Internal structure principle of precise control of robot joints

Today's level of automation is astonishing. 5-axis and 6-axis machines have so many joints and can accurately transmit motion and commands. All parts work closely together to complete complex tasks. One can't help but wonder what their transmission systems are like and what the structures of the joints are.

The joint is one of the most important basic components of industrial robots and also the core component of the movement: precision reducer. This is a precision power transmission mechanism that uses a gear speed converter to reduce the number of revolutions to the required number of revolutions and obtain a larger torque device, thereby reducing the speed and increasing the torque.

The reduction transmission at the robot joints requires a short transmission chain, small size, high power, light weight and easy control. At the same time, for robots with medium and high loads, sufficient stiffness, rotation accuracy and motion accuracy stability are also required.

Currently, there are not many companies in the world that can provide large-scale and reliable precision reducer manufacturers, and the vast majority of the market share is occupied by Japanese companies: Nabsco's RV reducers account for about 60%, Harmonica's harmonic reducers account for about 15%, and Sumitomo Heavy Industries (SUMITOMO, the proportion is not found). Especially in the field of robotics, the proportion of application is overwhelming.

▲Internal structure of precision reducer

Nabtesco is a merger of two Japanese companies, Teijin Seiki and Nabco, which produced Japan's first automatic door in 1956. As manufacturers of motion and parts, both companies have mastered high-end core technologies in their specific business areas and control a large market share.

As the world's largest manufacturer of precision cycloid reducers, Nabtesco produces high-performance reducers, hollow shaft reducers, and single-axis servo actuators and controllers.

The precision equipment it produces has high torque, high rigidity and high overload and impact load resistance, as well as high precision and very low return clearance. It is widely used in satellites, radars, industrial robots, and welding technology.

Japan's Harmonic Drive Systems Inc. (HDSI) is a leading company in integrated motion control. Its Harmonic Drive combined harmonic reducers are lightweight, compact, have no gear backlash, and have high torque capacity. They are widely used in industrial robots, humanoid robots, semiconductor liquid crystal production equipment, photovoltaic equipment, instruments, precision machine tools, and other cutting-edge fields.

In order to cover the low reduction ratio area that harmonic reducers cannot achieve, HDSI products also involve precision planetary gearbox type harmonic reducers. The unique inner ring gear deformation process can make the planetary gear mesh more tightly and eliminate backlash, achieving precision-level transmission error.

Japan's Sumitomo is a construction manufacturer under the Sumitomo Group, one of the world's top 500 companies with a history of more than 400 years. After Sumitomo developed the first hydraulic excavator in 1967 with its own technology, Sumitomo hydraulic excavators are now active all over the world.

Sumitomo reducers include various types of reducers, such as Sumitomo large helical gear reducers, Sumitomo planetary gear reducers, Sumitomo helical gear reducers, Sumitomo worm gear reducers, etc. They have large reduction ratios, high efficiency, pin-tooth meshing system sleeve-type rolling friction, no relative sliding on the meshing surface, and a first-stage reduction efficiency of up to 94%.

Editor: Huang Fei