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Subject: 
RE: IR scanner
Newsgroups: 
lugnet.robotics
Date: 
Tue, 30 Nov 1999 15:25:46 GMT
Original-From: 
Jim Thomas <jim.thomas@trw.*IHateSpam*com>
Viewed: 
560 times
  
There is the classic Polaroid ultrasonic range finder.  I think someone here
was working on one of these or similar for lego?  They work on the reflected
signal approach.  Now I thought you wanted to do off board triangulation.
You can accomplish that using a omni-directional source on the robot and
three sensors around the room hooked up to your PC.  You might need custom
acquisition hardware or else the PC might have a ton of data to wade
through.

JT

-----Original Message-----
From: Christian Jacobsen [mailto:xtian@net-collect.com]
Sent: Tuesday, November 30, 1999 7:18 AM
To: lego-robotics@crynwr.com
Subject: Re: IR scanner


The longer the delay, the farther away the robot is from • the sensor.  And
the converse.

I don't think that light-pulse based distance measurements • will ever be an
option for Lego robots. But your idea can be used in
another context (that
has
been talked about around here).

Duh.  I spoke before I thought.  Sorry about that.


Namely, using a light beam as a directional beacon. •   [snip]
There is a sore spot here: the robot will be turning and
spinning - thus
the
angular position cannot be absolute.

Taking Jim Thomas' suggestion of using ultrasonic sound
instead of lasers,
you could install two ultrasonic sound sources on your robot
to solve the
angular position problem.  Set one source to scan a 180
degree arc in front
of the robot, and the other could scan the 180 degrees
behind.  Receivers
around the room could then tell you which direction the robot
was pointing.
The question is, how tightly focused can you keep the sound "beam"?

Heck, you might even be able to measure the Doppler Effect to
determine
how/where the robot is moving!

OK...I'll try to think a little more before I speak next time!  ;-)

- Christian





Message has 2 Replies:
  Ultrasonic range finder
 
I'm interested in "ultrasonic range finder" type of sensors. One that can return a rough raw value that can be converted into a distance (from the sensor to an object in front of it) would be great. By rotating it, and coupled with an angle sensor (...) (25 years ago, 30-Nov-99, to lugnet.robotics)
  Re: IR scanner
 
Jim Thomas <lego-robotics@crynwr.com> wrote in message news:BFBCB00A4D7BD21...TRW.COM... (...) here (...) reflected (...) How about several (>= 3) light sources in an otherwise dimly lit room, and the robot tracking them with a light sensor mounted (...) (25 years ago, 30-Nov-99, to lugnet.robotics)

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