Motor Encoder

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Motor Encoder

Unread postby Derrick » Fri Feb 22, 2013 6:30 pm

Encoders let you know how much your motor (or any shaft) has rotated. If you've even taken apart an old mechanical mouse, you would have seen two of them in there for tracking the XY rotation of the ball.

For anyone interested in playing around with motor shaft encoders (wiki) with their Arduino , I found a nice one at digikey that supports multiple shaft sizes and pulses per revolution. Only $23.63 which seems like a bargain for this type of device.

Digikey: AMT102-V KIT
AMT102-V_sml.jpg
102-1307-ND
AMT102-V_sml.jpg (23.56 KiB) Viewed 5192 times


I just got two in, will post code and schematic when I get them working.

Of course, a more hardcore hacker would just repurpose an old mouse :)
-=Derrick=-

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Re: Motor Encoder

Unread postby garrettwilkin » Wed Feb 27, 2013 1:34 am

That sounds like a pretty awesome component. So basically you can use these to turn a shaft a certain number of degrees. Is that right?

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Re: Motor Encoder

Unread postby Derrick » Mon Mar 04, 2013 3:46 pm

They tell you how far the shaft has the shaft has turned. A stepper motor is a good way to do positioning like that, but even then these can be helpful for verifying that the motor actually did what you told it to.

I got these mounted on my CargoBot last week, still working out how to estimate world-position and heading from the results though. I really need to take more pictures...
-=Derrick=-

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Re: Motor Encoder

Unread postby Derrick » Fri Mar 08, 2013 3:30 pm

Found a well optimized Encoder Library for Arduino at http://www.pjrc.com/teensy/td_libs_Encoder.html

Includes a nice explanation of how reading of an encoder is accomplished:
Image
-=Derrick=-

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Re: Motor Encoder

Unread postby edburdo » Thu Jun 06, 2013 12:06 pm

If you can hunt up any of the "LEGO Rotation Sensors" from the old RCX kits (about 10 years old or more)... they are motor encoders.

Here is a sample of one: http://www.ebay.com/itm/Lego-ROTATION-A ... ORE:US:101

Not sure what they look like inside... but the cabling is two wires... so nothing fancy.

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