Two controller reduction methods based on convex optimization

This article Outlines two approaches for the computation of a Suitable low order controller if a linear discrete-time control system with I high order controller is given. Actually this step is of significant importance in the case of the so-called Q-design procedure and especially in l(1)-optimal control system design. Since the main focus during controller reduction is to maintain the performance of the closed loop system this task is quite different from the general order reduction problem and thus requires special methods. In this article two controller reduction methods are presented, which lead to linear programs. It is intended to augment the Q-design approach by a suitable controller reduction step and in this way it should become possible to utilize the full power of Q-design and to get controllers of reasonable order. The performance of the proposed methods is demonstrated by an example.