Subject:
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RE: One tip, and a few questions.
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 21 Nov 1998 02:15:09 GMT
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Original-From:
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Eric Hodges <eric.hodges@platinumSAYNOTOSPAM.com>
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Viewed:
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1224 times
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The scale is from 0-100, where 0 is dark and 100 is light.
Why does everyone want to use a laser pointer? This seems like the hard
way to do things. I use a big Mag-Lite flash light. The beam is fairly
directional, but large enough that the bot can stay within its bounds. A
laser pointer seems like it would be harder for the bot to detect, since
the light is coherent.
I have 2 basic strategies for driving into the light. One uses a single
light sensor. The bot swivels until the sensor value starts to decrease,
then swivels back and goes forward until the light decreases by some fixed
percentage. Then it starts swiveling again, but in the opposite direction.
This is good for finding the boundary between light and darkness.
The other uses 2 sensors and compares the values. The sensors are mounted
on a V shaped platform so they point in slightly different directions
(about a 20-30 degree angle between them). If both sensors are within a
fixed percentage of each other, I drive both motors. When the difference
becomes too great, I drive the motor on the dark side of the bot. This
tends to aim the bot directly into the light and it stays a very stable
course all the way in.
Both strategies deal with ambient light levels very well. Since I don't
have any fixed values to indicate what is light and what is dark, they
always end up going toward the first bright thing they see. If it's a
reflection off a wall they bump into the wall and start spinning around,
usually finding the source of the reflection.
-----Original Message-----
From: Richard Bram [SMTP:rbram@concentric.net]
Sent: Thursday, November 19, 1998 6:41 PM
To: lego-robotics@crynwr.com
Subject: One tip, and a few questions.
My one tip (probably you all already know this) is I just discovered
that Duplo blocks are compatible (i.e. will fit with) regular Lego
blocks. Duplos are the big toddler sized bricks, and come in all
shapes, etc. They might be useful for people wanting larger structural
elements in their robots, and appear to be a little lighter than an
equivalent volume of lego blocks.
My questions involve the light sensor. I am using the NQC tools since I
don't have a Windows machine. Can somebody tell me the allowable values
returned by the sensor? And which direction is lighter, lower numbers?
Also, I'm thinking of trying to activate the light sensor with one of those
cheapo laser pointers. I thought it would be cool to zap the sensor from
across the room, and make it change direction. But even the tiny lasers
have those "Do not look directly into beam" warnings. Wonder if anyone
could guess whether it might also blind a sensor permanently. How fragile
are those things?
Thanks
Rick
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Message has 1 Reply:
 | | Re: One tip, and a few questions.
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| In article <01BE14B1.B5C66E80.e...inum.com>, Eric Hodges <eric.hodges@platinum.com> writes (...) In the fifties I built a heat-seeking swivelling "eye" using that method with valve (tube) technology. The IR detector was an old fashioned glass (...) (26 years ago, 21-Nov-98, to lugnet.robotics)
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