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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Wed, 9 Aug 2000 22:28:12 GMT
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Viewed:
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712 times
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in article BB60654DFAA8D311B16400508B6F2538580B33@il27exm05.cig.mot.com,
Sattler Chris-QA1406 at lego-robotics@crynwr.com wrote on 8/9/00 12:11 PM:
<snipped large chunk of discussion of using a wide laser sensor to help
locate a robot>
>
> Rather than use the width of the sensor as one leg of your triangulation
> calculation, another way to do this is to collect two angle measurements
> from the tower to the robot, having the robot move slightly between
> measurements. You could then triangulate the robots location. I'm concerned
> that the width of the sensor is an awfully small delta if the robot is
> far away from the tower. If you move the robot you coul move it a little,
> and if the delta in the angle is very small you could then move it some more
> to get a more accurate reading.
That sounds like a good idea, but I don't know if it can be made to work.
The idea is to form a triangle with a known angle and a known opposite side
(the robot will know how far it crawled). Unfortunately you can't determine
the triangle this way - there's too many ways you can fit that opposite side
into the angle to make a triangle.
If you could be sure of moving at a particular angle, you'd be able to
determine the triangle. Ideally the robot would move a known distance at a
right angle to the line connecting the base station and the robot. The
problem is in determining the orientation of the robot.
However, I wasn't really suggesting actual triangulation using the width of
the sensor as the leg of a triangle. I was suggesting measuring the time it
takes the laser beam to traverse the sensor to figure out what angle it
subtends from the viewpoint of the base station, which gives us its distance
from the base station.
I guess it sort of comes to the same thing in the end, except that we can
measure the time very precisely with the RCX timers and so theoretically we
can get really good accuracy on this leg of the triangle.
I'll see if I can awaken my ancient trig knowledge and try to come up with
some numbers to see how feasible my idea is.
--
Doug Weathers, http://www.rdrop.com/~dougw
Portland, Oregon, USA
Don't spam me - I know how to use http://www.spamcop.net
"On a clear disk you can seek forever"
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Message is in Reply To:
 | | RE: Autonomous Robot
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| (...) Rather than use the width of the sensor as one leg of your triangulation calculation, another way to do this is to collect two angle measurements from the tower to the robot, having the robot move slightly between measurements. You could then (...) (24 years ago, 9-Aug-00, to lugnet.robotics)
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