Variable structure observer for a class of nonlinear large-scale interconnected systems with uncertainties

In this paper, a variable structure observer design approach is proposed for a class of nonlinear, large-scale interconnected systems in the presence of unstructured uncertainty. The modern geometric approach is exploited to explore the system structure and a transformation is developed to facilitate observer design. Using the Lyapunov direct method, a robust asymptotic observer is presented which exploits the internal dynamic structure of the system as well as the structure of the uncertainties. The bounds on the uncertainties are nonlinear and are employed in the observer design to reject the effect of the uncertainties. A numerical example is presented to illustrate the approach and the simulation results show that the proposed approach is effective.