Robust adaptive observer for a class of nonlinear systems

In this paper, a stabilization problem for a class of multiple-input multiple-output nonlinear systems is considered, where both the nonlinear term and the nonlinear uncertainty are mismatched and subject to time-varying delay. Under the assumption that the delay is known, a adaptive observer is designed, and the observer only has one adaptive parameter no matter how high the order of the system is. The proposed observer shown the state estimation error is uniformly bounded and can be made arbitrarily small.