Quote:
Originally Posted by Rex114
A key thing to keep in mind when deciding where to mount a potentiometer is where will the potentiometer get the most resolution. Generally there are two types of potentiometers, 3/4 turn and 10 turn. You'll want to mount the potentiometer where it will take close to full advantage of number of turns, in order to increase the resolution and give your programmers better feedback data. For instance, if you have an arm that goes from pointing directly down to directly up, that is a 180 degree change, and a 3/4 turn pot mounted directly to the arm joint would work. However, if you wanted to have your potentiometer in a slightly less precarious position (ie. not on the top of your robot) you could attach a 10 turn potentiometer to one of the gear/chain reductions (if you have any) that would roughly translate 10 turns of the pot to half a revolution of the arm (a 20:1 ratio), given that the arm is still only traveling from down to up.
As far as actually mounting the pot, be sure not to mount it anywhere where significant side load will be applied, since more than a little side load can break the pot. A safe bet would be to mount the pot directly to the one of the arms drive shaft that is already supported on both sides, via some sort of coupler. We've used pots every year the last 4 years for various things from arms to shooters to crab drives, unfortunately I don't have any close-up pictures on how we mounted them. Hope this helps.
Mike C.
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If you buy decent pots, (I'm very partial to the
ETI MW22 series. ~$10ish on mouser)you can get 3, 5 and 10 turns.
Also, using surgical tubing as a flexible coupler idea. I first saw 330 do this last year, and have used it in several situations since. Very easy to do, and makes up for poor tolerances. Also, it will slip before breaking the POT if you have it go too far for some reason.