Continuous rotary actuator using shape memory alloy

A continuous rotary actuator using a shape memory alloy, the continuous rotary actuator comprising:

• an inner drum in an outer cylinder, the inner drum rotating around an axis, the axis constituted by a rotating shaft;
• first and second movable contact members disposed between the outer cylinder and the inner drum so as to be able to rotate together with the inner drum;
• first and second shape memory alloy torsion springs each having first and second ends attached to the first and second movable contact members, respectively, the first and second shape memory alloy torsion springs being wound in opposite directions from each other, wherein one of the first and second shape memory alloy torsion springs is unwound so as to recover a memorized shape thereof when subjected to electrical heating, and wherein another of the first and second shape memory alloy torsion springs is wound accordingly;
• each of the first and second movable contact members being provided with an engaging member, the engaging members being freely engageable with the outer cylinder and the inner drum, wherein when the first and second movable members are engaged with either one of the outer cylinder or the inner drum, then the first and second movable members are not engaged with another of the outer cylinder or the inner drum, and wherein when one of the first and second movable contact members is engaged with the outer cylinder, then another of the first and second movable contact members is engaged with the inner drum;
• switching means for alternately switching the electrical heating of the first and second shape memory alloy torsion springs and the first and second movable contact members at every rotation of the inner drum at a fixed angle, thereby continuously rotating the inner drum in one direction.