Robust control for industrial systems

An overview of some problem associated with the robust control of industrial systems, together with some notions/design techniques which are potentially useful, are given in this paper. The paper begins by describing some representative "real system" examples (a large flexible space structure, a nuclear reactor control problem), and examines the type of problems which arise in attempting to control these systems. In this case, it is concluded that an input/output description of a plant does not by itself necessarily provide sufficient information to be able to guarantee robustness properties of a controller. The application of "gain margin" as a measure of robustness, and the parameter structural perturbation problem (which arises from "low frequency" uncertainty) are shown to be important for these classes of problems. Given that it is difficult to obtain even crude models for industrial systems, it is then suggested that a possible effective control design procedure is to use a "tuning regulator for unknown systems" approach, which does not require that a mathematical model of the system be available.