Abstract
The ordinary control method, PWM ( : pulse width modulation) control method, of SMA ( : shape memory alloy) actuator has the basic defect, that is, the response of SMA actuator controlled by this method is very slow, because the maximum supplying voltage to SMA must be limited low in order to prevent SMA burning, considering its unknown temperature. In this paper, a new control method is proposed to improve the response of SMA actuator fast by limiting the temperature of SMA below the limited value instead of limiting the maximum supplying voltage to SMA. Therefore, this new control method allows us to use powerful drivers with high supplying voltage to SMA so as to make the heating speed of SMA fast. At first, a temperature sensor system to detect the SMA's temperature was made by solving several problems. Next, the experiments of the position control by a new SMA actuator system with temperature threshhold for SMA were carried out. Their results show that the responses are much faster than those by the ordinary control method. Besides, some conditions to improve the response of the new proposed SMA actuator further are gotten.
