Exoskeletons are designed to protect employees from overwork. And they could even improve their output and work performance. A comparison of technologies.
With a loud rattle, the cordless screwdriver announces that it has done its job properly. The screw is tight, but not too tight. Alexander Esin immediately grabs the next screw from the box and fixes it in the underbody construction, which hovers about 20 cm above his head. Once again, he has exactly 2 s for the pure screwing process - these are the specifications of the workflow time analysis in industry.
Screw in 16 screws, set twelve clips, pull in two cables, brush 25 paint strokes accurately and horizontally onto a pad, then loosen the cables and clips again and also unscrew the screws: These are the activities specified in the specifications for the first station of the experiment set up by Stuttgart's Fraunhofer Institute for Manufacturing Engineering and Automation (IPA) and the University of Stuttgart's Institute of Industrial Manufacturing and Management (IFF) at the Wilhelm Maybach School.
How much relief does an exoskeleton provide at work?
The researchers want to find out how much relief an exoskeleton really provides during tiring activities. The Bad Cannstatt Vocational and Technical College is well chosen as a venue for this purpose, as it offers plenty of know-how in mechanical engineering, foundry technology and automotive engineering.
The exoworkathlon, as the experiment is officially called, is an international first, says Urs Schneider, head of the "Medical and Bioproduction Technology" department at Fraunhofer IPA. His team, which develops human-technology solutions, is the largest exoskeleton research group in Germany. The test stations were developed together with ergonomics and occupational safety specialists from industry. They reflect typical work situations in which forced postures frequently occur. At Esin's station, the task is to work overhead, at another to haul boxes.
Toil for one hour while recording physiological data
For one hour at a time, several vocational students perform this tiring activity in succession, once with and once without the support of the exoskeleton. Sensors record their physiological data such as muscle activity and cardiovascular parameters such as heart rate and oxygen uptake, and the test subjects also indicate their subjective feelings during the work process in a questionnaire.
- An exoskeleton or exoskeleton is a support structure that lies against the body. A distinction is made between active and passive systems, i.e. those with and without electrical drive.
- Exoskeletons were initially developed for medical applications to help paraplegics get back on their feet. The integrated motors are intended to replace the missing muscle power. Fraunhofer IPA was the first research institute worldwide to succeed in developing a walking simulator for stroke patients.
- The main market is in the industrial sector. Here, ergoskeletons help with lifting heavy loads, fatiguing activities or overhead work. The aim is to reduce physical fatigue and the frequency of errors, and to prevent accidents.
- Around 100 manufacturers worldwide are active in the market, including Ottobock, Parker, Panasonic, German Bionics and Laevo.
Exoskeletons are support structures attached to the body that can reinforce or even replace muscle strength in the arms, legs or torso. A distinction is made between passive and active systems, depending on whether battery-powered motors are integrated. The first developments were used in medicine to support people after a stroke or with paraplegia. But increasingly, industry is discovering exoskeletons to provide ergonomic relief for employees performing heavy physical work. Lugging boxes is one of them.
Lugging boxes becomes almost child's play with the exoskeleton
Simon Bader moves smoothly back and forth between the packing table and the container. He continuously carries boxes weighing 8 kg through the second station. Most of the time, he casually sets down his load, lightened by the exoskeleton, in the container. Like Esin, he also completes six rounds of 10 min. "Actually, you're supposed to bend your knees to lift the load from your legs and not from your back," says the employee of a medium-sized specialist for die casting technology from the Rems Valley, who is currently completing his second year as a mechanical engineer.
Several sensors on his body record data and transmit it for evaluation. The IPA team, together with the University of Stuttgart, will use this data to determine how much relief the exoskeletons used in the test actually provide for employees and to what extent they may be able to avert consequential damage.
"Overwork on the job leads to disability".
"Overloads, which are often hardly noticed by young people in particular, can lead to absences and disability in the course of a professional life," says the head of the IPA project, Verena Kopp. The sports scientist and biomechanics expert is convinced that exoskeletons, on the other hand, could protect professionals from such consequential damage in the long term. But the test evaluation will have to show that first. It is important to the Fraunhofer researchers that the tested exoskeletons do not compete with each other, as their manufacturers come from Germany, France, the Netherlands and the USA.
"This is just about comparing activity with and without support," Kopp says. "We just want to see if exoskeletons have the potential to reduce physical stress and maintain performance." And how that affects subjective perception. Kopp has devised a questionnaire specifically for this purpose, which the test subjects fill out immediately after their use.
Exoskeleton can increase output
"In the best case, you can even increase output with a work aid, then they might catch on in industry," Urs Schneider hopes. Purely for the health of the employees, the companies would not necessarily take money in hand, but probably if they achieve an increase in work performance with it. "We know that you can weld better overhead if your arms are supported by an exoskeleton. The employer is happy when the weld seam is clean," grins the IPA division manager. This was the experience of his team at the car manufacturer Audi.
The Stuttgart-based company also set up a welding station of this kind at the A+A occupational safety trade fair, which ran from October 26 to 29 in Düsseldorf. Employees of the car manufacturer Ford were able to test the exoskeletons on their own bodies there. "We will generate a database from the results of both events," Schneider says. In January, another course is planned at the Schweißtechnische Versuchsanstalt in Hamburg. There, port welders will be included in the experiment.
Occupational safety and accident insurers are interested in results
The Federal Institute for Occupational Safety and Health (Baua) and the German Social Accident Insurance (DGUV) are also interested in the results of the Exoworkathlon. They hope that the experiments will bring a bit of methodology to what has so far been a rather thin body of data on the use of exoskeletons. Employees in logistics or the automotive industry can quickly suffer herniated discs or, in the worst case, early retirement. This must be prevented.
In the future, recommendations could be made, especially for small and medium-sized businesses, on how they can make work processes more ergonomic. Because: "The really tough jobs take place at the small companies," Schneider is convinced. Unlike large corporations, they cannot afford elaborate process planning and teams that set up production lines with ergonomic aspects in mind. This is another reason why most manufacturers are currently selling their exoskeletons to smaller companies.
"Perceived exertion was nearly 30 % lower with exoskeleton."
Meanwhile, the evaluation is in full swing. Simon Bader has felt a clear support effect from the exoskeleton. "In the longer term, it can certainly contribute to making work easier, to safety and to employee satisfaction," he says. He can imagine his employer implementing such support systems as well. "We have jobs that involve lugging boxes weighing up to 25 kg, so it would be a great relief."
For project manager Kopp, it is particularly important whether there is a noticeable relief through exoskeletons. The tests clearly showed that. "The perceived exertion with exoskeleton was just under 30 % below the value given without the technical support," she says. In all muscle regions, there was a lower perceived exertion with exoskeleton.
Exoskeletons show great potential
However, Kopp also has a surprising result in store - with the exoskeleton, the test subjects were somewhat slower in the work process. "Maybe it's because the movement with the system was unfamiliar," Kopp suspects. Nevertheless, "The results show that exoskeletons definitely have the potential to support employees," says the project manager.