"What?" Not only Xu Qianqian, but Huang Ligong also had some doubts. Is Liu Ruiyang joking?

Liu Ruiyang nodded seriously, "I've been analyzing for a long time, and the problem should lie in rounding, resulting in cumulative errors." ”

"The most basic things are the most important." Xu Qianqian gave full play to the sense of smell of future investors, although she was still confused about the principle, but she captured the external reality meaning for the first time.

For her sensitivity, Liu Ruiyang smiled in return, and Huang Ligong snorted in his nose. Cumulative error is a common problem in industrial production, from college to entrepreneurship, Huang Ligong has experienced a lot, there are various causes, but the cumulative error caused by rounding is one of the most hidden, he has never heard of it before.

It's the stuff that this elementary school student can do, tossing such a big movement. There are very few real-world numerical relationships that are exactly divisible; Unfortunately, modern computer systems, although at least millions to hundreds of millions of times faster than the human brain, are essentially the same as the human brain, and are only good at integer operations, so almost every operation needs to be rounded, which means that almost every calculation will have errors. It's not so friendly to algorithmic models that require a lot of iterations.

"Iteration?"

"To put it simply, an operation is performed repeatedly, but the result of each operation is used as the starting point for the next operation. It's like the compound interest of the bank, as the saying goes. At this time, the error is not only inherited, but also amplified. Well, if it's not easy to understand, you just think so, no matter how small the number is, if you count it many times, will it become big in the end? ”

"I know, just like I dreamed when I was a child, if the people of the whole country gave me a penny each, and they didn't lose anything, I would immediately become a multi-millionaire!"

"It seems that children all over the country have fantasized about this. So did when I was a kid. Liu Ruiyang couldn't help laughing, turned his head and asked Huang Ligong, "Lao Huang, don't tell me, you haven't thought about it." ”

Huang Ligong snorted, "Childish, I have collected money, why do I only collect a penny, I want everyone in the country to give me a dollar, and become a billionaire in one step." ”

The three of them laughed, dispelling a little of the gloomy atmosphere.

Xu Qianqian suddenly remembered, "I used to read a Japanese mystery novel, there was a person who worked in a bank and knew that every account had to be rounded, so he ......" She struggled to recall, "Transfer the money that was supposed to be given up to your own account." Yes, transfer the odds you want to erase to your account. He has a lot of money in his account, but in other people's accounts, the accounts are still flat. ”

Liu Ruiyang nodded, in the banking and financial system, this is a common type of attack. In fact, the cause of rounding up is not only here, but there have also been accidents in the military field. A famous accident occurred during the Gulf War when the Patriot missile intercepted the Scud missile.

"Patriot?! Scud?! Huang Ligong hadn't heard the name he was so familiar with when he was a child for many years, and he suddenly felt a little warm. At that time, he and Liu Ruiyang were still in elementary school, and on the way to and from school every day, he danced and described to Liu Ruiyang the images of missile launches and bombings he had seen on television the day before.

Liu Ruiyang also had a warm smile on his face, and now it is my turn to tell you the story of the Patriot missile, although it is more than 20 years late. During the Gulf War, the Patriot missile intercepted a number of Scud missiles, but one of them accidentally missed. The missile hit a U.S. military camp in Saudi Arabia, killing 28 people and injuring more than 100, making it the heaviest casualty of the U.S. military in the Gulf War. After analyzing the cause, it was found that the problem was rounding. The calculation accuracy of the Patriot missile system is 24 bits, and the error caused by rounding can be controlled to less than 1 in 10,000 per second, but at that time, the missile battalion worked continuously for four days, close to 100 hours, and by the time of interception, it had accumulated an error of 0.34 seconds.

"It doesn't sound big, but the speed at which the Patriot missile flies at full speed is 6 speeds of sound, 6 340 meters, and a third of a second is 2 speeds of sound, 680 meters, an area the size of a half-playground, and to stop a 20-meter missile is tantamount to looking for a needle in a haystack."

Xu Qianqian completely understood, she stretched out her thumb and index finger and gestured, "As long as our robot accumulates, well, an error of more than ten centimeters, it will indeed smash the photovoltaic glass." The desperate look of the robotic arm smashing resolutely and forcefully into the recovery panel flashed in front of her eyes, and she couldn't help but shiver.

"No, a few centimeters is enough. All indicators are accumulating errors, and together they are exponential......"

"Didn't notice it before?" Huang Ligong asked.

Liu Ruiyang shook his head. He and his team have never had this problem. There was no sign at all. In the subdivision of photovoltaic cleaning, the cumulative error can be said to be a deep-water problem, and it will only emerge if it is more extreme. There are no such conditions in the desert of China, where they are commissioning, but in the desert of India, it is all encountered.

"There are two main situations, which are very small to say. The first is to enter the sand, which will affect the precise measurement and action, and the bearing is worn badly, which makes it worse......"

Speaking of this, Liu Ruiyang couldn't help frowning, the bearing was worn too much. He went on to say, "The question of the level of sealing. I guess it's because the sand in India is too fine, probably an old desert, much finer than in China. I have asked them to bring samples and return home for testing.

The second situation is strange, judging from the actual data, the sensors, control systems are under great pressure, even if it is a very ordinary routine operation, they are close to full load. For example, you need to constantly correct the positioning, distance, and various calculations, usually run three times, but now you have to run thirty times, and the accuracy has dropped significantly, and the problem of cumulative error is easy to amplify and explode. It's hard to know for sure, but I wonder if it's electromagnetic interference. This mistake should not be ......."

Liu Ruiyang shook his head heavily, a little frustrated.

"How?"

"I was negligent, the photovoltaic power station itself is a large magnetic field, and electromagnetic interference is inevitable." In fact, when the Kunpeng robot started testing, it encountered similar problems, and the sensors sometimes failed. Due to the occasional occurrence and the slight interference effect, he and his team did not dig into the root of the problem, but adopted an empirical solution, tried different sensors, and quickly determined a one with better practical effect and solved the problem. But this time it was very different, not only the sensors, but also the control system was affected, and almost all the exponents were accumulating errors at a rapid pace. Perhaps India's photovoltaic power plants are different from those in China, and there are unusual places. This will have to go back and analyze the detailed technical data to be sure. ”

"Is it hard to solve? …… Algorithms need to be moved? Huang Ligong decided to go straight in. He knows Liu Ruiyang. Liu Ruiyang is not a person who has a good face and taboos about problems, but since he entered the warehouse, Liu Ruiyang has been looking solemn and thinking very distressedly. Could it be that the problem is too tricky, and even the original algorithm model and even the robot design scheme have to be reversed?

"No, I don't." Liu Ruiyang is very sure, "If it weren't for the bidding, I would have felt that this accident was a good thing." The first is that I found a deep bug, and the second is that it stimulates me to find a better optimization solution, which is not difficult, but can make our robot self-detect and self-adjust, and be more intelligent. ”

"And ...... with your sad face?" Huang Ligong was a little irritable.