Extended state observer-based adaptive dynamic surface prescribed performance control for electro-hydraulic actuators...

For Electro-Hydraulic Actuators (EHA) with parametric uncertainties and mismatched and matched disturbances, most existing robust adaptive control strategies can achieve only uniformly ultimately bounded tracking errors. An Extended-State-Observer (ESO) based asymptotic control scheme is proposed by incorporating the prescribed performance control into the backstepping framework to ensure satisfied tracking performance and anti-disturbance ability of EHA systems. A novel ESO is designed to acquire an asymptotic estimation without prior bounds of the mismatched disturbance and its derivatives. Dynamic surface control with an adaptive adjustment mechanism is utilized to avoid the "complexity explosion" and guarantee the asymptotic stability of the closed-loop system. The efficacy of the proposed strategy is validated through simulation and experiments.