Sensor for linear distance

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Originally Posted by TAlholm

I'm experimenting with a method that may allow faster and safer rehab for people with arm or leg injuries or who recently had surgery. For safety of the user, I am staying away from tracking rotation.

Ok, I get what you're trying to do, but I'd like to know why tracking rotation is less safe. Is your end goal to measure the distance between two fixed points or is it to measure the angle of a joint?

Depending on details for straight linear distance there are also linear encoders. Do you require an absolute measurement or a relative measurement from startup? How much precision do you require?

We've had some use with the stringpots from Andymark. You'll need to protect your strings to ensure they do not get caught on anything. Also, you'll have to be mindful of sensor noise. Precision was something like 1mm before sensor noise dominated (RoboRio as voltage source & measurement). A question is will your system be able to keep the noise low enough you'll have the precision you require.