how should I tune the PID to improve 'Jog Axis' reponse?

[langtian]

In MAX the 'Jog Axis' reponse as the accessory.

When decelerating the velocity, it exceed zero more to a large negative velocity. And this makes the settling time long.

How should I tune the PID to disappear the phenomena? Anybody can tell me?

Thanks a lot.

[Jochen]

What you see here is an underdamped system behavior with a large overshot. In general I think you will have to increase Kd and Td and decrease Kp and Ki. Please refer to this document to learn more about servo tuning. If you don't get any further please post your PID settings (screenshot from MAX).

Best regards,

Jochen Klier
National Instruments Germany

[langtian]

Hi, Jochen. Thanks for your answer. Now I try to express my question in detail.

System: 2_D position table (50mm*50mm)

hardware:  PCI7344 + 2 voice coil motor + driver(no feedback,just a amplifier) + 0.5micron encoder(Renishaw) as the position feedback

software: Labview7.1 + MAX3.1

Aim: To get the setting time of single axis lower than 40ms (even if there is some overshot)

The document you mentioned I have read before. When I tune the servo,'Auto tune' can't get meaningful parameters. So all the time I tune it manually.

1, About Step reponse: I can get a setting time lower than 40ms(step 1000 counts + 200 sample) by accident, but the same PID I can't get the good result all the time.

2,When I use 'start motion.flx' moving 6000 counts (400000 counts/s+32000000 counts/s^2+S curve time 3) or use 'Jog axis',the setting time are more than 100ms (see axis.jpg). I try to increase the Td or Kd. It can change the overshot, but the setting time is not ideal.  IF Kd too large, the system will unstable.  I think maybe the aim is unpractical, right? Jochen, has you tune some table whose setting time lower than 40ms using 7344?

3,what's the relationship between 'step reponse' and 'Jog axis'.Should I tune the PID according to 'Step reponse' or 'Jog axis'? (In 'Jog axis', the velocity and Acceleration and Deceleration also play an important role.)

4,The driver have no current feedback.I guess it is an important problem.what'a your opinion?