A hand exoskeleton aims to improve everyday life for children after strokes. There are also numerous possible applications for exoskeletons in business.
An employee wears an exoskeleton while sorting the parcels in the Swiss Post parcel center
30 minutes by car south-west of Zurich: the children's rehabilitation center in Switzerland is located on the edge of the forest in the tranquil town of Affoltern. A modern concrete building. Children spend the afternoon with their parents outside on the playground. Inside, Professor Hubertus van Hedel and his team are working on a major technical development: a hand exoskeleton.
These are “systems that follow the shape of the human body,” explains van Hedel, “and – like ours – are connected to the hand from the outside.” This “external skeleton” ensures that certain movements can be performed with the human hand.
Exercise with wooden building blocks: hand exoskeleton from ETH Zurich
Anything but futuristic
Van Hedel's research team has developed a first, fully motorized and wearable handheld exoskeleton: Unscrew bottles, cut bread, pick up buttons from the floor and hold playing cards using robotics. The device is specially designed for children and young people with congenital or acquired brain damage – with the result that they can only move their hands to a limited extent.
Pexo – that's the name of the device – looks anything but futuristic: Each finger consists of three thin leaf springs on the top, which work like tendons and are connected to a motor via cables. The device is activated by voice control or with a blue button. Then the moving leaf springs exert a slight pressure on the human fingers and the patient's biological hand closes or opens. The electronics, motors and battery are housed in a back module weighing around two kilograms.
Pexo, the crocodile
The bright green hand module resembles a crocodile. Because the design should meet children's needs, as Jan Dittli, an engineer at ETH Zurich, explains: “We have developed different sizes to offer children between the ages of five and 18 a suitable size.”
Control unit including hand exoskeleton from ETH Zurich
But the exoskeleton still has mechanical limitations: Fingers cannot be controlled individually. Only the thumb and the remaining four fingers together can be activated separately to open or close the hand. Playing the piano: none. But this is the only way the low weight of the exoskeleton is possible from an engineering point of view. The hand module weighs around 120 grams, which is less than a smartphone.
Beginning of research
Van Hedel's team deliberately avoided sensor technology or even control via connections to nerves or the brain. Although this is medically exciting, the research is still in its infancy. So far, therapeutic robotic devices are very bulky, heavy and large. With Pexo, children and young people can easily practice movements with everyday objects and lift things that weigh up to half a kilogram. The big bar of chocolate is no problem, the full carton of milk is borderline.
Robotically operated exoskeletons were developed at the beginning of the millennium, first for the military and later for therapeutic purposes. Walking robots for stroke patients or paraplegics already exist – for example for standing, walking or gripping.
Power Suit for industry
In the meantime, handicraft businesses, the automotive industry, logistics service providers and providers of care facilities are also interested in exoskeletons. For example, for portable robots that do the lifting while protecting the employees’ spines. Forces acting on the spine, shoulders and neck are absorbed and redirected by the exoskeleton. The areas of application? Wherever physically demanding activities are performed. For example, when it comes to balancing several tons of spare parts, car bodies, suitcases, bags of cement or lifting bedridden patients in nursing homes every day. This potential has also been recognized by the German prosthesis manufacturer Ottobock. There, the exoskeleton segment is seen as a larger market than prosthetics in the long term, Ottobock boss Oliver Jakobi recently told the Frankfurter Allgemeine Zeitung. He expects sales in this segment to double this year.
Relief in physical Hard Labor: Parcel Center Clerk with Exoskeleton
Exoskeletons can be divided into two types: Passive models have no motors or batteries. They divert loads via springs and cable pulls to other parts of the wearer's body.
Differently active exoskeletons, such as those from the Augsburg company German Bionic. The company makes a variety of power suits. These have power-boosting motors and do the lifting. For example the Cray X: a so-called Power Suit exoskeleton, which is intended to improve the physical performance of workers and was specially developed for use in the manufacturing industry when lifting and lowering loads on pallets or racks.
The exoskeleton helps reduce stress on the upper body, preventing muscle fatigue and injury. It works in a similar way to the hand exoskeleton from Kinder-Reha Schweiz, is strapped on with leg loops and a vest on the upper body.
Huge market
Cray X has a modular structure, which means that the exoskeleton can be individually configured depending on the area of application and the needs of the wearer. It can also be equipped with various sensors and monitoring systems to monitor the wearer and his work, collecting data on performance and load.
Exoskeleton support, here loading luggage at Stuttgart Airport
German Bionic is not the only company experimenting with exoskeletons and offering such devices. Numerous startups are bustling about on the field. According to Indian analytics firm MarketsandMarkets, the global exoskeleton market is set to grow steadily and will be worth $6.8 billion by 2025. Other market research institutes estimate sales of industrial exoskeletons at 20 billion US dollars by 2030, up from 96 million US dollars in 2016.
Health prevention and risk assessment
A laboratory study by the Fraunhofer Institute for Material Flow and Logistics showed that the use of exoskeletons in production has a positive effect on productivity. Work efficiency is increased by up to 25 percent. Through the use of exoskeletons, employees were able to work faster and longer without showing any signs of fatigue. The study was conducted in collaboration with various companies that already use exoskeletons in their production.
Researchers also found that employees experienced fewer musculoskeletal disorders and strains as a result of using exoskeletons. The use of exoskeletons helped reduce the risk of repetitive strain injuries during strenuous physical activity.
However, there have also been criticisms of the use of exoskeletons in industry. For example, it was criticized that the exoskeletons are still quite heavy and bulky and can therefore limit the mobility of the employees. Also, some exoskeletons are still quite expensive, which makes them difficult to use in smaller companies. And there are no long-term studies to assess the consequences in real industrial use. These include possible side effects such as muscle loss with active exoskeletons or the increased stress on the cardiovascular system with systems for overhead work.
Back to children's rehabilitation in Switzerland. Wanda [real name known to the editors] comes into the treatment room; She is one of around 240 children and young people who spend several weeks or, like the 14-year-old, even months in rehab each year. The reason: They are struggling with the consequences of spinal cord or brain injuries after strokes.
Tough therapy
Wanda also had a stroke a year ago and couldn't use her left arm, leg or hand move more correctly; In addition, there were always speech disorders. Intensive rehabilitation has changed that. Wanda is speaking fluently again, but her hand still doesn't want to move as well as it used to.
Now she is supposed to use the hand exoskeleton to grab small building blocks from a wooden box and place them across a partition into a second box. What is easy for other children is difficult for Wanda.
She gives the command via voice control to close her hand, and suddenly the motors of the exoskeleton begin to whir softly. Her paralyzed fingers curl up, she grabs the small block of wood and places it in the opposite box.
Star Wars Fantasy
Will hand exoskeletons ever match the functions of real hands? Van Hedel's answer: No, the human hand is too delicate, too complicated to be artificially replaced like Luke Skywalker's robotic hand. It will remain a Star Wars fantasy from the Hollywood dream factory.
Nevertheless, an exoskeleton could be helpful for some children with brain damage, the head of research sums up. “Commercially, this is not a huge target group” and adds: “The humanity of a society is shown in how it treats its weakest. Children are our future!”