Multi-input multi-output automatic design synthesis for performance and robustness

A direct-design method for solving the problem of robustness to cross-coupling perturbations in multivariable control systems is presented. The method uses numerical optimization procedures to manipulate the system feedback gains as direct design variables. The manipulation is accomplished in a manner that produces desired performance by pole placement and robustness by modification of the minimum singular values of the system return difference matrix. Channels affected by cross-coupling perturbation may be recognized by the character of their transfer function plots. The pole placement and robustness routine uses gain equalization and zero assignment to modify the characteristics of the system in the design. A modification of the pole placement and robustness routine that may be applied to the design of robust observers is also presented.