A state observer for a special class of MIMO nonlinear systems and its application to induction motor

Presents an observer design methodology for a special class of MIMO nonlinear systems. First, we characterize the class of MIMO nonlinear systems that consists of the linear observable part and the nonlinear one with a block triangular structure. Also, the similarity transformation that plays an important role in proving the convergence of the proposed observer is generalized to MIMO systems. From this, we propose the state observer that can be seen as an interconnection of the existing observer for SISO triangular nonlinear systems. Since the gain of the proposed observer minimizes a nonlinear part of the system to suppress the stability of the error dynamics, it improves the transient performance of the high gain observer. Finally, the simulation results for an induction motor are included to illustrate the validity of our design scheme.