Why can’t “space hand in hand” not “pass by”

On December 6, the “chang’e-5” ascender successfully rendezvous and docking with the orbiter reentrant assembly, and the lunar sample container was safely transferred to the reentrant. This is the first time that a Chinese spacecraft achieves lunar orbit rendezvous and docking. The reporter learned from China Aerospace Science and Industry Group Co., Ltd. that the “inertial measurement team” composed of high-precision accelerometer combination, quartz flexible accelerometer and I / F conversion circuit developed by the company has provided high-precision acceleration information for “chang’e-5” with stable and reliable performance and stabilized the speed for this rendezvous and docking. In order to realize automatic rendezvous and docking, experts from Aerospace Science and Engineering said: “to achieve automatic rendezvous and docking, it is necessary to use very precise control to ensure that the relative velocity between the orbital return assembly and the lifter is as small as possible, and the acceleration reflects exactly the velocity change. The acceleration of rendezvous and docking is only one tenth of the order of magnitude of the maximum acceleration during the launch of the detector. The combination of high-precision accelerometers can realize the accurate measurement of micro acceleration. ” < / P > < p > in this rendezvous and docking stage, the high-precision accelerometer combination that mainly implements acceleration measurement is the “leader” of this “inertial measurement team”, which is the third time that it accompanies “Chang’e” to the Moon Palace. In order to provide high-precision and reliable measurement performance for “Chang’e”, a unique redundancy design scheme is adopted, and the mission reliability can reach 0.999983. It has helped the “chang’e-3” and “chang’e-4” missions to complete success with perfect performance. < / P > < p > “in this mission, the combination is mainly responsible for the measurement of translational acceleration of the probe in the phases of Earth Moon transfer, lunar orbit flight, lunar orbit rendezvous and docking, and lunar earth transfer, so as to realize the stable and accurate maneuver control of the probe in the process of orbital flight and rendezvous and docking.” Aerospace Science and engineering high precision accelerometer assembly chief designer Yu Huanan said. < / P > < p > for this “long journey”, the R & D team specially added a new component internal shock absorber to the combined product. Since the flight has put forward higher requirements on the anti shock characteristics of the combination, adding internal shock absorber is like adding a group of “cushion” for vibration absorption and isolation. With the blessing of these “cushion”, the accelerometer combination can still work normally in a relatively stable environment even if there is large impact and vibration in the external environment. < / P > < p > however, the design and installation of shock absorbers are not as simple as adding “cushions”. Fu Jibo, a designer, said: “the shock absorber is installed in multiple positions of the combination, just like being cushioned at the four corners of the cabinet. When the shock absorber is impacted, the deformation of each shock absorber is slightly different. If the cushion is not equal to the height, the accelerometer combination will rotate. Even if the rotation is very small, it will also have a great impact on the measurement accuracy.” < / P > < p > in order to eliminate the rotational deformation as much as possible, the team spent more than two months to carry out a large number of impact tests to find out the deformation of the shock absorber in different positions, different impact conditions and different installation methods, and finally controlled the deformation at the angle second level to ensure that the assembly measurement accuracy is not affected. < / P > < p > < p > < p > the quartz flexible accelerometer and I / F conversion circuit in the “team” are a group of “gold partners”. In this mission, the “gold partners” contracted the acceleration measurement tasks in all key stages of the whole journey of “chang’e-5” – not only in the application of high-precision accelerometer combination products, but also in the IMU of landing and rising assembly and reentrant Play a key role. < / P > < p > as the core device of acceleration measurement, this pair of partners can be said to be meritorious instruments. They have helped Shenzhou series of 11 missions and “Tianzhou”, “chang’e-3” and “chang’e-4” missions successively, and the I / F conversion circuit also has high reliability and high-precision measurement signal conversion ability, which is used in the Long March 4, Long March 6 series rockets and the new generation It has been successfully applied in the return module of manned spacecraft test ship. Quartz flexible accelerometer is the key sensor of sensitive acceleration, and I / F conversion circuit can convert the current signal of accelerometer into digital pulse signal suitable for computer processing. Because the tasks in different parts of the detector are different, the research team has equipped the accelerometer with different ranges of I / F conversion circuit. “The process of signal conversion is like weighing the signal with a balance and a weight. If the acceleration changes greatly and the current signal changes greatly, large ‘weights’ should be used.” I / F conversion circuit chief designer Zhao Hongli this analogy. < / P > < p > in the process of rendezvous and docking and orbit control, the acceleration of the orbiter does not change much. The team adopts a small range conversion circuit, which can provide more accurate acceleration measurement information under the same conditions, so as to achieve more accurate speed control of the detector. However, in the lunar landing and reentry phase, if the acceleration changes greatly, the “larger weight” will be adopted A large range conversion circuit, to meet the complete coverage of acceleration information, to ensure that the “Chang’e” flight speed changes in the whole flight. Continue ReadingVideo Number assistant internal test online! Four functions let you send 1g video on the computer