Implementation of Input Design for Structured Nonlinear System Identification via Linear IMC Control

Structured nonlinear system identification is a block oriented identification method for systems that can be described by the interconnection of known linear dynamic systems and unknown static nonlinearities. An identification algorithmfor this class of systems was previously presented in Hsu et al. (2008), and the related input design problem was solved in Vincent et al. (2009) when there is no feedback from the nonlinear blocks. In the present paper, we propose a strategy, based on linear Internal Model Control (IMC), for the implementation of the input design on a general structure. The strategy relies on the design of an IMC controller which minimizes a bound on the tracking error, defined as the difference between desired and actual input to the static nonlinearities. An application related to input design for the identification of semi-active suspensions is presented.