Shape memory alloy actuator

摘要

A controller ( 44 ) for a SMA actuator ( 2 ) includes an electgric power source ( 46 ) for applying an electric current through an SMA element ( 8 ), a sensor ( 48 ) to detect change in an electric resistance of the element ( 8 ); and a regulator ( 50 ) for controlling the magnitude of the applied electric current. The regulator ( 50 ) applies a first current above a safe limit current for the element ( 8 ) until a selected change in the electric resistance is detected and applies a second current less than the first current after the change is detected.