Since Germany proposed Industry 4.0, China has also put forward the "Made in China 2025" plan. With the acceleration of China's automation pace, China will become a super robot powerhouse in the future, and the demand for industrial robots will increase significantly. However, stimulated by the high growth of industrial robots, the development path of its control system and servo motor, a key automation product, will inevitably change. As the power system of industrial robots and the "heart" of robot movement, what is the future of servo motors?
According to the "Global Industrial Robot Servo Motor Industry Report 2015-2019", China became the world's largest industrial robot market starting in 2013, and its sales volume surged to 55% of global servo motor sales in 2014. It is estimated that by 2019, the demand for servo motors in the Chinese market will reach 182,000 units.
The rapid growth of industrial robots has stimulated the development of the servo motor market to some extent. According to ResearchandMarkets, 90% of industrial robots use servo motors, and each industrial robot is equipped with an average number of servo motors. Therefore, China's demand for servo motors increased by 231,000 units in 2014. This number is expected to reach 737,000 units in 2019.
Currently, in the Chinese industrial machinery market, 85% of servo motors are from foreign brands, while most domestic companies are still in the research and development stage, and there are almost no industrialized industrial robot servo motors.
The coexistence of industrial robots and servo motors
Servo motors are typically installed at the "joints" of a robot. The robot's joint drive is inseparable from the servo system. The more joints a robot has, the higher its flexibility and precision, and the more servo motors it needs to use.
Robots have very strict requirements for joint drive motors, and therefore also very strict requirements for electric servo drive systems, mainly in the following aspects:
1. Fast response: The higher the sensitivity of the electric servo system, the better its fast response performance.
2. High starting torque-to-inertia ratio: When driving a load, the robot's servo motor is required to have a large starting torque and a small moment of inertia.
3. Continuity and linearity of control characteristics: The motor speed can change continuously with the change of control signal. Sometimes the speed needs to be proportional or approximately proportional to the control signal. The speed regulation range is wide, and a speed regulation range of 1:1000 to 10000 can be used.
4. Small size, light weight, and short axial dimension to match the robot's body shape;
5. It can withstand harsh operating conditions and can perform very frequent forward and reverse and acceleration and deceleration operations.
Furthermore, the need for upgrades in domestically produced servo motors hinders the development of domestically produced robots. The current situation with domestically produced servo motors is that small ones are neither small nor large enough! What does this mean? Low-power servo motors cannot be miniaturized and are generally too long. For example, the 200W and 400W servo motors commonly used in light-duty robots are often short and compact, unlike Tamagawa's TBL-imini series servo micro motors, Panasonic's A6, and Yaskawa's Σ7 motors.
In contrast, domestically produced servo motors are generally longer and have a rougher appearance. This is not suitable for some high-end applications, especially for desktop robots with a light load of around 6kg, where the installation space for the robot arm is very limited, and there are strict requirements on the length of the servo motor.
Secondly, the reliability of signal connectors has always been a major point of criticism. Domestic servo motors need further improvement, and the miniaturization and high-density of connectors are also trends. Integration with the servo motor body is a good approach, and many Japanese servo motors are designed this way, which facilitates installation, debugging, and replacement.
Another core technology of servo motors is the high-precision encoder, especially the multi-turn absolute encoders used in robots, which are heavily reliant on imports. The lack of domestic production is a major bottleneck restricting the development of high-end servo systems in my country. Encoder miniaturization is also a crucial technology that cannot be bypassed in the miniaturization of servo motors. Looking at the evolution of Japanese servo motor products, it has always been accompanied by the coordinated development and upgrading of the motor's magnetic circuit and encoder!
Currently, most domestic servo motor OEM manufacturers, based on market share, imitate Japanese servo motor designs, with power mostly below 3kW, primarily focusing on small to medium power. There is a lack of medium to high power servo motors (5.5-15kW), forcing some equipment applications to abandon the entire system due to the absence of a high-power servo motor and drive.
In summary, the development model of Japanese servo systems is one of layered and collaborative development, resulting in excellent overall performance, which is very similar to the development of robots in Japan. In China, motor manufacturers produce motors, encoder manufacturers produce encoders, and drive manufacturers produce drives, without collaboration and cooperation, making it difficult to achieve good overall performance of servo motors and drive systems.
Secondly, there is a lack of fundamental research in servo systems, including absolute encoder technology, industrial manufacturing technology for high-end motors, breakthroughs in production processes, practical verification of performance indicators, and the formulation of evaluation standards. These are areas that core component manufacturers in the robotics industry need to improve.
