Humanoid Actuator Supply Chain

reducers · roller screws · modules

Actuators are about half of a humanoid's bill of materials. Japan leads the precision gears, China leads magnets and module assembly, and Chinese reducer and screw makers are closing the precision gap at half the price.

Inside one humanoid joint, who makes each part: magnet motor (NdFeB magnets about 90% from China; Tuopu, maxon, Kollmorgen), strain-wave reducer (Harmonic Drive Systems; Leaderdrive and Green Harmonic in China), planetary roller screw (GSA and Rollvis in Switzerland; Wuzhou Xinchun and Beite in China), encoders and torque sensors (Renishaw, Heidenhain, RLS; Keli Sensing in China), joint driver chips (TI, Infineon, EPC; Innoscience GaN in China) and module assembly (Sanhua and Tuopu in China; Schaeffler, Hyundai Mobis). The multiplier: Tesla Optimus uses 28 or more structural actuators plus dozens of small hand motors, so one million robots a year means tens of millions of joint modules. INSIDE ONE JOINT: WHO MAKES EACH PART Magnet motor NdFeB magnets ~90% China Tuopu, maxon, Kollmorgen Strain-wave reducer Harmonic Drive Systems Leaderdrive (China) Roller screw GSA, Rollvis (Swiss) Wuzhou Xinchun, Beite Encoders, torque Renishaw, Heidenhain Keli Sensing (China) Joint driver TI, Infineon, EPC chips Innoscience GaN (China) Module assembly Sanhua, Tuopu (China) Schaeffler, Mobis THE MULTIPLIER 28+ structural actuators per Tesla Optimus, plus dozens of small motors in the hands. One million robots a year means tens of millions of joint modules. Red: China-led. Gold: Japan-led. Blue: US, Europe. Gray: mixed or shifting.
Actuator share of BOM
~50%
Optimus structural actuators
28
Leaderdrive China share
30-40%
Humanoids shipped, 2025
~13,300
Hub
Supply Chain

Finding

Humanoid scaling is gated by precision mechanical parts - strain-wave reducers and planetary roller screws - more than by chips or batteries, and China is building that capacity fastest

Tesla's Optimus uses about 28 structural actuators: 14 rotary joints with strain-wave (harmonic) reducers and 14 linear joints with planetary roller screws, plus about 20 small motors in each dexterous hand. Schaeffler puts actuators at about half of a humanoid's bill of materials. Omdia counted about 13,300 humanoids shipped worldwide in 2025, so today's supply is sized for thousands of robots, not the millions OEMs project.

Strain-wave reducers were a Japanese near-monopoly: Harmonic Drive Systems invented the product and still sets the high end. China's Leaderdrive holds 30-40% of its home market, sold about 425,000 reducers in 2025 and is building toward about 1.4 million a year of capacity; Green Harmonic is a second source. Chinese reducers sell at 40-60% of Japanese prices. Planetary roller screws, used for knees, hips and elbows, came from Switzerland's GSA and Rollvis; Wuzhou Xinchun, Beite and Xinjian are scaling in China at about half the price.

Module assembly is mostly Chinese. Sanhua Intelligent Controls is reported as the Optimus linear actuator assembler with capacity near 500,000 sets a year, and Tuopu supplies rotary modules and hand motors; Schaeffler (with Ewellix) and Hyundai Mobis, for Boston Dynamics' Atlas, are the main Western module makers. Most Optimus supplier relationships are reported by investors and press, not confirmed by Tesla. Every joint also needs a rare earth magnet motor, tying humanoids to the same NdFeB chain as EV traction motors; MP Materials' Fort Worth magnet plant is the main US source being built. Tesla plans volume Optimus production at Giga Texas.

Components

What is inside a joint module

Humanoid actuator components
ComponentFunctionWhy it is hardLeading suppliers
Magnet motor (frameless BLDC or PMSM)Produces torqueTorque density in a small, hot packageKollmorgen, TQ RoboDrive, maxon; Tuopu, Zhaowei
Strain-wave reducerHigh ratio, zero backlash for rotary jointsMicron-level flexspline machining and heat treatmentHarmonic Drive Systems; Leaderdrive, Green Harmonic
Planetary reducerRobust, backdrivable reductionLess precise; bulkier at high ratioNidec, Neugart; many Chinese makers
Planetary roller screwLinear force for knees, hips, elbowsThread grinding precision; fatigue lifeGSA, Rollvis, Schaeffler; Wuzhou Xinchun, Beite, Xinjian
EncoderPosition feedbackResolution and latencyRenishaw, Heidenhain, RLS
Torque sensorForce control and safe contactIntegration without bulk or noiseATI, Bota Systems; Keli Sensing
Joint driverInverter and current controlThermal density in the limbSee Humanoid Actuator Power Electronics
BearingsCrossed-roller and thin-section supportStiffness in small envelopesSKF, NSK, THK, Timken

Bottlenecks

Bottleneck ranking

Humanoid actuator bottlenecks
ComponentBottleneck levelReasonConcentration
Strain-wave reducersVery highPrecision tooling; few qualified makersJapan high end; China volume rising fast
Planetary roller screwsVery highGrinding capacity; little prior volume demandSwitzerland; China scaling
Integrated actuator modulesHighMulti-part integration and testChina for volume
NdFeB magnetsHighRare earth refining and export controlsChina ~90%
Encoders and torque sensorsMediumCalibration and durabilityJapan, Europe; China rising
Power semiconductorsLow to mediumSmall low-voltage devices are plentifulUS, Europe, Taiwan, China

Regions

China and Japan supply structure

Regional roles
RegionStrengthWeaknessRole
JapanPrecision reducers, encoders, bearingsLimited volume ambitionPerformance leader
ChinaMagnets, module assembly, low-cost reducers and screwsVariable top-end precision, narrowingScaling engine
EuropeRoller screws, motors, sensors, Schaeffler modulesCostPrecision niches
USRobot OEMs, driver chips, frameless motorsLittle mechanical component capacityDemand and design

Sources

Sources and scope

Scope
Humanoid Actuator Supply Chain
Sources
Humanoid Guide supplier landscape (2026); Omdia (2025 shipments); J.P. Morgan; Schaeffler; Tesla AI Day
Updated
October 2026