Design of a novel compliant differential Shape Memory Alloy actuator

This paper presents a novel compliant differential (CD) Shape Memory Alloy (SMA) actuator with improved performance compared to traditional SMA actuators. This actuator is composed of two antagonistic SMA wires and a mechanical joint coupled with a torsion spring. The torsion spring is employed to reduce the total stiffness of SMA actuator and improve the range of motion. The antagonistic wires increase the response time as one wire can be heated up while the other wire is still in the cooling process. Dynamic model of this actuator was established for control design. Experimental results proved that this new actuator can provide larger output range of motion and faster response speed than traditional SMA actuators under the same conditions. Sine wave tracking with 0.05 Hz, 0.08 Hz and 0.1 Hz were performed and our results demonstrated that this compliant actuator has good tracking performance under simple PID control.