Experimental Evaluation of Textile Mechanisms Made of Artificial Muscles

Abstract

Pneumatic artificial muscles have some advantages. Especially, the flexibility of artificial muscles contributes to compose novel mechanisms. The flexibility of pneumatic artificial muscles releases us from the spatially strict design that is necessary for rigid mechanical mechanisms. It could actualize compact mechanisms consisting of fewer components. The thin McKibben muscles are more flexible than conventional McKibben muscles. Authors succeeded in manufacturing novel soft mechanisms that are composed of only woven artificial muscles and strings. We called this mechanism active textile. The structure is uniformed with woven artificial muscles; nevertheless, the forms and movements of mechanisms are diverse. We aim to establish a design method for these active textiles. Thus, we should know how the expansion of muscles affects the behavior of mechanisms. We reported that deformations of active textiles are changed by woven structures. In addition to that, wefts' characteristics such as cross-sectional shape, bending stiffness and elasticity determine the characteristic of a textile. Deformations of active textiles are caused by the contraction and the expansion of thin McKibben muscles. In this paper, authors focus the contraction in the wefts direction of active textile that is caused by the expansion of thin McKibben muscles as warps. We fabricated three different active textiles that made of thin McKibben muscle and three different strings. We observed experimentally the contraction behavior in the weft direction of active textiles: the contraction characteristics the relationship between applied pressure and contraction ratio and the relationship between applied pressure and contraction force. As result, the contraction characteristics of active textiles are changed by using different strings as wefts. Maximum contraction force is caused by using thin strings, and the hysteresis of the active textile that made of elastic strings is small.