With the development of industrial mechanization and automation, and the inherent advantages of pneumatic technology, pneumatic robots have been widely used in various industries of production automation. This article provides a brief overview of the current application status and development prospects of pneumatic robots.
1. Introduction
Over the past 20 years, the application fields of pneumatic technology have expanded rapidly, especially in various automated production lines. The combination of electrical programmable control technology and pneumatic technology has resulted in higher levels of automation, more flexible control methods, and more reliable performance in the entire system. The rapid development of pneumatic manipulators and flexible automated production lines has placed higher and more demands on pneumatic technology. The introduction of microelectronics technology has promoted the development of electrical proportional servo technology, and the development of modern control theory has enabled pneumatic technology to move from switch control to closed-loop proportional servo control, continuously improving control accuracy. Due to its simple structure, strong anti-pollution ability, and low cost, pneumatic pulse width modulation technology is being vigorously developed and researched both domestically and internationally.
Industry statistics from various countries show that the pneumatic industry has developed rapidly over the past 30 years. In the 1970s, the output value ratio of hydraulic to pneumatic components was approximately 9:1. Today, more than 30 years later, in technologically advanced countries like Europe, America, and Japan, this ratio has reached 6:4, or even approaching 5:5. my country's pneumatic industry started later but has developed rapidly. Since the mid-1980s, the annual growth rate of pneumatic component output value has exceeded 20%, higher than the average annual growth rate of China's machinery industry output value. With the development and application of microelectronics, PLC, computer, sensing, and modern control technologies, pneumatic technology has become one of the key technologies for realizing modern transmission and control.
2. The Development Process of Pneumatic Technology and Pneumatic Robots
Pneumatic technology is an engineering technology that uses air compressors as a power source and compressed air as a working medium for energy or signal transmission. It is one of the important means to realize various production controls and automatic controls. It began around 1776 when John Wilkimson invented an air compressor that could generate approximately one atmosphere of pressure. In 1880, a pneumatic brake device was first successfully made using a cylinder and applied to train braking. In the early 1930s, pneumatic technology was successfully applied to the opening and closing of automatic doors and the auxiliary actions of various machines. By the early 1950s, most pneumatic components were modified or evolved from hydraulic components, resulting in large sizes. In the 1960s, pneumatic technology began to form industrial control systems, becoming self-contained and no longer comparable to pneumatic technology. In the 1970s, due to the combined application of pneumatic and electronic technologies, it was widely promoted in the field of automation control. The 1980s ushered in an era of pneumatic integration and miniaturization. Since the 1990s, pneumatic technology has broken through traditional limitations and experienced leaps in development. The physical size limitations of valves have been overcome, vacuum technology has become increasingly sophisticated, high-precision modular pneumatic manipulators have emerged, and the concept of intelligent pneumatics has arisen. Pneumatic servo positioning technology enables automatic positioning of any point at high speeds with cylinders, and intelligent valve islands have ideally solved the problem of decentralized and centralized control in the entire automated production line. As a type of manipulator, the pneumatic manipulator is widely used due to its advantages such as simple structure, light weight, rapid and stable operation, reliability, energy saving, and environmental friendliness.
Pneumatic manipulators emphasize modularity. Modern pneumatic manipulators with transmission technology employ advanced valve island technology (reprogrammable, etc.) and pneumatic servo systems (capable of precise positioning at any location) in terms of control. All actuators adopt modular assembly structures.
In the early 1990s, the "Achilles" six-legged explorer, an electro-pneumatic robot developed by the Integrated Technology Department led by Professor Y. Bando of the Royal Military Academy in Brussels, was a "six-legged animal" created by the perfect combination of pneumatic technology, PLC control technology and sensing technology.
Each of the six legs has three degrees of freedom: a linear cylinder lifts and lowers the leg, a oscillating motor controls the leg's extension and retraction, and another oscillating motor is responsible for rotation around the leg's axis. Designed by the Institute for Materials Science at the University of Hanover, this pneumatic climbing robot integrates remote sensing and vacuum technologies, successfully solving operational problems such as vertical climbing, which are considered dangerous work.
The Tron-X electro-pneumatic robot can shake hands with people in a friendly manner. Its head, waist, and hands can bend and move like humans, exhibiting excellent flexibility. Under the operation of a behind-the-scenes operator (or through its own programming control), it can converse with people or introduce itself. The Tron-X electro-pneumatic robot integrates electronic technology, pneumatic technology, and artificial intelligence. It demonstrates that pneumatic technology can achieve the most challenging degree of freedom in robotics, possessing adaptability within a sufficient workspace, high precision, and rapid and sensitive response capabilities.
3. Current Status of Pneumatic Robotic Arm Applications
Because pneumatic transmission systems are safe and reliable, they can operate in harsh environments such as high temperatures, vibrations, flammable and explosive materials, dusty environments, strong magnetic fields, and radiation. As a type of robotic arm, pneumatic manipulators offer advantages such as simple structure, light weight, rapid and stable operation, reliability, energy efficiency, environmental friendliness, easy stepless speed regulation, easy overload protection, and the ability to perform complex movements. Therefore, pneumatic manipulators are widely used in the automotive manufacturing industry, semiconductor and home appliance industries, fertilizer and chemical industries, food and pharmaceutical packaging, precision instruments, and the military industry.
