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Author Topic: Servo tuning problem with IP-A  (Read 1436 times)

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Servo tuning problem with IP-A
« on: July 28, 2015, 05:32:47 PM »

     I'm having trouble tuning the Z axis servo on my Matsuura MC500v retrofit. Ive read through the manual and done enough research to understand the PID loop. I've tuned the X and Y axis fairly well with the help of the auto tuning function and manual tweaking. Something just isn't right with the Z axis though. The servos are the same on all three axis, but the gearing between the servo and the ball screw is a little lower on the Z axis to allow for more torque. The encoders are built into the back of the servos before the gearing.  When I attempt to auto tune, I end up with a Proportional gain around 600 and an integral gain around 200 while the P gain on my x and y axis is around 20000. Also, the axis should be capable of around 400 inches per minute. The fastest I can get the thing to move is 40 inches per minute. If I attempt to set a max speed of 400, the machine will move at 40 inches per minute until a following error is triggered.

    My thoughts are that there is something wrong with the drive. If I unplug the tach input from the encoder to the servo drive ( yaskawa cpcr-mr-052-nb), the servo seems to break free and will oscillate closer to 400 inches per minute for a moment before a following error is triggered in mach.

This is my first time tuning a machine with servos rather than steppers, so any and all help would be appreciated. Thanks!


Offline Hood

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Re: Servo tuning problem with IP-A
« Reply #1 on: July 30, 2015, 11:04:14 AM »
I would test the axis by using a battery box (essentially a  9v battery and a pot to vary the voltage) connected to the analogue inputs on the servo drive. If it acts like it should with the battery box then you need to look at the CSMIO/Mach/wiring, if it doesn't behave then it is the drive/motor side of things.