Subject:
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Re: Ultrasonic Sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 6 Feb 2002 14:06:52 GMT
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Original-From:
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Steve Baker <(sjbaker1@airmail.net)StopSpam()>
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Reply-To:
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SJBAKER1@AIRMAIL.NETstopspam
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Lee Wilson wrote:
> I would appreciate any comments or suggestions on what I have so far or any
> pointers to additional sources of information - in particular the operation
> and internals of the RCX (I have the usuals such as Rusell Nelson's page and
> Keoka Proudfoot's site). I'd also greatly appreciate tales of experiences
> with ultrasonic sensors and programming routines for them.
I guess the first question I'd ask is "What interface does the sensor
present to the RCX?"
I imagine there are two possibilities: It could be a raw interface that let
you send an acoustic "PING" on command and read a voltage back telling you
the amount of reflected acoustic energy (so you'd have to time the return
trip in software)....or it could be simple voltage that continuously
returns the range.
Both could have advantages and disadvantages I guess. The second approach
is definitely the simplest and most foolproof if you already have the
circuit designed for you. The first approach seems like it would offer
some interesting possibilities since you could perhaps read multiple
reflections to range multiple objects at the same time - and you might
be able to tell something interesting from the intensity of the reflection -
such as the size and/or acoustic reflectance coefficient of the thing you
have detected.
I would guess that the precision needed for timing in software would
mandate that you abandon NQC and use something like LegOS that gives
you more speed and sophistication in your software.
If you have a simple range-is-proportional-to-voltage sensor - then
there is almost nothing for the software to do other than display
the distance readout - or demonstrate the sensor in some practical
application (such as driving around without bumping into things or
navigating to a known point in a room or something)...dunno whether
a fancy demo is going to add much to the actual content of your work
on the sensor itself. Anyway, NQC would be fine for such a demo.
----------------------------- Steve Baker -------------------------------
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Message has 2 Replies:
 | | Re: Ultrasonic Sensor
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| (...) let (...) Thanks for that Steve. My circuit will be based on the latter of the two possibilities. It is based on a design by RA Penfold from Electronics and Beyond (Sept.2001) so I'm basically doing construction by numbers! However, the thesis (...) (23 years ago, 6-Feb-02, to lugnet.robotics)
| | | Re: Ultrasonic Sensor
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| (...) Sound travels on the order of 333m per second, so with the 3ms interval between sensor readings you will get a resolution of 1m. You could try some heavy machine level hackery inside legOS or leJOS to read the sensors in a shorter interval, I (...) (23 years ago, 6-Feb-02, to lugnet.robotics)
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Message is in Reply To:
| | Ultrasonic Sensor
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| Hello all. This topic might be a bit old hat for some of you, but as a relative newbie to the world of Mindstorms, I'm posting in the appeal for any information on Ultrasonic Sensors. The brief of my honours project was to design and build one such (...) (23 years ago, 6-Feb-02, to lugnet.robotics)
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