METHOD FOR DETECTING DISPLACEMENT OF SHAPE MEMORY ALLOY COIL ACTUATOR, AND ACTUATING APPARATUS AND SYSTEM USING THE METHOD

Provided is a method for detecting a displacement of a shape memory alloy coil actuator, and an actuating apparatus and system using the method, the method for detecting a displacement of a shape memory-alloy coil actuator comprising the steps of: (a) detecting steady state voltage (V_steady) and current (I_steady) of SMA coil actuator to which PWM voltage signal is applied; (b) detecting the time (t_nτ) to reach the current corresponding to nT (T is a time constant and n is an optional number) by analyzing the transient response of the current flowing in the SMA coil actuator; (c) detecting the inductance (L) of the SMA coil actuator by means of detected V_steady, I_steady, t_nτ values; (d) and detecting the displacement of the SMA coil actuator by means of the previously stored mutual relationship between the inductance of the SMA coil actuator and displacement, and the inductance (L) value of the SMA coil actuator.