The Core Component Driving the Next Generation of Humanoid Robots

The year 2025 is widely recognized as the beginning of the mass-production era for humanoid robots. Industry leaders such as Tesla Optimus, Figure 03, Unitree G1, and Fourier GR-2 are rapidly moving from research laboratories into manufacturing facilities and real-world applications.

Behind this wave of commercialization lies a critical technology that is quietly becoming both the industry's greatest challenge and its greatest opportunity—the humanoid robot joint actuator.

A joint actuator is the fundamental motion unit of a humanoid robot. It integrates multiple precision components—including the motor, transmission system, reducer, encoder, servo drive, brake, and optional torque sensor—into a highly integrated module responsible for generating and controlling every joint movement.

Much like muscles and joints in the human body, actuators determine how a humanoid robot moves, balances, manipulates objects, and interacts with its environment.

A typical humanoid robot incorporates 20 to 40 actuators, accounting for more than 55% of the total hardware cost. As a result, actuators have become the highest-value subsystem, the most technically demanding component, and one of the fastest-growing segments in the humanoid robotics supply chain.

 

As manufacturers compete in AI models, embodied intelligence, industrial design, and software architecture, the companies capable of achieving breakthroughs in actuator performance, cost efficiency, and scalable manufacturing will gain a decisive advantage in the next generation of humanoid robots.

 

 

1. Why Joint Actuators Are the Next Breakthrough

1.1 Cost Structure Defines Market Competitiveness

Among all hardware components in a humanoid robot, joint actuators represent the single largest cost contributor.

Industry research indicates that actuators account for over 50% of the robot's total bill of materials (BOM). Consequently, reducing actuator cost has the greatest impact on lowering the overall manufacturing cost of humanoid robots.

Tesla's Optimus provides a clear example. One of its long-term objectives is to reduce the selling price of a humanoid robot to below USD 20,000. However, during the prototype stage, actuator costs represented a significant portion of the entire system cost.

As humanoid robots transition from prototypes to large-scale production, actuator optimization has become the primary battlefield for cost reduction.

 

1.2 Force Control Expands the Boundaries of Robot Applications

Whether humanoid robots can perform complex tasks such as precision assembly, warehouse handling, household assistance, or healthcare services depends largely on the capabilities of their joint actuators.

Traditional industrial robots primarily rely on position control, offering excellent repeatability but limited adaptability during physical interaction.

Humanoid robots, by contrast, must continuously sense, respond, and adapt while interacting with unpredictable environments.

This requires advanced force control.

By integrating torque sensors with high-performance servo control algorithms, modern joint actuators can accurately measure interaction forces in real time, allowing robots to perceive contact forces, regulate output torque, and execute compliant motion with exceptional precision.

This capability transforms robots from rigid automation tools into intelligent machines capable of safe human collaboration, delicate manipulation, and adaptive motion.

 

1.3 High Integration Is Reshaping Actuator Architecture

Earlier generations of robotic actuators typically adopted a distributed architecture, where motors, reducers, encoders, drivers, and sensors were installed as separate components.

Although functional, these systems required more installation space, increased wiring complexity, and reduced overall reliability.

Today's actuator technology is rapidly evolving toward fully integrated modular designs.

Modern integrated actuators combine all essential components within a compact housing, delivering multiple advantages:

• Reduced size and weight

• Higher assembly efficiency

• Simplified electrical integration

• Improved system reliability

• Lower maintenance requirements

• Faster robot development cycles

The Techrobots MJBX Series Rotary Actuators exemplify this trend.

The MJB14T weighs only 0.84 kg, while the MJB25T delivers an average continuous output torque of 133 N·m. Through optimized harmonic drive architecture and high integration, the MJBX Series significantly improves torque density, enabling humanoid robots to perform movements that were previously difficult or impossible with conventional actuator designs.

 

2. Four Main Technology Paths for Humanoid Robot Actuators

 

As humanoid robots continue to evolve, actuator technology has diversified into several mainstream architectures. Each approach offers unique advantages in terms of power density, control accuracy, dynamic response, structural complexity, and manufacturing cost, making them suitable for different robot joints and application scenarios.

Today, the industry primarily adopts four actuator technologies.

 

2.1 Rotary Actuators — The Mainstream Solution for Today's Humanoid Robots

Typical Configuration

• Frameless Torque Motor

• Harmonic Drive or Planetary Reducer

• Dual Encoders

• Servo Drive

• Optional Torque Sensor

Rotary actuators are currently the most mature and widely adopted solution for commercial humanoid robots.

They are commonly used in shoulders, elbows, wrists, waist, neck, and upper-body joints, where precise rotational motion is required.

Many leading humanoid robots—including Tesla Optimus—adopt harmonic-drive rotary actuators throughout their upper limbs due to their excellent positioning accuracy, compact structure, and mature supply chain.

The combination of a frameless torque motor and a precision harmonic reducer enables high torque output within a compact form factor while maintaining excellent repeatability and stiffness.

