Canadian Occupational Safety

21 2019 JUNE/JULY pain. Due to their rural location and long workdays, farm- ers often don't have the same access to care for chronic back pain as do people in urban areas. During the study, farmers will wear the upper body type of exoskeleton. Using a portable electromyog- raphy (EMG) system in the field, researchers will measure the electri- cal activity of the study participants' muscles, Trask says. This will allow them to assess how hard the back muscles are working. Researchers will also have some inertial sensors to assess how fast a participant's limbs are moving and what kinds of postures people are getting into. In addition to collecting objective, quantitative data, the scientists also want to visit farms to see how the task performance varies with and without the exoskeletons, as well as to inter- view the farmers about their subjective experience: What did they like about wearing the exoskeletons? What chal- lenges did they encounter? What other types of activities do they think the devices could be useful for? One central issue they're trying to determine is how practical exoskel- etons will be. Does the cost-benefit trade-off make sense for the farmer? If a farmer has to get in and out of a trac- tor frequently, it may not be practical for them to wear a device that has some rigid structure on the back and the legs. The device may make it too tricky to safely climb in and out of a piece of machinery. "We know that in a lab exoskel- etons can decrease the physiological load so people get less fatigued when they're using an exoskeleton. They do decrease awkward posture in the spine. They decrease the biomechani- cal load on the spine, the compressive forces in the spine. The question is whether in a real-world environment it's possible for a worker wearing an exoskeleton to do real tasks and not just lab tasks," Trask says. POWERED EXOSKELETONS At the Fraunhofer Institute in Stutt- gart, Germany, the largest technology research institute in Europe, research- ers are working on the "Stuttgart exo-jacket," a motorized jacket that assists in lifting heavy weights. It can lift 15 kilos (about 33 pounds) on its own, but the intended function is to assist workers to lift up to 40 kilos (about 88 pounds). This would be useful for workers handling suitcases and luggage at an airport, for example, or lifting heavy objects in construc- tion work, says Urs Schneider, the institute's division director for health and head of Biomechatronic Systems, a research department at the institute. "It's like an e-bike or pedelec. You go yourself, but you have a power- assist. When workers lift a suitcase of 40 kilos, the system will support them about 25 per cent. It's still the same job, but it's a bit less (of a load). Our intention is that the fatigue will set in a little later and the load peaks on the joints will be reduced so that osteoarthritis of these joints is delayed into the future," he says. "It's not a miracle, but we're trying to reduce the chronic, absolute load on the muscle and the peak load on the joints. And we're trying to see to it that people don't work more but go home with a better quality of life and, ideally, have a reduced number of injuries." However, he adds, even with the lightest and most efficient technology available, the motor is still very heavy. While weight is not a problem in reha- bilitation, where the patient is moving slowly, it makes the use of powered exoskeletons in the workplace, where people often have to move very quickly, almost impossible. "Do you want something heavy on your body to help you lift something?" Schneider says, adding that research labs around the world are working to develop lightweight powered exoskel- etons. He expects they won't really be a big part of the market until about five years from now. In contrast to the powered devices, passive devices are lightweight, usu- ally less than 3 kilos. While they have this advantage, and thus are more practical, Schneider says, their over- all ergonomic effectiveness is much less than that of power-assist devices. They are also very task-specific. Still, they may help to reduce osteoarthri- tis in the shoulder, problems in the hip joint and may help prevent tennis elbow and carpal tunnel syndrome. They may also delay spinal issues, especially of the lumbar spine. Generally, Trask says, the effective- ness of exoskeletons in the workplace depends on which device is being used and what task needs to be done. Before buying a device, an employer should carefully consider what the goals are for the exoskeleton. "An exoskeleton can work in some circumstances and not others," she says. "As with any safety intervention, we want to make sure there is a good match between the workers, the task they need to do and the exoskeleton that we're choosing for them." Smets says even small companies should consider providing an exo- skeleton to employees, despite the expense. The potential hazard for a worker should be the central guiding factor in the decision to provide an exoskeleton. For example, the person at a television station who holds a boom microphone or a carpenter who spends many hours sanding a surface above their head could benefit pro- foundly from such a device. "A small employer could get value out of some of these devices if it was the right job. If 50 per cent or more of your work is overhead, the preference would be to use the device for at least a portion of the workday to reduce the fatigue build-up," Smets says. DRAWBACKS As with anything new, employers should be cautious about unintended consequences, Trask says. An exoskel- eton could constrain twisting or lateral movement, which may reduce ability to perform some tasks. Or, if someone needs to drive a lot during their work, or they're on and off different machin- ery, then some styles of exoskeletons might not be appropriate. Using a device might also introduce a new problem. The introduction of the combine, for example, eliminated many ergonomic risk factors that resulted from harvesting wheat with a scythe. But it created the new hazards of sedentary work and whole-body vibration, which arises from sitting on the machinery for hours at a time and which likely contributes to farm- ers' high rates of back pain. "Consider what the exoskeleton can help with, but also where it might intro- duce a limitation. Make sure there are not some unintended consequences. You need to be sensitive during that trial phase to what the range of out- comes might be because it's not always what you expected," Trask says. Moreover, many workers find exoskeletons to be very uncomfortable and don't like the way they look. In Germany, Schneider says, some com- panies that bought the devices ended up putting them in storage because workers didn't like them. "Yes, it is about function, but it is also about comfort and aesthetics and user acceptance. Only if the device is comfortable will the workers be com- pliant. And some look funny. On an assembly line, for example, if you have eight male workers and one of them looks funny, the device won't last five minutes. So, some improvement in comfort and looks has to be made in many of them," he says, adding users often have very different reactions. "Some people love them and wear them all day. They say they would buy the devices out of their paycheque if someone ever took them away from them. And others say, 'It doesn't really fit me, it's not comfortable, I can't move naturally in it, it's too warm,'" he says. The fact that the devices tend to increase body temperature remains the biggest barrier to the adoption of exoskeletons, he says, adding the safety team at Ford is now looking for cooling solutions. Differences in body shape can pres- ent problems for the exoskeleton, too. An adjustment to the spine post of the exoskeleton can be made to accom- modate different torso heights. Still, Smets adds, people who are five feet three inches tall or shorter can be dif- ficult to fit. An employer may need to provide a selection of different prod- ucts to allow for workers' different sizes and shapes. It usually takes a few weeks for an operator to break in the material and adjust it to their body height and weight, Smets says. Each person should have their own device and not be sharing it, for sanitary reasons but also to avoid constant re-adjustments. Exoskeletons are also very expen- sive. The arm support devices currently used in the Ford trials range from $4,000 to $7,000. On the other hand, he adds, the cost of the device should be compared with the cost to heal a shoulder injury, which for Ford can be more than $100,000. While exoskeleton technology seems futuristic now, in 10 years' time it will likely be a natural part of many workplaces, Smets says. The capa- bilities of the technology will grow quickly, and the difficulties we see now will be worked out. "These are all new devices. All these little challenges are just a result of the fact that we are in the first and second generation of the devices," he says. "They've just come to market in the past three to four years and they're only going to get better." COS Linda Johnson is a Toronto-based freelance journalist who has been writing for COS for eight years.

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