptotic tracking for plants with multiplicative norm bounded uncertaintFy is expressed as a bound on the sum of the weighted sensitivity and complementary sensitivity. In these and many other control problems there is a single bound that needs to be satisfied. Frequently, the implication this has on a robust stability formulation is that it becomes a robust stability requirement of a single feedback system or polynomial family. We have seen several examples of this in Chapters 4 and 8.