Trajectory tracking considering model uncertainty with interconnection and damping assignment passivity-based control for electro-hydraulic servo systems

In this paper, a novel dual closed-loop control framework is proposed for trajectory tracking of electro-hydraulic servo systems, utilizing interconnection and damping assignment passivity-based control alongside a finite-time extended state observer. First, a finite-time approach, coupled with an extended state observer, is employed to estimate system model uncertainties and stochastic disturbances, achieving fast finite-time uniformly ultimately bounded stability of observation errors. Second, the nonlinear state–space model is converted into a port-controlled Hamiltonian system with disturbances. Energy shaping and damping injection methods are then applied to transform the port-controlled Hamiltonian model into the desired closed-loop system. Subsequently, the cascade characteristics of the electro-hydraulic servo system are leveraged to establish virtual inputs, facilitating the development of a dual closed-loop interconnection and damping assignment passivity-based controller. The inner-loop controller utilizes spool displacement as an input to mitigate the effects of external disturbances and enhance single-loop control performance, thereby increasing robustness against model uncertainties and external disturbances. Finally, numerical simulations validate the effectiveness and performance of the proposed control strategy in the context of trajectory tracking control for the electro-hydraulic servo system. Compared with FLSMC-MPC and Backstepping-MPC, the proposed controller improve the tracking accuracy by 61.6% and 12.4%, and the velocity tracking performance by 75.7% and 34.2%, respectively.