We know that in the past space development, astronauts have created many miracles, such as landing on the moon, capturing faulty satellites outside the cabin, and repairing the Hubble telescope in space. But how much these activities cost is unknown. Although the future development and utilization of space is very bright, it needs a huge and complex life support system, environmental control system, material supply system, life-saving system and so on. And these systems are very expensive. According to scientists' prediction, the volume of life support system, living system and astronaut extravehicular activity system of the permanently manned space station accounts for about 16% of the total volume of the core cabin, and the power consumption accounts for 25% ~ 38% of the total power consumption of the space station, and the development cost accounts for 20% of the total expenditure. It is also estimated that in order to ensure astronauts' activities in space, each astronaut will spend 500,000 ~ 6,543.8+0,000 dollars a day.
From this point of view, the development of aerospace must not send thousands of engineers and technicians into space to engage in various aerospace materials processing, aerospace production, aerospace assembly, aerospace repair and other operations, as in ground factories. The only solution is to develop a large number of robots and send them into space to replace human beings and make them the main force of the labor force and the right-hand man of astronauts. We can use the human body as a metaphor for space robots. Robots are like human limbs and bodies, they perform all kinds of heavy work, and human functions are equivalent to the brain, commanding and monitoring all mechanical activities. If the aerospace science and technology industry wants to have the highest productivity and the lowest operating cost, one of the most effective ways is to combine robots with highly automated systems under the supervision of people to form a highly reliable and efficient man-machine hybrid system.
As we all know, robot is a universal mechanical system. Like human beings, it can complete all kinds of tasks under unknown environmental conditions in advance, and has the functions of perception, reasoning, judgment and decision-making for the external environment. 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 microgravity, high vacuum, ultra-low temperature, strong radiation and poor illumination, so they are very different from ground robots. In weightlessness, as long as the acceleration is not too great, slender hands can move behemoths. For example, the remote manipulator on the space shuttle is a 6-DOF manipulator made of composite materials, with a length of15m and a weight of 400kg. Although it is weak on the ground, it can't even lift its own weight. However, it can lift dozens of tons of load when it reaches space. But everything has advantages and disadvantages. In weightlessness, as long as you push the object a little, it will fly away immediately, which brings a lot of inconvenience to the operation, especially visual recognition. For example, on the ground, the object placed on the workbench always faces the visual lens with a fixed surface, while in space, the floating workpiece can face the lens in any direction. In this way, space robots must have a three-dimensional vision system and special identification codes to identify objects and their orientations. Fingers are also required to be able to flexibly select objects in the direction they want to grab, and have intelligent sensors such as proximity, touch, sliding and force to cooperate with the visual system to complete the operation task. In weightlessness, any object, including the robot itself, is floating, so the space robot must be multi-armed. A fixer holds a structural member with an arm to stabilize itself, a manipulator holds the workpiece, and the other manipulator is used to complete the operation task. Under the condition of high vacuum, the movable joints of space robots are essentially different from those of ground robots. It needs solid lubrication, which solves the problem of metal cold welding under high vacuum condition. Because of the microgravity environment in space, the dynamic equation of the manipulator is very different from that on the ground, so the space robot is a special robot.
It is worth mentioning that the space robot selected to work in space must be small, light and flexible besides being able to adapt to the space environment. High intelligence, full function and multi-arm; Micro power consumption, long life and high reliability. 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 are the main tasks of space robots, especially in the initial stage of space construction. Some large structural parts, such as the installation of radio antennas and solar panels, and the assembly of large trusses and cabins, are inseparable from space robots. Space robots will undertake a series of tasks, such as the handling of large parts, the connection and fastening between parts, and the disposal of toxic or dangerous goods. It is estimated that more than half of the tasks of space architecture will fall on robots that can carry out extravehicular activities. Extravehicular robot is characterized by advanced remote control device on its end manipulator, which can work with multiple arms, and is equipped with tool rack and supply tray. On-site computers and expert systems give work instructions and complete various construction tasks.
With the deepening of space activities, there will be more and more human property in space. Many countries in the world have launched many spacecraft into space, of which artificial earth satellites account for about 90%. Once these satellites fail, it is not economical to abandon them and launch new satellites. Secondly, it increases space junk, so we must try to repair it. The space robot will take the failed satellite back from orbit, take it to the space station for repair, and then put the repaired satellite back into space orbit with an auxiliary rocket or an orbiting mobile aircraft. If some spacecraft can't be brought back to the space station for maintenance, most of them use intelligent robots to perform tasks in free aircraft, disassemble some parts, or cut welded parts. In fact, there are many spacecraft, in order to prolong their working life, they need to constantly replenish the consumed materials, such as photographic film, nitrogen, fuel, coolant and so on. Among these materials, some are toxic, some are highly corrosive, and some are frozen at low temperature, which is difficult to handle under weightlessness. Sending an extravehicular service robot to perform these tasks is both economical and safe, which can be described as the best of both worlds. The extravehicular service robot carries an omni-directional antenna to keep communication with the space station. In addition, it is equipped with lidar and color stereo vision system for navigation and identification of targets. Moreover, the fingers of the robot are equipped with tactile sensors, sliding sensors and proximity sensors, and the wrists are equipped with powerful sensors, which increases the flexibility and accuracy of operation. Tools and components needed for work can be carried with you. If necessary, you can fly away from the space station by jet pack and perform various tasks.
The robots in the cabin mainly serve the scientific load, so there are many varieties to choose from according to the requirements of the experiment. They not only perform emergency and emergency repair tasks, but also perform a series of tasks such as adding reactants, harvesting products, intermediate sampling and analysis, and collecting various samples. The existence of the robot in the cabin greatly reduces the labor intensity and tension of the astronauts, and can take part in the work as body double when the astronauts leave the cabin. There is a small in-cabin robot named "Spider King" by scientists, which is connected with the working environment of the robot through eight Kevlar ropes. These Kevlar ropes extend from the corners of Spider King's body to the contacts in the work area. By increasing or decreasing the tension of a specific rope, the robot can move in the whole workshop, and its position accuracy and repetition rate are surprisingly high.
Therefore, whether it is to improve safety, production efficiency and economic benefits, space robots play an inestimable role in the production activities of aerospace science and technology industry. With the deepening of space activities, space robots will surely get new development. 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 great power with a new look!
Learning point
Konstantin Tsiolkovsky
Tsiolkovsky is the founder of modern astronautics. He first demonstrated the possibility of using rockets for interstellar communication, making artificial earth satellites and near-earth orbit stations, pointed out reasonable ways to develop space flight and make 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 in the cradle forever."