COMPARISON OF VARIOUS CONTROLLER-REDUCTION METHODS: SUBOPTIMAL VERSUS OPTIMAL PROJECTION

Several s uboptimal approaches to reduced-order controller design are compared with the new optimal projection formulation of the quadratically optimal fixed-form compensator problem. The substantial similarities and significant differences among the various design techniques are highlighted by placing the design e quations of all methods within a common notation. Basically, all methods characterize the reduced-order controller by a projection on the full state space. The suboptimal methods construct this projection on the basis of balancing considerations while the optimal projection equations define