Electronic Instrumentation for Shape Memory Alloy Actuators

Abstract

Shape memory alloy (SMA) actuators have been increasingly found applications due to their low weight and high power capacity. Additionally they are able to function as a sensor. Upon phase transformation, the material changes its electrical resistance. Phase transformation in SMAs occurs either by loading or heating the material. Since SMAs materials are usually metals, heat can be produced by passing an electric current through the alloy. This idea in mind, the present work reports the development of electronic circuits for power supply, current measurement and voltage measurement for shape memory alloy actuators. For validation of the operation of the designed circuits, a NiTi helical spring type alloy actuator was tested. The actuator was mounted on a mechanical platform; it was possible to determine its thermal behavior and force generation. Characteristic operation curves of the helical spring type actuator are presented.