Torchbearers at the Paralympics and their robotic arms and legs

On the last day of the Beijing Winter Paralympic torch relay, the torchbearers in the morning were a little special. The female torchbearer who was equipped with an upper limb power-assisted exoskeleton was named Peng Yuanyuan, and the torch was tightly held in her mechanical hand; another torchbearer was named Yang Shuting, who stood and walked with the help of a lower limb power-assisted exoskeleton, and the torch was inserted into the mechanical accessory on her waist.

Two female torchbearers passed the torch with the help of exoskeletons｜Oriental IC

According to relevant persons in charge of the event, Peng Yuanyuan underwent nine months of adaptation training with the exoskeleton device in order to achieve autonomous grasping; while Yang Shuting, who suffers from lower limb paraplegia, spent five months "running in" with the lower limb exoskeleton and is now able to walk upright and successfully pass the torch.

These complex mechanical structures have achieved a harmonious "symbiotic" relationship with the torchbearers: these mechanical devices can respond promptly to the actions that they want to do but their physical bodies cannot do, just like a natural extension of human functions.

At the opening ceremony of the 2014 Brazil World Cup, a paralyzed teenager kicked off the match successfully with the help of a brain-controlled exoskeleton.

A paralyzed teenager wearing a brain-controlled exoskeleton kicks off the game with style | Video screenshot

Exoskeletons are nothing new. Humans began exploring the technology in the 1960s.

Wearable Robot

Human skeletons are covered by skin and muscles, which is called endoskeleton; arthropods such as crabs and scorpions have skeletons that are "exposed" on the surface of the body. This segmented and hard outer shell is called exoskeleton. This biological term was later used to refer directly to the mechatronic device installed on the human body.

Simply put, an exoskeleton is a wearable robot that can support and protect the user's body and supplement human functions. It can also "read" their movement intentions through sensors, assist or even amplify the user's movements, thus enhancing human functions.

For example, people who have lost their legs can stand and walk by wearing lower limb exoskeletons; ordinary thin people can carry more weight than weightlifting champions by wearing exoskeletons.

The development of exoskeleton technology began in the 1960s, with the representative project being "Hardiman" supported by the US Department of Defense and implemented by General Electric and Cornell University. They created an exoskeleton prototype to help soldiers lift heavy objects: it can amplify human strength by 25 times, and lifting 110 kilograms is like lifting a large bag of apples.

Hardiman Prototype | Network

The lifting limit of this Hardiman exoskeleton is 682 kg, but its own weight is also 680 kg. It is a full-body exoskeleton with complicated metal joints and 28 links. It is driven by hydraulics and electricity and is equipped with a force feedback sensing system. Such a huge machine can only walk 0.76 meters per second. The response speed cannot be guaranteed. Usually the shoulder joint can move, but the elbow cannot be operated, which is a loss of one thing while taking care of the other. This is a disaster for military scenarios. Many scientific research institutions have realized the limits of current technology and have begun to turn to medical rehabilitation scenarios, such as designing standing exoskeletons for paraplegic patients and developing electric-driven prostheses.

Exoskeletons are not a single technology, but a highly integrated product of computer technology, sensor technology, human-machine collaboration, and energy technology. By 2000, the technologies required for exoskeletons had made breakthrough progress. From the results of the BLEEX project funded by the US Defense Advanced Research Projects Agency (DARPA), the components have been greatly miniaturized, more flexible, and more intelligent.

BLEEX Exoskeleton｜Wevolver

At the same time, exoskeletons have also begun to move out of the laboratory, and representative companies such as ReWalk, CYBERDYNE, and Ekso Bionics have been established one after another. Exoskeleton products cover military cooperation, medical rehabilitation, disaster relief, factory manufacturing and other scenarios.

What's in an exoskeleton?

The exoskeleton is like a "life" attached to a person - it has a very complete system that can sense, control, and drive. It also has a computer that acts as a "brain", a mechanical structure that simulates the human skeleton, and actuators that simulate muscles.

People usually use batteries, fuel and internal combustion engines to drive exoskeleton robots. Modern exoskeletons are usually precisely integrated with sensing, control, drive and mechanical systems. Sensors distributed everywhere collect information such as human posture, strength, movement trends, etc. in real time, and then transmit it to the built-in computer or control center of the device. The "brain" begins to analyze and then determines the human intention to drive the exoskeleton components, generally through motors and hydraulics to drive the machinery to produce corresponding actions.

Take a real patient as an example. In October last year, Weibo user @几木朵_ filmed a video of her trying to walk with the help of an exoskeleton, which sparked heated discussions. She said that she was declared paralyzed for life by a doctor twelve years ago, and could only stand with the help of a standing bed. It was not until last year that she started trying a lower limb exoskeleton and experienced the long-lost feeling of walking independently again. "I kept crying after I got off the bed."

