DPRG mailing list archives: DPRG: BOUNCE dprglist@dprg.org: Non-member submission from [brad.garton@lsil.com (Brad Garton)]

Thu Oct 22 22:51:47 CDT 1998

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[brad.garton at lsil.com (Brad Garton)]   
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>From: brad.garton at lsil.com (Brad Garton)
>To: dprglist at dprg.org
>Subject: Re: DPRG: Laser modules (line generating and others)
>Date: Fri, 23 Oct 1998 02:58:16 GMT
>Organization: LSI Logic
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>On Thu, 22 Oct 1998 16:58:40 -0500, you wrote:
>I was wondering how this implementation would deal with the following
>scenarios:
>
>1. You are not perpindicular with the wall but at an acute angle to
>the wall. When you come to the door the assumed relationship between
>adjacent side and opposite side wouldn't hold. 
>                 /
>R----------------
>            /
>          / 
>How would you use the CCD information to line the robot up with the
>door, how would you determine the doorway is not just too narrow.
>Without a center dot. You don't really know the relation ship between
>the opposite side for the left and right lasers. 
>
>
>2. You approach a doorway with an obstacle covering one facing of the
>doorway.  This is a variation on the problem above.
>
>                                              +
>R--------------------------------------------
>                      [  ]		      +
>
>It seems to me that implementation assumes a right triangle
>relationship where one might not exist. How would you resolve any of
>the other cases where the angle between the opposite and adjacent side
>is not 90 degrees?
>
>Brad 
>>I am sending this again because I really would like some criticism good/bad
>>whatever on the idea/design.
>>
>>I have made an image to explain what I described previously.
>>
>>I will recap briefly:
>>
>>Two lasers or 1 with a beam splitter are aimed away from the robot's center
>>line by a known x degrees.
>>The range can be calculated/estimated from the distance of the 2 spots on
>>the wall.
>>The range can be calculated by triangulation.
>>Think of the setup as a right triangle between the laser beam, a camera,
>>and an object.  The shape of the triangle varies with the  distance to the
>>object.  
>>
>>distance = tan(angle) * baseline
>>
>>This also gives a simple go/nogo for if a robot can pass through an
>>opening.  If the spots are too close, then the robot won't fit!
>>
>>For more info, go to my web site and follow the robotics link.
>>
>>
>>http://walden.mvp.net/~chandra/
>>
>>Thanks,
>>
>>Matt Minnis
>>
>>
>>=========================================================
>>Preferred Resources          (314) 567-7600 phone
>>701 Emerson rd.              (314) 993-6699 fax
>>Suite 475
>>St. Louis, MO
>>63141
>>=========================================================
>>
>
>
>
>
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