Precision reducer - the king of core components for humanoid robots
1、 Definition and Difference

Precision reducers, servo motors, and controllers are the three core components of industrial robots, with a high proportion of manufacturing costs. In 2023, the cost proportions of precision reducers, servo motors, and controllers, the three core components of robots in China, will be 32%, 22%, and 12%, respectively. The manufacturing cost of core components will account for nearly 70% of the total manufacturing cost of industrial robots.

According to different principles, precision reducers are mainly divided into precision planetary reducers, RV reducers, and harmonic reducers. Due to the different composition structures and characteristics of the three types of reducers, they also have certain differences in the subdivision fields of robot applications:

(1) The core transmission component of a planetary reducer is the planetary gear set, which operates on a pure gear mechanism and achieves deceleration effect through torque transmission between gears. Due to its high efficiency and load-bearing capacity, it is often used in the drive system of parallel manipulators.

(2) The RV reducer adopts a two-stage transmission structure, which has the characteristics of a large transmission ratio range, stable accuracy, high fatigue strength, higher rigidity and torque bearing capacity, and is suitable for applications in heavy-duty parts such as robot arms and machine bases. The technical threshold for RV reducers is relatively high, and the key lies in precision control, long-term stability, service life, and noise suppression.

(3) Harmonic reducer adopts the elastic deformation transmission mechanism of flexible wheels, which has the characteristics of light weight, small volume, large transmission ratio, and high motion accuracy. When the output torque is the same, the volume can be reduced to 1/3 of other reducers, and the weight can be reduced by 1/2. It is suitable for robot arms, wrists, or finger end axes with small loads. The technical barrier for harmonic reducers is high. To achieve independent research and development and domestic production of harmonic reducers, it is necessary to break through key technical bottlenecks in tooth design, materials, processing technology, testing and evaluation.

Overall, regarding the main indicators of the reducer, in terms of transmission efficiency, the precision planetary reducer is the best, followed by the RV reducer, and the harmonic reducer ranks third; In terms of transmission accuracy, precision planetary reducers are still the best, while RV reducers are on par with harmonic reducers; In terms of transmission ratio, RV reducers and harmonic reducers are slightly better than precision planetary reducers.