I. Technical Principles and Structural Innovations
The frameless torque motor discards the traditional motor housing, bearings, and other components, retaining only the core rotor (permanent magnet assembly) and stator (copper windings and steel laminations). It achieves power output by being directly integrated into the mechanical structure. Its design features include:
High Power Density: The frameless design reduces redundant components, cutting the volume by 30%-50% while increasing torque density by 15%-20%.
Low Inertia Response: With a low rotor inertia and short response time, it can support the instantaneous explosive force demands of robot joints (such as during jumping or sprinting).
Customization Compatibility: The modular design adapts to different joint sizes (for instance, Tesla Optimus uses 28 frameless motors to drive its joints).
The main technical challenges lie in optimizing the magnetic circuit and designing effective thermal management. For example, Germany's TQ Robodrive employs a 20-pole, 18-slot magnetic circuit layout with epoxy potting to boost cooling efficiency; meanwhile, the US-based Kollmorgen utilizes a 12-pole, 39-slot design to reduce torque ripple and ensure smooth operation.
II. Application Scenarios: Comprehensive Penetration from Industrial to Bionic Fields
The core application areas for frameless torque motors have expanded from traditional industrial robots to high-precision fields such as humanoid robots and medical equipment:
Humanoid Robot Joints:
In Tesla Optimus' 28 joints, the frameless motor handles both rotational and linear drives, accounting for approximately 15.4% of the unit's value.
Wolong Electric Drive's joint modules, integrated with AI technology, can mimic human motion characteristics, making them suitable for inspection and rescue missions in complex environments.
Collaborative Robots: Each collaborative robot requires 6-7 frameless motors. Their compact design (with a minimum diameter of 25 mm) supports high agility.
Medical and Precision Manufacturing:
In surgical robots, the motor precision can reach the micron level, supporting minimally invasive operations.
In machine tools, direct drive technology eliminates mechanical transmission errors, enhancing machining repeatability.
III. Manufacturing Process: Precision Machining and Breakthroughs in Domestic Production
Manufacturing frameless torque motors involves high-precision machining and advanced electromagnetic design. Key aspects include:
Materials and Equipment
Winding and Potting Processes:
Buke Corporation's third-generation products use a segmented winding design combined with frameless potting technology, improving cooling efficiency and structural stability.
LeiSai Intelligent's FM1 series optimizes the winding slot fill factor, achieving a torque density that is 15% higher than that of its competitors.
Domestic Progress:
Buke Corporation holds nearly 50% of the domestic market share, offering products with outer diameters ranging from 52 mm to 132 mm to suit various applications.
LeiSai Intelligent has introduced a 25 mm micro motor, which entered trial production in 2024, targeting several humanoid robot enterprises.
IV. Competitive Landscape: Opportunities for Domestic Substitution Amid Foreign Dominance
Foreign Brands: Companies like Kollmorgen (USA) and TQ Robodrive (Germany) dominate the high-end market, with technological advantages in magnetic circuit simulation and process stability.
Domestic Manufacturers:
Buke Corporation: Its third-generation products are on par with international standards, while its fourth-generation research focuses on lightweight design and cost optimization.
LeiSai Intelligent: Their micro drives and humanoid joint modules have begun trial sales, with clear production capacity plans set for 2024.
Wolong Electric Drive: By integrating AI technology, it is developing bionic joint systems that expand applications in power, medical, and other vertical markets.
Market Outlook: The global market for frameless torque motors in humanoid robots is expected to reach 6 billion yuan by 2025 and may exceed 28 billion yuan by 2030, with the domestic substitution rate potentially increasing from 30% to 50%.
V. Challenges and Future Trends
Technical Bottlenecks:
High-end products still lag behind foreign brands in terms of torque density and reliability.
Temperature rise control and increasing customization requirements add complexity to the manufacturing process.
Innovative Directions:
Dual Stator Design: For example, a patented solution uses an inner-outer stator layout to enhance impact resistance, making it suitable for high-load industrial robots.
Intelligent Integration: Combining the driver, encoder, and motor into one integrated design helps reduce signal interference (as seen in Haozhi Electromechanical's joint modules).
Supply Chain Collaboration: Upstream magnetic material companies and downstream robot manufacturers are jointly developing customized solutions to accelerate market adoption.
VI. Integrated Servo Wheel: A Leap in Frameless Torque Motor Performance
Our integrated servo wheel serves as an all-in-one carrier for the frameless torque motor, deeply integrating the motor, driver, encoder, and wheel to create a compact "power-control-execution" unit. Its core advantages include exceptional space utilization and explosive dynamic response. For example, with a typical design featuring an 80 mm outer diameter, it can deliver a peak torque of 150 N·m, support a dynamic load of 100 kg, and eliminate the need for traditional reducers and transmission structures-thereby increasing the layout freedom of AGV chassis or humanoid robot joints by over 40%.
Thanks to the low inertia of the frameless torque motor, the wheel's response time is compressed to around 2 ms. Whether achieving a ±0.1 mm precise stop in a 0.5-meter narrow warehouse aisle or executing an instantaneous reverse drive at the moment a humanoid robot's ankle contacts the ground, millisecond-level force control is achievable. Direct drive technology further minimizes mechanical transmission losses, reducing energy consumption by 15%-20% under the same load. Coupled with an integrated IP65-rated enclosure, it guarantees over 20,000 hours of fault-free operation even in industrial environments with dust, oil, or high-frequency vibrations.
More importantly, this design supports multi-wheel coordinated and force-position hybrid control via built-in bus protocols (e.g., EtherCAT). For instance, during uphill climbing or obstacle negotiation, the system can dynamically allocate torque among the wheels, simulating the coordinated effort of biological muscles; in high-sensitivity scenarios such as surgical robotics, its micron-level positioning accuracy and flexible output can even replicate the tactile sensation of a human finger. This "hardware as algorithm carrier" characteristic is redefining the boundaries of robot motion control.
Conclusion
As the "muscle system" of humanoid robots, frameless torque motors represent a technological breakthrough and manufacturing upgrade that directly affects the performance ceiling of robots. Although domestic companies still lag behind foreign brands in process maturity and high-end market presence, differentiated innovations (such as miniaturization and high cost-performance) and supply chain collaboration are gradually breaking the foreign monopoly. In the future, with the mass production wave of AI-driven humanoid robots, this sector could experience an "explosive growth cycle."
