In addition to smoother walking posture control, Tesla's second-generation humanoid robot, Optimus, impresses with its ability to effortlessly and accurately pick up and place eggs. The seamless and steady grasping demonstrates the robot's refined hand control capabilities.
The dexterous hand of a humanoid robot is a specialized end effector designed based on human kinesiology, completely different from the end effectors of ordinary industrial robots. Regular industrial robot end effectors can only perform specific tasks such as gripping or welding, whereas the dexterous hand, supported by multiple sensors and degrees of freedom, can mimic human hand functions. With the growing trend in the humanoid robot market, the hollow cup motors in these dexterous hands have also garnered significant attention.
Essential Hollow Cup Motors for Humanoid Robots
The end effector of a robot refers to any tool attached to the edge (joint) of a robot that has specific functions, necessary for the robot to complete tasks. The end effector determines the robot's load and operational precision. Traditional industrial robot end effectors, based on application requirements, can generally only perform single-type tasks such as gripping, lifting, or welding. Their versatility is limited, suitable only for specific or very few similar scenarios, far from the flexibility of human hands.
As an end effector for humanoid robots, the dexterous hand maps human hand functions, allowing easier use of various tools and instruments found in daily life. Without a dexterous hand, a humanoid robot can hardly be considered truly intelligent. In the introduction video of Optimus 2.0, Tesla equipped it with a more responsive dexterous hand featuring eleven degrees of freedom.
The degrees of freedom of a robot reflect its motion flexibility, its capability to handle different tasks, and its maximum operational performance. Generally speaking, the more degrees of freedom, the closer the robot gets to human hand functions, increasing versatility but also complexity in control. Industrial robots typically do not exceed six degrees of freedom, with most having only three to four.
Optimus 2.0’s end effector boasts eleven degrees of freedom. More degrees of freedom mean a more complex structure and higher motor requirements. Since the hand space is limited, the motors used must be compact. Quick response, precise start-stop, high torque, and small size are essential for motors controlling the dexterous hand.
As a representative of small, high-precision motors, the hollow cup motor plays an irreplaceable role in the dexterous hand. The hollow cup motor is a special type of DC permanent magnet servo motor with a coreless structure, available in both brushless and brushed versions. The coreless structure eliminates energy loss caused by the core, reducing weight and mechanical energy loss, thus achieving extremely high efficiency.
Moreover, with reduced mass inertia, the hollow cup motor can achieve dynamic driving in an extremely short mechanical time constant when combined with high torque. These characteristics align perfectly with the needs of humanoid robots.
### Accelerated Development of Hollow Cup Motors Driven by Humanoid Robots
According to estimates by NTCysd, the global market size for hollow cup motors was $700 million in 2022 and is expected to reach $1.2 billion by 2028. This forecast does not account for the potential surge in demand from humanoid robots. In Optimus 2.0, Tesla uses six hollow cup motors to achieve eleven degrees of freedom, with a unit price of $150-$300 per motor. Based on this volume, the future development of humanoid robots will significantly expand the market size of hollow cup motors in the humanoid robot sector alone.
Currently, companies like Maxon, Faulhaber, and Portescap are leading the field, having started early in the hollow cup motor market. In China, several motor manufacturers are also capable of providing or are planning to produce high-performance hollow cup motors to meet the huge future demand in this blue ocean market.
With the gradual application of humanoid robots like Optimus in the end market, the demand for hollow cup motors will undoubtedly increase significantly.
### Rapid Development of High-Performance Micro Motors Reflected in Hollow Cup Motors
Hollow cup motors are a type of DC motor, permanent magnet motor, and servo motor, and they can also be classified as micro motors. Micro motors generally refer to electromechanical products with power ranging from hundreds of milliwatts to hundreds of watts, with a frame diameter not exceeding 160mm or a center height not exceeding 90mm.
Previously, at the Advanced Motor Control Technology Seminar, there were reports on micro motors, highlighting that the entire micro motor field, driven by market demand, is experiencing rapid growth, especially high-performance micro motors with small size and high torque. The hollow cup motor is just one example of this trend.
According to an analysis report by Grand View Research, the global micro motor market size was $40.07 billion in 2022. The demand for miniaturization to achieve compact, high-performance equipment is driving rapid development in the micro motor field, with an expected compound annual growth rate of 6.2% over the next five years.
Besides humanoid robots, the automotive sector has been increasing its demand for high-performance micro motors. The automotive sector was the largest micro motor market in 2022. Various in-car systems, including door locks, rearview mirrors, windows, electric seats, cooling fans, water pumps, wipers, sunroofs, clutches, condensers, and steering wheels, all require smaller and lighter motors.
High-performance automotive micro motors provide precise and reliable drive in a small size, achieving more efficient motion control, ensuring vehicle performance, safety, and comfort, while maintaining high energy efficiency. Additionally, the use of high-performance micro motors in safety systems such as anti-lock braking systems is also increasing.
High-performance micro motors, exemplified by hollow cup motors, make it possible to achieve superior motor performance in a smaller frame. In the future, not only hollow cup motors but also high-performance micro motors with small size, fast response, precise start-stop, and high torque will find more applications across various industries, representing an important direction for motor development.
