A new representation of SISO systems for studying approximated models (Q1093602)

A nonlinear matrix equation is introduced and it is shown that a particular solution of the considered equation contains for SISO systems the same type of information carried in closed-loop characteristic values. In addition, it contains equivalent information on the so-defined closed-loop system ``signature'' where its importance in model reduction problems is outined. An illustrative example is presented, and results are compared to those of other methods by using the proposed approximated model in a closed-loop scheme.