A METHOD FOR NONLINEAR-SYSTEM CLASSIFICATION IN THE TIME-FREQUENCY PLANE

This paper presents a new method for the classification of nonlinear s ystems based on the time-frequency analysis of the free oscillations. In particular, oscillators described by a nonlinear second-order diffe rential equation are considered. The nonlinearity is due to a nonlinea r function of the state variable, which produces free oscillations wit h a time-variant spectrum. The classification is based on two differen t estimates of the fundamental frequency of the free oscillations. The comparison between the two estimates allows a very efficient system c lassification. Both the proposed estimators and the way of combining t he two estimates are new. Validation tests have shown the high perform ances of the proposed technique. (C) 1998 Elsevier Science B.V. All ri ghts reserved.