Accurate position control of shape memory alloy actuation using displacement feedback and self-sensing system

Numerous shape memory alloy (SMA) linear actuator designs have been proposed for accurate position control using different techniques such as displacement feedback, temperature feedback, force feedback and resistance feedback. Each of these techniques has its advantage, as well as constraint and limitation. Self-sensing SMA actuation is considered to be cost-effective as it eliminates the use of external sensor in the system. However, its performance relative to other methods has not been widely discussed. In this study, two techniques were proposed for accurate position control of displacement in the range of 2 mm. The performance of the system using position feedback and self-sensing SMA actuation was evaluated through an experimental test bench developed in this research. The results show that the position feedback system has faster time response and higher accuracy, however, it is costly due to the laser displacement used in the system. The self-sensing SMA actuation produced slower time response and the accuracy was less than 90%. It was found that by providing tension to SMA actuator, the actuation temperature of the SMA actuator increased and the accuracy of the self-sensing system can be improved.

Automated summary

Two techniques were proposed for accurate position control: position feedback system and self-sensing SMA actuation system. The position feedback system showed faster time response and higher accuracy, but with higher cost due to the use of laser displacement. On the other hand, the self-sensing SMA actuation system had slower time response and accuracy below 90%, which could be improved by providing tension.