Decentralized block triangular observer design for nonlinear systems

A decentralized approach in the observer design for multiple output nonlinear systems offers degrees of freedom which can be used to fulfill more easily the rather strict requirements for the application of nonlinear design methods. To apply this technique, observable subsystems have to be connected in a block triangular form. If the system is not given that way, the form may be obtained by a nonlinear state transformation. This transformation and the decentralized observer design are illustrated via two simple examples.