At Harvard University a team of scientists and engineers developed an exosuit that uses ultrasound to measure muscle activity. The capability allows for rapid calibration of the suit for users’ needs. The soft wearable device continuously assists when walking or running, reducing the energy required to perform these tasks, which could be very useful for patients with neurological issues or muscular dystrophy. By directly measuring muscle dynamics, the suit provides activity- and user-specific assistance, bringing such wearable technologies a step closer to fruition.
Wearable ‘exosuits’ have significant potential in assisting those with mobility issues by providing supplemental power when a wearer is walking or running. Medgadget has featured these technologies in the past. However, at present, it is not straightforward to calibrate an exosuit to optimize for a particular user or for different activities a single user might take part in. For instance, the mechanics of running and walking are quite different and uneven terrain can drastically change the requirements of the exosuit.
Currently, it is typical that hours of fine tuning are required before an exosuit is ready for the needs of a particular user performing a specific task. This is laborious and impractical, and a barrier to the wider adoption of such technology. In response to this, the Harvard researchers designed an exosuit that can directly measure the muscle activity of its wearer as they perform a specific task and then enable rapid customization of the suit so that it fulfills the needs of the user.
“We used ultrasound to look under the skin and directly measured what the user’s muscles were doing during several walking tasks,” said Richard Nuckols, one of the developers of the new exosuit technology, in a Harvard press release. “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.”
The new system consists of a portable ultrasound system that is strapped to the leg of a user, which images the underlying muscle activity. “From these pre-recorded images, we estimated the assistive force to be applied in parallel with the calf muscles to offset the additional work they need to perform during the push off phase of the walking cycle,” said Krithika Swaminathan, another researcher involved in the study.
After just a couple of seconds of walking, the suit can accurately assess the muscle activity. “By measuring the muscle directly, we can work more intuitively with the person using the exosuit,” said Sangjun Lee, another researcher involved creating the device. “With this approach, the exosuit isn’t overpowering the wearer, it’s working cooperatively with them.”
See a video about the technology below.
Study in Science Robotics: Individualization of exosuit assistance based on measured muscle dynamics during versatile walking