Performance Preserving Controller Reduction in the μ Setting

This paper is concerned with the order reduction of controllers produced by μ-synthesis controller design paradigm. A new proof has been proposed for the additive perturbation reduction technique with sufficient conditions to guarantee the closed loop structured singular value to remain less than unity. Reduction of unstable controllers is achieved through a new coprime factor reduction technique with sufficient conditions to guarantee preservation of closed loop performance. The coprime factor perturbations to the controller have been shown to have a block diagonal structure. The proposed algorithms have been tested on a widely studied benchmark HIMAT aircraft and have been found to work satisfactorily producing more than 50% reduction in the controller order without optimization. Keywords— Controller Reduction, Structured Singular Value, Coprime factors