Reduced-order solutions to H∞ and LPV control problems involving partial-state feedback

We solve a parameter-dependent control problem for a linear parameter-varying (LPV) plant in which both noisy outputs and/or exact measurements of some plant states are fed back. Known bounds on the parameters´ rates of variation are used to reduce conservatism. We give necessary and sufficient conditions, expressed as linear matrix inequalities (LMIs), for solvability by full- and reduced-order controllers. If the desired controller order equals the plant order minus the number of exactly measured states, then the intractable rank condition currently required for reduced-order synthesis can be avoided; moreover, this controller order is the largest needed for a solution. The solutions of the solvability LMIs are used to derive explicit controller formulae