Chapter 659: By mistake

"What's the defect?" Tan Zhenhua asked.
"This defect was actually discovered after I got your work." Lu Hesheng replied in a slightly ridiculous tone, "Although some tricks have been used to solve this problem in your work, but Your solution can only be applied to unmanned and micro-systems, and it is completely undesirable when you want to apply it to high-load systems. Why don't you know?"
Tan Zhenhua touched the back of his head awkwardly and replied with a wry smile: "Old Lu, I have already admitted that the huge improvement from the prototype to the mass production is actually done by Professor Guo Rongwei's team. I also listened to his introduction later. I probably know what has been changed, and I am completely a layman to the aviation industry, please don't sell it, I'm so curious."
Hearing Tan Zhenhua once again admitted his shortcomings, Lu Hesheng finally let him go, and then began to explain: "As I said, in order to realize the stable flight of a statically unstable four-rotor aircraft, it must be equipped with a set of "attitude sensors-flying." Control-power" negative feedback system, and after getting your mass-produced model, out of curiosity, I conducted some tests on the system you used. During the tests, I found some interesting places."
He smiled and glanced at Tan Zhenhua before continuing: "In order to meet the requirements of the CIA, I did some calculations. The calculation results told me that in order to meet the basic control rate of the entire 4-rotor system, the attitude sensor- Flight control-power" negative feedback system must meet some specific conditions, and in these conditions, the most important point is the response time. Simply put, when the quadrotor encounters disturbance and deviates from the equilibrium state, the negative feedback The feedback system must detect the deviation of the aircraft within a short period of time and figure out the "solution" required to restore balance, and then quickly change the speed of each motor to correct the attitude of the aircraft."
"The key point of the problem is a quick word," Lu Hesheng continued in a deep voice: "If the system responds too slowly, then when the flight control solves the "solution" and directs the motor to change the speed, the attitude of the aircraft has already changed. Large changes have caused the previous solution to be outdated, and the aircraft cannot return to balance and enter a state of loss of control. Therefore, for the quadrotor system, the response speed is very important. The response speed depends on the sensor and the flight. The delay of controlling these two purely electronic parts is actually very limited. The main contradiction is concentrated in the two mechanical transmission parts of the motor and the propeller. Due to the existence of inertia and air damping, the speed of the motor increases or decreases relative to the electronic system. Signal transmission is very slow."
"To solve this problem, my initial idea was to use a variable pitch propeller, that is, to change the pitch to change the lift to maintain balance; the advantage of this method is: even if the size and power are further increased, the response The speed can also meet the requirements, and the power-load efficiency will be relatively high. However, the problems caused by this solution are also obvious. The mechanical structure of the entire transmission system is greatly increased, which also brings the reliability of the system. Risks, and the cost will become very high!"
"But when I got your real thing, I found out that you cleverly used a very simple method to solve this problem. By increasing the power of the motor and reducing the inertia and damping of the propeller, you formed a "Malaysia In this state, the power and speed of the motor are actually in the middle state when your quadrotor is in normal flight. This leaves enough reserve power for the entire system. This greatly increases the increase and decrease of the simple power system of motors and propellers. As a result, when the flight controller needs to adjust the attitude of the aircraft, its response time is greatly shortened."
Having said that, Lu Hesheng paused for a moment, and then glanced at Tan Zhenhua with a smile and a smile before continuing: "This method is obviously speculative, because although you do this solves the trouble of response speed, it also brings Another problem: due to the "big horse-drawn trolley" matching pattern, while reserved enough power reserve, it also leads to the power of your quad-rotor system-the load efficiency is very low, because there is a half The power must be reserved to correct the attitude of the aircraft at any time! But I also have to admit that your solution is the most practical for this micro-unmanned system, because it is the cheapest, cheapest and simplest solution Program, although this program cannot be scaled up to apply to heavy loads or even manned aircraft."
Lu Hesheng eloquently said such a big deal, Tan Zhenhua finally figured out why Lu Hesheng attaches so much importance to this toy-like 4-rotor, and solemnly extended an invitation to him to meet him. He also vaguely guessed that Zhan Nuozhu originally said this. There was an uproar in the U.S. aviation industry for small aircraft. The reason why many U.S. arms giants have reported soaring prices-they are used to designing large-scale manned aircraft, of course, they should adopt the most efficient. I never thought that this micro-drone could use its own opportunistic method to achieve its goal!
But to be honest, Tan Zhenhua had to admit that when he made the first prototype, which was called the "Flying Brick" by Wang Zetian, he did not consider this issue at all. He just followed the previous life. I copied what I saw and heard, and then used the materials I could find to restore it as much as possible. I knew it completely but I didn't know the reason. How could I know that there are so many official tricks? As for the later two professors, Song Wenhua and Guo Rongwei, teamed up to change it beyond recognition-well, they must know the origins of it, but Tan Zhenhua did not ask. The two professors probably assumed that since he designed it this way, it must be I knew the reason, so I never told him.
This is really a mistake. Tan Zhenhua thought to himself that if he hadn't visited Lu Hesheng today, he would have been kept in the dark for the rest of his life. If one day he blatantly declared himself to be the inventor of the 4-rotor drone, who would be exposed to the public? It's ugly if you slap your face.
Thinking of this, Tan Zhenhua sincerely said to Lu Hesheng: "Old Lu, thank you for giving me such a lesson. I originally made a small toy, kid, but after being improved by Professor Guo, the kid didn’t have the chance to understand it. The subtlety, if it weren’t for you to teach me today, I wouldn’t know the subtleties at all. I’m so grateful!"
After all, he stood up and bowed respectfully to Lu Hesheng.
Lu Hesheng did not reach out his hand to stop him either. First, because he did spend a lot of words to teach him, and second, because this kid is the love of his baby granddaughter. If he becomes his grandson-in-law in the future, it would be fine to receive him as an elder. inappropriate.
After receiving this ceremony, Lu Hesheng again invited Tan Zhenhua to sit down and continued: "Eric, although you don’t know many of the principles of your system, I must also admit that this aircraft There are many very genius ideas in the overall configuration, such as power and control systems, such as flight control systems, etc. In my opinion, it may be that you don’t understand airplanes, so you can come up with these wild ideas. Like the great aviation explorers at the beginning of this century, they may not be scientists or engineers, but they are passionate explorers. In their ideas, they are not bound by restrictions. It is precisely because of this that they make them. An extraordinary achievement."
Tan Zhenhua said abruptly: "Lady Lu praised me. The kid was just a whim."
Lu Hesheng solemnly said: "Many genius inventions and discoveries often come from a whim, such as Newton and his apple. Well, we will not discuss this topic, Eric, since you invented this 4-rotor drone, What do you think of its future?"
After hearing what Lu Hesheng said, Tan Zhenhua sighed, and finally it was his turn to perform!