Detailed Explanation of Three Major Types of Speed Reducers
Precision reducers enable precise control of mechanical transmission and are mainly used in high-end manufacturing fields such as robotics, new energy equipment, high-end machine tools, electronic equipment, and printing machinery. Among them, the precision reducers mainly used in robots include harmonic reducers, RV reducers, and precision planetary reducers. Due to their different product technologies, they have different characteristics in application scenarios and performance.
Precision planetary reducers mainly consist of planetary gears, planet carriers, and a sun gear. Each precision planetary reducer has multiple planetary gears and features high rigidity, high precision (single-stage precision within 1'), high transmission efficiency (97%~98% for a single stage), a high torque-to-volume ratio, and lifetime maintenance-free operation. Therefore, planetary reducers are mostly installed on stepper motors and servo motors to reduce speed, increase torque, and match inertia. In the field of robotics, precision planetary reducers are core components of mobile robots, primarily forming the drive unit of a mobile robot together with servo motors and controllers.
Harmonic reducers consist of a wave generator, a flexible wheel, and a rigid wheel. Their working principle typically employs a wave generator as the active component, a fixed rigid wheel, and a flexible wheel as the output component. They offer advantages such as a large single-stage transmission ratio, small size, light weight, high motion accuracy, and the ability to operate normally in confined spaces and under conditions of media radiation. Compared to conventional reducers, harmonic reducers can reduce volume by 2/3 and weight by 1/2 while maintaining the same output torque. Therefore, harmonic reducers are widely used in applications requiring high transmission accuracy, such as 3C, semiconductor, food, injection molding, mold making, and medical fields. In the robotics field, harmonic reducers are primarily used in components such as forearms, wrists, and hands.
An RV reducer consists of a planetary gear reducer as the pre-stage and a cycloidal pinwheel reducer as the post-stage. The advantages of an RV reducer include a wide transmission ratio range, relatively stable precision, high fatigue strength, and higher rigidity and torque capacity. However, its heavy weight and large size limit its application to lightweight, flexible, and light-load applications. Therefore, RV reducers are mainly used in automotive, transportation, and port applications requiring heavy loads. In robotics, they are commonly used in multi-joint robots for positions such as the base, upper arm, and shoulder.
In summary, the three types of precision planetary reducers are ranked according to different performance indicators as follows: Ranked by transmission ratio (reduction performance), the three reducers from largest to smallest are: RV reducer > harmonic reducer > precision planetary reducer (single stage);
Based on transmission precision, the three types of reducers are ranked from highest to lowest as follows: precision planetary reducer > harmonic reducer > RV reducer;
Based on transmission efficiency, the three types of reducers are ranked from highest to lowest as follows: precision planetary reducer > RV reducer > harmonic reducer.
Tesla humanoid robot speed reducer solution
Tesla's humanoid robot has progressed rapidly, achieving rapid iteration in less than two years. It has completed the construction of its development platform, unveiled the Optimus product, and implemented capabilities such as motor torque control, environmental detection and memory, and complex tasks with both hands. Musk predicts that Optimus will be mass-produced to the "million" level, with an estimated unit cost of less than $20,000.
Precision reducers are core components of robot rotary joints. The accelerated industrialization of humanoid robots has opened up new opportunities for precision reducers. Looking at specific joint applications, Optimus rotary joints such as the elbow and wrist joints, which are typically small and have low loads, are likely to use harmonic reducers. Optimus linear joints such as the hip, knee, and ankle joints, which are typically large and have high loads, are likely to use RV reducers. Optimus dexterous hands use planetary reducers.
Tesla's latest humanoid robot is expected to have a total of 52 degrees of freedom and 28 joints. The design can be divided into two main categories of actuators: rotary and linear. Each category includes three rotary actuators and three linear actuators.
Potential solutions for the Tesla Optimus reducer include: 20 reducers in the upper body and hands using harmonic reducers; 8 reducers in the lower limbs and waist using high-load-capacity RV reducers; and 6 planetary reducers in the joints. Specifically, the upper body includes 8 servo motors + reducer joints and 2 linear actuator motors + reducer joints; the lower body includes 6 linear actuator motors + reducer joints; and the hands include 12 coreless motors + reducer joints.
Humanoid robots are currently in the research stage, with mass production expected in 2025 and sales expected to see significant growth between 2030 and 2035. Looking at future applications, harmonic reducers are the most widely used reducers in humanoid robots. Conservatively estimated, the market size for harmonic reducers in the humanoid robot market will reach tens of billions of RMB by 2035.
Major domestic speed reducer players
01 Green Harmonics
Products include harmonic reducers, mechatronic actuators, and precision components. The company pioneered the integrated CNC rotary table, combining a high-precision, high-rigidity reducer for machine tools with a high-power-density direct-drive motor. It has accumulated a large number of leading clients in high-end equipment industries such as industrial robots and CNC machine tools, and has successfully entered the mainstream international market. Currently, it is the leading harmonic reducer manufacturer in China, second only to Harmonic Drive Systems globally. In 2020, the company's revenue from harmonic reducers was 204 million yuan, and it remained stable at around 416 million yuan in 2021-2022. In 2022, the company's sales volume of harmonic reducers approached 260,000 units, with harmonic reducer business accounting for the vast majority of its operating revenue, representing 93.4%.
