New results for identifiability of nonlinear systems

The parameter identifiability problem of deterministic non-linear control systems is studied. Relations between nonlinear observability, nonlinear functional expansions, the uniqueness theorem of nonlinear realization theory, and identifiability are investigated. By using these relations, necessary and sufficient conditions for identifiability are obtained for the first time. These results provide insight into the identifiability problem for nonlinear systems.