>
As it turns out, a couple of months ago I bought an inexpensive $10
laser level, and then completely forgot about it. Found it in a box
yesterday. It transmits both a bright spot and also a less bright
straight line, emanating from the spot. It is very interesting to
scan it around onto different surfaces. You can easily distinquish
different shapes by how the "line" beam bends around the surfaces.
For boxlike shapes, you see 2 straight beams at an angle, with a bend
at the edge of the box.
For complex-shaped objects, you see multiple discontinuities in the
reflected beam.
For close on objects, you see a discontinuous line, as the beam falls
off the edge of the object. It's easy to distinquish an object
isolated from the background.
You can also do rough ranging measurements directly. Eg, at 6" from a
flat surface, the line beam is 4" long. Of course, if the surface is
not perpendicular to the sensor, then the line is elongated.
I am thinking one could use 2 such devices [or else laser pointers
with line outputs], one with a vertical beam and one with a
horizontal beam to pan around on a 2-D servo mount. I imagine the
beams are bright enough, compared to normal ambient lighting, that
one could easily filter the red output from a vid-cam, and isolate
the beams from the background. This technique is like simple computer
vision with about 10,000X less processing power required.
One probably needs to adopt some safety measures, so the beams aren't
projected directly in people's eyes. Also, depending upon the
sensitivty of the vid-cam used, it may be possible to reduce the beam
intensity.
> > OTOH, in Joe Engelberger's 1989 book Robotics in Service, that I
have
> > been reading lately, he does mention a simpler way to use a video
> > camera. Namely, you use a laser [could be a laser-diode pointer
> > today] to cast a single bright "line" onto an object, and then use
> > the camera to analyze the deflections as the line bends around
> > objects, etc.
>
> That sounds similar to what I was describing.
>
> Brian Lloyd
> Granite Bay Montessori School 9330 Sierra College Bl
> brian AT gbmontessori DOT com Roseville, CA 95661
> +1.916.367.2131 (voice) +1.791.912.8170 (fax)
>
> PGP key ID: 12095C52A32A1B6C
> PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A
1B6C
>
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