Extended state observer‐based finite time control of electro‐hydraulic system via sliding mode technique
Quan Zou
Abstract
Abstract The position tracking control of electro‐hydraulic system (EHS) is disposed in this paper via sliding mode control (SMC) with nonlinear sliding surface. The main feature of the proposed controller is the combination of a totally singular‐free recursive terminal sliding mode controller (RTSMC) with an extended state observer (ESO). The uncertainties (including the unknown external disturbance) together with its derivatives and the unmeasured states of EHS are estimated simultaneously by the ESO while the controller is designed by employing the recursive nonsingular TSMC (RNTSMC), and a nonlinear sliding surface is employed to totally avoid the singularity in the traditional RNTSMC. Moreover, the observer dynamics are considered during the controller design. The position tracking error is proven to be bounded in finite time via Lyapunov theory, and the bound can be effectively reduced by tuning the parameters of the controller and observer. Simulation results show that the proposed controller is not sensitive to model uncertainties and external disturbances.