Frequency-response design of robust optimal controllers

A simple guide to specifying the bandwidth of an optimal control feedback system (as measured by the unity-loop-gain crossover frequency) is developed. A brief description is given of how the guide helps in the design of robust optimally controlled systems. The only information necessary to use the guide is an open-loop gain plot for the plant, thus providing the designer with a powerful design tool, independent of the method used for solving the optimisation problem.