Shape memory alloy actuators with controller(cont'd...)
Prior work on shape memory actuator(cont'd...)
In 2004 Pulnev et. al. [Pulnev 2004] proposed two kinds of linear actuators (for one and two directions of movement) based on SMA bending elements made of Cu-Al-Ni alloy single crystal [Pulnev 2004]. Figure below displays the scheme of the actuator generating force in one direction: heating causes the SMA element to straighten, thus forcing the output element to shift from point A to point B and deforming the steel spring. During cooling the steel spring forces the SMA element to bend again and the output element to return to point A.
Figure presents the scheme of the actuator generating force in two directions: heating causes the first SMA element to straighten and forces the output element to shift from point A to point B. The second shape memory alloy element is thus deformed [Pulnev 2004]. When the second shape memory alloy element is heated the first shape memory alloy element is forced to bend back and the output element to return to point A. Also for this kind of actuator no mechanical or experimental tests were carried out. This functioning principle that uses a shape memory alloy bending is also used in the rotational actuators developed by Priadko et al.
Figure: SMA linear actuator by Pulnev 2004. (a)Force in one direction (b) Force in two direction
In year 2005, Haga et al. [Haga 2005] proposed a mini-actuator used in a Braille display. In year 2005, Donnellan [Donnelan 2005] replaced the shape memory alloy wire with a shape memory alloy compression spring in order to obtain a larger stroke [Donnelan 2005].
[Jansen 2004] S. Jansen, J. Breidert, E.G. Welp, "Positioning actuator based on shape memory wires", 9th International Conference on New Actuators, Bremen, Germany, 2004.
[Strittmatter 2004] J. Strittmatter, P. Gumpel, "Shape memoryactuator for hydraulic valve ", 9th International Conference on New Actuators", Bremen, Germany, 2004.
[Pulnev 2004] S. Pulnev, I. Vahhi, A. Priadko, A. Rogov, "Miniature linear actuators based on CuAlNi shape memory single crystals ", in: Proceedings on SMST, 2004.
[Haga 2005] Y. Haga, W. Makishi, K. Iwami, K. Totsu, K. Nakamura, M. Esashi, "Dynamic braille display using SMA coil actuator and magnetic latch ", Sens. Actuators A, 119(2):316-322 ,2005.
[Donnelan 2005] Q.A. Donnelan, "Design and testing of linear shape memory alloy actuator, Final Report", National Science Foundation ,2005.