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Unread 04-28-2015, 11:27 AM
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tr6scott tr6scott is offline
Um, I smell Motor!
AKA: Scott McBride
FRC #2137 (TORC)
Team Role: Mentor
 
Join Date: Dec 2007
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Location: Oxford, MI
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Loop timing crio vs. roborio.

A few times this year, there have been programming posts, that seemed to lead me to believe the timing loops on the roborio are far less consistent than they were on the cRIO.

At TORC we log data to a .csv file every 100 milliseconds. Attached are sample match log files from 2014 crio based, and 2015 roborio based.

The 2014 data is pulled from a timed tasks control loop with a 50ms metronome timer, the 2015 data is pulled from a timed task control loop with a 20ms metronome timer. Labview picture attached.

The data from this year is all over the place as compared with the cRIO data.

We controlled our elevator with a home brew pid, so the students would learn how to pid, and not use the labview provided pid, but as typically is done, we ignored the delta-t as the loop time was to be consistent.

Which it was consistent enough to not give us issues with control, just not nearly as consistent as the crio.

discuss...

EDIT:
2014 Avg = 49.9796 with STD = 0.21929
2015 AVG = 19.67855 with STD = 3.797736
Attached Thumbnails
Click image for larger version

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Attached Files
File Type: xls 2014-cRIO-100006.xls (533.5 KB, 26 views)
File Type: xls 2015-RoboRIO-100125.xls (1.22 MB, 29 views)
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Last edited by tr6scott : 04-28-2015 at 01:37 PM.