Thread: control system programming
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Unread 23-06-2002, 22:14
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#0047 (ChiefDelphi)
  
Join Date: May 2001
Location: Pontiac, MI
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Loosing output & breaking worm gears
Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]


Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.

Posted on 3/4/2000 5:09 PM MST


In Reply to: Re: Adjustment Screw on Motors. posted by Justin Stiltner on 3/4/2000 4:08 PM MST:



One option we explored last year when we discovered to our shame and horror just how backdriveable the Delphi Power Sliding Door Motors were, we too looked at the option of overtightening the screw on the motor armature.

It may work in the case you are looking into because you are really only trying to match free speeds,

BUT...

... I have a word or two of caution for teams trying to use such methods as a means of not falling when their robot is hanging:

Be careful.

There are two problems you can run into.
#1, you can easily loose 50% of the output of your motor this way -- even if you can afford the loss of stall torque, that is a lot of heat into those motors. If it is a motor you use a lot during a match you will run the risk of tripping the internal circuit breaker on the Delphi Power Sliding Door Motor (the same holds true for the window motor and the seat motor by the way).

#2, Even if you can stand the loss of output and the heat in the motors, you can tighten them so tight that if something DOES backdrive the motor (another robot trying to pull you off the bar, for example ;-) the plastic worm gears or the even the motor shafts can be damaged. Again, using our robot last year as an example, we tightened the nut so tight at one point that we could not backdrive the motor even with the weight of the robot working against it BUT our nice double D shaft looked like a piece of saltwater taffy after a match or two. Even our team, with as relatively easy access to spare power sliding door motors as we have, thought this was an unreasonably short motor life ;-) A redesigned mechanism allowed us to sleep at night without fear of having to replace motors rapidly.

Just a message from a team that has been there and done that. Take it for what it is worth.

Joe J.


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