Let's see if you can help me... (Motors)

[mentorDon]

on our arm, we decreased voltage input to the motors when the arm moves down because gravity is doing the work. We also use pots to determine arm position to adjust the voltage depending upon arm angle.

[Richard McClellan]

that sounds like a coding problem to me. Since the window motors have worm gears, they should have anti-backdrive, i.e. they should never just fall when you are going down. You should be able to program the arm to go to a certain height and stay there without stalling the motors or anything.

[Al Skierkiewicz]

Justin,
You would think that the motors you have chosen would not back drive but in the configuration you are using them, once they are moving the arm weight will continue the motion. Even if you set the "brake" jumper on your victors, it might not help. Some of the suggestions above will help the situation, I am a big fan of surgical tubing but it might not be suitable for you design. Changing the ratio of the output shaft to arm might also help. I think a combination of a few ideas will solve your problem.

[Cowmankoza]

[quote=richardmcc2;584083]that sounds like a coding problem to me. Since the window motors have worm gears, they should have anti-backdrive, i.e. they should never just fall when you are going down. [quote]

contrary to popular belief, worm gears do backdrive, it just takes a lot more force to do so, and given that it is being used on an arm, it is very possible that it will backdrive