Braiding Thin McKibben Muscles to Enhance Their Contracting Abilities

This letter presents a novel concept of braiding thin McKibben muscles to improve their contracting ability compared to original muscles. Whereas a single original muscle and the conventional bundled muscle had a contracting ratio of 28%, braiding the muscles realized a contracting ratio of 37%. We designed, fabricated, and tested several prototypes with different braiding parameters, and demonstrated their effects both theoretically and experimentally. The results were promising and we believe that thin braided McKibben muscles will facilitate the development of novel musculoskeletal robots and be useful in various applications requiring soft robotic abilities.