Characteristics of a SMA Actuator of Knitted Structure for Artificial Muscle

To realize an artificial muscle type actuator, which has both the large contraction and force, we examine a SMA (shape memory alloy) actuator of knitted structure. Concerning about the contraction and the force of the experimental models, which have cylindrical knitted structure, we investigate the characteristics of the unit structure and the total, respectively. The expirimental results, which are knitted with SMA wire of 0.15 mm diameters, show that the actuators have enough output force and contraction using as artificial muscles. We propose a fundamental model to estimate the mechanical characteristics about SMA actuators of knitted structure. Comparing the calculational results about the contraction and the tension with the experimental, we verify the validity of the proposed model. It is found that we can design the artificial muscle type actuator, which has both the large contraction and force using the characteristics of the unit in the knitted structure.