Gregory S. Mason

Reduced-order multirate compensator synthesis

A method for synthesizing reduced order multirate compensators is presented. Necessary conditions for which the compensator parameter values minimize an infinite time quadratic cost function are derived. An algorithm for finding compensator parameter values which satisfy the necessary conditions is described. This algorithm is then used to design several tip position controllers for a two link robot arm.

Robustness analysis of a multirate flutter suppression system

A unified approach for analyzing the robustness and performance of multirate systems is presented. The approach is a compilation of existing multirate performance and robustness analysis results, along with some new results, all presented in a consistent state-space formulation. The approach is used to analyze the robustness of a multirate flutter suppression system designed for a model wing. The example highlights some of the practical considerations in multirate performance and robustness analysis.

Robustness analysis of multirate and periodically time varying systems

A new method for analyzing the stability and robustness of multirate and periodically time varying systems is presented. It is shown that a multirate or periodically time varying system can be transformed into an equivalent time invariant system. For a SISO system, traditional gain and phase margins can be found by direct application of the Nyquist criterion to this equivalent time invariant system. For a MIMO system, structured and unstructured singular values can be used to determine the systems robustness. The limitations and implications of utilizing this equivalent time invariant system for calculating gain and phase margins, and for estimating robustness via singular value analysis are discussed.