| The mathematical models of many dynamic systems of interest in the aerospace industry are inherently complex and of high order. Rather than grapple with the full complexity models for such systems, control designers often elect to derive low order, reduced complexity models for which controllers can be designed using the control system design methodology most suited for the application, e.g., pole-placement or a linear quadratic method. Because modern control design techniques generally produce controllers of order at least equal to that of the model used to develop it, the subject of model order reduction has recently received a significant amount of attention. A novel active control methodology that can be used to design a control system that automatically forces the full complexity system to behave like a chosen reduced complexity model is developed in this dissertation. This is accomplished by treating as disturbances the time-variation effects of the original complexity related terms acting on an assumed reduced complexity system and canceling out or reducing those effects by controller actions. The new method, called Complexity Mitigation by Active Control, is demonstrated on a wide range of engineering examples involving both linear and nonlinear systems and verified by simulation results. |
