Winder/unwinder pid

Hello All,

On a wire machine, i want use pid control for uncoiler and coiler with dancer.

Machine is work with error=sp-pv and main speed. When go big diameter it make oscillation. without calculate diamater how i use pid? Any advice?

Plc is siemens s7-300. Drivers are lenze.

Best regards


Nec

Originally posted bu necyil:

without calculate diamater how i use pid?

Click to expand...

Generally speaking, you don't. Your PID is correcting dancer position using linear displacement at the outside of your coil generated by rotating the shaft of your coil. Since the linear displacement per degree of shaft rotation changes with coil diameter there isn't a good way to correctly apply the tangetial correction from the core if you don't know diameter. Actually, I'm not sure how you are using main machine speed without knowing diameter.

If your system is slow speed relative to the amount of dancer travel you have you could tune the system to be stable at full coil and then hope you have enough correction at core to keep up. But if you have tried that and it doesn't work you will need diameter.

There are a couple of different ways to calculate diameter that would probably be close enough for your purposes. The easiest in your case may be to add a diameter sensor. You can also use spindle speed relative to line speed or spindle displacement relative to line displacement to calculate diameter.

Keith

Don't control the drive in speed mode with the PID.
Use the PID output directly as a torque reference to the drive.