2018 年 84 巻 857 号 p. 17-00299
A pneumatic artificial muscle is a rubber actuator activated by air pressure. It is lightweight and has the high power density compared to other actuators such as motors and fluid powered cylinders. In addition, it can provide high compatibility with human since its flexibility. Authors have developed the Straight-fiber-type pneumatic artificial muscle which has high output and high contraction amount compared to the McKibben type artificial muscle that is widely used. However, the lifetime of the Straight-fiber-type pneumatic artificial muscle has not been considered so far. In this paper, effects of aspect ratio and materials on the lifetime of the artificial muscle are examined for prolonging the lifetime. Firstly, the desirable maximum stretch rate of the material is developed. Secondly, fatigue life is measured by reducing the elongation of the rubber material by changing the aspect ratio of length and inner diameter in the SF-ARM. Finally we measure the influence on the output characteristics by changing aspect ratio. The result shows relationship of the lifetime and the aspect ratio of the artificial muscle. We showed that the artificial muscle’s lifetime and contraction characteristics can be selected according to the application.