SHAPE MEMORY ALLOY ACTUATOR PROTECTED BY ROLLED FILM TUBE FOR ARTIFICIAL MUSCLE

Abstract

In this study we aim to realize an actuator that is comparable with a natural muscle from a viewpoint of flexibility, the output force and the responses. We constructed the Shape Memory Alloy (SMA) coil actuator protected by “a rolled film tube” with the high heat resistance and the high flexibility, and it is named “the unit cell”. The SMA coil in the unit cell is cooled down by inert liquid flowing through the rolled film tube. Then we constructed an actuator named “a motor unit” with the larger output force by bunching up seven unit cells, and the characteristics of the motor unit are investigated by the experiments in which the motor unit is driven in Pulse Frequency Modulation (PFM) found in the bio-motion. The result of the experiments shows that the static characteristics of the output force and the displacement to the input pulse frequency in the motor unit near proportion relations in comparison with the unit cell still more and the output force increases almost seven times as large as the unit cell. Consequently, it is found that these actuators proposed can be employed as applications to a flow control valve and an artificial arm.