Single axis motion with PLC, DC motor, PID

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Thread Starter

Mike Robinson

I have a small project that i need to move a cutter in 1 axis to various positions. Speed is not a major concern for this project, but accuracy is somewhat critical.

One question I have is whether or not a PLC (GE-Fanuc), with an analog output via a PID block to a DC drive work, and what repeatability can i expect.

Any help and insight would be greatly appreciated.
 
D
Positioning is usually done with axis modules (eg GE Fanuc 90-30 APU), which will interface an incremental encoder and an analog output for speed control. If it's only the one axis, a micro-PLC with an analog expansion module will be a low cost solution.
 
What do you using for feedback? I see that you're planning on a PID loop. If speed isn't an issue, the main thing will be the resolution of the feedback used to close your position loop.
 
What do you using for feedback? I see that you're planning on a PID loop. If speed isn't an issue, the main thing will be the resolution of the feedback used to close your position loop.
 
B
Are you closing the loop with an encoder input card or an analog pot? If not, forget about any accuracy.

If so, low speed performance of the drive will be a limiting factor, but you should be able to position reasonably well. You will probably need a regen drive (4 quadrant) There are so many factors, that it is hard to give a more concrete answer.

Bill Sturm
 
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Davis Gentry

Actually, while resolution of the feedback is very important, the cycle time of the plc will be even more critical if he is looking at controlling motion using a plc. Typical motion control loops update at a minimum of 2 kHz, and I have run multi-axis updates at up to 20 kHz in applications with tight tolerances.

Davis Gentry Delta Tau Data Systems
 
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DAVCO Automation

Not very good in my past experience... if position is critical then most likely you are into servo and encoder type of system but not my bag... am learning....

And as always I have big shoulders... literally... if I am wrong here... peaple say so and two of us will learn...

Dave
 
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