Adding Damping to Energy-Efficient Electro-Hydraulic Drives Using Observed Pressure

Abstract

The increasing focus on energy efficiency directs the research for hydraulic systems towards electro-hydraulic drives, namely actuators directly coupled to pumps driven by electric motors. This approach removes functional power dissipations while enabling energy recovery. However, these drives have inherently low damping that causes harmful payload oscillations, deteriorating the position control's accuracy of the actuator. Adding active damping via pressure feedback is essential, but the pressure in both actuator chambers must be measured. Thus, this paper proposes using observed pressure where a virtual pressure sensor implemented via software replaces two physical pressure transducers. Direct pressure feedback is applied by relying on a model-based approach for designing closed-loop position control. This method is validated numerically on a heavy-duty robotic manipulator, showing that observed pressure feedback can reduce payload oscillations and ensure proper position tracking.