02 Dual-ring transmission
The company's main business is the research and development of mechanical transmission gears and related components, focusing on precision transmission for over 40 years. In 2020, it established a wholly-owned subsidiary, Huandong Technology, specializing in the research and industrialization of high-precision reducers for robot joints and high-precision hydraulic components. It provides customers with comprehensive high-precision reducer solutions covering loads of 3-1000KG robots, and its products are widely used in high-end manufacturing fields such as industrial robots, collaborative robots, multi-legged robots, and industrial automation. According to public data, Huandong Technology's market share in 2022 was approximately 15%, ranking among the top in the domestic RV reducer market, second only to the Japanese giant Nabtesco (which holds a 51% market share in China).
03 Kefeng Intelligent
The company has developed a complete product series including helical planetary reducers (45-235 series), spur planetary reducers (16-1720 series), miniature planetary reducers, and intelligent reducers. According to QYResearch statistics, in 2022, the company ranked fifth globally and second in China in terms of planetary reducer sales, and first among domestic brands. The company's planetary reducers have achieved import substitution in high-end machine tools, pipe jacking machines, semiconductors, medical equipment, and packaging machinery. According to Kefeng Intelligent's prospectus, in terms of revenue, the company's precision planetary reducers generated RMB 295.4052 million in 2022, accounting for 77.70% of total revenue. In 2020, 2021, and 2022, Kefeng Intelligent's precision planetary reducer production capacity was 165,900 units, 252,200 units, and 357,800 units, respectively, with capacity utilization rates of 97.05%, 92.80%, and 66.42%.
04 Zhongda Lide
A leading manufacturer of precision gearboxes, the company's integrated strategy drives product upgrades. Its main products include precision gearboxes, planetary gearboxes, and various small and micro geared motors. Since its establishment in August 2006, the company has been engaged in the production and sales of gearboxes and geared motors, successively launching new products such as micro brushless DC geared motors, precision planetary gearboxes, roller motors, and RV gearboxes.
In line with the industry's trend towards miniaturization, integration, and unification, the company continuously upgrades its geared motor integration and testing technology, as well as its precision transmission and control technology, based on the personalized needs of domestic market customers. It is committed to integrating core component systems, focusing on industrial automation and industrial robots, and has formed an integrated product architecture of reducer + motor + drive. The company has launched modular products such as the "Precision Planetary Reducer + Servo Motor + Drive" integrated machine, the "RV Reducer + Servo Motor + Drive" integrated machine, and the "Harmonic Reducer + Servo Motor + Drive" integrated machine, achieving product structure upgrades.
05 Zhaowei Electromechanical
The company's main business is the research, development, production, and sales of micro-drive systems. Micro-drive systems are closely related to the field of humanoid robots, and the company's related products include planetary gear reducers and coreless motors. From a technological perspective, the company can provide a range of planetary gear reducers with a wide size range (outer diameter 3.4mm-38mm), with planetary gear sets ranging from 1 to 5 stages, which are expected to be used in coreless motors. The company can also directly supply coreless geared motors with an outer diameter of 6mm.
06 Haozhi Electromechanical
Since 2014, the company has been developing harmonic reducers and has now formed a product series of double-wave and triple-wave with 6 major series, 9 specifications, and 6 reduction ratios. The harmonic reducers produced by the company have reached high precision and life standards, and related products have been sold in batches.
Leveraging its deep technological expertise in the robotics field, and through exchange, learning, and collaboration with R&D personnel from the Swiss Infanor Group, the company has successively overcome a series of core functional component technologies for intelligent robots, including "high-performance harmonic reducers," "high-precision encoders," "integrated joint modules," "six-dimensional force sensors," and "control systems." This has broken the reliance on imports for core functional components of intelligent robots, achieving complete domestic production of these components. Simultaneously, the company is developing RV reducers, which are expected to become a new growth driver for its performance.
In March, the company plans to establish a wholly-owned subsidiary, "Guangzhou Haozhi Robotics Co., Ltd.", to take over the business of the company's robotics division and be responsible for the research, development, production, and sales of core functional components for robots. The registered capital is RMB 60 million, and the company will hold 100% of its equity.
07 Zhuolan Automation
Products include high-precision planetary gearboxes, robot-specific harmonic gearboxes, electric rollers, and hollow rotary platforms. In 2021, Zhuolan Automation invested in the Zhuolan Precision Transmission Manufacturing Project in Wangniudun Town, Dongguan, primarily engaged in the research and development and production of precision planetary gearboxes and harmonic gearboxes. The project has a planned total investment of 350 million yuan, covering an area of 26.43 mu (approximately 1.7 hectares). Upon reaching full production capacity, the project is expected to have an annual production capacity of 500,000 planetary gearboxes and 100,000 harmonic gearboxes.
