Andras Varga

SLICOT Working Note 1999-18: December 1999.

This working note presents a short overview of methods suitable for controller reduction. A first class of methods considered are general purpose methods for reduction of unstable systems, as for example, absolute and relative error methods or frequency weighted methods, both in combination with modal separation or coprime factorization techniques. Special frequency weighted controller reduction methods able to preserve closed-loop stability and even closed-loop performance are also discussed. A selection of user callable and supporting routines to be implemented for controller reduction is proposed. The new routines will be included in the SLICOT library.