Subject:
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Re: IR Collision avoidance
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 4 Mar 1997 01:02:00 GMT
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Original-From:
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Bill Richman <bill_r@inetnebr.NOSPAMcom>
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Reply-To:
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BILL_R@INETNEBR.ihatespamCOM
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Viewed:
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1749 times
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The part number on the device from Radio Shack is "GP1U52X". In our
earlier discussions, I thought I made it clear that I was using "the
Radio Shack IR detector module", although I may not have quoted the
number. If Sharp makes a module without the AGC and all the
annoyances it's caused me, I'll get some and try them out. My
initial success with an older sensor operating in the mode of "switch
the 40Khz off and on a few times at random and see if the sensor
shows the same pattern so I know it's really my signal I'm seeing"
led me to believe this would be simple to implement in software.
Then I got the new Radio Shack modules with the AGC and ended up
building the 555/567 modulator/demodulator circuit to get the silly
things to work. If I can go back to just plugging a handful of
sensors into the digital inputs on the HB, and a handful of IR LEDs
into the LED driver output and do it all in software, that would be
great. Apparently a large part of our initial confusion was due to
the fact that we thought we were using the same part, when in fact we
were not.
-Bill
...<snip> ...
> Bill (the heretic :-) Richman's description of how these things work
> is essentially correct except that we disagree on the frequency
> response of the AGC and the operation of the AGC in the presence of
> a valid signal. Of course "IR module" isn't a precise description of
> the part under test. After talking with Bill privately about his
> theories on why he was getting the behaviour he saw I tested the
> seventeen IS1U60 (http://www.sharp.co.jp/ecg/unit/is1u60/is1u60.html)
> parts in my stock bin and, under controlled conditions, (closed box
> testing) the IS1U60 will produce an output as long as the lens
> sees a 38Khz signal. However, I reccomend using a modulated output
> because it aids in the discrimination against background noise that
> is so essential. (Which means the discussion of the actual operation
> is moot if all parties advocate a usage scheme that accomodates their
> notion of the operational aspects of the part :-)
-Bill Richman
bill_r@inetnebr.com
http://incolor.inetnebr.com/bill_r
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Message is in Reply To:
 | | Re: IR Collision avoidance
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| (...) The Sharp IR modules are not being used to detect distance, they are being used simply as non-contact bumpers. This allows one to inexpensively put an arbitrarily long 'whisker' on your robot. The advantage to these things are that they are (...) (28 years ago, 3-Mar-97, to lugnet.robotics.handyboard)
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