In order to make the robot run, the industrial robot manipulator needs to install a transmission device for each joint, that is, each degree of freedom of motion, which is the drive system. The drive system can be hydraulic drive, pneumatic drive, electric drive, or an integrated system combining them; It can be driven directly or indirectly through mechanical transmission mechanisms such as synchronous belt, chain, gear train and harmonic gear.
The drive systems of industrial robots can be divided into three categories according to the power source: hydraulic, pneumatic and electric. According to the needs, these three basic types can also be combined into composite drive systems. Each of these three basic drive systems has its own characteristics.
1、 Hydraulic drive system
Because hydraulic technology is a relatively mature technology. It has the characteristics of large power, large ratio of force (or moment) to inertia, high rapid response, and easy to realize direct drive. It is suitable for application in these robots with large load carrying capacity, large inertia and working in the anti-welding environment. However, the hydraulic system needs energy conversion (electrical energy converted to hydraulic energy). In most cases, the speed control adopts throttle speed regulation, which is lower than the electric drive system. The liquid sludge discharge of the hydraulic system will pollute the environment, and the working noise is also high. Because of these weaknesses, in recent years, electric systems have often replaced robots with loads below 100 kHz.
2、 Pneumatic drive system
It is characterized by high speed, simple system structure, convenient maintenance and low price. It is suitable for use in robots with medium and small loads. However, because it is difficult to realize servo control, it is mostly used in robots controlled by programs, such as loading, unloading and stamping robots.
3、 Electric drive system
Due to the wide use of low inertia, high torque AC and DC servo motors and their supporting servo drives (AC frequency converter, DC pulse width modulator), such drive systems are widely used in robots. This kind of system does not need energy conversion, and is convenient to use and flexible to control. Most motors need to be equipped with precise transmission mechanism behind them. Brushless DC motor can not be directly used in explosion-proof environment, and its cost is higher than that of the above two drive systems. But because of its outstanding advantages, this kind of drive system is widely used in robots.