SMA power drives for engines

One of the studies that was dealt by Ing. Peter Drahoš, PhD. on KAR STU was system of motor drives for robots with the help of shape memory alloys – SMA. These materials are able to change the thermal enengy into the mechanic work by the inner molecular power – the change of inner crystal grid. These alloys represents so called intelligent materials that might be use in automatic control actuators

SMA:
Shape memory alloys are able to remember particular and complicated shapes and mechanical work, but only in one direction, on the basis of the temperature changes. Half-way and two-way memory of intermetalic compounds such as NiTi, CuZnAl, CuAlNi and other are used.The best known and also the most frequently used SM alloys that was made in 1962 in USA is Nitinol (nickel 55 % and titanium 45 %).

Usage in robotics:
SMA is used in robotic motor drives, when it’s possible to specify the position with temperature regulating. The movements can be controlled with electric heating.The micro manipulators were developed, when using NiTi wires with the diameter 0,2mm and return spring. It was possible to prove, that SMA manipulators are very efficient for microrobots. The most succesful usage shoulg be in the area of microrobots, micro manipulators, tentacles, artificial fingers etc.



SMA power drives:
SMA can have several variants . The basic shapes are: wire, bar, strip, spring and general shape . The usage of SMA wire is visigle on the following picture. As an example of SMA drive usage in robotics, the fully functional model ROBOT HAND (on the picture), that was created on SjF SVŠT is presented.

Conclusion:
Generally, SMA motor drives are able to act with great power on relatively short path. Their shape adaptability enables to design appropriate power engines. They are very reliable in the area up to 100g and also simple when talking about construction