Achieving Breakthroughs in Lightweight Design and High Precision: A Blue Ocean for Humanoid Robot-Specific Harmonic Gear Reducers Worth Hundreds of Billions

2024 marks a golden era for humanoid robots, often referred to as the year of humanoid robotics. The rise of humanoid robots can be attributed to two main factors: the involvement of tech giants and the maturity of recent research and development technologies, closely linked to advancements in AI and hardware technologies.

Among the core components of humanoid robots, the controller acts as the brain, the servo motor serves as the power center, and the precision gear reducer functions as the tendons and joints. In terms of composition, the value of precision gear reducers accounts for approximately 30% to 40% of the robot's overall value, with costs making up around 35%. Thus, they are among the most critical core components of humanoid robots.

If AI models dictate the capabilities of humanoid robots in multimodal interaction, integrated perception, and autonomous decision-making, precision gear reducers determine their mobility, flexibility, and lightweight design. Currently, for AI models to flourish in the field of humanoid robots, they must address the challenge of unifying mathematical and physical models. Ultimately, it is the research and production of precision gear reducers that establishes a scientific barrier for humanoid robots, representing a significant divide between software and hardware technologies in the future.

Precision gear reducers are categorized into harmonic reducers and RV reducers. RV reducers are typically used in the base, upper arm, and shoulder of industrial robots, while harmonic reducers are primarily applied to the arms and joints of humanoid robots. The higher the degree of freedom in humanoid robots, the more joints they possess, leading to an exponential increase in the use of harmonic reducers. Tesla's latest humanoid robot, Optimus, has 42 degrees of freedom and is equipped with 28 gear reducers, of which a staggering 20 are harmonic reducers, accounting for 71.4% of the total. Similarly, Tianlian's humanoid robot has 71 degrees of freedom and uses 41 harmonic reducers, comprising 57.7% of its total gear reducers. These examples highlight the significant role of harmonic reducers in the research and application of humanoid robots.

The human body has approximately 78 named joints, with 60 located in the elbow, wrist, finger, leg, and toe joints, which are highly flexible and compact, making them suitable for harmonic reducers. For humanoid robots to achieve flexibility and degrees of freedom close to that of humans, the demand for harmonic reducers will be substantial. The harmonic reducers used in robots are generally precision-grade reducers, requiring a precision level of grade 2 or above. This necessitates that harmonic reducers possess a long lifespan and high precision.

Enhancing the fatigue resistance and lifespan of harmonic reducers while ensuring high precision has always been our primary research and development objective. As one of China's leading manufacturers of harmonic reducers, we are committed to innovation and self-research production. Based on the fundamental theory of harmonic transmission, we determine the shape of the flexible wheel teeth and overall structure, flexible wheel deformation curve, wave generator profile, rigid wheel teeth shape, and rigid wheel structure according to actual working requirements. We also conduct fatigue strength checks on the flexible wheel, which is prone to fatigue failure. After theoretical validation, we ensure the fatigue strength of the flexible wheel meets the required standards. We establish a three-dimensional model of the rigid-flexible wheel system and create a finite element model based on the actual working conditions of the harmonic reducer. We study the assembly process of the rigid-flexible wheel system and the engagement process under rated load through simulation analysis. This allows us to determine whether the deformation, nodal displacement, and stress distribution of the flexible wheel during assembly and engagement are reasonable, ensuring that the positional relationships between components of the rigid-flexible wheel system align with actual conditions. Ultimately, we achieve the development of a compact, high-load, high-precision harmonic reducer.

Simultaneously, we utilize multifunctional friction and wear testing machines to conduct tests on friction and wear coefficients, wear depth, and the detection of solid lubricant film detachment via acoustic emission voltage curves. Through experimental studies on samples under varying loads, sliding speeds, deformation amounts, roughness, and lubrication methods in atmospheric conditions, we analyze the wear mechanisms under different conditions. We have established a methodology for experimental and analytical studies on the fatigue failure and friction wear of the rigid-flexible theory system in harmonic reducers, which is applied to fatigue life prediction and structural optimization design of the flexible wheel, ensuring high-efficiency and high-precision operation of harmonic transmission.

After various optimization designs, we have developed proprietary RS arc 3D tooth profiles that significantly enhance gear meshing accuracy, achieving a meshing ratio increase of 25% to 30%. The application of surface nano-enhanced lubrication technology has improved friction and wear performance, increasing gear hardness by HRC 2.5 to 3.5, with lifespans exceeding 15,000 hours and backlash less than 10 arc seconds. Through the optimization of flexible wheel fatigue life, the enhancement of flexible wheel materials, and heat treatment processes, we have realized the miniaturization of harmonic reducers, boosting their torque load capacity and rigidity to support ultra-lightweight integrated joint operations.

Our miniaturized harmonic reducer development has introduced four new models: 03, 05, 08, and 11, each designed with different input and output options (shaft and flange) and tailored to various torque and speed settings with reduction ratios of 30, 50, 80, and 100. These new reducers maintain high performance while emphasizing compatibility with humanoid robots.

Considering the demand for humanoid robots, the global harmonic reducer market is expected to reach 14.75 billion yuan by 2025. This projection reflects not only the expanding market scale but also highlights the pivotal role of harmonic reducers in humanoid robot technology.

From a technical standpoint, the precision and efficiency of harmonic reducers make them one of the key components of humanoid robots. As the requirements for motion precision and stability in humanoid robots increase, the demand for harmonic reducers will correspondingly rise. Their unique transmission principles enable high torque, low noise, and smooth motion output, which are crucial for simulating human movements in humanoid robots. Furthermore, the compact design of harmonic reducers makes them suitable for the limited spatial layouts of humanoid robots, providing greater flexibility in design and production.

In terms of research and development, the continuous innovation of harmonic reducers is a key driver for advancing humanoid robot technology. With ongoing developments in material science, manufacturing processes, and control technologies, the performance of our harmonic reducers continues to improve. The application of new materials allows harmonic reducers to achieve higher strength and wear resistance at lighter weights. Additionally, advanced manufacturing processes and precision machining techniques enhance production efficiency, reducing costs and accelerating the commercialization of humanoid robots.