Industrial robot is a kind of universal machine equipped with memory device and end-effector device, which can complete various movements or processes to replace human labor. Usually in the production can replace workers to do some monotonous, frequent and repetitive long time operations, or dangerous, harsh environment operations. It can improve the efficiency of production and product quality, and is an effective scheme for enterprises to supplement and replace labor force.

At present, the development of industrial robots is characterized by high speed, accuracy, compact body mechanism, multiple degrees of freedom and improved rigidity. Key areas also require heavy load or fast response speed. For example, the load of welding robots in automobile production is mostly 150-300kg, while assembly robots in the field of electronics need to quickly respond to the accessories on the assembly line.

Reducer in the field of mechanical transmission is connected between the power source and the implementation of the intermediate device, usually it puts the motor, internal combustion engine and other high-speed operation of the power through the input shaft of the small gear meshing output shaft of the big gear to achieve the purpose of deceleration, and transfer greater torque. At present mature and standardized reducer has: cylindrical gear reducer, turbine reducer, planetary reducer, planetary gear reducer, RV reducer, cycloid gear reducer and harmonic reducer. Since the 1980s, in the emerging industries such as aerospace, robotics and medical equipment, such as the development of the need for a simple and compact structure, transmission power, low noise, smooth transmission of high-performance precision reducer, RV reducer and harmonic reducer is an important two kinds of precision reducer.

RV（Rot-Vector）reducer

RV reducer is developed on the basis of cycloid pin wheel transmission, with two deceleration and central disc supporting structure. Since it was put into the market in 1986, because of its large transmission ratio, high transmission efficiency, high motion precision, small return error, low vibration, high rigidity and high reliability and other advantages, it is the "royal" reducer of robots

Harmonic reducer

       Harmonic reducer consists of three parts: harmonic generator, flexible theory and rigid wheel, its working principle is that the harmonic generator makes flexible wheel produce controllable elastic deformation, by the flexible wheel and rigid wheel meshing to transfer power, and achieve the purpose of deceleration; According to the wave generator different CAM type, roller type and eccentric disc type. The harmonic reducer has large transmission ratio, small contour, fewer parts and high transmission efficiency. Single transmission ratio can reach 50-4000, and transmission efficiency is up to 92-96%.

Planetary reducer

A planetary decelerator, as its name suggests, is a decelerator with three planetary wheels rotating around a solar wheel. The planetary reducer is small in size, light in weight, high in carrying capacity, long in service life, smooth in operation and low in noise. It has the characteristics of power shunt and multi-tooth meshing alone; Is a widely used industrial products, its performance can be comparable with other military grade planetary reducer products, but has the price of industrial grade products, is used in a wide range of industrial occasions.

The role of precision planetary reducer in industrial robots
The power source of industrial robots is generally AC servo motor, because driven by pulse signals, the servo motor itself can achieve speed regulation, why industrial robots also need a reducer? Industrial robots often perform repetitive actions to complete the same process; In order to ensure that industrial robots can complete the process tasks reliably and ensure the quality of the process, the positioning accuracy and repeated positioning accuracy of industrial robots are required to be very high.

Therefore, to improve and ensure the accuracy of industrial robots need to use RV reducer or harmonic reducer. Another function of precision reducer in industrial robot is to transfer more torque. When the load is large, it is not cost-effective to increase the power of the servo motor blindly, and the output torque can be improved through the reducer in the appropriate speed range. In addition, the servo motor is prone to heating and low frequency vibration under low frequency operation, which is not conducive to ensure accurate and reliable operation of the industrial robot for long time and periodic work.

The existence of the precision reducer makes the servo motor run at an appropriate speed, and accurately reduces the speed to the speed required by each part of the industrial robot, and improves the rigidity of the mechanical body at the same time output greater torque. Compared with the general reducer, the robot joint reducer requires short transmission chain, small volume, large power, light weight and easy to control and other characteristics. There are two kinds of reducer widely used in joint robot: RV reducer and harmonic reducer.

Compared with harmonic reducer, RV reducer has higher stiffness and rotary accuracy. Therefore, in the joint robot, the RV reducer is generally placed in the frame, arm, shoulder and other heavy load position; The harmonic reducer is placed in the forearm, wrist or hand; Planetary retarders are commonly used in cartesian robots.