Analysis and synthesis of model reference ILQ servo system using robust L∞ performance measure for a fixed input

A robustness problem of output trajectories is considered here in the design of servo systems. Our purpose is to design a robust servo system with tracking robustness in that its output trajectory remains in a neighborhood of the nominal trajectory when the dynamics of the system is perturbed. For this purpose we propose a control configuration of robust servo system with a conditional feedback. In this configuration the robust servo system is designed by the inverse linear quadratic (ILQ) design method as proposed by the second author, and the conditional feedback is added to achieve tracking robustness of the output response. First, we state the configuration of this servo system and then provide a theoretical basis for parameter tuning. Second, we consider analysis and synthesis of model reference ILQ(MR-ILQ) servo systems by using the robust L_∞ performance measure for a fixed input. Finally, we illustrate a numerical example to show the validity of our results.