Anders,
You want some overshoot in your tuning to make your drives snappy in their response. In the tuning process, there is no deceleration, so the drive should overshoot. When running a real time cnc operation there is always some deceleration to bring the mass of the machine to a smooth stop. During this decel time the drive will slow down and there will therefore be no overshoot.
Try to adjust the drive so that you have some ki in the final adjustment.
You definately want no oscilation. Even during tuning, keep it to a BARE minimum. Shut off the VM power almost instantly if it starts to oscillate wildly.
If your current trip value is too low, the drive may hesitate. Take the peak current specification of the motor and divide it by .2
That is the number you put into the current trip value.
Set the fall back current much lower so that if you ever ram into something after 2 seconds the drive will fall back to that current level and not fry the motor or blow the drive.
Tom Eldredge
Rutex LLC
__________________
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
|