After realising that we could not get enough power through a long length of nitinol with a 6volt battery we decided that proper calculations be made to determine exactly how much power we would need to power a certain length. To work this out we used good old Ohms law, which states that V= I X R, where V is Power, I is current and Ris resistance. The first step then is to measure the resistance of the nitinol - Not successful as the video below shows:
We decided to go with the figures printed on the Card that comes with a pack of flexinol for the values. Bizzarely it was concluded that the thicker the wire the less voltage required to power the nitinol. And if using nitinol of 375um, the maximum length you can power from a 9volt battery is 38cm. This link is a really good primer on nitinol calculations and even has some values to use in rough calculations. As a general rule for muscle wire for every centimetre you add 0.3 volts. which when tested was near true, but what we did learn from today was the fact that the thicker the wire the less amount of power it needs... which is the complete opposite to many other wires. So onwards we go, its better this way as it means less batteries and more movement.
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