Linear Methods in Observability and Controllability of Nonlinear Systems

The paper is devoted to the development of approach to analyze observability and controllability of nonlinear dynamic systems by linear methods. The main idea of this approach is as follows: observability (controllability) of the initial nonlinear system linear part is checked and if it is unobservable (uncontrollable), one examines whether or not the nonlinear term violates this conclusion. Sufficient conditions for unobservability and uncontrollability are obtained.