The space technology industry is developing rapidly in the new century. At the same time, it has also led to the rapid development of the space robot industry. Research shows that space robots will gradually take the leading role, while people will take a back seat. According to scientists' estimates, it takes more than 600 people to work in space for half a year to build a 5-million-kilowatt space solar power station, of which more than 100 people work in low-orbit space bases, while the rest work in geosynchronous orbit space bases. And it is also necessary to establish a maintenance team for the space base and power generation system. It can be imagined that future space development activities will require a large number of people to complete.
We know that in the past space development, astronauts have created many miracles, such as landing on the moon, capturing failed satellites extravehicularly, repairing the Hubble Telescope in space, etc. But exactly how much these activities cost is unknown. Although the prospects for developing and utilizing space in the future are very good, for humans to stay in space, large and complex life support systems, environmental control systems, material supply systems, life-saving systems, etc. are necessary, and these systems are incredibly expensive. According to estimates by scientists, the volume of the three parts of the permanent manned space station, the life support system, the habitation system and the astronaut extravehicular activity system, account for about 16% of the total volume of the core module, and the power consumption accounts for 25% of the total power consumption of the space station. %~38%, and research and development expenses account for 20% of the total funds. It is also estimated that each astronaut spends US$500,000 to US$1 million per day to ensure that astronauts can move in space.
From this point of view, the development of space must not be like a ground factory, sending thousands of engineering technicians and workers to space to engage in various space material processing, space production, space assembly, Space repair and other operations. The only solution is to develop a large number of robots and send them into space to replace humans, making them the main force of labor and the right assistants of astronauts. We can use the human body to vividly describe space robots. Robots are like human limbs and bodies, which perform various heavy tasks, while humans function as the brain, commanding and monitoring all mechanical activities. If we want the space technology industry to have the highest productivity and the lowest operating costs, one of the most effective ways is to combine robots and highly automated systems under human supervision to form a highly reliable and efficient human-machine hybrid system. .
We know that a robot is a general mechanical system. Like humans, it can complete a variety of tasks under unknown environmental conditions in advance and has the ability to perceive, reason and judge the external environment. and decision-making functions. But it must be pointed out that people have long realized that not all robots can work in space, because the space environment is very different from the ground environment. Space robots work in environments of microgravity, high vacuum, ultra-low temperature, strong radiation, and poor lighting, so they are very different from ground robots. In a weightless state, as long as the acceleration is not too great, slender hands can move the giant thing. For example, the remote-controlled manipulator on the space shuttle is a 6-degree-of-freedom manipulator made of composite materials. It is 15 meters long and weighs 400 kilograms. Although it is weak and weak on the ground, it cannot even lift objects of its own weight. However, once in space, it can lift loads weighing dozens of tons. But everything has advantages and disadvantages. In a weightless state, as long as the object is pushed a little, it will fly away immediately, which brings a lot of inconvenience to the operation, especially visual recognition. For example, on the ground, objects placed on the workbench always face the visual camera with a fixed surface, while in space, floating workpieces can face the camera in any orientation. In this way, the space robot must have a three-dimensional vision system and a special marking code to identify objects and their orientation. And the fingers are required to flexibly select the object in the direction to be grasped, and have intelligent sensors such as proximity, touch, sliding, force, etc., in order to cooperate with the visual system to complete the operation task. In a weightless state, any object including the robot itself is in a floating state, so the space robot must be multi-armed. One fixed arm grasps a structural part to stabilize itself, one operating arm stabilizes the workpiece, and the other operating arm is used to complete the operating task. Under high vacuum conditions, the movable joints of space robots are essentially different from the movable joints of robots on the ground. They need to use solid lubrication and solve the problem of metal cold welding under high vacuum conditions. Due to the microgravity environment of space, the dynamic equation of the operator is quite different from that on the ground. Therefore, the space robot is a special form of robot.
