Subject:
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Re: cool idea for all-around range sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 10 Jan 1999 23:23:42 GMT
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Viewed:
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1328 times
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Have you devised some way for the output of each IR receiver to be bistable
as opposed to analog ?
In order to wire-or a bunch of them with resistors and get a unique,
repeatable reading for each receiver being "active" would require two stable
states for each element (and nothing in between).
This is easily done with switches, but I don't think such a scheme will work
for IR phototransistors without some more electronics between them.
Varying IR light levels will not always saturate the receiver elements
(assuming that was what you were planning to use as your active state), and
the resistance values you designed in will be compromised.
A time-shifted scheme might be interesting. Maybe you could setup the
emitters to fire in a predetermined order at precise intervals. Create an
"index" element (resistors only) that returns the same fixed level (a level
not achievable by any of the actual IR receivers) when the firing sequence
first begins. Syncronize the reading of the rest of the elements based on
seeing this "sync" level. This would permit you to read a range of values
from the receivers directly, and you could wire-or them without any
resistors.
--
SeeYa !
------------
Jim
-----------------------------------------------------------------------
From the keyboard of Cyberia - (the machine's name, not mine)
Mark Williamson <lego-robotics@crynwr.com> wrote in message
news:007d01be3cd4$f4be5440$6119fea9@mark.pacbell.net...
> i've read all the messages on all-around bump sensing, and have an idea.
>
> I'm not actually a mindstorms owner, but have the MIT Handyboard and bought
> some Radioshack IR emitter/detector LED's which i'm making into sensors.
> I'm using the 1x2 legos to house the sensors (pic attached). I've come up
> with an idea on arranging these sensors (5 of them) in a triangular patter
> to give 180 degree ranging view. How this works is all of the sensors are
> tied together in such a way that the values of each one are in steps. • Using
> different values of resistors on the detectors will give you a range.
> Starting at the left side, the first sensor gets the lowest (or none) value
> resistor. Moving up to the next sensor, we increment the resistor's value,
> etc. Now by actually wiring all 5 of the IR detectors together, we can • read
> the entire array with one input on the RCX or Handyboard. An input on
> sensor 1 will give a higher value than input on sensor 2, with sensor 5
> giving off the highest value. If more than one sensor gets input, you will
> still know what "side" the input occurred on by noting that the value was
> excessive. Then, just mount the IR emitters on the top of the detectors
> (using another 1x2 lego), you have an IR 180 degree eyeball.
>
> I'm sure there are flaws in this design; but it sounds good in theory.
>
> Regards,
> Mark Williamson
>
>
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
>
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Message is in Reply To:
 | | cool idea for all-around range sensor
|
| i've read all the messages on all-around bump sensing, and have an idea. I'm not actually a mindstorms owner, but have the MIT Handyboard and bought some Radioshack IR emitter/detector LED's which i'm making into sensors. I'm using the 1x2 legos to (...) (26 years ago, 10-Jan-99, to lugnet.robotics)
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