Hydraulic Actuation

Driving a joint with pressurized fluid that pushes a cylinder or hydraulic motor.

Hydraulic actuation uses a pump to pressurize hydraulic oil, which valves route to a hydraulic cylinder or hydraulic motor, converting fluid pressure into the force or torque that drives a joint. Its advantages are high power density and strong, shock-resistant force output; its downsides are the need for a pump, hoses, and valves, which make the system heavy, noisy, prone to leaks, and expensive to maintain, with more complex control as well. Early high-dynamic legged robots were mostly hydraulic — the best-known examples are Boston Dynamics' BigDog and the original hydraulic version of Atlas. As electric motors and reducers improved, humanoid robots have largely shifted to electric actuation; Boston Dynamics itself retired the hydraulic Atlas in 2024 in favor of an all-electric version. Hydraulics are still used in heavy-duty construction machinery and some large legged robots.

ExampleBoston Dynamics' hydraulic Atlas used hydraulic actuation to perform parkour and backflips, before being replaced by the electric Atlas in 2024.

Also called

Hydraulic Actuator, Hydraulic Drive

Related

Boston Dynamics Atlas (Hydraulic) · Electro-Hydrostatic Actuator (EHA) · Pneumatic Actuation · Actuator · Power Density (W/kg) · Boston Dynamics BigDog

Sources

Hydraulic machinery - Wikipedia
Atlas (robot) - Wikipedia

As of

2024-04