Force Estimation and Motion Control of Hydraulic Manipulators Based on Extended State Observer

Hydraulic manipulators have enormous developmental potential in the automation progress across diverse industries. However, challenges arise in controlling them due to joint coupling, friction, the complexity of high-order nonlinear dynamics, and other contributory factors. Furthermore, the control effectiveness can be influenced by external forces acting on the manipulators during their operational processes. For this objective, the manuscript formulates a robust controller within the backstepping control framework. The approach utilizes generalized momentum and extended state observer (ESO) theory to estimate external forces and torques without relying on explicit (physical) sensors. These estimated forces and torques are then compensated for and managed within the controller. The overall system stability is confirmed through Lyapunov theory. Simulation results demonstrate both the controller’s accuracy and the precision of the external force/torque estimation.