Why is it the ideal choice of frameless torque motor for humanoid robots? Unlike traditional motors, frameless torque motors are compact and lightweight, offering greater design flexibility and higher torque density. They are specifically tailored to meet the demands of humanoid robot joints, providing rapid response, low friction, and high efficiency.
What Is a Humanoid Robot?
A humanoid robot is an intelligent machine designed to resemble human characteristics and movement capabilities. It walks on two legs and performs functions through coordinated arm and body movements.
Equipped with general-purpose algorithms and generative AI, it possesses semantic understanding, human-machine interaction, and autonomous decision-making abilities. These robots use interactive capabilities to understand and respond to tasks, requiring strong sensing, computing, and motion control capabilities.
What Are the Key Structural Components?
A humanoid robot consists of critical components such as the brain, cerebellum, mechanical arms, dexterous hands, rotary joints, linear joints, and torso. These elements enable environmental perception, motion control, and task execution.
We take Tesla’s Optimus Prime as an example and disassemble the core component structures of its joints.
Tesla’s humanoid robot, Optimus, incorporates frameless torque motors in its 14 linear actuators and 14 rotary actuators.
What Is a Frameless Torque Motor?
A frameless torque motor is a frameless permanent magnet brushless synchronous motor composed of two primary components:
Rotor: The internal component, consisting of a rotating steel ring embedded with permanent magnets. It is directly mounted onto the machine shaft.
Stator: The external component, featuring laminated silicon steel sheets and copper windings, generating electromagnetic force tightly integrated within the machine housing.
Why Use Frameless Torque Motors?
Frameless Motor Design: Contains only the stator (coil) and rotor (permanent magnet), eliminating the need for an outer casing or bearings. This significantly reduces weight and size while enhancing power density (typically 5-10 Nm/kg).
High Torque Density: Utilizes high-performance permanent magnet materials (e.g., neodymium-iron-boron) and optimized magnetic circuit designs, achieving 30-50 Nm/kg torque density (e.g., Kollmorgen TBM series).
Direct Drive: Eliminates the need for a gearbox, minimizing transmission losses and mechanical backlash while improving control precision (±0.001° positioning accuracy).
Wide-Speed and High-Efficiency Operation: Achieves over 90% efficiency across a broad speed range (from 0 to several thousand RPM), making it suitable for frequently varying joint movements.
Current Market for Frameless Torque Motors
The frameless torque motor market is currently small but growing rapidly. According to Technavio, the global torque motor market grew 6.95% in 2023, reaching $657 million. As humanoid robots become commercially viable, this growth is expected to accelerate.
While international companies like Kollmorgen, AVS Mechatronics GmbH, Maxon Motor, TQ Robodrive, Aerotech, and Allied Motion dominate the market with their expertise and advanced technology, Chinese companies are quickly catching up.
Companies such as Leadshine Technology, Estun Automation, Haozhi Mechanical, and Leadshine Intelligent have significantly narrowed the performance gap with international competitors.
For instance, comparing Kollmorgen and Leadshine, the output torque difference for motors of the same size is minimal, indicating rapid progress in China’s torque density advancements.
What Other Motors Are Used in Humanoid Robot?
| Motor | Characteristic | Application |
| Servo Motor | High-precision closed-loop control (encoder feedback) with ±0.01° positioning accuracy. Fast dynamic response (acceleration time <10ms), suitable for quick start-stop applications. Integrated with gear reducers (e.g., harmonic reducers) for high torque output. | High-precision joints (e.g., wrist and finger joints). |
| Coreless Motor | Iron-core-free rotor, using a coil with no internal support structure, typically under 40mm in size. Small size, high control accuracy, long lifespan, fast rotation, high efficiency, and high energy density. Compared to iron-core motors, they are 1/3 to 1/2 lighter and smaller while maintaining the same power output. | Finger joints |
Stepper Motor | Open-loop control, low cost, and simple structure. High torque at low speeds, but prone to step loss (requires a closed-loop driver for improvement). Positioning accuracy depends on step angle (e.g., 1.8° per step). | Low-cost joints or auxiliary drives (e.g., head rotation) |
| BLDC Motor (brushless dc motor) | High efficiency (>90%) and long lifespan (no brush wear). High-speed operation (>10,000 RPM), suitable for high-speed joints or wheeled drives. Requires an electronic speed controller (ESC) for precise control. | Mobile platform drive wheels, high-speed rotary joints. |
| Linear Motor | Direct linear motion, eliminating the need for mechanical transmission (e.g., lead screws). Ultra-high acceleration (>10g) and ±1μm positioning accuracy. High cost, making them suitable for precision positioning applications. | Precision assembly, high-accuracy linear joints. |
With strong governmental support for private enterprises and emerging production forces, along with the rapid development of AI-driven robotics, humanoid robots are poised for explosive growth. The industry is currently at a stage similar to electric vehicles in 2014, on the brink of mass production and entering a decade-long industrial boom.
Custom Robot Motor Stator and Rotor – Choose Lamnow
Lamnow designs and manufactures robotic motor lamination in China. Our laminations include coreless motor lamination, torque motor stator and rotor, servo motor lamination, stepper motor stator and rotor lamination, and permanent magnet synchronous motor lamination core. If you need robotic motor core, please contact us.
