The optimal mix of structure redesign and active dynamic controllers

For a given plant, this paper begins with the assumption that a controller is given which yields desired closed-loop properties. Both the controller and the original plant are simultaneously redesigned so as to closed-loop properties are maintained. The initial linear controller before plant redesign is not restricted: it could be static or dynamic. We call this the optimalmix problem since we optimally mix parameter changes of the plant with parameter changes of the controller. The problem requires matching the entire plant matrix of the original system (before and afterstandard mathematical quadratic program, globally optimal applicability of the optimal mix theory to a general mechanical system is demonstrated by mumerical examples of a spring-mass-damper system.