Since about 1985, extremely efficient and nonconservative methods have been developed for the analysis of robust stability of control systems subject to parameter variations. However, there are no synthesis procedures available at all. On the other hand, H-infinity control theory has a well-developed synthesis procedure. This theory, however, is highly conservative when applied to the parametric stability problem. In this proposal we intend to develop synthesis procedures for control problems containing parameter uncertainty. A promising opening is given by recent results (obtained by the PI's) proving that the extremal stability margins (including H-infinity margins) occur on certain manifolds derived from Kharitonov's theorem. This link suggests that H-infinity (and other classical synthesis methods) might be intelligently tailored to give nonconservative synthesis procedures for parameter variation problems. This will form the main area of our research. We expect the results of this research project to have an impact on the analysis and design of control systems arising in many applications.
