appConfigEntityId

bodyType

customContents

entityId

entityUuid

isVideo

articlePageQuery

article

articleSchemaContent

content

hooksArticlePageAdvertisementConfigArticle

hooksArticlePageFloatingButtonConfigArticle

appConfig

filter

json

liveArticle

Stephen Chen

A rail system that accelerates heavy objects faster than the speed of sound using pure electromagnetic force has been operating in the eastern Chinese city of Jinan for more than two years.
But one of the biggest mysteries remains: how does it stay in control?
The sonic boom the system generates at ground level could blind or wreck traditional sensors, while the slightest miscalculation due to missing data could mean disaster at supersonic speeds.
The system, known as the electromagnetic sledge, made headlines in 2023 when it became the first large-scale electromagnetic launcher to break the sound barrier, accelerating one-tonne test vehicles beyond Mach 1.
In a peer-reviewed paper published this month, Xu Fei and his colleagues at the Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology said the experience was like driving a car blindfolded at more than 1,200km/h (746mph).


“When linear induction motors operate at supersonic speeds – around 340 metres (1,120 feet) per second – at altitudes below 100 metres and temperatures below 30 degrees Celsius (86 Fahrenheit), unsteady aerodynamic forces caused by shock waves can create severe disturbances to the mover,” they wrote.
“This disruption can interfere with speed and position sensing devices, ultimately causing failures in motor speed control,” the researchers added in the paper, which appeared in the Transactions of China Electrotechnical Society journal.
Other countries, including the United States and the former Soviet Union, tried to solve the problem for decades but were unsuccessful. The electromagnetic launch system on a US aircraft carrier, for comparison, delivers a top speed of around 78 metres per second.
Common wisdom held that the way to solve this problem was to add new hardware. But these external sensors – and their signals – proved to be fragile.
Xu’s team took a different approach and taught the system to “listen” to the pulse of its own power supply instead.
The Chinese scientists’ innovation was a sensorless speed estimation method that extracted velocity data from tiny, fleeting changes in voltage across multiple segments of the rail.
As the sledge moved along the track, it passed over segmented electromagnetic coils, each powered in sequence, according to the paper. The way the voltage changed in these coils contained hidden clues about speed, the researchers wrote.
The team developed an algorithm that fused data from several adjacent segments, cancelling out noise and distortion and dynamically recalibrating itself in real time.
The algorithm then combined two independent speed estimates from different electrical axes and intelligently weighted them, giving the most reliable result possible, the paper said.
The result was a speed tracking accuracy of within 1.1 per cent in real-life experiments conducted at up to 370 metres per second – good enough for stable operation at supersonic speeds, the researchers found.
According to the paper, the only pitfall identified was that the method failed when the sledge was gliding at extreme speed after the power input was cut off. “This will be the next step of our study,” the researchers wrote.
Xu and colleagues are also with the Chinese Academy of Sciences’ Institute of Electrical Engineering, which said the facility was now serving China’s push into hypersonic flight, advanced materials and next-generation space launch systems.
Passionate about science? Dive deeper with the Dark Matters newsletter, a weekly in-depth analysis on China’s rise in science, technology and military that goes beneath the surface. Sign up for free now.


China gets closer to Jupiter mission by bringing Nasa’s StarNAV concept to life

Some of China’s 11,000 mega bridges could be at risk from small drones: study

China tests first practical submarine solar power plant at 10-metre depth in the open sea

Rare earth exposure can triple low birthweight risk: Chinese study

Science

Flying blind at Mach 1: how China is bringing world’s first supersonic rail to life

A team of scientists in China has likened the experience of breaking the sound barrier with the large-scale electromagnetic rail system to driving blindfolded at more than 1,200km/h. Photo: CCTV

Could flying wind farms be the future of energy generation in China?

The airship was tested in the skies above Sichuan. Photo: Weibo/ 爱信阳

The airship is tethered to the ground by a cable that transmits electricity. Photo: Weibo/ 爱信阳

China’s Shenzhou-20 spacecraft returns to Earth broken and unbroken

The uncrewed Shenzhou-20 spacecraft after touchdown at the Dongfeng landing site on Monday. Photo: Xinhua

The uncrewed Shenzhou-22 pictured before docking with the Tiangong space station last November. Photo: China Manned Space Agency

Could China’s Yaogan-47 satellite have a lens as wide as the Hubble Telescope?

The Yaogan-47 satellite was launched aboard a Long March 4B carrier rocket from the Jiuquan Satellite Launch Centre on December 9. Photo: Xinhua

One of China’s latest Earth observation satellites operating in low orbit, the Yaogan-47 satellite, could have a lens as wide as the Hubble Telescope. Photo: Xinhua

How can China help Uruguay battle beetles threatening to invade South America?

Authorities in Uruguay are battling the red palm weevil, an insect that devours native palm trees. Photo: AP

This tiny but destructive beetle is threatening Uruguay’s native and beloved palm trees. Photo: Getty

News

China

Peer-reviewed paper sheds light on Chinese research team’s sonic breakthrough, achieved by ‘listening’ to system’s power supply


Peer-reviewed paper sheds light on Chinese research team’s sonic breakthrough, achieved by ‘listening’ to system’s power supply.


Xue Fei

Flying blind at Mach 1: how China is bringing world’s first supersonic rail to life

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}Peer-reviewed paper sheds light on Chinese research team’s sonic breakthrough, achieved by ‘listening’ to system’s power supply

Peer-reviewed paper sheds light on Chinese research team’s sonic breakthrough, achieved by ‘listening’ to system’s power supply