Robustness analysis and controller synthesis with non-normalized coprime factor uncertainty characterisation

A new robust controller synthesis method is proposed, based on a non-normalized coprime factorization of an uncertain plant. It achieves robust stabilization for very large uncertainties as measured by the n-gap metric, as well as robust performance. It is shown that a non-normalized coprime factorization enables less conservative robust stability and performance guarantees than a normalized coprime factorization. In a numerical example, a controller is synthesized for a benchmark robust control problem, demonstrating the good robustness properties obtainable with the method of this paper.