This paper develops a low-order controller design method for linear discrete time-invariant single-input, single-output systems. Using the coprime factors and the properties of discrete outer functions, the low-order controller design becomes a zero-placement problem which is convex. The solutions are obtained using the linear matrix inequality techniques. The proposed design method is used to solve for several optimal control problems, such as pole-placement design, model-matching design, and H∞ optimization problems.
Tamkang Journal of Science and Engineering=淡江理工學刊 7(1), pp.29-36