Finite-time continuous extended state observers: design and experimental validation on electro-hydraulic systems✰

In this paper, a time-varying chattering-free observer for electro-hydraulic actuators able to provide finite-time estimations of the full state variables as well as uncertainties is presented. The key idea is to employ a positive-increasing function associated with the observer objectives to improve the convergence time performance. First, the model of an electro-hydraulic actuator as a case study for the proposed observer is presented. Then, an extended state observer is introduced, and the time-varying gains are provided to ensure that without neither any knowledge about the upper bounds of the uncertainties nor its derivative, the observation error dynamics is convergent to a neighborhood of zero in a finite time. Comparative simulations are presented to analyze the effectiveness of the proposed observers. Then, further simulations are performed in the presence of measurement noise. It is concluded that the proposed scheme can compete with other leading strategies, making it a qualified alternative approach in the observer design with noteworthy potential. Finally, the effectiveness of the proposed approach in real-life conditions is demonstrated through experimental studies.