ROBUST EIGENSTRUCTURE ASSIGNMENT USING THE GENETIC ALGORITHM AND CONSTRAINED STATE-FEEDBACK

This paper describes a robust eigenstructure assignment methodology fo r a constrained state feedback problem. The method, which is based upo n the linear quadratic regulator and involves the minimization, via th e genetic algorithm, of a multiobjective cost function, is applied to L1011 Tristar aircraft lateral dynamics. The design example generates a fixed-gain state feedback solution which shows independent phase mar gins of 51 degrees in each channel, while exhibiting an eigenstructure close to that desired, lying well within specified handling quality r equirements. If two states are made unavailable for feedback, the robu stness properties are seriously eroded. When a dynamic feedback compen sator is then used, there is a substantial recovery of the robustness. It is concluded that the genetic algorithm approach described here is easy to use and generates good multivariable stability margins.