抄録
This paper discusses stacked and folded bimetal sheets as a compliant actuator. The actuator consists of eight folded bimetal sheets. The sheets are stacked such that the folds of the eight sheets are aligned at the same location. As the folds are heated by using nichrome wire wound around them, the folds open to create rotational motion. The bimetal actuator was installed in a rotary swivel joint. The experimental results showed that the joint could rotate more than 90 degrees when the bimetal was heated at 140 °C. When the rotation motion was blocked, the maximum torque of over 30 gf·cm was obtained. The joint is compliant and thus can be rotated by an external torque. The measurement found that the stiffness is higher when the joint was rotated in the direction to narrow the bimetal folds. The joint was applied to a prototype multi-DOF arm with another bending joints. Total of eight joints, with four swivel and four bending joints, were installed in the arm such that each joint can be selectively actuated by heating. A simple motion was demonstrated, in which the bottom joints were actuated, such that the arm bends and swings around the vertical axis.
