Subject:
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Re: Sonar Sensor problems
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 17 Feb 2000 19:22:16 GMT
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Original-From:
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William Bain <MONTANAWILL@YAHOOstopspam.COM>
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Viewed:
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1034 times
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Did your team solder the proper capacitor into the sonar board
in accordance with the instructions on the HB web site? I was
just wondering, because others who forgot the capacitor have
reported similar problems.
Also, you may want to try tweaking the blanking interval from
1000 to 1200 in the sonar_closeup() function in order to get
good readings; my sonar wouldn't reliably read quite as close
as some others, I guess.
It's important to realize that occasionally you're supposed to
get a -1 back from the function; it means that an error
occurred -- typically that no echo was received before the
timer counter maxed out.
Even when I got my Polaroid sonar operating well, I still got
noisy readings. I almost completely eliminated the problem by
writing a new sonar sample function that always takes three
sonar readings, but returns only the median (middle) value. You
need only two or three comparison (if) statements to do this,
so it's pretty fast, and it works extremely well in practice.
There are almost never going to be two noisy readings out of
three. Some others have suggested using the average of three
readings, but I found that not to work very well at all (e.g.,
what's the average of 99, 101, and -1,000?). Best of luck!
-- Will
--- Jyotirmayi Jogdand <jyotirmayij@yahoo.com> wrote:
> Hi,
>
> Our team is using the Polaroid Sonar Ranging Module
> for our collision avoidance system.
>
> We used the code from sonar.c to find the time
> elapsed. However we get readings ranging from negative
> to positive numbers... Could you explain why this is
> so.
>
> Next we tried to incorporate the distance equation but
> it wouldn't give us the values.. could you please
> guide us to the right source code so that we can get
> the distance measurements as well?
>
> Your help is really appreciated. Iwould also
> appreciate it if you could reply as soon as possible
>
> Thanks
>
> Jodi
=====
Any sufficiently advanced technology
is indistinguishable from magic.
-- Arthur C. Clark
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Message has 1 Reply:
 | | Re: Sonar Sensor problems
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| Hi all if anyone has problems using the 6500 series for distances below 35cm by using the binh signal I have a possible solution to the problem. We also expierienced problems using the sensors for distances between 15cm and 40cm. We finally found (...) (25 years ago, 17-Feb-00, to lugnet.robotics.handyboard)
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