Development of a Novel Micro-actuator Driven by Shape Memory Alloy

Abstract

This paper presents a novel microactuator driven by shape memory alloy (SMA). First, the helical spring-shaped SMA is fabricated from SMA wire (Ti50%-Ni45%-Cu5%) with one way shape memory effect and 0.6 mm in diameter. Subsequently, a compliant tube-type microactuator driven by helical spring-shaped SMA is developed. The performances of the helical spring-shaped SMA and the compliant tube-type microactuator, such as the response time, the recovery force and the surface temperature in terms of the driving currents, are investigated. The driving circuit system comprising a pulse width modulation (PWM) control circuit is used to drive the actuator. Experiments demonstrate that control of the SMA actuator using PWM effectively reduces the energy consumption and ensures a short cooling time to guarantee a high response time in actuating cycles. Finite element software (COSMOSWorks) is applied for the analysis of the compliant tube-type actuator, which aim is to demonstrate the agreement between the theoretical analysis and experiment as well as to improve the performance of the actuators.