[oopic] Re: New range finder needed

--- In oopic@yahoogroups.com, Shaggy <charrington@...> wrote:
>
>

It's not clear what you mean by "binary pair". Are they interfering
with each other by any chance ???

In any case, you might be having problems with sidelobe pickup with
the SRF0x units. I abandoned them myself, and went to the Ping sonars
from Parallax. Other people mentioned the SRF0x units should be
mounted "vertically", with the receiver transducer above the xmtr, so
there is nothing for the sidelobes to reflect off of.

I found the Ping units work well both close in, and at distances out
to 12' or so. The only problem I did have was using them on a walker
to turn at a wall, and align perpendicularly for moving away from the
wall. When close in [about 6"], and positioned at an oblique angle to
the wall, there appeared to be multiple reflections between the wall
and the bot frame, and which produced spurious readings. However,
once the bot was away from the wall 12" or more, the readings were ok.

> I have been working under the assumption that the SRF08 ultrasonic
range
> sensor was somewhat reliable at distances over 1 meter as a binary
pair.
> After testing two pairs extensively, the readings bounce around so
badly
> that depth perception cannot be calculated using them, though some
rough
> distances are possible after averaging for several repetitions. The
sensors
> seem pretty accurate at ranges under about 50cm, but not so much
beyond
> that.
>
> Therefore, I am looking at my options. One option is to switch to a
camera
> (like the CMUCam) and do a whole bunch of visual processing. The
other
> option is a far more accurate range finder such as a laser, perhaps
on a
> panning servo. However, after a brief search of the net, it appears
that a
> suitable laser would be over $1000. Are there any other options out
there?
> --
> View this message in context: http://www.nabble.com/New-range-
finder-needed-tp15923461p15923461.html
> Sent from the OOPic mailing list archive at Nabble.com.
>

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