Modern rotary actuators increasingly integrate motor, reducer, encoder, servo drive, brake, and optional torque sensor into a single compact module, simplifying robot assembly while improving reliability.

Advantages

• High positioning accuracy

• Mature manufacturing ecosystem

• Compact integrated design

• Excellent repeatability

• Suitable for most upper-body joints

Challenges

• Relatively high structural stiffness

• Limited natural compliance during high-speed impacts

• Harmonic drives may experience wear under long-term heavy cyclic loading

 

2.2 Linear Actuators — Delivering High Thrust for Lower-Limb Motion

Typical Configuration

• Frameless Torque Motor

• Planetary Roller Screw (Heavy-Duty)

• Ball Screw (Medium-Load Applications)

• Integrated Force Sensor

• Servo Drive

Unlike rotary actuators, linear actuators generate direct linear motion, making them particularly suitable for hips, knees, ankles, and other high-load joints.

Tesla's Optimus employs electric cylinder actuators in parts of its lower body to mimic the contraction and extension behavior of human muscles.

The core technology behind these actuators is the Planetary Roller Screw (PRS).

Compared with conventional ball screws, planetary roller screws offer:

• Higher load capacity

• Greater stiffness

• Longer service life

• Higher transmission efficiency

• Better shock resistance

As a result, PRS technology has become one of the most competitive areas within the humanoid robotics supply chain.

Techrobots HJL Series Linear Actuators utilize planetary roller screw transmission across the entire product line. Designed specifically for high-performance humanoid robots, they integrate motors, encoders, force sensors, and precision drive systems into a lightweight, compact actuator capable of delivering outstanding thrust density and motion stability.

Advantages

• Extremely high thrust output

• Compact mechanical structure

• Excellent impact resistance

• Ideal for heavy-load leg joints

Challenges

• Higher manufacturing cost

• Complex machining and assembly

• Tight precision requirements for screw manufacturing

 

2.3 Quasi-Direct Drive (QDD) Actuators — Optimized for Dynamic Motion

Typical Configuration

• High Torque-Density Motor

• Low-Ratio Planetary Gearbox

• High-Speed Servo Drive

Quasi-Direct Drive (QDD) actuators have become increasingly popular in recent years, particularly among robots designed for running, jumping, balancing, and agile locomotion.

Unlike conventional high-ratio reduction systems, QDD actuators employ gear reduction ratios typically below 10:1, allowing more direct torque transmission from the motor.

This architecture dramatically improves backdrivability, force transparency, and dynamic responsiveness, enabling torque output to change within milliseconds.

Robots equipped with QDD actuators demonstrate impressive athletic performance, including:

• Running

• Jumping

• Squatting

• Dynamic balancing

• Somersaults

• Rapid recovery after impacts

These characteristics make QDD one of the most promising actuator architectures for future embodied AI platforms.

Advantages

• Extremely fast dynamic response

• Excellent torque transparency

• Superior agility

• High backdrivability

Challenges

• Lower position holding capability

• Continuous motor current required to maintain static posture

• Higher motor torque requirements

• Greater thermal management demands

 

2.4 Series Elastic Actuators (SEA) — Bringing Compliance Closer to Human Muscles

Typical Configuration

• Servo Motor

• Elastic Element (Spring, Elastic Mechanism, or Advanced Biomaterials)

• Position and Force Sensors

Series Elastic Actuators (SEA) introduce a compliant elastic element into the drivetrain, allowing the actuator to naturally absorb impacts while measuring interaction forces with exceptional accuracy.

Unlike rigid transmission systems, SEA actuators provide intrinsic mechanical compliance, significantly improving safety during physical human-robot interaction.

This technology has become particularly attractive for:

• Dexterous robotic hands

• Service robots

• Rehabilitation robots

• Wearable exoskeletons

• Human-interactive humanoid robots

The elastic element also stores and releases mechanical energy during cyclic movements, improving motion efficiency and producing smoother, more human-like locomotion.

Recent research is extending SEA concepts by incorporating:

• Soft robotics materials

• Artificial muscles

• 3D-printed lattice structures

• Variable stiffness mechanisms

These innovations are expected to further narrow the gap between robotic and biological movement.

Advantages

• Excellent compliance

• High interaction safety

• Smooth biomimetic motion

• Improved energy efficiency

Challenges

• Lower positioning accuracy than rigid actuators

• More complex control algorithms

• Durability of elastic materials remains an ongoing research focus

 

Technology Comparison

Technology	Best Applications	Primary Advantages	Key Challenges
Rotary Actuator	Shoulder, elbow, waist, wrist	Mature technology, high precision, compact integration	Limited compliance
Linear Actuator	Hip, knee, ankle	High thrust, compact structure, excellent impact resistance	Higher manufacturing cost
QDD Actuator	Dynamic locomotion	Outstanding responsiveness and agility	Requires continuous power for position holding
SEA Actuator	Human-robot interaction	High compliance and interaction safety	Lower positioning precision

 

3. Market Landscape: A Billion-Dollar Growth Curve and China’s Rapid Rise

Global Market Size and Growth Outlook

According to the latest report from QYResearch, the global humanoid robot actuator market was valued at approximately USD 150–162 million in 2024. It is projected to reach USD 9.86–16.97 billion by 2031, representing an extraordinary compound annual growth rate (CAGR) of around 80%.

