Decentral nonlinear observer design using a block-triangular form

The observer design for nonlinear multiple-output systems is shown to be considerably simplified in a decentral approach. The method requires a block-triangular system representation which either can be detected in the system differential equations or may be obtained by a state transformation. The transformation is investigated in detail, and necessary and sufficient conditions for its existence are discussed. Moreover, the method is illustrated by the ball-and-beam example.