Subject:
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Re: GBC at BrickFest 2006
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 6 Sep 2006 03:48:24 GMT
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Viewed:
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5131 times
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Brian Davis wrote:
> In lugnet.robotics, David Hurley wrote:
>
>
> > we had a few ball counters going: Rafe's impressive
> > digital [mechanical] counter, Greg's analog one, and
> > Brian's optical one...
>
>
> Actually, my counter was mechanical, in that each ball temporarily opened a
> normally closed touch sensor, and the RCX was just counting touches. For an
> optical one, you can use a ball breaking a lightbeam (two light sensors pointed
> at each other, for instance), but detecting the ball itself via reflected light
> is a tougher issue... because each of those dang soccer balls could read as
> nearly all black, or nearly all white... or anything inbetween.
I had success with a ball detector using only one light sensor in my
little interactive get-the-ball-in-the-hole module. If the ball went
into the hole, it rolled past a light sensor (old RCX version; is there
a new nxt one?). Across from the light sensor, two studs away, was a
silver brick, the one from the 25th anniversary bucket of a number of
years ago. If the ball wasn't there, I got light readings in the
neighborhood of 65+ (?) I think. With either a regular or special
soccer ball, or a basketball of any of the three colors, or my soccer
ball with almost all the black worn off (I wonder how that happened?),
or my finger, the light reading dropped into the 40s, I think, so I had
a nice threshold to use to tell the rcx that a ball had passed by and it
should spin the spinner and light the light. This is how I kept track
of the high score on the GTBITH game. The only problem was the uneven
table causing a ball to not roll all the way through, resulting in an
insane count...
>
> > is there agreement on what the final ball tally was?
>
>
> Probably not to any high accuracy - too often, something broke down and balls
> had to be moved by hand, sometimes bypassing counters... and at least on Rafe's,
> I think smnall hands may have dropped some balls in inappropriate places. I can
> tell you on the spur line (not penalty box - there is *always* a section that's
> less error prone than another, trust me) we counted up to 6663 balls during the
> event.
Greg's analog counter just downstream from me seemed to function very
well the whole time, so I would expect it to have the closest count. As
Brian mentioned, too many little fingers and too much of me showing
people how to count in base 2 and how it worked led to counts that were
nowhere near accurate. Precise? Yes, digitally precise. :-) Accurate?
No. :-(
For what it is worth, my little prototype bit that I used to explain the
counter disappeared sometime between late Saturday evening and early
Sunday morning. If it showed up in anyone's stuff, please let me know.
I don't think I need the parts but it sure compromised my ability to
explain things to the kiddies on Sunday when I didn't have the example.
As far as theft goes, I like to think that the RCX sitting right
beside it was more valuable, although with the new NXTs out, that might
not be the case. Then again, my single-bit mechanical prototype has
only 1/8 of a byte (perhaps 1/16 ?) of memory; so I gotta believe the
RCX is still a preferred computing device!
Did anyone else have anything walk off under its own power? I am a
rather trusting soul and BrickFestites tend to be honest folks as well,
but now I don't know if I should be worried or not...
Rafe
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Message has 1 Reply:
 | | Re: GBC at BrickFest 2006
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| (...) Now that is a nice solution, and not one I'd thought of. Not having the silver brick, I could still use a (non-LEGO! Aaah!) solution of a small pice of reflective tabe or something. Cool. (...) I know that there's one power transformer that is (...) (19 years ago, 6-Sep-06, to lugnet.robotics)
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Message is in Reply To:
| | Re: GBC at BrickFest 2006
|
| (...) Actually, my counter was mechanical, in that each ball temporarily opened a normally closed touch sensor, and the RCX was just counting touches. For an optical one, you can use a ball breaking a lightbeam (two light sensors pointed at each (...) (19 years ago, 6-Sep-06, to lugnet.robotics)
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