The ADRC strategy research of electro-hydraulic servo pump control system based on dynamic load torque compensation for high-performance force control

The force control performance of electro-hydraulic servo pump control system (EHSPCS) is constrained by the nonlinear disturbance, volume servo response delay, hydraulic parameter uncertainty, nonlinear excitation disturbance, etc. Compensating control based on the force-speed-torque three-loop control framework has been a popular method for force control from the perspective of nonlinear system models. However, the performance of traditional control methods (e.g., PID) is limited by multi-loop response delays and nonlinear model time-variation due to system pressure and temperature. This paper proposes a dynamic load torque compensation active disturbance rejection control strategy based on a force-torque double loop control framework. The core is to obtain reference balance torque via ADRC. During force control, the system needs dynamic “excess flow” to compensate for leakage, oil compression, and hydraulic cylinder flow due to load deformation. Guided by “excess flow” compensation, the expected servo motor speed is derived, and the speed error is converted into a dynamic load torque compensation command, which is superimposed with the reference balance torque to achieve high-performance force control. Comparative experiments showed that under 30–100 bar conditions, the strategy reduced steady-state error to 0.094 %, representing a 58.6 % and 77.8 % improvement over traditional ADRC (0.227 %) and PID (0.423 %), respectively. This strategy provides a new path for solving the problem of dynamic flow compensation in the EHSPCS under high-voltage conditions and has significant engineering value for improving the performance of precision force control equipment in fields such as high-end manufacturing.