Reborn Tech Scholar

Chapter 410 Falling Moon Calculations and Models

Before he knew it, Qin Yuanqing had already begun to calculate the workload from orbit around the moon to soft landing.

First of all, it is the main deceleration section of the first stage.

According to the configuration characteristics of Chang'e-[-] in the data, Qin Yuanqing established the working model of the navigation, guidance and control system and the center of mass and attitude dynamics model of the small lunar probe.In the model, the influence of the thrust eccentricity and deflection of each engine is considered, and the discrete working characteristics of the guidance, navigation and control subsystems are considered.

Then, the guidance law of the main deceleration section under the condition of terminal horizontal velocity constraint is studied.

Using the corresponding relationship between the orbital parameters of the Kepler orbit and the terminal motion parameters, the terminal motion parameter constraints are transformed into orbital parameter constraints, so that the trajectory planning problem is transformed into a limited thrust orbit change problem, and then the guidance law is obtained by the least squares correction method .

Next, the guidance law of the main deceleration section under the terminal height constraint condition is studied.

Then, the dynamic equation in the guidance-inertial polar coordinate system is established, and the target constraint quantity is used as the state quantity, and the values ​​of some parameters can be easily obtained by using the pseudo-spectral method.

On this basis, for a given engine configuration, the value range of the main deceleration range is studied, and the orbital characteristics within this range are studied. The quaternion is used as a parameter, and the deviation quaternion is introduced to construct a quasi-Euler In order to eliminate the binary value of the target attitude, and use the time optimal control of the perturbed double integral system to design the attitude control, try to get an optimal control solution.

Throughout the process, there is no room for error.In fact, knowing that Chang'e-[-] used the model Qin Yuanqing built on Chang'e-[-], Qin Yuanqing broke out in a cold sweat, because the model he made was based on Chang'e-[-] and the rocket. is optimal.However, Chang'e [-] has changed compared to Chang'e [-]. That is to say, the optimal solution of Chang'e [-] does not mean that it is the optimal solution of Chang'e [-]. It can be said that Chang'e [-] has achieved complete success. , There is really an element of luck, but Qin Yuanqing estimates that there is definitely a big deviation between the moon landing location of Chang'e-[-] and the calculated value.

This time, Chang'e-[-] needs to log in on the back, which is similar in theory, but the difficulty in reality is much higher. One of the problems is the signal problem!
On the back of the moon, it is impossible to receive wireless signals from the earth.

Of course, Huaxia Aerospace Engineering also has a corresponding plan for this. It plans to launch a relay satellite of the Chang'e-2 lunar probe, that is, "Queqiao". , which is scheduled to launch on May 5.

The role of 'Magpie Bridge' is to maintain the communication between the Earth Control Center and the Chang'e-[-] probe.

Of course, because the distance between the earth and the moon is relatively long, there is a certain delay in communication.As a result, when the Chang'e-[-] probe landed on the moon, the technicians at the Earth Control Center could not control the probe's landing trajectory according to the actual situation.This is completely equivalent to a blind landing, so the technical difficulty is more difficult than the landing process that can be controlled in real time.

Qin Yuanqing's calculation work is to control every parameter to an extremely precise level.In daily life, it is customary to keep 2 digits after the decimal point, which is not applicable to aerospace engineering, which is extremely accurate, so Qin Yuanqing always keeps 10 digits after the decimal point to reduce the error as much as possible.

Sometimes it has to be said that mathematics is the most rigorous of all sciences, and mathematicians are a group of idealists who pursue perfection.

As for the landing point on the back of the moon, Qin Yuanqing chose the SPA Basin. SPA Basin is the largest and oldest impact crater on the moon, with a diameter of up to 2500 kilometers.

At the same time, the SPA basin is 13 kilometers deep and is the deepest impact basin on the moon, which means that the impact event of that year is likely to dig out the material deep in the moon's crust and even the moon's mantle. key".

Once the Chang'e-[-] probe discovers something in this area, it may be a step closer to China's complete conquest of the moon!
The completion of the computational workload is the first step, and the second step is to build a complete model for supercomputer simulations.

If it is other mathematicians, maybe they can only complete the calculation part, and the model has to be completed by other professionals, but Qin Yuanqing does not need it. He is also an expert in this aspect, which avoids the difficulty of understanding what the other party needs between different people. caused by human error.

After Qin Yuanqing finished all his work, it was already a week later, Qin Yuanqing got up, stretched, and yawned.After coming to the secret base, his working hours are 16 hours a day, which is considered short, and sometimes he even works continuously for 24 hours.

"Academician Qin, how are you?" Academician Ouyang asked.

"Fortunately, everything is finally done!" Qin Yuanqing handed the data disk to Academician Ouyang: "The next supercomputing simulation will be handed over to you, I will go to sleep, I am sleepy!"

