Accurate sensorless displacement control based on the electrical resistance of the shape memory actuator

This paper aims to implement the controllable deformation of a structure using Shape Memory Alloys (SMA) actuators. A sensorless displacement estimation method is proposed. This method is tested on a prototype composed of a disc, beams, and SMA actuators. By measuring the variation of electrical resistivity in SMA springs, as a feedback signal in the closed-loop position control, the surface displacement is obtained without any external displacement sensor. The proposed method is validated by comparing the displacement values estimated by the electrical resistivity measurement with those measured by a laser sensor. The estimated displacement and the measured displacement follow the reference displacement with steady-state errors, respectively of 1.14% and 0.42%.

Automated summary

This paper aims to implement controllable deformation of a structure using Shape Memory Alloys (SMA) actuators. A sensorless displacement estimation method is proposed, which measures the variation of electrical resistivity in SMA springs as a feedback signal in closed-loop position control to obtain surface displacement without external displacement sensors. The proposed method is validated by comparing estimated displacement values with those measured by a laser sensor, showing steady-state errors of 1.14% and 0.42% for the estimated displacement and measured displacement, respectively.