Improved Features of An Amagnetic Push/Pull Linear Actuator Including NiTi Wire: Design and Characterization

With respect to other SMA linear actuator designs, tensed wires can provide high force output but a limited stroke length. In order to maintain elevated loading capabilities and extend the motion range, a possible actuator design is obtained by spooling the wire between two sets of pulleys. The presented linear actuator is an implementation of this type of design displaying several improved features. In particular, the actuator is able to provide force both for pulling and pushing loads. Wire coiling design is optimized to boost force output and to impart amagnetic characteristics to the actuator. A prototype of this device has been built, which mounts 0.2mm commercial educated NiTi wire, generating a maximal force in excess of 30N and a maximum pushing/pulling length of 7.5cm. The actuator is activated by a minimum voltage of 40V and it is 15cm×10.5cm×2.5cm in dimensions and 300g in weight. The possible application spectrum comprises mechanical actuation, particularly in environments requiring low electromagnetic noise levels, biomedical devices, robotics, aerospace, automotive, etc.  Furthermore, the same actuator can mount wires of different diameters, allowing for fine adjustments in terms of force output requirements, and the general design is easily scalable, so that it can become a viable solution for even more applications.