It is worth mentioning that, in addition to being able to adapt to the space environment, the space robots selected to work in space must also have small size, light weight, high flexibility; high intelligence, full functions, and multiple functions. Arm type; micro-power consumption, long life, high reliability and other characteristics. The main tasks of space robots in space are: space construction and assembly; maintenance and repair of satellites and other spacecraft; space production and scientific experiments.
Space construction and assembly is a major task for space robots, especially in the early stages of space construction. Some large structural parts, such as the installation of radio antennas and solar cell sail panels, the assembly of large trusses and cabin sections and other extravehicular activities, are all inseparable from space robots.
When space robots go outside the cabin, they will undertake a series of tasks such as the transportation of large components, the fastening of connections between components, and the handling of toxic or dangerous goods. It is estimated that more than half of the tasks of space construction will fall on robots capable of extravehicular activities. The characteristic of the extravehicular activity robot is that it has an advanced remote control device on its end operator, which can work with multiple arms, and is equipped with tool holders and supply trays. The on-site computer and expert system give work instructions to complete various tasks. construction tasks.
As space activities continue to deepen, human beings will have more and more assets in space. Countries around the world have launched many spacecraft into space, of which artificial earth satellites account for about 90%. Once these satellites malfunction, it is very uneconomical to discard them and launch new satellites. Second, it will increase space debris, so they must be repaired. The space robot will grab the malfunctioning satellite from orbit, bring it to the space station for repair, and then use auxiliary rockets or orbital maneuvering vehicles to put the repaired satellite back into space orbit. If some spacecraft cannot be brought back to the space station for repair, most intelligent robots are used to perform missions on free-flying vehicles, disassemble and reassemble certain parts, or cut and weld components. In fact, there are many spacecrafts that need to continuously replenish consumed materials, such as photographic film, nitrogen, fuel, coolant, etc., in order to extend their working life. Among these materials, some are toxic, some are highly corrosive, and some are frozen at low temperatures, making them difficult to handle in a weightless state. Sending extravehicular service robots to perform these tasks is both economical and safe. It can be said to be the best of both worlds. The extravehicular servicing robot carries an omnidirectional antenna to maintain communication with the space station. In addition, it also has lidar and color stereo vision systems for navigation and target identification. In addition, the robot's fingers are equipped with tactile sensors, sliding sensors, and proximity sensors, and the wrist arms are equipped with force sensors to increase the flexibility and accuracy of operation. The tools and components needed for work can be carried inside the body. When necessary, you can fly away from the space station on a jetpack to perform various tasks.
In-vehicle robots mainly serve scientific payloads. Therefore, robots should be selected according to the requirements of the experiment. There are many varieties to choose from. They not only have to perform emergency and repair tasks, but also perform a series of tasks such as adding reagents, harvesting products, intermediate sampling and analysis, collecting various samples, etc. The existence of robots in the cabin greatly reduces the labor intensity and nervousness of astronauts, and can serve as substitutes for astronauts when they leave the scene. There is a small cabin robot named "Spider King" by scientists, which is connected to the robot's working environment through eight Kevlar ropes. These Kevlar ropes extend from the corners of the "Spider King" body to various touch points in the workspace. By increasing or decreasing the tension on a specific rope, the robot can move throughout the work cell with astonishing positional accuracy and repeatability.
So, space robots play an inestimable role in space technology industrial production activities, whether in improving safety, production efficiency and economic benefits. With the continuous deepening of space activities, space robots will surely receive new developments. In the near future, when humans return to the moon, fly to Mars, and fly out of the solar system, space robots will show their power with a new look!
Knowledge Points
Constan Din Tsiolkovsky
Din Tsiolkovsky is the founder of modern astronautics. He was the first to demonstrate the possibility of using rockets for interstellar transportation, manufacturing artificial earth satellites and low-Earth orbit stations, pointed out reasonable ways to develop aerospace and manufacturing rockets, and found a series of important engineering and technical solutions for rocket and liquid engine structures. He has a famous saying: "The earth is the cradle of mankind, but mankind cannot be bound to the cradle forever.
”