The study followed 12 volunteers who were made to use two pneumatic tools: A torque wrench weighing about 10 pounds and an impact wrench that weighed about 30 pounds. They used the tools with and without the aid of an exoskeleton. The test ran for several hours, over which time the researchers measured the forces acting on the volunteers' spine and back muscles.
Commercially available exoskeletons are far from those seen in science fiction movies. They usually consist of a metal arm connected to a vest-like harness, which attaches the unit to the user's upper body and torso.
The exoskeleton's design transfers the load from the arms to the back, giving users additional support and allowing them to carry heavy loads with minimal use of their arms. The benefits they offer make them ideal for use in construction and industrial areas.
Researchers noted that while the exoskeleton did reduce stress on the volunteers' arms, it proved taxing to their backs. Wearing it increased compressive spinal loads by up to nearly 53 percent compared to when the volunteers were not wearing it. The stress on different muscles in the torso also increased by anywhere from 56 to 120 percent while using the exoskeleton.
“This exoskeleton is meant to offload weight from your arms, so for your arms it’s great,” explained Gregory Knapik, senior researcher at Ohio State University's Spine Research Institute. “The problem is, the weight of the tool, the weight of the mechanical arm and the weight of the vest you’re wearing—that all goes to your back. At the end of the day, you’re just trading one problem for a potentially even worse problem.”
The volunteers did not report any strain from wearing the harness but found the stiff metal rods that lined the unit uncomfortable and cumbersome.
“The simplest way to describe it is like dancing with a really bad partner,” said William Marras, director at the institute and Honda Chair Professor of Integrated Systems Engineering at Ohio State. “Someone is tugging and pulling on you in directions you’re not expecting, and your body has to compensate for that. And the way you compensate is by recruiting different muscles to perform the task.”
The exoskeleton's manufacturer concedes that the unit does cause back fatigue and so recommends muscle conditioning to protect users from bodily injury.
The future of exoskeletons
Commercially available exoskeletons, such as the one used in the study, are passive units that utilize a combination of springs and braces to reduce load and support specific areas in the body. Active exoskeletons are more comparable to Iron Man's metal suit and use a power source, as well as motors to facilitate movement, offer support, and provide a certain level of enhancement to the wearer.
Powered exoskeletons are seeing potential use not just in industry, but also in the military. Several types and models are undergoing testing to determine the viability of their use in the field. They are expected to provide several advantages to soldiers, ranging from increased mobility to greater resistance to injuries.
Active exoskeletons are also being developed to help older people stand up by themselves, move, and engage in more active activities. These portable robotic skeletons are seen as a means to provide additional independence and potentially improve their users' quality of life.
Learn more about other advances in ergonomics at FutureScienceNews.com.
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