China News Service, Beijing, March 29th (Ma Shuaisha, Zheng Yingying, Chen Baojuan) On March 29th, the Long March 6 Modified (hereinafter referred to as "Chang 6 Modified") carrier rocket successfully made its first flight at the Taiyuan Satellite Launch Center. China's Long March series of carrier rockets The addition of a new member to the family has also successfully filled the gap in the field of solid-liquid joint control of domestic launch vehicles.
As China's first solid-bundled launch vehicle, the Chang-6-modified rocket is a new generation of non-toxic and pollution-free medium-sized launch vehicles using "solid booster + liquid core stage". The four strong and powerful solid boosters are different from The biggest feature of the active launch vehicle is that the electric servo system, as the supporting execution subsystem of the booster solid motor, is a key part of the attitude and orbit control of the launch vehicle.
launch site.
Photo courtesy of Zheng Bin
Triple jump from "bare arrow" to "hard and soft"
Zhou Jing, head of the control system for the Eighth Changzheng No. 6 modification of the China Aerospace Science and Technology Corporation, said that the launch vehicles currently in service in the Eighth Institute are of single-core stage configuration. The institute's first rocket with core-level bundled 4 boosters is also the first solid-liquid hybrid rocket in China. It has achieved from single-core stage to core-level booster binding, and then to liquid core-level solid booster at one time. Mixed bundle of triple jumps.
As China's first "hybrid" new-generation Long March series of launch vehicles, the Chang-6-modified rocket takes full advantage of the comprehensive advantages of high liquid engine performance, long working hours and solid engine thrust, reliable operation, and simple use and maintenance.
Zhou Jing said that the four solid boosters provided nearly 70% of the thrust for the entire rocket, making the Changliuqi rocket more able to carry and fly higher.
"As a control system development unit, our mission is to make the rocket have a smarter and more robust 'brain', so that the Chang-6 rocket can fly more stably and 'deliver' the satellite to the predetermined orbit more accurately."
launch site.
Photo courtesy of Zheng Bin
Cross-border mix and match "sailor group" to ensure the smooth flight of the rocket
The rocket flies in the air, like a giant ship swimming in the ocean. The control system is the helmsman, directing the navigation track, the engine is the sail, providing forward power, and the servo system is the sailor, who obeys the helmsman to pull the sail to change the sailing direction.
For the Chang-6 modified rocket, an extremely strong "sailor group" is needed to promote its own solid engine flexible nozzle. The electric servo system has the inherent advantages of simple structure, low development cost, high reliability, and convenient maintenance as a booster. The first choice for solid motor actuators.
"The solid engine has a large thrust, but it has the problem of unstable thrust throughout the entire process, unlike the liquid engine that can continuously output a smooth straight line." said Hu Cunming, deputy director of the control system for the Eighth Long March No. 6 reform of China Aerospace Science and Technology Corporation, " Moreover, the solid boosters bundled in the four directions of the rocket cannot be completely 'in step' after ignition, some are impatient, and some are slightly slower, which will generate a certain turning moment on the rocket."
To this end, the control system development team innovatively adopted the three-channel joint swing control scheme of the solid bundled rocket, and firmly "handled" the cross-border mix and match combination of "liquid oxygen kerosene engine + hydraulic servo mechanism" and "solid engine + electric servo mechanism" , to ensure the smooth flight of the rocket.
Self-diagnosis and repair to realize intelligent rocket flight
For the servo system that plays a key role in attitude adjustment during rocket flight, the research team also proposed and applied online fault diagnosis and adaptive reconstruction technology for the first time in China.
According to Hu Cunming, in the past, developers would list the possible failure modes of the servo system one by one, formulate a control strategy, and pre-install it into the flight software.
"But for the Chang-6 modified rocket, there are as many as 12 servos, and there are as many as 18 failure modes for a single servo, so we have to 'teach' it how to self-diagnose and repair itself online, and use intelligent control methods to make Intelligent rocket flight." Hu Cunming said.
During the flight, when a servo mechanism fails, the control system will recalculate and assign instructions according to the results of self-diagnosis to ensure that the resultant control force remains unchanged.
Zhang Fei, deputy chief designer of the control system of China Aerospace Science and Technology Corporation's eighth-long March 6 modification control system, said, "To be neither 'missed diagnosis' nor 'misdiagnosed', this is not only related to flight stability, but also to the booster's performance. Separate security and drop point control.”
Let the "big head" and "tall" rockets fly in the wind
In addition, the Chang-6 modified rocket is as high as 50 meters, and the diameter of the fairing is 4.2 meters.
Wang Peng, deputy chief designer of the control system for the Eighth Long March No. 6 modification of China Aerospace Science and Technology Corporation, pointed out that this means that the structural strength of the secondary rocket body is relatively weak, and the interference of aerodynamic loads will be more obvious, that is, the influence of high-altitude wind .
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"For example, when we cross the bridge at high speed, we will obviously feel the effect of the side wind on the car. The higher the speed, the easier it is to blow the car away from the lane. It is best to adjust the direction and drive against the wind. The same is true for rockets. ." Wang Peng said.
In this regard, the control system team adopted the accelerometer-based active load shedding control technology to reduce the aerodynamic load acting on the rocket body, so that the rocket can flexibly adjust its attitude, fly against the airflow, reduce the impact of high-altitude wind on the launch, and better Adapt to fast, high-density launch requirements.
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