Development of contraction and extension artificial muscles with different braid angles and their application to stiffness changeable bending rubber mechanism by their combination

Recently, there has been increasing researches on the McKibben type artificial muscle, because it is small, light, and high powered. In this study, in addition to the contraction artificial muscle, the stiffness change artificial muscle and the extending artificial muscle have been developed. By nonlinear finite element method analysis, the best sleeve knitting angle has been derived to achieve the stiffness change and the extension and contraction motions. From the results, three kinds of artificial muscles realizing contraction and extension motion, and the stiffness change have been fabricated. To apply high hydraulic pressure on the muscles, these are composed of the three layer tube and the reverse tapered plug. We confirmed that the three muscles respectively generate stiffness change, contraction, and extension motions successfully. In addition, the novel bending actuator has been developed by combining contractional and extensional artificial muscles. Bending motion with high stiffness has been realized.