A new observation algorithm for nonlinear systems with unknown inputs

This paper provides some new developments in the design of unknown input observers for nonlinear systems. This note is a generalization to nonlinear system of an algorithm for linear systems that states if it is possible to design or not an observer for systems subject to unknown inputs. The algorithm for nonlinear systems with unknown inputs is derived and a step by step sliding mode observer is built. An example is given in order to highlight the efficiency of the proposed method.