What did nanoscientists do in track cycling to break the 0.0001-second limit, to make the race fairer?
On July 21, 2024, Zhang Ting, a distinguished guest researcher of the Institute of Sports Science of the General Administration of Sport of China and a member of the Suzhou Institute of Nanotechnology of the Chinese Academy of Sciences, delivered a speech "0.001 Seconds of Limit Breakthrough" at the theme field of "Science Eyes on the Olympics" at the Science Popularization China Star Forum.
The following is an excerpt from Zhang Ting's speech:
Hello everyone, I'm Ting Zhang, from the Suzhou Institute of Nanotechnology and Nanobionics, Chinese Academy of Sciences.
My research direction is intelligent micro-nano sensing materials and devices, which is simply to use nano materials and structures to develop high-sensitivity, fast-response intelligent sensor devices.
So, how did our sensors spark with the Olympics?
In the modern Olympic arena, every millisecond or even every microsecond counts. This is especially true in track cycling, where today's track bikes can reach speeds of more than 20 meters per second, and the difference between the top riders is often milliseconds.
For example, in the 2016 women's track cycling women's individual sprint final at the Rio Olympics, Germany won the gold medal by 0.004 seconds. Therefore, in the Olympic arena, every thousandth of a second is extremely important.
We have a slogan: "For thousandths of a second, everything is possible." "We just hope to use the power of science and technology, with the help of interdisciplinarity, to break through the limit of 0.001 seconds.
A high-precision timing system is necessary
For track cycling competitions, a high-precision timing system is essential.
At present, there are two sets of Olympic-approved timing systems in the world, both of which are monopolized by foreign companies. Due to the design of foreign timing systems for events, the price is very expensive, up to more than 2 million yuan per set, and the operation requires the cooperation of multiple people, and the current function can not meet the personalized needs of coaches and trainers. At the same time, our national team still stays in the method of manual pinching or video analysis, which is not only low in accuracy, but also time-consuming and laborious, and the feedback speed is slow.
How does a high-precision timing system work? It is a pressure detection belt installed in the track, and when the bicycle passes through the detection belt, an electrical signal is generated, which is received and processed by the tracking box, and the timing is realized. This type of system is not only expensive, but also has significant drawbacks.
For example, the pressure detection belt is currently used in foreign countries to use two layers of arc-shaped copper sheets to achieve pressure detection of bicycles through contact and separation. This leads to two crucial questions:
One is the material, because when the bicycle passes through the detection belt at high speed, the two layers of copper will collide and produce strong static electricity, which will affect the system and may lead to inaccurate signal monitoring;
The second key problem is that the two layers of arc-shaped copper sheets will make the pressure detection belt thicker, just like driving through the speed bump will be bumpy, in the race, the bicycle will also bring a short impact when passing through the raised detection belt at high speed, causing the bicycle to slow down, which may bring great safety hazards, increase the risk of falling or injury to the player, and is also very unfavorable to the racing competition.
Therefore, we urgently need to develop a more advanced high-precision timing system with independent intellectual property rights to achieve localized substitution, which is of great significance for improving the core competitiveness of mainland track cycling.
To achieve this goal, the key is to break through the independent development of the core sensing elements of high-precision timing systems, including high-performance pressure detection belts, tracking boxes, start-up consoles and software systems.
What do you do to achieve your goals?
In order to develop more advanced pressure detection bands, we have innovatively used nanotechnology to design carbon nanotube composites that are very sensitive to pressure.
Carbon nanotubes are a very unique conductive nanomaterial that is 10,000 times thinner than a human hair and 100 times stronger than steel, just enough to solve the problem of excessive pressure bands.
The next step is to solve the problem of accuracy.
Our team came up with a lot of ways to do this, and in the end, it was the game stick that brought us a lot of joy when we were children that inspired us. Scattered game sticks can overlap each other to form a network, and as you can imagine, if the carbon nanotubes are also overlapped in this way, forming such a network, provoking any one of them could significantly affect the performance of the entire network.
The exquisite material composite process makes the conductive carbon nanotube nanotubes and nanomaterials scattered with each other and intertwined into a network, and when the bicycle wheel is quickly pressed over, tens of millions of carbon nanotubes will undergo morphological changes and changes in electrical properties between the square inches under the wheels, so that the conductive network will fluctuate quickly and significantly. In this way, we can accurately record the moment the bicycle comes into contact with the detection belt.
Carbon nanotubes are made into conductive ink
With this design principle, the next step is to achieve highly sensitive and flexible pressure sensing tape devices and batch production through trial and error, which is also one of the core challenges. To do this, we need to iterate over a long period of time, trial and error, and iteration.
First of all, we disperse the carbon nanotubes in the reagent to make a homogeneous composite conductive ink, which has the advantages of good uniformity and controllable fluidity, and can be printed on many flexible substrate materials by printing or 3D printing.
Then, by continuously optimizing the printing process and controlling the physical and chemical properties of the flexible substrate material, we make the flexible substrate have a very strong adhesion to the carbon nanotube composite film, so as to increase the stability of the device, so that the sensitive material will not fall off the upper surface of the flexible substrate during bending and use. The result is a new flexible pressure sensor that is thin and flexible.
