Some effective approaches to check the identifiability of uncontrolled nonlinear systems

The problem of identifiability of parameters has hardly ever been considered in the case of uncontrolled systems whereas many efficient methods have been developed for controlled systems. In this paper, we are pointing out two procedures to get global identifiability results of uncontrolled nonlinear systems. The first one derives from an algorithm. proposed by Ljung and Glad, It is based on differential algebra and its complexity, due to the system size, does not increase as fast as the complexity of their algorithm. The second one is a heuristic approach. It builds a new model from various input datasets which expresses an experimental reality. Therefore, we will analyze the identifiability of this new model. Indeed, this procedure has been tested on an intricate system for which the other methods failed and it has given global identifiability results. (C) 2001 WACS. Published by Elsevier Science B.V. All rights reserved.