What Motors Do Top Humanoid Robots Use?

A Look at the Actuators Behind Leading Humanoid Robots

Humanoid robots are becoming one of the fastest-growing sectors in robotics. Companies such as Tesla, Boston Dynamics, Unitree, UBTECH, and Figure AI are developing robots designed to work alongside humans in factories, warehouses, and service environments.

At the core of every humanoid robot are joint actuators powered by electric motors. These motors determine the robot’s strength, speed, precision, and efficiency.

In this article, we analyze the types of motors used in the world’s leading humanoid robots and explain why these motors are critical for advanced robotic systems.

Why Motor Technology Is Critical for Humanoid Robots

Unlike traditional industrial robots, humanoid robots must replicate human motion. This means their actuators must provide:

  • High torque output

  • Precise position control

  • Smooth motion

  • Compact structure

  • High power density

Most humanoid robots rely on electric actuators, which combine motors, reducers, sensors, and control electronics to drive robot joints.

Main Motor Types Used in Humanoid Robots

1. Frameless Torque Motors

Frameless torque motors are currently one of the most widely used motors in humanoid robot joints.

These motors are designed without a traditional housing so they can be directly integrated into robotic joints, reducing size and weight.

Advantages

  • High torque density

  • Compact integration

  • Excellent thermal performance

  • Smooth rotation

Applications in Robots

Frameless torque motors are used in:

  • Shoulder joints

  • Hip joints

  • Knee joints

  • Waist rotation

For example, Tesla’s humanoid robot uses frameless torque motors as the power source for its joint actuators.

2. Brushless DC Motors (BLDC)

Brushless DC motors are widely used in modern robotics because of their high efficiency and reliability.

Advantages

  • Long service life

  • High efficiency

  • Low maintenance

  • Stable performance

Applications

BLDC motors are commonly used in:

  • Joint actuators

  • Robot mobility systems

  • Drone propulsion

  • Industrial robotics

Many humanoid robots combine BLDC motors with harmonic or planetary gearboxes to achieve high torque output.

3. Coreless (Hollow Cup) Motors

Coreless motors are compact motors used in precision applications such as robot hands and fingers.

Advantages

  • Extremely lightweight

  • High responsiveness

  • Smooth low-speed control

  • High efficiency

Applications

Coreless motors are often used in:

  • Dexterous robot hands

  • Finger joints

  • Small precision mechanisms

Because these motors are very small (often under 40 mm), they are ideal for fine manipulation tasks.

4. Servo Motors

Servo motors are commonly used in robotics when precise position control is required.

Advantages

  • Closed-loop control

  • High accuracy

  • Easy integration with control systems

Applications

Servo motors are often used in:

  • Small humanoid robots

  • Educational robots

  • Research platforms

Many research robots and early humanoid designs relied on servo motors to control joint angles.

5. DC Motors with Gearboxes

Some humanoid robots still use brushed or brushless DC motors combined with gear reducers.

These motors are typically paired with:

  • Planetary gearboxes

  • Harmonic drives

  • RV reducers

This configuration increases torque while reducing motor speed.

Older humanoid robots and research platforms often used DC motors with planetary gearheads to drive their joints.

Case Study: Motors Used in Tesla Optimus

Tesla’s humanoid robot Optimus provides a good example of modern humanoid robot actuation systems.

The robot contains:

  • 28 actuators total

  • 14 rotary actuators

  • 14 linear actuators

These actuators combine:

  • Frameless torque motors

  • Harmonic reducers

  • Planetary roller screws

  • Encoders and torque sensors

The motors are distributed across shoulders, elbows, wrists, hips, knees, and feet to enable complex human-like movement.

Typical Structure of a Humanoid Robot Actuator

Most humanoid robots use integrated electric actuators rather than standalone motors.

A typical actuator includes:

  1. Electric motor (BLDC or torque motor)

  2. Gear reduction system (harmonic or planetary)

  3. Sensors (encoder / torque sensor)

  4. Motor driver and controller

This integration allows robots to achieve high precision motion and efficient power transmission.

Trends in Humanoid Robot Motors

The humanoid robotics industry is evolving rapidly, and several trends are emerging:

Higher Torque Density

Robots require stronger motors in smaller spaces.

Integrated Joint Modules

Motor, gearbox, and sensors are combined into compact actuator modules.

More Electric Systems

Modern humanoid robots increasingly favor electric actuators instead of hydraulic systems due to efficiency and lower maintenance.

Advanced Precision Sensors

Encoders and torque sensors improve balance and movement accuracy.

Conclusion

The performance of humanoid robots largely depends on the motors used in their joints. Leading humanoid robots commonly rely on several motor types, including:

  • Frameless torque motors

  • Brushless DC motors

  • Coreless motors

  • Servo motors

  • DC motors with gear reducers

These motors are typically integrated with gearboxes, sensors, and control electronics to form advanced robotic actuators.

As humanoid robotics continues to evolve, improvements in motor technology will play a key role in making robots stronger, lighter, and more efficient.

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