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How to Achieve Precise Control of Robot Joints? The internal structure is so complicated!

At present, the automation degree of industrial robots is amazing. 5-axis and 6-axis robots have so many joints and can also accurately transmit motion and commands. All parts cooperate closely to complete complex work, which makes people wonder what their transmission system is and what the structure of joints is?

robot joints
Japanese Yaskawa robot waves a knife to cut peas

Joints in robotics are one of the most important basic components of industrial robot, and it is also the core component of motion: precision reducer. Joints in robotics are a precise power transmission mechanism, which uses the speed converter of the gear to decelerate the rotation number of the motor to the required rotation number and obtain a device with large torque, so as to reduce the speed and increase the torque.

Robot Joints

The deceleration transmission at the joints in robotics requires short transmission chain, small volume, high power, light weight and easy control. At the same time, for the industrial robot with medium and high load, it also needs sufficient stiffness, rotation accuracy and motion accuracy stability.

Robot joint deceleration transmission structure ↓↓!


At present, there are few precision reducer manufacturers that can provide large-scale and reliable performance in the world, and the vast majority of the market share is occupied by Japanese Enterprises: nabtesco’s RV Reducer accounts for about 60%, harmonica’s harmonic reducer accounts for about 15%, and Sumitomo heavy industry (Sumitomo, no comparison is found). Especially in the field of robotics, the application proportion is overwhelming.

Precision reducer

Nabtesco (nabtesco) is a strong merger of two Japanese companies, teiren Seiki and nabok (Japan’s first automatic door was produced in 1956). As manufacturers of motion control systems and parts, the two companies have mastered high-end core technologies in their specific business areas and controlled a large market share.

Robot Joints

As the world’s largest manufacturer of precision cycloidal pin gear reducers, nabtesco produces high-performance reducers, hollow shaft reducers, and single shaft servo actuators and controllers.

High performance reducer

Its precision equipment has high torque, high rigidity and high resistance to overload impact load. At the same time, it also has high precision and very low return clearance. It is widely used in industrial automation fields such as satellite, radar antenna, industrial robot, semiconductor and welding technology.

Precision equipment
Precision reducer for each joint of industrial robot

Japan’s Harmonic Drive Systems Inc. (hdsi) is a leading enterprise in overall motion control. Its harmonic drive combined harmonic reducer has the characteristics of light weight, small size, no gear clearance and high torque capacity. It is widely used in various cutting-edge fields such as industrial robots, humanoid robots, semiconductor liquid crystal production devices, photovoltaic equipment, optical instruments, precision machine tools and so on.

Harmonic Drive

In order to cover the field of low reduction ratio that cannot be achieved by harmonic reducer, hdsi products also involve precision planetary gearbox harmonic reducer. The unique deformation process of the inner ring gear can make the planetary gear mesh tighter and eliminate the back clearance, which has reached the precision level of transmission error.

Sumitomo is a construction machinery manufacturer under Sumitomo Group, one of the world’s top 500 with a history of more than 400 years. Sumitomo products developed the first hydraulic excavator with its own technology in 1967. At present, Sumitomo hydraulic excavators are active all over the world.

Sumitomo reducer

Sumitomo reducer includes various types of reducer, such as Sumitomo large helical gear reducer, Sumitomo planetary gear reducer, Sumitomo helical gear reducer, Sumitomo worm gear reducer, etc. Large reduction ratio, high efficiency, needle tooth meshing system sleeve rolling friction, no relative sliding on the meshing surface, and the primary reduction efficiency can reach 94%.

You are welcome to visit our video centre of Tallman Robotics Limited to watch more projects and applications.