A versatile controller design software for unstable systems

A new software utility for use with linear unstable plants is developed. The software is in the Matlab environment, and it is based on Youla parameterization. The software optimizes the location of all coprime factors. A two-layer optimization approach is used to arrive at the desired controller. At the inner layer, an exact model-matching optimization procedure is utilized, and a stable design is obtained. This optimization process is then placed inside a nonlinear optimization routine to optimize the assumed locations of the poles of the coprime factors. The software is applied to an unstable plant, and the results are compared with two other techniques.