Motor position error

Question

As a beginner in motor contol,
one of my motor systems consisted of Thorlab Z612B(0.4 nm/step, 8 micrometer blacklash) and Precision MicroControl DCX-PC100.
The motor was used in XY scanning; the x direction(fast axis) will move in small interval continuously in a y position (slow axis).
Normally, we use more than 32 by 32 data points.
In roughly thinking,  the image shape of scanning should be a rectangular or squre type in XY surface depending on the ratio of each data points.
But, the returning X to the start point, or final X is shifting as time goes on, therefore parallelogram shape in XY surface. (please see the attachement. the number in micrometer)
Of course, I checked the complete of motion for each interval X, and then read the current position.
I had better notify we have already calibrated PID and motion(v & a) parameters by the tunning program.
Is the second problem related to whether Motor or Controller?
메시지가 02-27-2008 09:09 PM에 labmaster에 의해 편집되었음
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Answer 1

Hi labmaster,
It's hard to say whether or not it is the motion controller or the drive that may be causing the error. It could be something else entirely. I have a few questions for you to help figure out where the problem might be occurring
1) I see that you said you are reading the position each time you complete a move. Is the position you are reading ever changing significantly from the expected position, or do you always get the position you expect?
2) This may be a gradual problem that shows up when you make a large number of different moves. What happens if you start from the beginning and only move to each corner of the rectangle you are trying to cover, do you still get that parallelogram shape?
3) What kind of feedback setup are you using (encoder, ADC, something else?) for your closed loop, and how do you have it configured in Measurement & Automation Explorer?
Regards,
Vijay S.
National Instruments