Subject:
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Re: Backlash in Lego Gear Trains
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 8 Jan 2001 20:55:05 GMT
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Viewed:
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1150 times
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If you working on a Mindstorms project, then measure your position as close to
the output of your gear train as possible. This will eliminate the effect of
backlash on your positioning. However if the gear train is expected to hold
the final position against a torque in either direction, this won't work.
The way to eliminate backlash it to find a way to maintain a constant torque on
the drive train in one direction only. This way the gears only run off one
side of the teeth. The slop in the gear train is caused when the teeth switch
contact from one side to the other. If you can maintain contact to one side
only then the backlash will be greatly reduced.
How you implement this and whether it is possible to implement, depends greatly
on what you are doing.
For example: Take a device that needs limited horizontal positioning, Like a
plotter arm. An elastic or counter weight could be applied to the arm so it
was always pulled in one direction. The motor would then pull the arm in one
direction, and just let out the slack in the other but the pull through the
gear train would always be in one direction.
Derek
In lugnet.technic, Chris Mattson writes:
> Jerry,
>
> Precise positioning is my objective. And of course too much friction is a
> problem. I have'nt fooled around with this too much but, the LEGO gears, as
> designed, have too much backlash for my project (and as you suggest probably
> to keep the friction down). My project also involves a gear train which
> leads to a tolerance stack-up that ruins my precision.
>
> Do you know if the LEGO chain elements could help here?
>
> Chris
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Message has 1 Reply:
 | | Re: Backlash in Lego Gear Trains
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| (...) If you are building a scanning thing, this works really well. I built a camera that used the Lego light sensor, and I would get zig-zags between scan lines. I changed the software to wind it all the way back and scan from the same direction (...) (24 years ago, 9-Jan-01, to lugnet.technic)
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Message is in Reply To:
| | Re: Backlash in Lego Gear Trains
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| Jerry, Precise positioning is my objective. And of course too much friction is a problem. I have'nt fooled around with this too much but, the LEGO gears, as designed, have too much backlash for my project (and as you suggest probably to keep the (...) (24 years ago, 8-Jan-01, to lugnet.technic)
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