Author Topic: About IR object detection  (Read 6517 times)

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Offline JesseWellingTopic starter

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About IR object detection
« on: April 30, 2006, 04:03:07 PM »
I'm not so much interested in range but I was going to make my own object detection (about 4 of them) for an improvement upon my robot.

I've read the IR tutorial and was wondering on the specifics of the LED's. I wen through the Digi-Key catalog and then this very importan question came up about beam angles. I think it would be best to go with the same beam angle, but I'm not sure on this. And what about beam angles in big should you or should you not go?

The Emitters I was looking at are Sharp kind digi key part no. 425-1026-5-ND.
The Transistors I was looking at are 425-1006-1-ND.

the only problem that I see is that they don't really seem like regular LED's from the picture although from thier specifications they seem to be the best option.

Any advice?

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Re: About IR object detection
« Reply #1 on: April 30, 2006, 05:17:27 PM »
A lot depends on how you plan to use them.

First about the beam angle. A small beam angle is less distance sensitive. This means you can detect things at further distances. If you were doing line following, this means changing the height of the sensor to the ground has less effect to the line detection ability. A wide angle beam is more likely to see thin objects, such as chair legs. Also dont forget intensity of light. More candela is better.

Also, you do not specifically need to use infrared. Any wave length will work. You can easily use a pretty bright green LED and a simple photoresistor. I have a robot that glows a bright neon green because of this. Works well AND looks cool.  8)

The advantage to infrared is that the human eye cant see it, and that infrared generally has a higher response speed. Just make sure your emitter and detector both operate on the same wavelength (should be specified in the datasheet). Also recommended not to use a wavelength of light found in the environment your robot will operate in.

Side note, you do not need an equal number of emitters to detectors. One emitter and 10 detectors will also work . . . just depends on what you are doing.

Those parts you list look right. I didnt check the wavelength though. They also sell some that have the emitter and detector built in to the same package. There is a huge variety out there, I recommend looking around.