New Cascade Observer for a Class of Nonlinear Systems with Time-delayed Outputs

This paper presents a new cascade structure for the estimation of the delay-free state vector for a class of nonlinear systems with long time-delay output. The base in the cascade observer is a standard high-gain observer to estimate the delayed state vector, and this new cascade presents the redesign of the subsystems present in the cascade compensating in a time horizon the delay of the system output, achieving the estimation of the delay-free state vector. Sufficient conditions are proposed to establish that the observation error exponentially converges to zero. The performance of the proposed observer is evaluated by considering as example an uncertain nonlinear system with long time-delayed output.