Author Topic: Poor IR Pen Tracking  (Read 7476 times)

Offline keithmcd

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on: October 14, 2008, 11:12:10 PM
I've so far been testing my IR pen and such on my iMac which naturally has a very glossy screen - great for tracking!

Tonight I went and tested it in a classroom with a high quality projector screen and was very much saddened by the results.  I had two wiimotes connected and the tracking was really bad if it even existed.

My question is how have you been able to solve this?  I'm using a 1.2V IR LED with a 1.5V LR1 battery so the pen is definitely getting enough power.

Any ideas are appreciated.

Thanks,
Keith



Offline benpaddlejones

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Reply #1 on: October 15, 2008, 01:23:37 AM
keithmcd

What IR-Led are you using?
Was their any direct rays of sunlight
Is the whiteboard an ultrlow glare

Benpaddlejones :)


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Offline keithmcd

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Reply #2 on: October 15, 2008, 06:31:41 AM
I've been using IR LEDs from Radio Shack:
Radiant Power Output (100ma):  16mW min
Forward Voltage:  1.2V
Forward Current: 100mA
Viewing angle to 1.2 intensity:  45 degrees
Wavelength:  940nm

This was done in a new smart classroom at Purdue University.  The classroom is in the middle of the building so no sunlight at all.  And this was using a standard projector screen - not a whiteboard.  This room actually doesn't have any whiteboards in it.  As it was a semester break, it was the first room I found that was open that I could use just for some quick tests.

Thanks,
Keith



Offline benpaddlejones

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Reply #3 on: October 15, 2008, 06:58:29 AM
keithmcd
Your primary problem is a low quality IR-led. You will need a Vishay TSAL6400. Projector screens are also very low glare so not helping. you will find your current IR-led will work OK in close range or on shiny whiteboards. But the better IR-Led should cure all.

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Offline keithmcd

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Reply #4 on: October 15, 2008, 07:27:30 AM
Come on Benpaddlejones,

Don't go crushing all my hopes this early in the morning!  :-)

I was really hoping to not have to buy anything from an online distributor.

Any good suggestions on where to buy them from?  One person had recommended www.farnell.com so just trying to get various sellers at this point.



Offline benpaddlejones

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Reply #5 on: October 15, 2008, 07:32:37 PM
keithmcd
Read: http://www.wiimoteproject.com/for-sale/vishay-ir-led's/

Goodluck.

benpaddlejones :)


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Offline jamesKL

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Reply #6 on: October 15, 2008, 10:42:09 PM
hmm wats the distance between the screen and the wiimote. cause if its too far wiimote may not be able to detect it perfectly



Offline keithmcd

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Reply #7 on: October 15, 2008, 11:38:13 PM
I'd say it was about 5-6 feet away from the screen.  It was a quick setup as I was just taking over that classroom after a class had left.  :-)

I've got 20 TSAL6400's on the way and will give it another go once I've built a pen containing one of those.  I've no idea how this will actually perform, but I'm now working on my third pen - this one is a lot larger and will have four IR LEDs and will be powered by a 9-volt battery.



Offline benpaddlejones

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Reply #8 on: October 16, 2008, 12:43:11 AM
keithmcd
Overkill, big time.

1x Vishay TSAL6400 and a AAA is all you need.

A single IR-Led is fine for it to track, if the wiimote can't see it, it won't see 4 any better.

Benpaddlejones :)



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