Reborn Technology Scholar

Unknowingly, Qin Yuanqing was already starting the calculation workload from the lunar orbit to the soft landing.

First, there is the main deceleration section of the first stage.

Based on the configuration characteristics of Chang'e-4 in the data, Qin Yuanqing established a working model of the small lunar probe's navigation, guidance and control system and a center of mass and attitude dynamics model. The model considered the thrust eccentricity and deflection of each engine.

The impact produced by the system 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 terminal horizontal speed constraint was studied.

By using the corresponding relationship between the orbit parameters of the Kepler orbit and the terminal motion parameters, the terminal motion parameter constraints are converted into orbit parameter constraints, thereby converting the trajectory planning problem into a limited thrust orbit change problem, and then the guidance law is obtained through the least squares correction method

.

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

Subsequently, the dynamic equations in the guidance inertial polar coordinate system are established, the target constraint is used as the state quantity, and the values ​​of some parameters can be easily obtained using the pseudospectral method.

On this basis, for a given engine configuration, the value range of the main deceleration section range was studied, and the orbit characteristics within this range were studied. Quaternions were used as parameters, and deviation quaternions were introduced to construct quasi-Eulerian

The angle is used to eliminate the dual value of the target attitude, and the attitude control is designed using the time optimal control of the perturbation double integral system, trying to obtain an optimal control solution.

The entire process was error-free. In fact, when he learned that Chang'e-3 used the model built by Qin Yuanqing on Chang'e-2, Qin Yuanqing himself broke out in a cold sweat, because the model he made originally was based on Chang'e-2.

Chang'e-2 and the specially built model of the rocket are optimal. However, Chang'e-3 has changed compared to Chang'e-2. In other words, the optimal plan for Chang'e-2 does not mean that it is

As for the optimal plan of Chang'e-3, it can be said that the complete success of Chang'e-3 was really due to luck. However, Qin Yuanqing estimated that the original landing location of Chang'e-3 was definitely quite different from the calculated value.

This time Chang'e-4 has to log in from the back, which is similar in theory, but in practice the difficulty is much higher. One of the problems is the signal problem!

On the far side of the moon, wireless signals from the earth cannot be received.

Of course, China Aerospace Engineering also has a corresponding plan for this. It plans to launch a relay satellite for the Chang'e-4 lunar probe, which is the 'Queqiao'. According to the plan, the relay satellite will be allowed to be at the Earth-Moon gravitational balance point l2.

, is scheduled to be launched on May 21.

The role of the 'Queqiao' is to maintain communication between the Earth Control Center and the Chang'e-4 probe.

Of course, because the distance between the earth and the moon is relatively far, there is a certain delay problem in communication. This means that during the landing stage of the Chang'e-4 detector, the technicians at the Earth Control Center were unable to control the detector according to the implementation situation.

Landing track. This is completely equivalent to a blind landing, so the technical difficulty is more than one level higher than the landing process that can be controlled in real time.

Qin Yuanqing's calculation work is to control every parameter to be extremely precise. In daily life, it is customary to maintain 2 digits after the decimal point. This does not apply in aerospace engineering. Aerospace engineering pays attention to extremely accurate, so Qin Yuanqing is

Keep the number after the decimal point to 10 digits to minimize the error.

Sometimes I have to say that mathematics is the most rigorous of all sciences, and mathematicians are a group of idealists who pursue perfection.

As for the landing site on the far side of the moon, Qin Yuanqing chose the Spa Basin. The Spa Basin is the largest and oldest crater on the moon, with a diameter of up to 2,500 kilometers.

At the same time, the spa basin is 13 kilometers deep and is the deepest impact basin on the moon. This means that the impact event that year is likely to dig out materials from the depths of the lunar crust and even the lunar mantle. These may become the basis for humans to study the internal composition of the moon.

key".

Once the Chang'e-4 probe makes discoveries in this area, it may further promote China's progress in completely conquering the moon!

Completion of the computational workload is the first step, and the second step is to build a complete model for supercomputer simulation.

If it is other mathematicians, they may only be able to complete the calculation part, and the model must be completed by other professionals, but Qin Yuanqing does not need it. He is also an expert in this aspect. This avoids the difficulty between different people in understanding what the other party needs.

caused by human error.

