Determination of the nonlinear system observability

A method to determine nonlinear system observability will be introduced here. For the determination of the deterministic nonlinear system observability two conditions connectedness and univalence, are developed and used. Depending on how the conditions are satisfied, observability is classified in three categories : observability in the strict sense, wide sense, and the unobservable case. Including simple linear and nonlinear system example an underwater acoustical locaization tracking nonlinear system, the bearing-only tracking example is analyzed.