China’s snake-like robot designed to move or manipulate a large object in space, according to paper

Researchers say their serpentine attachment – with each segment an independent robot – can get into tight corners for in-orbit repairs
The robotic tentacle could crush a small satellite like ‘a python strangles its prey’ but that China does not plan to use it as a weapon, says observer

Science

Stephen Chenin Beijing

Published: 11:00pm, 14 Feb 2022

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A large robotic snake of unprecedented strength, flexibility and lifespan has been built to explore space, the Chinese research team behind the project said amid long-running concerns about China’s potential to damage other nations’ satellites.

The 1.5-metre (5-foot) long robot, which attaches to a spacecraft, consists of nine segments, each capable of generating a torque of 190 Newton-metres – nearly double that produced by a 1,200cc Harley-Davidson Iron motorcycle.

The joints between segments can twist and rotate extensively, allowing the robot to snake through a complex environment to reach a narrow corner of a space station or satellite that is inaccessible to astronauts or robotic arms at present, according to the researchers.

An artist’s impression shows how the robotic arm might work. Its developers say the technology will save China’s space programme money and increase access to tight spots on a space station or satellite. Photo: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences

A damaged or malfunctioning segment of the robot can be removed or replaced with a new one, allowing it to be in service for an unlimited time, in theory.

“Making repairs in a complex space environment costs a great deal of human and material resources. The modular hyper-redundant manipulator is an effective solution to this problem,” said the team led by Professor Xu Zhenbang, of the key laboratory for on-orbit manufacturing and integration for space optics system at Changchun Institute of Optics, Fine Mechanics and Physics in a paper published in the domestic peer-reviewed journal Robot last month.

The robots could also work together as tentacles to move or manipulate a large object, Xu and his colleagues said.

Last month, China’s Shijian 21 satellite pulled a dead BeiDou navigation satellite into a graveyard orbit, according to commercial space monitoring company ExoAnalytic Solutions.

Although details remain classified, the mission suggested China had acquired cutting-edge robotic technology to track, capture and control a non-cooperative target in a weightless environment.

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There are concerns China could use similar technology to disable other countries’ satellites. The US military voiced concerns about China’s anti-satellite capabilities, in particular Shijian 17, an experimental probe with a robotic arm that conducted unusual manoeuvres after its launch in 2016.

The Chinese government has said China’s space robotic technology was developed for peaceful purposes, such as building large-scale infrastructure, serving spacecraft or satellites in orbit and removing space debris.

In a white paper released this month, the China National Space Administration said it planned to turn the clean-up of space junk into a profitable business within five years.

Snake-like robots are already used to inspect undersea cables and other tasks but, because of engineering challenges, there are no reports of their use in space.

In the Chinese machine developed by the Changchun Institute, for instance, each segment is technically an independent robot, each with motors, transmission, a processor and high-precision sensors inside.

The researchers said packing the components into a limited space and under multiple layers of protection was not easy.

Another challenge was to build a joint that was strong as well as flexible. Xu’s team came up with a unique design that could boost the torque of an electric motor more than 3,000 times.

Each segment needed to communicate with other segments, share power and coordinate every movement to complete a task, requiring the help of cutting-edge artificial intelligence technology, according to the researchers.

Xu’s team said they had tested the snake robot in simulated tasks on the ground, including exploring unknown territory. The robot had to identify gaps, enter a narrow space and adjust its body segments quickly to avoid contact with obstacles while moving forward.

Despite its strength, the robot could write letters on a blackboard with chalk or nudge a party balloon safely, the researchers said.

The modular hyper-redundant manipulator developed for China’s space programme moved through obstacles in a ground experiment. Photo: Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences

Xu said they would further improve the robot before it went into space. Some components made of metallic alloy, for instance, would be upgraded to carbon fibre to reduce weight.

The machine has used some electric motors from Switzerland, microprocessors from Texas Instruments in the US and gearboxes from Japan.

The researchers did not say whether these parts would be replaced, but Chinese space authorities usually require critical components to be made in China to reduce security and sanction risks.

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A Beijing-based space scientist said the robot was strong enough to crush a small satellite like “a python strangles its prey”.

But revealing the machine in a publicly accessible journal suggested China had no plan to use it as a weapon, said the researcher who asked not to be named because of the sensitivity of the issue.

The design and specifications of similar technology used in military applications could be quite different, he added.