ABSTRACT
This paper is concerned with the problem of robust control design of uncertain systems. The plant is supposed not exactly known, but described by a perturbation model which can take into account both parametric and dynamic uncertainties. The main concern of the paper is to check if a given controller satisfies a given set of performance specifications, for all plants in the uncertainty set. The solution is obtained by introducing the concept of performance margin, extending the well known concept of stability margin.
It is shown that the performance margin can be actually computed for several sperificalions. such as stabihty. bandwith. damping, disturbance attenuation and many other. If the controller has some free design parameters, a technique similar to perfomance margin compulation allows the computation of maximal ranges of variation around their nominal values, guaranteeing robust performances.
The control of a d.c. motor is used as an example to demonstrate the feasiblity of the approach.
