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#1
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Re: Optical Sensors Used as Encoders?
Just me 2 cents, but if you are going to go through the trouble to do all this, then why not just use encoders or gear tooth counters?
If you use reflective tape and banner sensors, it will work, but i don;t see how you can possibly get much resolution. Last edited by Rickertsen2 : 29-02-2004 at 23:26. |
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Re: Optical Sensors Used as Encoders?
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Thank you everyone for all of your help.... |
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Re: Optical Sensors Used as Encoders?
Personally, I think unless the bot is very slow, the extra resolution wont matter. You still cant stop the bot
theres just too much inertia. And we are not using the sensor on the actual wheel. We have it on a gear that is in a ratio of about 18:1 to the wheel. So that increases the resolution. And about the tape... The rules say "no adhesive-backed tape on the robot. The only exception is electrical tape, and it can only be used as as insulator". So a "decorative" explanation might not go over with the inspectors too well. White paint works very well, and is completely legal. |
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#4
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Re: Optical Sensors Used as Encoders?
We used Banner sensors last year for wheel encoders and have included them this year as well. We use a custom wheel so when the wheel was being assembled we just slipped a piece of dark papaer between the spokes of the wheel. By using two encoders (outlined above) you can tell direction and distance traveled. Last year we were able to get accurate down to at least an inch which made auto mode pretty easy. You need to couple the wheel sensors with a direction device to really know where you are.
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#5
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Re: Optical Sensors Used as Encoders?
Last year we used banner sensors and tape marks, but this year we went ahead and spent a whopping $80 for shaft encoders (300 clicks per revolution ... as opposed to the 8 at best we had before).
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Re: Optical Sensors Used as Encoders?
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#10
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Re: Optical Sensors Used as Encoders?
We tested the banner sensors to measure RPM's, and from what I saw it worked quite well, but our team decided to go with shaft encoders.
We also were going to use a potentiometer to measure the position of our arm, but also went with shaft encoders for that since the potentiometers from RadioShack were only responsive over about 180 degrees of their range, and we needed the full 270 degrees. We could have geared down the potentiometer, or gone with higher quality potentiometer, but we already had the shaft encoders. |
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