Electro-Hydrostatic Actuator (EHA)

电动静液作动器EHAAdvanced

A self-contained hydraulic actuator with its own motor-driven pump and closed oil loop, needing no external hydraulic supply.

An electro-hydrostatic actuator packages a motor, a small bidirectional oil pump, a cylinder, and a reservoir into one self-contained module: as the motor spins one way or the other, the pump pushes oil to one side of the cylinder, extending or retracting the piston, with the oil loop closed entirely inside the module. It keeps hydraulics' advantages — high force, shock resistance — while eliminating the central pump station, long hoses, and servo valves a traditional hydraulic system needs; it only needs power and a control signal to run, and is more efficient too. EHAs were first adopted in aerospace, for aircraft control-surface actuation, and have since been used in the leg joints of heavy-load legged and humanoid robots, as a middle ground between purely electric joints and traditional hydraulics.

Also called: Electrohydrostatic Actuator
Related: Hydraulic Actuation · Actuator · Linear Actuator (Electric Cylinder) · Boston Dynamics Atlas (Hydraulic) · Torque Density
Sources: Electro-hydraulic actuator - Wikipedia