Observer Design for a class of uniformly observable MIMO nonlinear systems with coupled structure

A high gain observer is synthesized from a canonical form that characterizes the class of uniformly observable systems. Two main contributions are to be emphasized: the first is related to the considered structure of the canonical form which does not assume a complete triangular structure. That is, each block may contain nonlinearities which depend on the whole state. The second main contribution lies in the simplicity of the observer gain synthesis since the expression of this gain is given and its calibration is reduced to the choice of a single design parameter. Moreover, this involves a design function that has to satisfy a mild condition which is given. Different expressions of such a function are proposed. Of particular interest, it is shown that high gain observers and sliding mode like observers can be derived by considering particular expressions of the design function. An example with simulation results is given for illustration purposes.