It’s understandable for most of us to think that a human wearing a sort-of robotic suit is a concept mostly restricted to animé and children’s cartoons—but they’re here, and they’re constantly being improved.
The concept of powered exoskeletons has long been a tantalizing vision in the minds of scientists and engineers; now, recent advances in engineering and robotics has given us a glimpse into what the future might look like in this burgeoning field of research.
The latest addition in the long line of research for this field comes from Harvard University’s John A. Paulson School of Engineering and Applied Sciences (SEAS), whose research team attempted to address a crucial issue in powered exoskeletons concerning natural movements.
You see, normal human motion involves both moving the body forward and maintaining a human’s gait as well, or their very manner of walking. Thing is, exoskeletons must follow the gait of the person using them, or they otherwise risk hindering or even fighting against their wearer’s natural set of movements.
In usual cases, this “adaptation” the exoskeleton must perform in order to match their wearer’s movements takes time—time which not all wearers may have available to them, like for wearers with limited mobility.
The Harvard team decided to take a step forward in addressing this issue using an unlikely tool: ultrasound transducers. The effort was a collaboration between the Harvard Biorobotics Laboratory and the Harvard Biodesign Lab.
In using the transducers, now condensed in a “portable” form then fitted on a treadmill, the Harvard team scanned the feet of volunteers who were to wear the new exoskeleton later on in the study. In their scanning, the research team searched for markers like muscle activity profiles, which enabled the team to compute for the “assistive” force the robot is required to exert in order to augment the wearer’s movements. This entire profile-generating process only took a few seconds, according to the team.
Said first author and SEAS postdoctoral research assistant Richard Nuckols: “We used ultrasound to look under the skin and directly measured what the user’s muscles were doing during several walking tasks. Our muscles and tendons have compliance which means there is not necessarily a direct mapping between the movement of the limbs and that of the underlying muscles driving their motion.”
After converting the profiles into a set of parameters then injecting them into the exoskeleton, the researchers found that their wearers exerted less metabolic energy while using the exoskeleton compared to them doing the same task unassisted—proof that the exoskeleton truly does assist in the task, the team says.
The researchers also found the robot to exert less force to do the same task when “calibrated” using ultrasound compared to an uncalibrated attempt, meaning the calibration step also makes the exoskeleton more energy-efficient.
Said study co-author, Abbott and James Lawrence Professor of Engineering Robert Howe: “This study shows that you can provide more effective walking assistance if you time it to when the muscle starts contracting, rather than starting the assistance based on how the leg is moving. It turns out there’s considerable variation between individuals in the timing of calf muscle contraction, and the ultrasound lets you determine the best time for assistance for each individual.”
Future steps to take in improving the study will involve making the adaptations to the wearer’s movements realtime, meaning the exoskeleton adjusts as the user moves with it.
Finally, senior author and Harvard Biodesign Lab head Conor Walsh said in a statement: “This approach may help support the adoption of wearable robotics in real-world, dynamic situations by enabling comfortable, tailored, and adaptive assistance.”
This landmark study was published in the journal Science Robotics.
(To read similar tech that aids humans in various ways, read about how brain implants helped a woman “see” for the first time in years. Afterwards, check out how scientists may have made the next generation of hearing aids battery-free.)
References
- Coxworth, B. (2021, November 15). Ultrasound used for better calibration of assistive exoskeletons. New Atlas. https://newatlas.com/science/ultrasound-calibration-exoskeleton/
- Exoskeleton (Robotics)—An overview | sciencedirect topics. (n.d.). Retrieved November 16, 2021, from https://www.sciencedirect.com/topics/engineering/exoskeleton-robotics
- Nuckols, R. W., Lee, S., Swaminathan, K., Orzel, D., Howe, R. D., & Walsh, C. J. (n.d.). Individualization of exosuit assistance based on measured muscle dynamics during versatile walking. Science Robotics, 6(60), eabj1362. https://doi.org/10.1126/scirobotics.abj1362
