Krithika Swaminathan, Sungwoo Park, Fouzia Raza, Franchino Porciuncula, Sangjun Lee, Richard W Nuckols, Louis N Awad, and Conor J Walsh. 2021. “
Ankle resistance with a unilateral soft exosuit increases plantarflexor effort during pushoff in unimpaired individuals.” Journal of NeuroEngineering and Rehabilitation, 18, 1, Pp. 1–17.
Raziel Riemer, Richard W. Nuckols, and Gregory S. Sawicki. 2021. “
Extracting electricity with exosuit braking.” Science, 372, 6545, Pp. 909-911.
Publisher's VersionAbstractAn exosuit lets wearers tense their muscles less and save energy in portions of their stride Exoskeletons and exosuits are wearable devices designed to work alongside the musculoskeletal system and reduce the effort needed to walk or run. Exoskeletons can benefit users by reducing the mechanical power and metabolic energy that they need to move about on the factory floor, in the rehabilitation clinic, on the playing field, and out at the shopping mall (1). Portable exoskeletons can use motors to add mechanical power into movement phases [net-positive exoskeleton power (2, 3)] or use springs to store and later return mechanical energy in a regenerative braking action [net-zero exoskeleton power (4, 5)]. On page 957 of this issue, Shepertycky et al. (6) describe a wearable assistive device that uses a generator to extract mechanical energy from the walking cycle (net-negative power) and convert it to electricity. At the same time, the walker actually uses less metabolic energy with the exosuit, saving on the cost to operate muscles as “biological brakes.”
R.W. Nuckols, S. Lee, K. Swaminathan, D. Orzel, R. D. Howe, and C. J. Walsh. 2021. “
Individualization of exosuit assistance based on measured muscle dynamics during versatile walking.” Science Robotics, 6, 60, Pp. eabj1362.
Publisher's VersionAbstractAn ankle exosuit tuned to the measured muscle dynamics of the user during multiple walking tasks improves energy economy. Variability in human walking depends on individual physiology, environment, and walking task. Consequently, in the field of wearable robotics, there is a clear need for customizing assistance to the user and task. Here, we developed a muscle-based assistance (MBA) strategy wherein exosuit assistance was derived from direct measurements of individuals’ muscle dynamics during specific tasks. We recorded individuals’ soleus muscle dynamics using ultrasonographic imaging during multiple walking speeds and inclines. From these prerecorded images, we estimated the force produced by the soleus through inefficient concentric contraction and designed the exosuit assistance profile to be proportional to that estimated force. We evaluated this approach with a bilateral ankle exosuit at each measured walking task. Compared with not wearing a device, the MBA ankle exosuit significantly reduced metabolic demand by an average of 15.9, 9.7, and 8.9% for level walking at 1.25, 1.5, and 1.75 meters second−1, respectively, and 7.8% at 1.25 meters second−1 at 5.71° incline while applying lower assistance levels than in existing literature. In an additional study (n = 2), we showed for multiple walking tasks that the MBA profile outperforms other bioinspired strategies and the average profile from a previous optimization study. Last, we show the feasibility of online assistance generation in a mobile version for overground outdoor walking. This muscle-based approach enables relatively rapid ( 10 seconds) generation of individualized low-force assistance profiles that provide metabolic benefit. This approach may help support the adoption of wearable robotics in real-world, dynamic locomotor tasks by enabling comfortable, tailored, and adaptive assistance.
Benjamin A Shafer, Sasha A Philius, Richard W Nuckols, James McCall, Aaron J Young, and Gregory S Sawicki. 2021. “
Neuromechanics and energetics of walking with an ankle exoskeleton using neuromuscular-model based control: a parameter study.” Frontiers in bioengineering and biotechnology, 9.