Active Damping in Electro-Hydraulic Systems via Low-Pass-Filtered Observed Pressure

Abstract

The growing demand for energy efficiency in heavy-duty industry points the research focus toward electro-hydraulic systems. They couple directly pumps driven by electric motors to hydraulic cylinders, removing functional power dissipations and allowing for energy recovery. However, these drives have inherently very low damping, degrading position control's precision and affecting operational safety via harmful payload oscillations. Adding active damping via pressure feedback helps greatly, but both actuator pressures must be sensed. Therefore, this study considers observed pressure (i.e., a virtual pressure sensor implemented via software) to replace those two physical pressure transducers. Low-pass-filtered pressure feedback is involved in the process utilizing model-based design for closed-loop position control. The results from a heavy-duty robotic manipulator support this technique and pinpoint critical aspects to ensure that the payload oscillations are minimized and the position tracking is satisfactory.