Re: [oopic] New range finder needed

Let me see if I can describe the optical rangefinder using a scanning
LASER a bit better.

The rangefinder is optical and works by geometry. It requires a 2D
imager that is capable of "seeing" the reflected light from the LASER
in very high contrast or the imager must be able to discern the color
of the LASER from all other colors.

The imager looks forward with the focal plane vertical (normal to the
floor). The scanning laser is mounted well above (or below) the imager
and projects a plane of light that makes an acute angle to the normal
line through the center of the imager.

Imagine a wall that is (relatively) far away. Also imagine that you
are looking at the whole lash-up from the side. You will see that the
scanned plane intersects the wall near the floor. After passing
through the lens of the imager it will appear near the top of the
focal plane.

Now imagine the wall moving closer to the sensor system. The scanned
plane now appears higher on the wall and its image is lower on the
focal plane of the sensor.

So if we examine the focal plane of the imager, variations in the
position of the scanned line on the Y axis denote distance and
variations on the X-axis denote left/right angular displacement.

I believe that the CMUcam has a mode for tracking certain colors. If
calibrated to track the color of the LASER, it can give back the
coordinates of the scan line. From that you can determine direction
and distance to multiple objects very quickly.

Is this any clearer?

--

Brian Lloyd Granite Bay Montessori
brian AT gbmontessori DOT com 9330 Sierra College Blvd.
+1.916.367.2131 (voice) Roseville, CA 95661, USA

http://www.gbmontessori.com

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— Antoine de Saint-Exupéry

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