Weibo user @几木朵_'s Weibo

From the video, we can see that in addition to the mechanical joints that fit tightly against her thighs, there are also armrests and bottom pulleys. The latter can support her body. The sensor will first determine her force direction and posture, and then adapt to her initial steps. In addition, this exoskeleton used for rehabilitation training also provides modes such as "constraint training" and "resistance training". The former requires the patient to follow the steps set by the program and gradually increase the amplitude. The latter requires the patient to go against the resistance applied by the machine, and then exercise the lower limbs to continuously stimulate the motor nerves.

According to the blogger, the price of this exoskeleton is "more than 100,000". In other markets around the world, the prices of medical rehabilitation exoskeletons are also generally high, with CYBERDYNE's HAL 5 costing about $20,000 and Ekso's costing more than $100,000.

The high cost is related to the fact that the exoskeleton system has not yet ushered in a revolutionary design breakthrough. At present, the structure of the exoskeleton is still heavy and complex, and the continuous power output capacity is positively correlated with the product volume. In other words, with current technology, it is not possible to achieve more reasonable miniaturization and lightweight, which is still a considerable burden on the human body.

Little girl wearing lower limb exoskeleton｜Internet

"The biggest problem with exoskeletons is safety. I think costs, energy, materials, etc. will be gradually resolved or compromised after the safety issues are resolved and put on the market. The most critical safety issue is balance and potential secondary injuries." A researcher whose five-year doctoral thesis was centered around rehabilitation exoskeletons wrote on Zhihu.

Development in sports events

In order to make exoskeletons lighter, smaller, more comfortable, and safer, scientists are actively exploring ways to improve them. For example, researchers from Caltech and Tsinghua University started with algorithms. In 2020, they proposed an algorithm called "COSPAR," which updates the model based on user feedback and uses it to select new experimental movements and induce feedback, ultimately helping patients find their preferred gait and improve comfort.

Some researchers are also experimenting with non-invasive brain-computer interfaces to obtain the user's movement intentions, which means allowing the exoskeleton and the human body to interact more directly. DARPA launched "The Warrior Web" project in 2011, pointing out that flexible exoskeletons are lighter and more comfortable, and the system design combined with functional clothing can improve the wearer's mobility, activity quality and endurance, and extend the continuous wearing time.

DARPA’s “Warrior Loom”｜DARPA

In addition to scientific research, sports events are also driving the evolution of exoskeletons.

You may have heard of Marathon, but you may not know Cybathlon. In 2016, Cybathlon was initiated by the Swiss Federal Institute of Technology in Zurich and successfully held two competitions in 2016 and 2020. In Cybathlon, disabled athletes can use mechanical prostheses, brain-computer interfaces, exoskeletons and other peripherals to participate in the competition. In 2020, the competition listed six major events, including brain-computer interface competition, functional electrical stimulation cycling competition, powered arm prosthesis competition, powered leg prosthesis competition, powered exoskeleton equipment competition and powered wheelchair competition. All tasks are closely related to the daily lives of people with disabilities, focusing on showing the research progress in related fields.

Cybathlon｜CGTN

The contestants need to complete actions such as climbing stairs, cooking, playing video games, etc. The one who completes the most tasks in the shortest time will win. Unlike the Paralympics, which mainly tests the human body's athletic ability (the contestants are required to use only equipment available on the market), Cybathlon emphasizes the pursuit of technological innovation, and contestants can use the latest developed power-assisted devices.

Professor Robert Riener, the initiator of Cybathlon, recalled the original intention of holding the competition: the assistive technology developed by the laboratory is very advanced, but it cannot be used in time for ordinary disabled people, who have too many difficulties to overcome in their daily lives. He hopes that through Cybathlon, the development of assistive systems for the disabled and academic exchanges can be promoted, and that laboratories and companies can compete and inspire each other, thus "giving birth" to prosthetic limbs and exoskeletons with lower costs and more advanced technologies.

From this perspective, the Olympics, Paralympics, and Cybathlon are all challenges to human limits. You will also be inspired when you see a competitor install a light bulb with a robotic arm or stand up from a wheelchair and take an unusual step.

References

[1] Energy dressing: exoskeletons on the job https://sportnews.blogdady.com/energy-dressing-exoskeletons-on-the-job/

[2] Cybathlon: World's first 'bionic Olympics' gears up https://www.bbc.com/news/technology-37196860

[3] Warrior web closer to making its performance-improving suit a reality https://phys.org/news/2013-08-warrior-web-closer-performance-improving-reality.html

[4] Where will exoskeleton robots go in the future? https://mp.weixin.qq.com/s/LHmLkmlBEu9LUkji_1xT6w

[5] Passing the torch with the help of an exoskeleton! The Winter Paralympic torch has just arrived at the Winter Olympics Organizing Committee’s headquarters https://www.takefoto.cn/news/2022/03/04/10050159.shtml

[6] Zhihu user Simpleway’s answer to the question “Why did the exoskeleton industry decline before it even took off?” https://www.zhihu.com/question/304939541/answer/809791972

Author: biu

Editor: Lying insect

Planning: Guokr Technology Group