Exploring SMA & TEC Devices for Response Time Improvement

[petitericeball]

Hi, I'm currently working on a project and I was wondering whether you guys were familiar with these "devices". SMA's are shape memory alloys, and TEC's are thermoelectric coolers/peltiers. I tried looking for a pretty long time to find the specs on shape memory alloy (more specifically NiTiNOL) and can't seem to be able to find the any force tests. The idea for this project is to increase response times by using a TEC rather than air cooling, and possibly using the TEC to heat the wire as well, depending on if it would be faster to heat with current running through the wire, or with the TEC.

I'm also wondering how I would control this. I'd assume I'd need to monitor temperatures so I don't "reset" the SMA, and I'd also need to monitor position (length) of the SMA, but since length/force/temperature are related, there might be a way to connect the 3 with some amount of error due to changes in ambient. I'm planning on using wires around 1mm maybe, and will probably eventually be using a 100ma or so lipo battery to run this.

Thanks so much!

 

[anorlunda]

I'm also wondering how I would control this. I'd assume I'd need to monitor temperatures so I don't "reset" the SMA, and I'd also need to monitor position (length) of the SMA, but since length/force/temperature are related, there might be a way to connect the 3 with some amount of error due to changes in ambient.

In control design, that would be a bad idea. We normally try to make each control loop as independent as possible. Although there might be come cross dependencies in the process between loops, that is an obstacle, not an advantage. A control system adding the three kinds of error in one controller would be a mess.