Design of thin McKibben muscle and multifilament structure

Abstract Current McKibben muscles are usually 10–40 mm in diameter, which makes them very stiff during contraction and difficult to deform rendering them unsuitable for dense mounting with shape adaptability in small spaces. In this research, to solve these problems, our group has developed the thinnest McKibben muscle reported until now. Bundling the muscles results in a multifilament muscle of the desired shape and flexibility. This paper reports the design of the thin McKibben muscle and the multifilament muscle and their static characteristics. In addition, we propose two theoretical models of multifilament muscles and derive their theoretical characteristics. The static characteristics of multifilament muscles with various design parameters have been evaluated through experiments and modeling. As a result, the greater contraction ratio of the multifilament muscles compared to that of the single muscle was demonstrated both theoretically and experimentally.