Sensorless Position Control Based on Resistance and Heat Transfer Models in Shape Memory Alloy Actuators

Abstract

This paper presents a sensorless position control approach based on the electric resistance model in shape memory alloy (SMA) actuators. The position estimation approach using electric resistance value has been proposed as the sensorless control in this approach for SMA actuators. However, a simple relationship between the resistance value and position results in position estimation error. Therefore, an accurate model is crucial to improve the position estimation performance. In this study, the resistance model is considered the material properties of austenite, martensite, and their phase transforms. In addition, the effect of the temperature in the SMA is considered by the heat transfer model. The position is computed using the applied voltage and current signals through the constructed electric resistance and heat transfer models. Based on the estimated position, a sensorless feedback control system is designed. The effectiveness of the proposed sensorless control approach is verified by conducting experiments using the SMA actuator.