Why is it the ideal choice of frameless torque motors for humanoid robots? These motors are key components that enable precise, efficient movement in robots designed to mimic human actions. 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.
Types of Motors in Robotics
Motors are indispensable in robotics, serving as the driving force behind a robot’s movements and actions. Several types of motors are commonly used, including stepper motors, servo motors, torque motors, asynchronous motors, and permanent magnet synchronous motors. Each motor type is chosen based on the specific requirements of the robot.
For instance, industrial robots typically rely on servo motors and stepper motors, whereas humanoid robots, which demand high precision and flexibility, predominantly use frameless motors and coreless motors.
What is a Frameless Torque Motor?
A frameless torque motor is a type of torque motor specifically designed to produce high torque directly at low speeds. It is characterized by its absence of an external housing, retaining only the core components necessary for generating torque and speed: the rotor and the stator.
The rotor, usually located internally, comprises a rotating steel ring equipped with permanent magnets and is directly attached to the robot’s axis. The stator, the external component, consists of electrical steel laminations and copper windings, creating electromagnetic forces that adhere closely to the robot’s structure.
This design allows frameless torque motors to integrate seamlessly into the joints of humanoid robots. The compact and lightweight nature of these motors provides greater design flexibility, reduced mechanical transmission losses, and enhanced torque density, heat dissipation, and noise reduction.
Key Features of Frameless Torque Motors
Frameless torque motors are distinguished by several key features that make them particularly well-suited for humanoid robots:
High Pole Count
These motors typically have a high number of poles, allowing them to operate at low speeds without the risk of damage, even when the rotor is unable to rotate. This characteristic ensures a steady torque output under low-speed conditions and an automatic adjustment of speed and torque based on the load, providing excellent low-speed, high-torque performance, strong overload capacity, rapid response, good linearity, and minimal torque ripple.
Compact and Lightweight Design
The absence of a frame allows for a more compact design, making the motor ideal for space-constrained applications like robot joints. This also contributes to a higher power density, which is crucial for the high demands of humanoid robot applications.
High Efficiency
With new electromagnetic and bearing structures, frameless torque motors offer low energy consumption and minimal friction, making them highly efficient. This is essential for humanoid robots, which often require prolonged operation and high power output.
Flexibility and Customization
The flexibility in design allows these motors to be tailored to specific robotic applications, particularly in the complex and highly customized joints of humanoid robots.
Application of Frameless Torque Motors For Humanoid Robots
Given their characteristics, frameless torque motors are highly compatible with the demands of humanoid robot joints. For example, Tesla’s Optimus robot, which features 28 joint actuators, is powered by frameless torque motors. Of these, 14 rotational joints utilize a combination of frameless torque motors and harmonic reducers to replicate the rotational movement of human joints, while the remaining 14 linear joints employ frameless torque motors paired with planetary roller screws to mimic the extension and contraction of human muscles.
Similarly, Walker X, a humanoid robot from UBTECH Robotics, uses frameless torque motors as the driving solution for most of its joints. The robot is equipped with 36 high-performance servo actuators, which are integrated drive units composed of frameless torque motors, precision harmonic reducers, drive controllers, and dual encoders.
The Current Market for Frameless Torque Motors
The market for frameless torque motors, while currently small, is growing rapidly. According to a report by Technavio, the global torque motor market grew by 6.95% to $657 million in 2023. This growth is expected to accelerate as humanoid robots become more commercially viable.
As production scales and manufacturing processes improve, the price of these motors is likely to decrease, further boosting their adoption in the robotics industry.
Despite the strong presence of international companies like Kollmorgen, AVS Mechatronics GmbH, Maxon Motor, TQ Robodrive, Aerotech, and Allied Motion, which dominate the market with their extensive experience and advanced technologies, domestic companies are catching up.
Chinese companies such as Leadshine Technology, Estun Automation, Haozhi Mechanical, and Leisai Intelligent have made significant strides in closing the performance gap with their international counterparts. For instance, a comparison between products from Kollmorgen and Leadshine shows that in similar-sized motors, the difference in output torque is minimal, indicating rapid advancements in torque density by domestic manufacturers.
Conclusion
Frameless torque motors are at the heart of the rapidly evolving field of humanoid robotics. Their unique design, which combines high efficiency, compactness, and adaptability, makes them the preferred choice for powering the intricate and demanding joints of humanoid robots.
As the market for humanoid robots grows, driven by advancements in AI and manufacturing, the demand for these specialized motors will likely surge. With continued innovation and scale, both global and domestic manufacturers are poised to capitalize on this emerging opportunity, pushing the boundaries of what humanoid robots can achieve.
Lamnow designs and manufactures robot motor lamination in China. Our lamination, includes coreless motor lamination, torque motor stator and rotor, servo motor lamination stacks, stepper motor stator and rotor stacks, and permanent magnet synchronous motor lamination core. If you need a robotic electric motor core, please contact us.
