Hydraulic Actuator

Hydraulic actuators use pressurized fluid (typically oil) to create linear or rotary motion. A hydraulic pump pressurizes fluid, which flows through valves to cylinders containing pistons. Fluid pressure pushes the piston, creating powerful mechanical force. Servo valves control fluid flow direction and rate, enabling precise position and force control. Hydraulic systems deliver exceptional power density - generating much higher forces than electric motors of equivalent weight. They also provide inherent compliance and shock absorption. However, they require pumps, fluid reservoirs, and sealing systems, making them more complex than electric actuators.

Hydraulic actuators power the dynamic movements of advanced humanoids like Atlas, enabling running, jumping, and backflips. High-payload industrial humanoids use hydraulics to lift heavy objects. Legged robots employ hydraulic legs for powerful, energy-efficient walking over rough terrain. Exoskeletons leverage hydraulics for amplifying human strength. Construction and disaster response robots need hydraulic strength for manipulating debris. Explosive ordnance disposal robots use hydraulic grippers for powerful manipulation.