An improved super-twisting extended state observer and sliding mode controller strategy for electro-hydraulic position tracking systems

In engineering practice, electro-hydraulic position tracking systems (EHPTS) inevitably suffer from the detrimental effects of nonlinear dynamics and uncertain disturbances. This paper proposes an Improved Super-Twisting Extended State Observer (ISTESO) and develops an applicable observer-based sliding mode controller specifically designed for EHPTS. The designed observer effectively estimates the lumped uncertain disturbances while simultaneously providing noise-suppressed reconstructions of the available system states. Comprehensive convergence analysis of the proposed observer and controller is presented, with rigorous proof steps established using Lyapunov stability theory. Finally, experimental results under various operating conditions demonstrate the feasibility and superior performance of the proposed Improved Super-Twisting Extended State Observer-based Sliding Mode Controller (ISTESOSMC).