Subject:
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Re: Autonomous Robot
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 8 Aug 2000 17:11:03 GMT
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Viewed:
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1354 times
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"Ian Warfield" <ipw47@hotmail.com> wrote:
> In lugnet.robotics, sjbaker1@airmail.net writes:
> > The only snag I can see is that when the first laser is being acquired, • both
> > the tower and the robot have to spin. It might take a LOT of rotations • for
> > them both to happen to be pointing in the right direction for an
> > acquisition.
>
> Not if you used an omnidirectional laser sensor. Picture, instead of only • one
> face of paper, a paper cylinder. There would be a tube of paper mounted • on
> top of a circular LEGO piece (or *pieces* arranged in a circle) with a • paper
> top. All sides of the cylinder except from the bottom would be paper. • Now
> stick a light sensor vertically upward through the bottom of the cylinder.
> Assuming the paper is diffuse enough, a laser striking anywhere on the • paper
> should make it grow brightly enough to be seen by the light sensor.
>
> (Even better, if it's available - use a block of frosted or translucent
> glass. This would transmit light even better than the paper would. • Wherever
> the laser strikes the block, the whole thing would glow bright rose pink.
> Stick it on top of a light sensor.)
I find Ian's proposal about the laser tower very clever.
The only bad point about using an omnidirectional laser sensor on the robot
is it can't get any idea of its heading.
> > Thinking about precision - how accurate can you make a lego gear
> > train/rotation sensor point? Seems to me like the slop in the gears • would
> > limit you to perhaps 1 degree precision.
>
> Only if you hooked the rotation sensor directly to the motor. The slack • isn't
> all that bad unless you use millions of gears. If you geared the turning • down
> quickly enough (i.e. with the shortest gear train) you wouldn't have that • much
> to worry about.
I love Paolo Masetti's solution to reduce the slop in the gears: the movable
part is attached to a rubber that keeps it gently pulled. This way the teeth
of the gears stay always in touch on the same face and you can get very
precise measurements.
His Indy robot used that idea and won our ItLUG line following contest
running at an amazing speed :-)
Ciao
Mario
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Message is in Reply To:
 | | Re: Autonomous Robot
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| (...) Thanks! (...) Not if you used an omnidirectional laser sensor. Picture, instead of only one face of paper, a paper cylinder. There would be a tube of paper mounted on top of a circular LEGO piece (or *pieces* arranged in a circle) with a paper (...) (25 years ago, 8-Aug-00, to lugnet.robotics)
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