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Subject: 
Re: MAP Bot
Newsgroups: 
lugnet.robotics
Date: 
Sun, 22 Nov 1998 16:39:27 GMT
Original-From: 
John Donaldson <jdonaldson@ghg.STOPSPAMnet>
Viewed: 
2324 times
  
Looking at the sensor inputs for the brick, I see they can be set to
  RAW
  BOOLEAN
  PULSE
  PERCENT
  DEG F
  DEG C
  ROTATION ANGLE

  I suppect ether the RAW or PULSE Modes would be usefull. The PULSE
Input would allow a FIX Range and the RAW would allow the BRICK to
determine Range.
  I too have found sites for the Sonar Sensor. PAUL/BOB you may know
these site.

   http://wirz.com/sonar/index.html - sonar
   http://www.robotstore.com/sensors.html - sonar
   http://www.acroname.com/robotics/parts/r15-sonar2.html - IR
   www.vernier.com/probles/motion.html - sonar
  Question 1: What is the best way to detect Motor Stall? Is it with the
Rotation Angle Sensor or is there a way to determine this from the Motor
Itself?
  Question 2: What is the voltage range of the analog input to the
brick, such as for the light sensor??

John A. Donaldson

Paul Davis wrote:

This is exactly what I wanted to attempt, I wonder how small those >units are
now, would it be possible to modify a brick to hold the parts?

-Paul-


Bob Wind wrote:

I like your idea, John.  I have an old Heathkit Hero Jr. robot
that had a Polaroid sensor, and tried to do what you are
describing.  The sensor was mounted directly in the body,
so the only way that I could scan was to turn the whole
robot.  When it turned, I couldn't get to accurately return
its original direction.  I thought of adding a rotatable sensor
but I never did it because the sensors cost $50 to $75
and I didn't want to cobble Hero by removing his internal
one.

A few months ago I found note on the web that old Polaroid
660 cameras have a sensor and drive circuit that is nearly
identical to the expensive Polaroid 6500 sensor.  They have
the same signals, but with different connection points.
Other web pages gave me the 6500 spec sheet and
a description how to use the sensor with a Basic Stamp.
Since that time I have bought two of these cameras for
less than $5 each at a garage sale and a Goodwill store.
I haven't used them yet.

A Basic stamp can easily create pulse signals to control
a radio control servo.  Perhaps the camera sensor could be
mounted to a radio control servo and be aimed and read by
a Basic Stamp.  The Stamp could communicate to the Lego
RCX via a the infrared link since it can send and recieve serial
data easily.  It could could gate a 38kHZ oscillator that
drives an infrared LED, and it could sense IR with a
$3.50 receiver circuit from Radio Shack.  Mount that
stuff and a battery to a Lego base plate, and you'd have a
nice ultrasonic ranging add-on for the RCX.

Bob Wind
rwind at gfn dot org
----------
From: John Donaldson <jdonaldson@ghg.net>
To: lego-robotics@crynwr.com
Subject: MAP Bot
Date: Saturday, November 21, 1998 5:34 AM

  I have a idea which is based on a project I worked on back in the
70's. It used one of the sonar devices that Poliord used to foucse their
camera with. This device is availible without the camera. It sends a
signal based on how far the object is.
  My idea is

  1. 2 motors to run bot foward/back/right/left.
  2. 1 motor to rotate sonar right to left.

  A. The bot would move forward a few feet.
  B. Stop then scan right to left with sonar.
  C. if opening found set bit in memory map
  D. if sonar detects dead end. turn bot 180 degs
  E. move back to first opening.
  F. if more than one opening, deceided which one to enter
  G. Turn bot to enter opening.
  H. goto A.

With enough battery power, it could roam the house or office.

John A. Donaldson



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