After Qin Yuanqing completed all his work, it was already a week later. Qin Yuanqing stood up, stretched and yawned. After arriving at the secret base, his working hours were considered short, including 16 hours a day. Sometimes

Even working 24 hours a day.

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

"Fortunately, everything is done!" Qin Yuanqing handed the data disk to Academician Ouyang: "Then the supercomputer simulation will be left to you. I'm going to take a nap, I'm so sleepy!"

He stayed up all night last night and was so immersed in work that he didn't feel it yet. Now that work was over, Qin Yuanqing felt tired and sleepy. What he wanted to do most was to have a good sleep.

Not to mention that Qin Yuanqing went to his room to sleep, but after Academician Ouyang got the data disk, he immediately arranged for a supercomputer simulation. As an aerospace engineer, he has a supercomputer dedicated to aerospace engineering.

What made Academician Ouyang extremely happy was that there were no accidents in the entire simulation process. On the big screen, it can be clearly seen that the Chang'e-4 probe was launched into space with the rocket, then entered the predetermined orbit, and then orbited the earth.

After the flight, it entered the earth-moon orbit, and then changed its orbit and was captured by the moon. It flew around the moon on the set orbit, and then changed its orbit and entered the moon landing orbit. Then it continued to perform variable speed control. The Chang'e-4 probe finally landed steadily.

Predetermined landing point in the spa basin.

After several consecutive supercomputing simulations, they all landed in the spa basin, and the location was exactly the same.

"Sure enough, asking Academician Qin to come over for help is the wisest choice. Academician Qin solved the problem that our team has not been able to solve in a week!" Academician Ouyang muttered to himself.

In fact, before inviting Qin Yuanqing to help, their team naturally conducted calculations and supercomputer simulations, but the results were not satisfactory.

It is also true that after more than a year of ups and downs, satisfactory results have not been obtained. Academician Ouyang simply applied to his superiors and invited Qin Yuanqing to help solve this problem.

"Academician Ouyang, you see, including the orbit around the moon, the migration of the earth-moon orbit, the orbit around the moon, and the landing point are quite different from our original ones..." A middle-aged scientist hesitated: "Is it possible?

Would it be inappropriate?”

"If there's 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 abilities. What's more, Qin Yuanqing has made rapid academic progress in recent years, gained worldwide recognition, and established his academic status early.

For Academician Ouyang, all he had to do was believe in Qin Yuanqing.

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

As for inputting the parameters into the original model, the results were different. Academician Ouyang didn't care at all. After all, that model was developed by Qin Yuanqing a few years ago, and it was for Chang'e 2. But now, after so many years, the situation has changed.

, should we use new things to adapt to the old rules?

There is no such truth.

"You should study hard during this period to study why this is like this. People, you must remember to live and learn, and never rest on your laurels!" Academician Ouyang said seriously.

The rest of the team couldn't help but look ashamed when they heard Academician Ouyang's words.

"In the field of aerospace engineering, we are still far behind the United States. We must not be complacent and complacent just because we have achieved some results. This is unacceptable. We are not trying to compare with others, we are trying to constantly surpass ourselves.

You are comparing yourself with yourself!" Academician Ouyang said: "I am already over 70 years old, and I am no longer motivated. Our Chinese aerospace project still has to rely 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 become proud and complacent, thus clinging to their own selves.

Qin Yuanqing woke up and slept for 12 hours. When he woke up, he realized that he had just completed the supercomputing simulation. There were no problems in the supercomputing simulation. The results of several supercomputing simulations were consistent.

Qin Yuanqing smiled, all this was as expected, so Qin Yuanqing said goodbye and left. Of course, when Chang'e 4 was launched, Qin Yuanqing had to participate, but this was to prevent some accidents so that they could be repaired in time.

But at that time, Qin Yuanqing could just be directly at the command center.

Academician Ouyang personally escorted Qin Yuanqing out of the base gate and returned to Shuimu from the secret base. Special departments used special vehicles to escort Qin Yuanqing back.

Although he slept for 12 hours, Qin Yuanqing's energy was not very good. After a week of high-intensity work, which was extremely mentally demanding, once it was over, his whole body relaxed and his mental state was not shaken.

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

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