A New High Gain Observer Based on Artificial Delays

This paper develops a novel high-gain observer for nonlinear systems that has a lower gain compared to the standard high-gain observer. This new observer called Artificial Delayed High Gain Observer (ADHGO) is obtained by combining the standard High-Gain methodology with two steps: the first one is defining artificial delayed outputs of the system and incorporating them in the proposed observer’s structure. The second step consists in applying Taylor’s series development to these artificially delayed measurements in order to annihilate the nonlinear unknown or uncertain term. This step allows the reduction of the gains of the high gain observer. Through analytical developments, the conditions of existence of the observer and the choice of the artificial delays are determined. Consequently, the obtained lower gains allow to answer to the problems of peaking phenomenon and noise amplification. The performances of the proposed observer are illustrated through a numerical example with comparisons and discussions.