Author Topic: optical interrupt encoder on roller chain?  (Read 1024 times)

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Offline dacbTopic starter

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optical interrupt encoder on roller chain?
« on: March 11, 2011, 01:18:34 PM »
I'm wondering if anyone has any experience or thoughts on a roller chain based optical interrupt encoder.  Imagine a motor that drives a wheel using standard roller chain, e.g. #25, 1/4 pitch.  The open space in the links of the chain transmit the light and the pins in the chain block it resulting in a pulsed encoder signal.

I can imagine a problem related to chain tension that might result in the chain contacting the transmitter or the receiver, but that should be surmountable by placement and design.

Thanks!

Offline vinniewryan

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Re: optical interrupt encoder on roller chain?
« Reply #1 on: March 11, 2011, 03:35:28 PM »
The best way to ensure the chain will not come in contact with the encoder is to use a laser diode with plenty of distance from the chain as your light source.

Offline Soeren

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Re: optical interrupt encoder on roller chain?
« Reply #2 on: March 12, 2011, 12:37:45 AM »
Hi,

[...] Imagine a motor that drives a wheel using standard roller chain, e.g. #25, 1/4 pitch.  The open space in the links of the chain transmit the light and the pins in the chain block it resulting in a pulsed encoder signal.
Imagining... Resolution = Wheel diameter x Pi / number of cogs.

Besides, it would be just as easy to just measure the cog wheel, either optic or eg. by a Hall element.


I can imagine a problem related to chain tension that might result in the chain contacting the transmitter or the receiver, but that should be surmountable by placement and design.
Yes, a dual pulley chain tensioner, with the optic components mounted in between the two pulleys - no slack there... But why bother, there's better ways to get low-res odometry?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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