Nonlinear Unknown Input Observer Design for Nonlinear Systems: A New Method

This paper provides new developments in the design of observers for nonlinear systems with unknown inputs. The proposed methods guarantee the error system stability and yield many additional degrees of freedom available to the designer. The algorithms for designing a nonlinear observer for nonlinear systems with unknown inputs is derived in detail. The proposed observers may be used for fault detection and isolation. A nonlinear mass-spring-damper model is given in order to highlight the efficiency of the proposed method.