It's only 0.3 mm thick, which is as thin as a piece of paper. Therefore, when the wheel is pressed over quickly, the accuracy of the detection can be well improved, and it will not cause the bicycle to slow down, which also greatly improves safety. At present, our flexible pressure detection belt can be up to 8 meters long and can withstand more than 1 million cycles of repeated cycling at 90 kilometers per hour.
On this basis, we further overcome the problems of batch integration molding of flexible pressure sensors, and then through flexible packaging and interface design, we finally realized the batch preparation of high-precision flexible pressure detection belts for track bicycle tracking and timing.
At this point, we have completed the first step in the development of a high-precision timing system.
Next, we will carry out a distributed layout of this kind of flexible pressure detection belt that is the first in the world to be distributed on the track cycling track in the training venue in Beijing, with more than 7 of them.
The counting error is controlled within 1/10,000th of a second
The second step of our research work was to transmit and process the signals detected by these flexible pressure detection bands quickly and synchronously, which was also a challenge.
To this end, we have cooperated with the team of Professor Zhong Daidi and Professor Huang Zhiyong of Chongqing University to establish a distributed time synchronization network to control the entire counting error within one ten-thousandth of a second.
In addition, during high-speed riding, the tire and the floor will be constantly rubbed, a large amount of charge will be accumulated, and a strong discharge of more than 10,000 volts will occur when it comes into contact with the pressure belt, which will greatly affect the accuracy of information collection and the safety of the system.
Therefore, we use a variety of methods such as precision discharge, hardware isolation and software filtering to achieve harmless treatment of some strong interference signals that may be generated by the outside world, so as to ensure the accuracy of data acquisition and the safety of the system.
Precise control of the opening time of the departer gate
Before the start, the track bike is controlled by the starter, and after the countdown time for the start, the timing system opens the starter with a delay of 100 milliseconds, and the athletes react quickly and set off.
This brings us to the third core element of the high-precision timing system: the start-up console.
In this process, the speed of the athlete's reaction is crucial to the performance of the competition. In general, athletes will train repeatedly based on the time the starter is opened, which develops muscle memory.
At the same time, this also requires us to accurately control the opening time of the gate when designing the starter, and the control accuracy must also reach one thousandth of a second, otherwise, it will cause "rushing" early and affect the performance of athletes if it is late.
The opening of the gate is a mechanical movement, and it is very difficult to control the accuracy of the mechanical movement in such a short time. We teamed up with the team from Chongqing University to use high-speed cameras combined with high-precision control algorithms to accurately control the opening time of the gate, and control the error within 1/10,000th of a second.
Based on the above research, we collaborated with multiple groups through interdisciplinary research to achieve a high-precision timing system that broke the 0.001-second limit.
In the future, we will continue to optimize, such as introducing more exquisite micro-nano structures, and further improving the pressure sensing sensitivity of the flexible timing belt by optimizing the mechanical and electrical models, and striving to improve the timing accuracy to the microsecond level.
In fact, these technologies can be applied not only in track cycling, but also in fencing, boxing and other sports events.
At the same time, our flexible intelligent perception technology based on nanotechnology can cooperate more deeply with information collection, transmission and processing systems to achieve the reduction of counting errors. Through intelligent algorithms, multi-technology coupling and grid layout, real-time and accurate perception of bicycle position and speed can be realized, so that track cycling has entered a comprehensive intelligent era and made sports more scientific.
How else can new materials be used to reduce resistance?
In fact, the application of new materials and technologies in the Olympic arena does not stop there.
We are also looking for possibilities to reduce the drag of the bicycle in combination with biomimetic design, and some progress has been made.
Together with the team of Professor Yuan Weizheng and Professor He Yang of Northwestern Polytechnical University, we tested and measured the frame, wheels, handlebars, jerseys, helmets and the riding posture of each rider in the wind tunnel to find out the possibility of reducing drag from these 6 aspects.
We borrowed from the unique tongue-shaped fractal sand ridge structure in the Kumtag Desert in Xinjiang, where the undulation of the sand ridge surface can affect the flow of wind and form a relatively smooth resistance distribution. This distribution allows the wind to maintain a high velocity and flow rate as it passes through the ridges, reducing drag and energy loss.
Based on the inspiration of this bionic design, we designed and manufactured a micro-nano structure drag reduction film that imitates sand ridges for the first time in the world, combined with aerodynamics and other theories, and designed a unique micro-nano structure for bicycle wheel rotators and helmets, achieving a drag reduction rate of 3%.
At the same time, we have teamed up with Professor Su Weifeng from Beijing Normal University-Hong Kong Baptist University United International College to efficiently and intelligently analyze moving images through artificial intelligence methods such as motion estimation intelligent algorithms and computer vision technology, and combined with ground timing bands, to form a multi-dimensional and multi-modal accurate judgment of time and space, which can eliminate misjudgments in millisecond-level competition.
We hope that through the intersection of multiple disciplines, combined with nanotechnology, biomimetic technology and AI technology, we can build the most accurate clock, make the competition fairer, and contribute to the "faster, higher, stronger" of Olympic athletes.
Source: Popular Science China