Reports.RotaryEncoder History

Hide minor edits - Show changes to output

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related project - [[http://itp.nyu.edu/~ms1434/atech/index.php/Project/WheelchairDJ/ | Ramps]]
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related project - [[http://itp.nyu.edu/~ms1434/atech/index.php/Project/WheelchairDJ/ | Ramps]] by Wlodek Koss, Tristan Perich, John Schimmel
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related project - [[http://itp.nyu.edu/~ms1434/atech/index.php/Project/WheelchairDJ/ | Ramps]]
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The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation. This shouldn't necessarily be a problem but physically the contact points might be misaligned. The problem is smoothed out with [[ http://en.wikipedia.org/wiki/Gray_code | Gray code]]. Gray codeis a binary numeral system where two successive values differ in only one digit.
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The problem with encoders is that some contacts get to the next step before the other contacts on the ring. The problem is smoothed out with [[ http://en.wikipedia.org/wiki/Gray_code | Gray code]]. Gray codeis a binary numeral system where two successive values differ in only one digit.
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The code is avoid the alignment problem by cutting the resolution in half. In our project, it was unnoticeable.
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The code is avoid the alignment problem by cutting the resolution in half. In our project, it was unnoticeable.
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The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation. This shouldn't necessarily be a problem but physically the contact points might be misaligned.
to:
The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation. This shouldn't necessarily be a problem but physically the contact points might be misaligned. The problem is smoothed out with [[ http://en.wikipedia.org/wiki/Gray_code | Gray code]]. Gray codeis a binary numeral system where two successive values differ in only one digit.

!!The code
[[RotaryEncoderCode | Sample Code]]
This code is from http://www.picbasic.co.uk/forum/showthread.php?t=778
The code is avoid the alignment problem by cutting the resolution in half. In our project, it was unnoticeable.
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#on-off - 10
#off-on - 01
#off-off - 00
#on-on -
11
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*01
*00
*
10
*11
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This image shows an encoder with 3 contact points (rings)

There are two contact points on the Grayhill encoder, 2^2 = 4 positions for the encoder to be in
#on-off - 10
#off-on - 01
#off-off - 00
#on-on - 11
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The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation.
to:
The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation. This shouldn't necessarily be a problem but physically the contact points might be misaligned.
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A rotary encoder is used to measure rotation and provide a digital output. It looks just like a potentiometer but can spin freely in both directions. There are a few different types of encoders, some mechancial, some optical but all produce there output with a similar rotating pattern - this pattern is what gives encoders a bad name.

You can accquire
encoders at places like jameco and digikey, I used the Grayhill Series 61R 5-Pin from Digikey, it was about $40.
to:
A rotary encoder is used to measure rotation and provide a digital output. It looks just like a potentiometer but can spin freely in both directions. There are a few different types of encoders, some mechancial, some optical but all produce there output with a similar rotating pattern - this pattern is what gives encoders a bad name. The pattern involved gives the encoder a resolution, the Grayhill model above gives 128 steps per rotation. You can get encoders at places like jameco and digikey, I used the Grayhill Series 61R 5-Pin from Digikey, it was about $40.
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''This sensor report is not finished but great information is on [[http://en.wikipedia.org/wiki/Rotary_encoder | Wikipedia]]
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''This sensor report is not finished but great information is on [[http://en.wikipedia.org/wiki/Rotary_encoder | Wikipedia]]''
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Attached to the shaft of an encoder is a patterned disc. A mechancial encoder would look for a variation in several contact points as the shaft was turned, in smaller more "relative" encoders the spinning disc is
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Attached to the shaft of an encoder is a patterned disc. A mechancial encoder would look for a variation in several contact points as the shaft was turned, in smaller more "relative" encoders the spinning disc is a group of transparent radial lines like a bike wheel on a dark disc. As light shines through the radials a photodiode on the other side can detect angular movements.

The problem with encoders is if the shaft stops between two contact points, it might not know the correct position for the next rotation.
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2 pins for digital output
1 pin for +5 volts
1 pin for common ground
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*2 pins for digital output
*1 pin for +5 volts
*1 pin for common ground
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''This sensor report is not finished but great information is on [[http://en.wikipedia.org/wiki/Rotary_encoder | Wikipedia]]
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Attached to the shaft of an encoder is a patterned disc. A mechancial encoder would look for a variation in several contact points as the shaft was turned, in smaller more "relative" encoders the spinning disc is
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http://embrace.grayhill.com/embrace/images/products/1v0170-c.jpg
to:
http://embrace.grayhill.com/embrace/images/products/1v0170-c.jpg

A rotary encoder is used to measure rotation and provide a digital output. It looks just like a potentiometer but can spin freely in both directions. There are a few different types of encoders, some mechancial, some optical but all produce there output with a similar rotating pattern - this pattern is what gives encoders a bad name.

You can accquire encoders at places like jameco and digikey, I used the Grayhill Series 61R 5-Pin from Digikey, it was about $40.

!! The Pins
The 61R has 5 Pins, another version the 61K has 4 pins they both operate the same way.

2 pins for digital output
1 pin for +5 volts
1 pin for common ground

!!How it works
http://upload.wikimedia.org/wikipedia/en/thumb/4/42/Encoder_disc.png/180px-Encoder_disc.png
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by John Schimmel

December 6, 2005


http://embrace.grayhill.com/embrace/images/products/1v0170-c.jpg