Further results on the identification problem for the class of nonlinear systems

For the class of nonlinear systems , the structure of the identification problem based on steady-state frequency response is considered. Two approaches using amplitude and phase measurements are presented, one of which requires measurements of only the first two harmonics of the steady-state response. Furthermore it is shown that with a minimum phase restriction the system can be identified from amplitude measurements of the first two harmonics. In each case we obtain a considerable reduction in the number of measurements and inputs required by previous approaches.