Study: Exoskeletons Designed to Thwart Worker Injuries May Create New Worker Risks

College Station, Texas (WorkersCompensation.com) – A new study from Texas A&M University and The Ohio State University has found that while exoskeletons may help reduce worker injuries, they may pose other risks. 

Exoskeletons are wearable technologies that support workers and reinforce human performance. The technology sits on the workers hand, lower back or shoulder, and helps lifted objects seem lighter, making them easier for the worker to lift. 

The study, published in Applied Ergonomics and analyzed by Science Daily, found that the exoskeletons aid workers when it comes to heavy lifting, and reduce the risk of musculoskeletal injuries. According to the study, lower-back injuries from lifting and handling heavy objects on the job accounts for an estimated $100 billion in medical bills annually in the U.S. 

But, when workers were asked to do a cognitive activity while they were lifting, they lost the biomechanical benefits the exoskeleton provided, researchers said. 

“Researchers at Texas A&M University and The Ohio State University have determined that increased cognitive demands in the workplace, often associated with new technologies or automation, can offset the mechanical advantages of wearing a low-back exoskeleton, a wearable device that is aimed to reduce or redistribute biomechanical spine loading associated with heavy manual work,” the study said. 

Researchers said they looked at the brain function of workers who wear an exoskeleton when they are lifting something. In their research, they were able to “document the neurocognitive ‘cost’ of wearing an exoskeleton and identify adaptation strategies adopted by users over time to mitigate the cognitive risks introduced by the exoskeleton.” 

"We wanted to shed some light on how the use of an industrial exoskeleton impacts the worker's motor and cognitive capabilities, given that the worker has to learn new motor strategies to work efficiently while wearing exoskeletons to do their work," Ranjana Mehta, Associate Professor, Industrial & Systems Engineering, Director, NeuroErgonomics Lab, Texas A&M University, said. “While exoskeletons hold great promise in alleviating physical loads in the workplace, these findings can guide the development of decision support tools for ergonomists to determine when/how and during what tasks exoskeletons should be used on the factory floor to maximize worker safety.” 

Researchers used both male and female workers with no history of lower back injuries in their study. Participants were asked to do extensive lifting, both with and without the help of a lower back skeleton. 

The participants attended two sessions – one focused on performing lifting tasks while wearing the exoskeleton; and another without the exoskeleton. Each participant was fitted with an exoskeleton attached to their chest and legs while they repeatedly lifted a medicine ball for 30 minutes. After a rest break, they were asked to perform the same task, with an exoskeleton, while simultaneously performing a mental task – subtracting 13 from a number between 500 and 1,000 – every time they lifted the ball. 

Researchers then measured the spinal load using advanced electromyographic (EMG)-assisted biomechanical modeling, and monitored the brain activation during the task using ambulatory brain imaging devices called functional near-infrared spectroscopy, which allowed them to assess the human-exoskeleton interaction. 

Researchers said the exoskeleton did not significantly reduce spinal compression loads and had marginal practical benefit in reducing spine shear loads, compared to not wearing an exoskeleton. However, the researchers did find that the “cost” of wearing the exoskeleton was reflected in brain activity. When using exoskeletons, the researchers said, additional regions of the brain regulating alertness and vigilance were recruited to help with lifting. 

When workers were asked to solve math problems while lifting, they lost whatever biomechanical benefits the exoskeletons offered. 

"Cognitive demands have been shown to exacerbate spinal loading during lifting. That these demands completely offset the small mechanical advantage of the exoskeleton is a remarkable finding of the study," Mehta said. “A neuroergonomics approach, i.e., evaluating brain-behavior relationships at work, was able to capture cognitive risks of exoskeletons that traditional ergonomics and biomechanical measures were not able to."

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