Hardware

Actuator

An actuator is a device that converts stored or supplied energy, most commonly electrical, hydraulic, or pneumatic, into mechanical motion. In robots, actuators drive every joint and gripper; the dominant modern choice is an electric motor paired with a gearbox, encoder, and driver electronics, often packaged as an integrated joint module. Key specifications include peak and continuous torque, speed, backdrivability, transparency, and torque density.

Why it matters for physical AI

Actuator bandwidth, torque density, and backdrivability set hard physical limits on what any policy can achieve, and proprioceptive actuator designs enable the force sensing that contact-rich learned manipulation depends on.