This positions humanoid robot actuators as one of the fastest-growing segments in the global robotics industry.

China’s market is expanding in parallel with global trends. According to data released at the China Humanoid Robot Industry Conference, the domestic humanoid robot market reached approximately CNY 2.76 billion in 2024, and is expected to grow to CNY 75 billion by 2029, accounting for over 32% of the global market share.

By 2035, the market is projected to exceed CNY 300 billion, making China a leading global hub for humanoid robotics development and commercialization.

As actuators represent the largest cost component in humanoid robots, their market growth is expected to closely track—and in some cases exceed—the overall robot market expansion.

 

4. Four Key Technology Trends Driving Actuator Evolution

4.1 Full Integration: Smaller Modules, Lower System Cost

The industry is rapidly moving toward highly integrated actuator architectures, where the motor, reducer, driver, encoder, and sensors are all embedded into a single compact module.

Compared with traditional distributed architectures, integrated actuators can:

• Reduce system volume by 20–30%

• Decrease assembly complexity

• Improve system reliability

• Lower overall system cost by up to ~40%

• Accelerate robot development cycles

This trend is expected to become the dominant direction in the next 2–3 years of humanoid robot commercialization.

 

4.2 Intelligent Sensing: From Force Feedback to Full Perception

Next-generation actuators are evolving from simple force sensing systems into multi-modal intelligent sensing units.

In addition to torque feedback, emerging actuator designs are integrating:

• Tactile sensing

• Temperature monitoring

• Vibration analysis

• Health diagnostics

• Predictive maintenance capabilities

This transformation enables actuators to function not only as motion units, but also as self-aware intelligent components capable of monitoring their own operational state.

As a result, humanoid robots gain significantly improved:

• System reliability

• Fault prediction capability

• Maintenance efficiency

• Long-term operational stability

 

5. Industry Impact: Actuator Innovation Will Reshape the Humanoid Robotics Ecosystem

Breakthroughs in joint actuator technology will have a system-level impact across the entire humanoid robotics industry chain, extending far beyond hardware design.

5.1 Expansion of Application Scenarios

With improvements in force control accuracy, compliance, and dynamic performance, humanoid robots will be able to enter high-value scenarios that were previously inaccessible, including:

• Precision assembly and manufacturing

• Elderly care and assisted living

• Medical and surgical assistance

• Logistics and warehouse automation

• Hazardous environment operations

These applications require safe human-robot interaction and fine manipulation capabilities, both of which depend heavily on advanced actuator performance.

 

5.2 Reshaping Competitive Dynamics

Companies that master high-performance actuator technology will gain strategic advantages in:

• Product pricing control

• System architecture design

• Iteration speed

• Supply chain autonomy

In contrast, robot manufacturers relying on external actuator suppliers may face increasing pressure in terms of:

• Cost structure

• Supply chain stability

• Customization flexibility

By 2027, industry forecasts suggest that humanoid robots could reach a penetration rate exceeding 25% in industrial environments, with the service robotics market potentially expanding to over CNY 200 billion.

The realization of this growth trajectory depends heavily on continued breakthroughs in actuator performance and manufacturing scalability.

 

6. Challenges and Risks: The Reality Behind Rapid Growth

Despite strong momentum, the humanoid robot actuator industry still faces several fundamental challenges:

6.1 Long Reliability Validation Cycles

Joint actuators must withstand millions of load cycles under real-world conditions.
As a result, reliability validation typically requires 12–24 months, creating a natural tension between rapid commercialization and engineering maturity.

 

6.2 Shortage of Cross-Disciplinary Talent

High-performance actuator development requires expertise in:

• Mechatronics

• Control systems

• Materials engineering

• Precision manufacturing

Such multidisciplinary talent remains extremely scarce, significantly limiting R&D scalability.

 

6.3 Lack of Standardization

The industry currently suffers from fragmentation, with more than 20 different interface standards coexisting across platforms.

This increases:

• Integration complexity

• Supply chain management costs

• Compatibility issues between robot platforms

Standardization will be a critical milestone for large-scale commercialization.

 

Conclusion: Actuators Will Define the Future of Humanoid Robotics

While humanoid robotics is often perceived as a competition in AI algorithms, system integration, and form factor design, the underlying foundation remains the joint actuator system.

A compact module weighing only a few kilograms—yet accounting for more than half of the robot’s total cost—ultimately determines whether a humanoid robot can truly move, interact, and operate in the real world.

Across multiple technological paths—from rotary actuators and linear actuators to QDD and SEA architectures—innovation is accelerating at an unprecedented pace.

The period between 2025 and 2027 will be a decisive window, marking the transition of humanoid robot actuators from technology validation to large-scale commercial production.

 

This is not only a revolution in component technology, but also a preview of the future structure of global manufacturing.