SOME REALIZATIONS IN THE STUDY OF OSCILLATIONS WITH A FREQUENCY METHOD

Some state-space realizations, critical when applying certain types of frequency methods, are more appropriate than others for studying oscillations in nonlinear systems. In this paper we suggest some few criteria and a procedure, based mainly on controllability and observability properties, that yield satisfactory state-space realizations. Some simple non trivial examples are presented and discussed. Keywords: Hopf bifurcation, Frequency domain, Controllability, Observability. AMS (MOS) subject classiflcation: 34A34; 34H05; 93B05; 93B07; 93C80.