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Subject: 
May SMART meeting; retro-reflector data
Newsgroups: 
lugnet.org.us.smart
Date: 
Wed, 9 May 2001 06:38:54 GMT
Viewed: 
929 times
  
This is a reminder of the upcoming SMART meeting.  It will be May 19th, 2pm,
at the Bellevue Library, room 1.  (Check out our meeting page at
http://www.lugnet.com/org/us/smart/~48/meetings/ if you haven't done so yet!)

At the meeting we'll have brief introductions, a show & tell of robots
brought by attendees, we'll run the mini challenge, and then vote on the
next mini challenge.

The mini challenge is to build a robot that will move around a table without
using rotating wheels or equivalent, without falling off the edge, and stops
next to a heavy object covered with reflective tape.

Not using rotating wheels or equivalent means no tracks, and nothing
rotating touching the ground and moving in a simple rotational movement that
could just as easily have been a wheel.  Use some other method of
locomotion: walking, shuffling, wobbling, or what ever other novel ideas you
can come up with.

I have done some quick tests with the retro-reflector tape we'll be using on
the object, and I suggest that if you intend to actively search for it, that
you set your light sensor to raw.  Calibrate your own light sensor, don't
rely on these readings; they are just to give you an idea of what you're
working with.  Light sensors have different sensitivities, and the room
light makes a big difference as well.

The values I got in a moderately lit room are as follows:

Rest of room: 760-800
Reflector at 3 feet: 750-760
Reflector at 9 inches: 740-750
Reflector at 6 inches: 730-740

So you can see that you have to be pretty close to get a significant
reading, but sweeping around, you should probably be able to narrow down
your search to a couple of directions.  Unless you're extremely clever, I
would recommend against simply trying to detect the object and moving in a
straight line towards it!  Remember to test for the edge of the table!

After the mini challenge, we will vote for the next meeting's mini
challenge.  The three options up for vote are:

Trailer push - push a trailer six feet
Obstacle Course - climb over 2x4s
Line Tracking - follow a narrow line with very sharp turns

You can read the more detailed descriptions here:

http://www.lugnet.com/org/us/smart/~48/ideas/challenge-004
http://www.lugnet.com/org/us/smart/~48/ideas/challenge-005
http://www.lugnet.com/org/us/smart/~48/ideas/challenge-006

Hope to see everyone at the meeting!

--
  David Schilling



Message has 1 Reply:
  Re: May SMART meeting; retro-reflector data
 
(...) Thanks, David. I would like to add that using a Lego lamp will significantly improve your ability to detect the reflector. These lamps are part if the ultimate accessory kit and can also be purchased from Lego Shop-At-Home and/or Lego Dacta. (...) (24 years ago, 9-May-01, to lugnet.org.us.smart)

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