He stayed up all night last night and didn't feel it when he was immersed in his work. Now that the work is over, Qin Yuanqing feels tired and sleepy. What he wants to do most is to have a good sleep.

Not to mention that Qin Yuanqing went to sleep in the room, but also that Academician Ouyang arranged for a supercomputing simulation as soon as he got the data disk. As an aerospace engineering, he has a supercomputer dedicated to aerospace engineering.

As a result, Academician Ouyang was extremely pleased that there were no accidents in the whole simulation process.On the big screen, it can be clearly seen that the Chang'e-[-] probe was launched into the sky under the transportation of the rocket, then entered the predetermined orbit, then flew around the earth and entered the earth-moon orbit, and was captured by the moon after the orbit change. Flying around the moon on the set orbit, and then changing orbit to enter the moon landing orbit, and then continuously changing the speed control, the Chang'e-[-] probe finally landed steadily at the scheduled landing point in the SPA Basin.

After several consecutive supercomputing simulations, all of them landed in the SPA Basin, and the location was not bad at all.

"Sure enough, asking Academician Qin to come and help is the most sensible choice. The problem that our team has not solved for a long time, Academician Qin solved it in a week!" Academician Ouyang muttered to himself.

In fact, before inviting Qin Yuanqing to come to help, their team naturally carried out calculations and supercomputing simulations, but the results were not satisfactory.

It is also true that after more than a year of ups and downs, no satisfactory results have been obtained.Academician Ouyang simply applied to his superiors and invited Qin Yuanqing to come and help to solve this problem.

"Academician Ouyang, look, the orbit around the moon, the migration of the orbit around the moon, the orbit around the moon, and the landing point are all quite different from ours." A middle-aged scientist hesitated: "Is there something wrong?"

"If there is anything wrong, just follow Qin Yuanqing's set of parameters and models!" Academician Ouyang said angrily: "You guys, do you still doubt Academician Qin's ability!"

With the last cooperation, Academician Ouyang is very aware of Qin Yuanqing's ability, not to mention that in these years, Qin Yuanqing has made rapid progress in academics, won the recognition of the world, and established his academic status early.

For Academician Ouyang, he just chose to believe in Qin Yuanqing.

Even if Qin Yuanqing's calculation results are different from the supercomputing simulation, Academician Ouyang will undoubtedly choose Qin Yuanqing.What's more, supercomputing simulation is no problem.

As for inputting the parameters into the original model, the results were different, and Academician Ouyang didn't care at all. After all, that model was made by Qin Yuanqing a few years ago, and it was for Chang'e-[-].Now that the situation has changed in the past so many years, is it possible to use new things to adapt to the old rules?
There is no such reason.

"During this period of time, you should study hard and study why this is the case. People, you must remember that you will never rest on your laurels!" Academician Ouyang said earnestly.

The rest of the team couldn't help showing shame when they heard Academician Ouyang's words.

"In the field of aerospace engineering, there is still a big gap between us and the United States. We must not be complacent and complacent just because we have achieved some achievements. It's comparing yourself!" Academician Ouyang said: "I'm over 70 years old, and I'm powerless. Our China Aerospace Engineering depends on you. We must always remember that our goal is not the United States, but the stars and the sea!"

Aerospace engineering is also divided into various fields, and they are only part of the lunar exploration project.

Academician Ouyang does not want to see these young people, proud and complacent, so they stand still.

As soon as Qin Yuanqing woke up, he slept for 12 hours. Only after waking up did he realize that the supercomputing simulation had just been completed. There was no problem with the supercomputing simulation, and the results of several supercomputing simulations were consistent.

Qin Yuanqing smiled, all of this was within his expectations, so Qin Yuanqing left and left. Of course, Qin Yuanqing had to participate in the launch of Chang'e [-]. This was to prevent some accidents so that they could be remedied in time.

But at that time, Qin Yuanqing was directly in the command center.

Academician Ouyang personally sent Qin Yuanqing out of the gate of the base, and returned to Shuimu from the secret base. A special department escorted Qin Yuanqing back with a special car.

Although he slept for 12 hours, Qin Yuanqing's spirit was not very good. After a week of high-intensity work, he still used his brain extremely. Now when it was over, his whole body relaxed and his mind was not shaking.

Qin Yuanqing greeted the office and took a three-day vacation temporarily, which happened to coincide with May Day, so Qin Yuanqing directly rested at home. As for some activities, Xu Jiayi and other vice principals participated.

Qin Yuanqing now just wants to relax himself and be with his children.Taking advantage of the May Day holiday, he took his wife and children back to his hometown. After all, he hasn't been back to his hometown for a long time, and he also misses home.

(End of this chapter)