Model-Based Position Control of Energy-Efficient Electro-Hydraulic Linear Drives

The rising interest in energy efficiency for hydraulic systems directs the research towards electro-hydraulic drives, namely linear actuators (i.e., hydraulic cylinders) directly coupled to pumps driven by electric motors. This approach removes functional power dissipations, enables energy recovery, and facilitates system commissioning. However, these drives are characterized by inherently low damping that causes unwanted payload oscillations and deteriorates the position control’s accuracy of the actuator. Adding active damping via proper control techniques is essential. Hence, this paper develops a model-based design for closed-loop position control with the addition of high-pass-filtered pressure feedback. The model supports identifying crucial control parameters, such as the proportional and integral gains of the position feedback and the gain and time constant of the pressure feedback. This method is experimentally tested on a heavy-duty robotic manipulator. The results show that the payload oscillations are reduced dramatically, and the position tracking is accurate and robust for different load cases.