Macroscopic SMA wire bundle actuator/sensor system: Design, measurement, control approach

Prestrainend shape memory alloys (SMA) change their length when heated above their transformation temperature. Based on this property this paper presents the design of macroscopic SMA actuators scalable in force and length that keeps up a short cool down time to guarantee a high frequency of contraction/stress cycles and the possibility of arranging the fixings in any direction. A new model of the macroscopic actuator has been developed. The model describes the actuator's behaviour and offers the possibility to use the resistance of the actuator as a linear position encoder. Experimental results demonstrate that the newly developed SMA device can be used as actuator and position sensor. The measurement shows that the fixings of the actuator can be shifted or rotated without influence on the actuators behaviour and therefore various uses are possible. Based on the measurement a first control approach has been developed and tested.