Modern automobile manufacturing plants, especially their main welding production lines, largely utilize pneumatic robotic arms. The movement of the car body at each stage; the lifting and lowering of the car body shell by vacuum suction cups, clamping and positioning at designated stations; the rapid approach of the spot welding machine head, and the voltage-controlled spot welding after deceleration and soft landing—all employ pneumatic robotic arms with various specialized functions. The high-frequency spot welding, the accuracy of force control, and the high degree of automation in completing the entire process make this one of the most representative applications of pneumatic robotic arms.
On assembly lines for home appliances such as color TVs and refrigerators, and on assembly lines for various electronic products such as semiconductor chips and printed circuits, one can see not only cylinders and grippers of various sizes and shapes, but also many dexterous vacuum suction cups that gently pick up items such as picture tubes and cardboard boxes that are difficult for ordinary grippers to lift, transporting them to designated target locations. Chip handling systems, which have very strict acceleration limits, utilize SIN cylinders with smooth acceleration. Pneumatic robots are used for the automatic metering and packaging of powdery, granular, and lumpy materials in the food industry; and for many processes in the tobacco industry, such as automatic cigarette making and packaging. Examples include pneumatic robots for wine and paint filling; automatic capping, installation, and tightening pneumatic robots; and milk carton packing pneumatic robots. Furthermore, pneumatic systems and pneumatic robots are widely used in pharmaceuticals and medical devices, such as pneumatically adjustable hospital beds, Robodoc robots, and da Vinci surgical robots.
4. Development Prospects and Directions
4.1 High repeatability
Accuracy refers to the precision with which a robot or manipulator reaches a designated point; it is related to the resolution of the actuator and the feedback device. Repeatability refers to the precision with which the manipulator reaches the same position when the action is repeated multiple times. Repeatability is more important than accuracy. If a robot's positioning is not precise enough, it will usually exhibit a fixed error, which is predictable and can therefore be corrected through programming. Repeatability defines the range of random error and is determined by repeatedly running the robot a certain number of times. With the development of microelectronics and modern control technology, and the advancement of pneumatic servo technology from the laboratory to the standardization of pneumatic servo positioning systems, the repeatability of pneumatic manipulators will continue to increase, and their application areas will broaden, such as in the nuclear industry and military industry.
4.2 Modularization
Some companies refer to pneumatic robots with integrated guide drive systems as simple transmission technology, while calling modularly assembled pneumatic robots modern transmission technology. Modularly assembled pneumatic robots offer a more flexible installation system than combined guide drive systems. They integrate electrical interfaces and guide systems with cables and air hoses, allowing for free movement of the robot. Because the drive components of modular pneumatic robots use specially designed ball bearings, they possess high rigidity, high strength, and precise guiding accuracy. Excellent positioning accuracy is also a key feature of the new generation of pneumatic robots. Modular pneumatic robots allow the same robot to have different functions depending on the application of different modules, expanding the application range of robots and representing an important development direction for pneumatic robots.
The emergence of intelligent valve islands has played a crucial supporting role in improving the performance of modular pneumatic manipulators and pneumatic robots. Because intelligent valve islands are inherently modular devices, especially compact CP valve islands, they play a vital role in centralized control of distributed systems, particularly for the moving modules within manipulators.
4.3 Oil-free
To meet the pollution-free requirements of industries such as food, pharmaceuticals, bioengineering, electronics, textiles, and precision instruments, oil-free lubrication components that do not require grease have been developed. With the advancement of materials technology and the emergence of new materials (such as sintered metal graphite materials), lubrication-free components with special structures and made of self-lubricating materials not only save lubricating oil and do not pollute the environment, but also have simple systems, stable friction performance, low cost, and long service life.
4.4 Mechatronics
Typical control systems composed of "programmable logic controllers, sensors, and pneumatic components" remain an important aspect of automation technology; the development of adaptive control pneumatic components that combine with electronic technology enables pneumatic technology to move from "on/off control" to high-precision "feedback control"; and integrated systems that save wiring not only reduce wiring, piping, and components, but also simplify disassembly and assembly, greatly improving system reliability.
Today, the power of solenoid valve coils is decreasing while the output power of PLCs is increasing, making it increasingly possible for PLCs to directly control the coils. Pneumatic robots and pneumatic control systems are becoming increasingly reliant on PLCs, and the development of valve island technology has made PLCs even more adept at handling pneumatic robots and pneumatic control systems.
5. Conclusion
Pneumatic technology has undergone a long development process. With pneumatic servo technology moving out of the laboratory, pneumatic technology and pneumatic robots have ushered in a new era. Currently, the world is characterized by a three-way balance of power in pneumatic technology and pneumatic robots, with Japan, the United States, and the European Union as the leading players. my country started its research and application of pneumatic technology and pneumatic robots relatively late, but with increased investment and R&D efforts, many domestically developed pneumatic robots are already playing a vital role in the country's development and progress in industries such as automobiles. The rapid development of microelectronics technology, the improvement of machining processes, and the application of modern control theory have laid a solid material and technological foundation for the research of high-performance pneumatic robots. Due to the unique advantages of pneumatic robots, such as simple structure, easy stepless speed regulation, easy overload protection, and the ability to perform complex movements, it is foreseeable that in the near future, pneumatic robots will increasingly be widely used in industrial, military, aerospace, medical, and daily life fields.
