Static normalizing pre-compensator: The first step for addressing robustness in the design of multivariable controllers using the Characteristic Locus Method

This paper shows that the first step in the design of multivariable controllers within the Characteristic Locus Method must be the design of a static normalizing pre-compensator that makes the pre-compensated plant as closely as possible to a normal matrix at the vicinity of the crossover frequency, if robustness is to be addressed in a later stage of the design. Following this conclusion, the design of a static normalizing pre-compensator with no constraint in its structure is presented, being based on an optimization problem whose solution can be obtained directly by solving a simple eigenvalue problem. A numerical example illustrates the efficiency of the proposed design strategy.