Soft actuator having cooler, wearable robot having the same, massage device having the same, and method for controlling the same

A method for controlling a soft actuator, in which the soft actuator comprises:

• a plurality of shape memory alloys configured to be contracted or relaxed according to a temperature change;
• a cooling part configured to cool down the shape memory alloys of the plurality of shape memory alloys forcibly;
• and
• a controller configured to control a power supply part so that a power is blocked to be supplied to the shape memory alloys of the plurality of shape memory alloys and the power is supplied to the cooling part, when the shape memory alloys of the plurality of shape memory alloys are changed to be in a relaxation state,
• the method comprising:
• spraying cooling air to make direct contact with the shape memory alloys of the plurality of shape memory alloys, for increasing a relaxation speed of the shape memory alloys of the plurality of shape memory alloys, when the shape memory alloys of the plurality of shape memory alloys are in the relaxation state,
• wherein the shape memory alloys of the plurality of shape memory alloys extend in a first direction, and
• wherein the cooling part comprises an inlet flow, having a plurality of inlet portions, the inlet flow being extended in a second direction perpendicular to the first direction and configured to flow the cooling air to the plurality of inlet portions.