Jacqueline Hannan, a PhD student in industrial and operations engineering, demonstrates walking with an ankle exoskeleton. Photo courtesy of Brenda Ahearn U-M Engineering.
Ankle exoskeletons that can help people extend their endurance are a step closer to reality with a new control algorithm, developed at the University of Michigan (U-M), that could enable future exoskeletons to automatically adapt to individual users and tasks. The new control algorithm demonstrates the ability to handle different speeds, as well as changes in gait between running and walking. This would reduce or eliminate the need for manual recalibration.
The control algorithm directly measures how quickly muscle fibers are expanding and contracting to determine the amount of chemical energy the muscle is using while doing its work. Then, it compares that measurement with a biological model to determine the best way to assist. Measuring muscle physiology directly is a key departure from current methods, which use broader measures of motion. Going straight to the source of motion could result in more accurate measurements over a larger range of movements with far less computing power required.
Human testing is an important next step and will require the measurement of muscle fibers in real time using ultrasound. While much work and refinement remain, the researchers are confident that the new avenue of research will one day help people on the ground.
“This has the potential to help just about anyone,” said Paul Pridham, PhD, U-M senior research area specialist in industrial and operations engineering. “From someone who walks a lot for their job, to individuals in the military that perform tasks for long periods of time, to people with muscular disorders that need some extra assistance, and the elderly who need help day-to-day.”
