Who supplies humanoid robot joints? Japan's Harmonic Drive and Nabtesco, China's Leaderdrive and Germany's Schaeffler lead, while Tesla and Figure build their own

The joints of a humanoid robot are supplied today by a small group of precision-gear and motion companies, led by Harmonic Drive Systems and Nabtesco in Japan, Leaderdrive in China and Schaeffler in Germany, with the Chinese manufacturers Tuopu Group and Sanhua Intelligent Controls moving into complete actuators. The robot makers with the largest stated volumes, Tesla and Figure AI, design their actuators in-house, which leaves the merchant suppliers a market that is smaller and more contested than humanoid shipment figures suggest.

The stakes come down to arithmetic. Schaeffler says an average humanoid needs 25 to 30 actuators for joints such as shoulders, knees and hips. IDC counted nearly 25,000 humanoids shipped worldwide in the first half of 2026, which implies roughly 625,000 to 750,000 joint actuators, by a ROBOTNESS calculation. Tesla says its first Optimus line in Fremont is designed for 1 million robots a year. At the same ratio that is 25 million to 30 million actuators a year, about 22 times the 1.15 million precision reduction gears Nabtesco says its three plants can turn out annually. The sections below set out who makes each part of the joint, what their filings show, and where the bottleneck is likely to form.

A humanoid joint is three parts, and each has its own champions

An electric joint combines a motor, a gear that trades speed for torque, and the sensors and electronics that close the control loop. Rotary joints in shoulders, elbows and wrists usually rely on a strain-wave gear, widely called a harmonic drive after the company that commercialised it, or on a planetary gearbox. A strain-wave gear flexes a thin toothed ring inside a rigid one, giving a high reduction ratio with almost no backlash in a small, light package; planetary gears are sturdier and cheaper but bulkier for the same ratio. Linear joints in knees, ankles and hips often use planetary roller screws, in which many threaded rollers share the load as a motor's rotation is turned into a push. Frameless torque motors, a rotor and stator sold without a housing so the robot maker can build them into the joint, supply the force. Schaeffler's planetary gear actuator, shown at CES in January 2026, packs a two-stage planetary gearbox, motor, encoder and controller into one unit rated at 60 to 250 newton-metres, the company said. The more of that stack a supplier owns, the more of the joint's value it captures, which raises the question of who is booking humanoid business today.

The Japanese incumbents are booking the first orders

Harmonic Drive Systems reported sales of 59.56 billion yen for the year to March 2026, up 7.0%, and orders of 61.61 billion yen, up 16.2%, according to its exchange filing. The company said it had won orders from customers moving robots that use AI technology into mass production. Momentum then accelerated: in April to June 2026 sales rose 23.6% to 16.68 billion yen and orders jumped 55.7% to 24.13 billion yen, leaving a backlog of 29.46 billion yen, up 45.6%. That is a book-to-bill ratio of 1.45, by our calculation. On Aug. 7 the company lifted its full-year forecast to 74.5 billion yen in sales and 8.5 billion yen in operating profit, from 68.0 billion yen and 6.2 billion yen set in May. Its quarterly filing credits surgical-robot orders in North America and semiconductor equipment tied to generative AI for the growth, not humanoids, a reminder that the humanoid share of its book is not disclosed.

Nabtesco, whose precision reduction gears have so far gone mainly into industrial robots, sold 45.1 billion yen of precision reduction gears in the first half of 2026, and its component segment took 48.0 billion yen of orders, up 23%, according to its August results briefing. Full-year component sales of 79.33 billion yen in 2025 rose 17.3% as industrial-robot inventories normalised, the company said. Nabtesco puts its reducer capacity at 1.15 million units a year across Tsu (890,000), Hamamatsu (170,000) and Changzhou in China (90,000), and began delivering a smaller "RV mini" in the second half of 2026 to capture what it calls physical AI demand. Japan's incumbents therefore have the order books, but the faster growth rates are in China.

China's suppliers are growing faster from a smaller base

Leaderdrive, the Suzhou harmonic-reducer maker listed on Shanghai's STAR Market, reported 2025 revenue of 570.71 million yuan, up 47.31%, and net profit of 124.37 million yuan, up 121.42%, according to its annual report summary, which describes the company as a core supplier to several leading embodied-AI robot makers and lists planetary roller screws and planetary joint modules among its products. First-half 2026 revenue rose 38.64% to 348.55 million yuan and net profit 31.25% to 70.11 million yuan, its sponsor CITIC Securities reported in a filing that also notes substantial growth in the embodied-AI robot business. Research spending climbed 50.26% to 9.93% of revenue, with projects that include miniature planetary roller screws for dexterous joints.

Ningbo-based Tuopu Group booked 14.05 million yuan of robot-actuator revenue in the first half of 2026, up 83.43%, according to its interim report. That is about 0.1% of group revenue of 14.2 billion yuan. The company says its linear and rotary actuators and dexterous-hand motors are in small-batch delivery and that the first phase of a robot-components base, part of a planned 5 billion yuan investment, is essentially complete. Sanhua Intelligent Controls, which is applying its thermal-management know-how to robots and reported 2025 revenue of 31.01 billion yuan, calls electromechanical actuators for bionic robots a strategic emerging business and plans to expand their overseas production, but its annual report gives no revenue for the line. Neither company names a robot customer. Unitree, the largest humanoid shipper, says in its STAR Market prospectus that it has built a self-developed and self-produced system that covers core components, and that about 20% of its raw-material purchases were imported goods bought through domestic agents.

Europe's play is the integrated actuator, sold with a customer attached

Schaeffler has built its humanoid position through deals that tie actuator supply to robot purchases for its own factories. In November 2025 it agreed to supply Neura Robotics with a significant share of its actuator needs and plans a mid-four-digit number of humanoids in its plants by 2035. In April 2026 Hexagon said Schaeffler would deploy at least 1,000 AEON humanoids by 2032 and supply actuators to AEON. In May 2026 London-based Humanoid named Schaeffler its preferred supplier under a five-year agreement covering more than half of its joint-actuator demand through 2031, a seven-digit number of units, while Schaeffler takes a four-digit wheeled fleet by 2032, starting with box handling at Herzogenaurach from December 2026. Timken, the US industrial group that owns the harmonic-gear brand Cone Drive and the linear-motion firm Rollon, grew its Industrial Motion segment 14.6% to 453.9 million dollars in the second quarter but does not break out robot sales.

The biggest buyers are building their own

Figure AI says the actuators, batteries, sensors and electronics of its Figure 03 were designed completely in-house, and that the first line at its BotQ plant can make up to 12,000 robots a year. Tesla said in April that its Fremont Optimus line is designed for 1 million robots a year and that a later Texas line is designed for long-term capacity of 10 million; by July it reported the Model S and X lines decommissioned and first-generation Optimus lines being installed, with production expected later this year. Tesla has not named actuator suppliers in its shareholder updates. In Japan, Yaskawa Electric's Dash 35 plan of May 2026 commits to motors and actuators optimised for AI robotics, adding a motion-control incumbent to the in-house camp. If the largest programmes keep the joint in-house, merchant suppliers will compete for the long tail of robot makers, which is where the implied volumes below matter.