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View Full Version : Encoder ticks/revolution change?

flameout
22-02-2012, 23:50
We're running a mix of old and new encoders on our bot this year. I recently noticed that two of our encoders were reading significantly lower than the other two, but were reliable (and matched with each other), suggesting that it's not a failure.

Did kit encoders ever had a ticks/revolution value not equal to 360? I didn't have the opportunity to check counts/rev for each wheel before bagging... I don't know if I'll have time at regionals to verify, but I want to be ready to re-tune our drivetrain code if this is the case (and come prepared with the correct ticks/rev count per wheel).

Thank you.
Ether
22-02-2012, 23:56
Did kit encoders ever had a ticks/revolution value not equal to 360?

Yes. 250. 2009 KoP
andreboos
22-02-2012, 23:57
In the past (2010 or before), US Digital supplied 250 CPR encoders, because we had some lying around last year that were 250 CPR. Last years', and those offered in FIRST Choice this year, are 360 CPR. I believe CPR is solely a property of the hub disks, so you should be able to swap out the disks without having to unmount your encoder.
apalrd
22-02-2012, 23:57
The 2009 kit had 250 count/rev encoders. Later kits had 360 count/rev encoders.

AndyMark sells 250 count/rev encoders.
Alan Anderson
22-02-2012, 23:58
We have used E4P encoders with 250 and 360 counts per revolution. I believe both types were provided along with AndyMark gearboxes in the Kit of Parts in various years, but I don't have definitive documentation to that effect.
slijin
23-02-2012, 00:26
We have used E4P encoders with 250 and 360 counts per revolution. I believe both types were provided along with AndyMark gearboxes in the Kit of Parts in various years, but I don't have definitive documentation to that effect.

2009 KoP (http://www.usfirst.org/uploadedFiles/2009%20KOP%20Checklist%20Rev%20B.pdf)
OEM Miniature Optical Kit Encoder
E4P-250-250-D-D-D-B
250 CPR, 1/4” bore

2010 KoP (http://www.usfirst.org/uploadedFiles/Community/FRC/Game_and_Season__Info/2010_Assets/2010%20Kit%20Of%20Parts%20Checklist_RevC.pdf) and the 2011 KoP (http://www.usfirst.org/uploadedFiles/Robotics_Programs/FRC/Game_and_Season__Info/2011_Assets/Kit_of_Parts/2011%20Kit%20of%20Parts%20Checklist%20Rev%20E.pdf) Encoder - Codewheel
E4P-360-250-S4149
360 CPR
flameout
23-02-2012, 00:32
Thank you for all the help. I'll have the fix (adjusted drivetrain parameters and tuning constants) prepared for regionals.