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HUMANOID ROBOTICS / THE MUSCLES

Motors & actuators

Turn electrical energy into precise motion. Torque density, heat management, transmission, structure and control all affect robot motion and payload.

How this system works

Electrical power becomes controlled joint torque through a motor, transmission, and feedback loop.

Sequenced phase currents create a rotating stator field that interacts with the rotor magnets. Position feedback helps the drive control motion.

Illustrative rotary actuator example with its component parts separated for study
Illustrative rotary actuator example. Designs differ by manufacturer; the model is not an OEM bill of materials.

What to look for: Copper windings around the magnets, then the shaft and reduction gears.

Read the engineering reference

Compare the right roles

A motor, an actuator, or a drive?

A motor generates rotation. An integrated actuator can combine a motor, transmission, sensing, and housing. A drive controls electrical power. Compare companies at the same level of the system.

What establishes humanoid exposure?

Look for a named humanoid application, dedicated product, development program, or partnership. General servo expertise alone does not establish a humanoid production contract.

Harmonic Drive offers focused precision-motion exposure. Kollmorgen, owned by Regal Rexnord, brings frameless motor expertise. Schaeffler has a disclosed humanoid actuator partnership.

Open each company below for its source and limitations. Sector membership does not establish a confirmed supply contract.

Inside the assembly

Housing & mounting flange

A rigid enclosure locates the motor and transfers heat and mechanical loads into the robot link.

Stock-link scope: Integrated actuator developers; a housing is part of the system. These are not verified standalone casting suppliers.

Stator & copper windings

Sequenced phase currents in stationary windings create a rotating magnetic field. Winding geometry, current and cooling affect torque and heating.

Stock-link scope: Motor suppliers integrate windings and stators. This does not imply that they sell copper wire or isolated stator laminations.

Permanent-magnet rotor

The rotor magnets interact with the stator field to produce torque on the motor shaft. The transmission connects this input to the joint output.

Stock-link scope: Permanent-magnet motor products, rather than raw magnet or rare-earth suppliers.

Reduction stage

Reduction trades speed for torque, with power lost to friction and other losses. This example is planetary; humanoids also use strain-wave, cycloidal and other transmissions.

Stock-link scope: Planetary product families include Schaeffler’s disclosed two-stage humanoid actuator, Nidec ABLE and Zhaowei miniature drives. Their designs differ from this illustration. Strain-wave and cycloidal suppliers appear in the broader Joints & gears sector.

Encoder & drive electronics

Position feedback and a motor drive close the control loop so the joint follows commanded motion.

Stock-link scope: Includes position encoders, motor-control chips, drive power devices, and integrated controls. Open a company to see its specific role.

COMPANY RESEARCH

Motors & actuators stocks

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Evidence groupings are not investment ratings. Companies may appear in multiple sectors.