A Soft-Exosuit Enables Multi-Scale Analysis of Wearable Robotics in a Bipedal Animal Model

Abstract

Wearable robotics offers a unique opportunity to explore how biological systems interface with engineered parts. But, due to a gap in understanding of the underlying biological mechanisms at work, the state of the art in design and development is a sophisticated form of automated trial and error. Progress is hampered by the difficulty of assessing the direct impact of wearable robots on underlying muscles, tendons and bones during human experimentation. While animal models have provided an experimental platform to explore other biological mechanisms, as of yet, no animal model of a wearable robot during locomotion has been developed. To fill this gap, we have built the first ever wearable robotic device for a freely-Iocomoting, non-human, bipedal animal (Numida melaegris = Guinea fowl), a species whose gait closely mirrors human locomotion mechanics. We found that a spring-loaded soft-exosuit that passively augments the energy stored in distal tendons was both well tolerated and provided consistent torques. Preliminary data showed birds systematically change their kinematics in response to changes to exo-suit spring stiffness, adjusting the timing but not magnitude of the assistive torques. This animal model for wearable robotics allows experiments up and down the broader spatiotemporal scale that are not currently possible in humans. With it we can address questions from short-term adaptations in musculoskeletal dynamics within a single step to broader behavioral and physical changes that come with long term use.