Observer Design For Nonlinear Systems With Implicit Output

This paper investigates the problem of observer design for nonlinear systems when only a transformed output is available for measurement. More precisely, we first assume that there exists an observer design that requires the output of the system. We then suppose that this disturbed output is only available under a transformation and we propose a new observer design. We establish small-gain type conditions ensuring the asymptotic convergence of the proposed observer and we provide an illustration example.