Basic study for new type actuator using shape memory alloy

The actuators currently used practically in the industrial world are electric actuators and fluid actuators. Most actuators of small and medium size industrial robots have adopted electric actuators. The form of an electric actuator consists of AC or DC motors of a rotary type or a linear type. However, weight, sound of operation, the hardness of motion, and the power-weight ratio is mentioned as problems when using these motors especially for prosthetic hands. A new type of lightweight actuator is needed instead of a heavy weight motor. This actuator should solve the problems. We directed our attention to the new type shape memory alloy wire as a new actuator that can replace a motor. This shape memory alloy wire is called muscle wire. However, there are little data about this muscle wire. We have to know the characteristic of a muscle wire in case of new type actuator manufacture. Then, the purpose of this research is investigating the dynamic characteristic of a muscle wire. We measured the tension of a muscle wire, temperature change, and the rate of contraction.