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Everything posted by RainG

  1. Hi All, I just take over a project which involve accurate positioning and movement up to 0.010mm(around 10 microns) of a servo motor. I found out that my motor always move to an incorrect position. Let's say I want it to move to absolute position of 5.210mm, I found out that it may move more till 5.235 or move less 5.190(something like that). So i start to check if I'm outputting correct pulse. Using CX-Drive, I connect to the driver then i found out that the pulse is correct and consistent(for example i use my pulse per revolution and pitch to determine how many pulses) Currently I'm using an incremental encoder and servo motor and my PLC cycle time is around 12 ms and my servo move at a speed of 0.66mm/s. So I was wondering if my PLC scan time will affect my accuracy in moving ?? I'm using a CJ2M PLC with CJ1W-NC413 pulse card , incremental encoder and a servo motor. I want to make sure is not software limitation or anything wrong on software side before I bring it to my mechanical team   Appreciate all inputs here and thanks!
  2. Cycle Time and Accurate Positioning

    Will using absolute encoder or incremental encoder affect the accuracy of me reading the live pulse feedback from encoder?
  3. Cycle Time and Accurate Positioning

    Yes, my motor is the R88M-KE series which comes with an incremental encoder...
  4. Cycle Time and Accurate Positioning

    I got use CX-drive to connect to my drive and monitor the pulse status. Is that what you meant with testing using driver encoder value?
  5. Cycle Time and Accurate Positioning

    I had tried to do some testing to determine the servo motor movement behavior, which i think is similar to the one u suggested above? ex. Move to 10mm - Move to 10.05mm(record actual position) - move back to 10mm, repeat for a few times... i had find out that every time the motor does not stop at 10.05mm but *consistently stop at around 10.06 mm *(i forget the actual value..) I find it stop at consistent position so i worried it might because of scan time issue, since the scan time is always fix and there... Does that means once my PLC start instructs the NC card to output 35673 pulses...it will output that said amount of pulses immediately and regardless of scan time? once reach the amount of pulses it will stop. is my sentence correct?
  6. Cycle Time and Accurate Positioning

    So does that means, part of the accumulated positioning error is caused by the scan time???? based on what you said that there is a 0.00792mm variance, meaning i will still have run off positioning around 8 microns???? Servo is 10000 pulse per revolution so if i move one pulse , then it would be 0.0005 mm which is very hard to measure physically..... Yea im trying to determine the root cause from my side first before I start argue if the ball screw or the mechanical system something is loose or anything else...
  7. Cycle Time and Accurate Positioning

    I'm using G5-series Pulse Train Input Type AC Servomotors/Servo Drives R88D-KP15H and an incremental encoder...