Development of a smart artificial muscle using optical fibres

Abstract

A McKibben artificial muscle is a fluid-driven soft actuator comprising sleeve fibers and rubber tube. However, as typical bulky and rigid displacement sensors are unsuitable as sensor elements in soft actuators, displacement sensing is challenging for the McKibben artificial muscle. Therefore, we propose an optical fiber-based smart artificial muscle (OSAM) to estimate self-displacement from the bending loss of the optical fiber used as the sleeve fiber. The optical fiber can be effortlessly integrated into the OSAM sleeve using a braiding machine, which is generally used for manufacturing strings, easing the mass production process. the radius of curvature of the optical fiber changed when the OSAM was driven. The displacement of the artificial muscle was estimated based on the sensor output. To demonstrate the usefulness of OSAM, displacement feedback control experiments were conducted using optical fiber sensors integrated into OSAM. From the results, OSAM's displacement showed a good response to the target displacement. Therefore, the developed artificial muscle can facilitate displacement feedback control without requiring external sensors, which in turn can improve the performance of rehabilitation and wearable devices.