Motion Control and Motor Drives

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Why servo continue run after going to a reference position?

Hi,

My project has a motion system use PXI 3750 + UMI 7774 + 3 AKD. I am using FlexMotion (NI 73xx) library to program. So far I can drive 3 axises to limit sensor (no home) with reset position, then it can goes to an absolute position. Now what I want is from that absolute position, 3 axises drives to a relative position. By some reason, after go to the relative position point, one or two servo continue run until it is stopped by limit sensor. What I do in my program is configure the motion for 3 axises (velocity, accel, decel), set the operation mode (absolute, relative), load vector space position, then start motion.

 

Thank you for your time reading and answering my question.

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There is one more thing I have just notice is the Z axis's limit switch is actived which make it continue goes to limit on the X axis.

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Hi NTT,

 

Just to confirm, you home your coordinate system using limit switches and then do an absolute position move. After that you then do a relative move. But what is occuring is that you get one or two servos continuing to move. Another thing you mentioned is that one limit switch is active, meaning it will do the behavior of whatever you programmed your limit switch to do. One thing I might do is to monitor the position to see where LabVIEW might think the motor is, in case it is different from the actual position. Another thing I would check is to see if there is a portion of your code which handles the z axis limit switch being active to see if that moves the other servos to certain positions. 

Paolo F.
National Instruments
Applications Engineer
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