Sensor for linear distance

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Originally Posted by TAlholm

Alright, I got the chance to post a more in depth description.

The method for this is to track the human arm or leg and assist the recovery process by assist the movement of the arm or leg with an exoskeleton like frame. By slowing decreasing the assistance given to the arm or leg, the theory is that this could allow a way to possibly allow a faster recovery.

I feel like I'm doing my thesis again. Stroke recovery, accident, CP, or what? I'm interested in following this. Alright, so what you're after is a power assist. There's a few options here. Any chance you looked at HAL-5 by Cyberdyne?

I can see a few ways to do this. If you're trying to track the human limb relative to the exoskeleton, a string pot is one way to do it. Another way would be to use a pressure sensor between the exoskeleton and the limb. If you only need position of the skeleton, then you should probably use an absolute encoder hard attached to the limb joints. There are a few options for these.

The andymark string pot will work as a good prototype string pot, but it's a bit bulky and can be fragile. You don't want to hit the housing and damage it. If you go with an absolute at or geared to the hinge, andymark also sells a US Digital absolute encoder as well. You can get these with a 0-5V signal output, similar to the stringpot. Pressure sensors come in enough types, I'm not sure what to post but are usually a variable resistance.

What your best choice is will also be based on how you decide to implement your control loop feedback for the power assist. Have you decided on your process variable?