Decentral nonlinear observer design using a block-triangular form

The observer design for nonlinear multiple-output systems is shown to be co nsiderably 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 t ransformation is investigated in detail, and necessary and sufficient condi tions for its existence are discussed. Moreover, the method is illustrated by the ball-and-beam example.