Low-order H∞ suboptimal controllers

The paper presents a methodology for the problem of reducing the order of H_∞ suboptimal controllers. It is shown how the order of H_∞ suboptimal controllers may be reduced to n-p₂ and how for some plants the order may be less than n-p ₂, where n is the size of the system matrix of the generalised plant and p₂ is the number of process outputs. A set of H_∞ suboptimal controllers of order n-p₂ is characterised. A numerical example is given to illustrate the results