Humanoid Joint Actuators

CategoryActuators

Market classPrototype

Introduction date11 August 2022

6 components

Agility Robotics cycloidal actuator

Agility Robotics' proprietary cycloidal actuator powering the new, human-like leg design of the Digit 5 humanoid, engineered for repetitive lifting of up to ~22.7 kg.

Deployed

Actuators·Boston Dynamics

Atlas Electric Actuator (Boston Dynamics, 2024)

Boston Dynamics' proprietary joint actuator used in the fully-electric Atlas (2024+) — high torque density and 360° continuously rotating joints.

TorqueNot disclosed; Boston Dynamics reports higher torque density than the hydraulic Atlas generation

DOFStosowany w ok. 28 stopniach swobody robota Atlas (2024+); część stawów rotuje ciągle przez 360°

Deployed

Actuators

Fourier Smart Actuator (FSA)

Integrated PMSM joint actuator with reducer, driver and absolute encoder used in Fourier GR-1 and GR-2 humanoid robots.

TorquePeak up to ~230 N·m (largest variant in the portfolio)

PrecisionAbsolute encoder on both input and output shaft

Voltage48 V DC

Announced

HIGEN HFA joint actuator (Human-Friendly Actuator platform)

Actuators·HIGEN RNM

Human-Friendly Actuator Platform (HIGEN HFA)

HIGEN RNM platform of integrated joint actuators for humanoid robots and cobots: axial-flux (AFPM) motors, compliance and sensorless force estimation, <100 ms local reflex.

TorqueNominal 20–116 N·m; peak 60–348 N·m (model-dependent)

SpeedNominal 54–127 rpm (model-dependent)

PrecisionBackdrive torque < 1 N·m

Deployed

Actuators·Tesla

Tesla Optimus Roller Screw Linear Actuator

Tesla's planetary roller-screw linear actuator — 14 units in the legs of Optimus Gen 2, shock- and brinelling-resistant.

PrecisionHigh-resolution linear position encoder + torque-mode control

Prototype

Joints·Xiaomi

Xiaomi Self-Developed Humanoid Joint Motor (CyberOne)

Family of Xiaomi’s self-developed humanoid joint motors built for the CyberOne prototype (2022). The strongest variant (knee) reaches a peak torque of 300 Nm; the robot has 21 total degrees of freedom.

Last updated: 23 March 2026