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Old September 13th, 2013, 02:36 PM   #1
victorg
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Speed Compensation Cyclinder Lag???

First off the controls being used are an AB L1 Processor RSLogix 5000 V20, Connected to a PowerFlex 525 drive and an absolute encoder to trigger different outputs. I wanted to see if anyone has any good ideas on how i would compensate for the lag time on an air cylinder as the system gets faster or slower. In the past i have added count positions on the output flag (EX: 15 cycles per minute = position of 60, And at 30 cycles per min = a position of 50). Problem is i have to add and cannot subtract because i may get negative numbers and than the output will for sure not fire. Which means i have to set the system up at full speed then add counts as the system gets slower. Is there any ideas on how i would not have to compensate for many ranges of speeds with lots of math rungs added to my logic?
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Old September 13th, 2013, 02:41 PM   #2
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Does the air cylinder have limit switches on it to indicate whether it's extended or retracted?
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Old September 13th, 2013, 02:44 PM   #3
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No as this is not important. Just when it starts and ends its function. So i have a start position and an end position.
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Old September 13th, 2013, 02:52 PM   #4
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Well, then I don't exactly understand your question. Is your air cylinder not responding fast enough under certain circumstances?
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Old September 13th, 2013, 02:52 PM   #5
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Basically im trying to compensate for the amount of time it takes the cylinder to get to the full stroke when the machine speeds up to place it in the same position at 10 Cycles/Min or 50 Cycles/Min. In order to do that i have had to write logic that starts the cylinder sooner when the machine speeds up later when it slows down. Is there an easier way to get the functions linear based on speed. Other then saying EX: >or= 10 but <15 Subtract 5 from cylinder down position And writing it and moving it ten times or more for different speeds.

Last edited by victorg; September 13th, 2013 at 03:01 PM.
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Old September 13th, 2013, 02:56 PM   #6
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So do you need the cylinder to act faster or your process to wait for it?
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Old September 13th, 2013, 03:05 PM   #7
victorg
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Depends on the speed the operator tells the system go. The cylinder must remain in time with the rest of the system.
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Old September 13th, 2013, 08:00 PM   #8
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If I am understanding you correctly I would just use a SCP instruction and tie it to the actual machine speed and the to a timer. So if machine speeds up the offset the timer preset.
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Old September 14th, 2013, 03:43 AM   #9
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yeah and check if it gets negative then use zero.
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Old September 16th, 2013, 08:17 AM   #10
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Is the encoder measuring position of the air cylinder, or something else? If you give a better description of the "mechanical" outline of the system it would help better answer your question. What determines the system speed?


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No as this is not important. Just when it starts and ends its function. So i have a start position and an end position.
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