Simultaneous Improvement of Time and Frequency Performance.

Quasi-linear feedback theory (Kelemen 2002; Kelemen and Bensoussan 2004) enabled simultaneously improving time performance and frequency performance of feedback systems, by using compensators whose poles are gain dependant. Although simulation results show theoretical improvements, the gain magnitude of quasi linear compensators is prohibitive. Moreover, the underlying conditions for the application of quasi-linear feedback assume that the model of the plant is known with great accuracies, i.e. that the difference between the poles and the zeros of the plant is known with precision. This paper intends to present a different quasi-linear controller (Bensoussan 2011) that achieves simultaneous time and frequency optimization. It will be shown to be by far the best and most practical solution.