Patent ID: 7839260

Claim:
A method of controlling a shape memory element actuator including a tube member which is hollow and a shape memory element which is inserted through the tube member, where, one end of the tube member and one end of the shape memory element are fixed, and the other end of the shape memory element is mechanically linked to a driven body, and the other end of the tube member is fixed to a supporting member, and further including a force imparting member which exerts an external force in a direction opposite to a direction of shape change, by heating of the shape memory element, and a stopper which limits a movement of the driven body to a predetermined position in a direction of movement of the driven body, by the heating of the shape memory element, which is a method of controlling by passing an electric current through the shape memory element, and changing a shape of the shape memory element by changing a temperature of the shape memory element, and changing relative positions of the driven body, and one end of the tube member, on a side which is not fixed to the shape memory element, comprising: a limit resistance value detection step of storing in a control unit a resistance value when a resistance value of the shape memory element in a predetermined time interval has not changed by a predetermined resistance value step width, as a limit resistance value which limits a setting range of a first target resistance value; and an input electric power optimization step of optimizing an electric power setting which is to be input to the shape memory element by a feedback resistance circuit by changing an input voltage pattern such that, the resistance value is in a predetermined acceptable range, with respect to the target resistance value which is set as a first target resistance value, wherein the limit resistance value detection step and the input electric power optimization step are carried out upon moving the driven body by inputting a constant voltage pattern at a predetermined frequency, at the time of using the shape memory element actuator, by using a control means which includes a target resistance value determining means which sets the target resistance value of the shape memory element for moving a predetermined position of the driven body, as the first target resistance value, a resistance value detecting means which detects the resistance value of the shape memory element, and a resistance feedback control circuit which carries out a control of a feedback based on information of the target resistance value and the resistance value, and an input voltage of the voltage pattern at the limit resistance value detection step is input by a first voltage value, and the input voltage at the input electric power optimization step which drives the shape memory element is input by a second voltage value which is smaller than the first voltage value.