B.8.4 Behaviour Of Standstill Control - Festo CPX Series Manual

B. Basic controlling principles

B.8.4 Behaviour of standstill control

Festo P.BE−CPX−CMA X−CONTROL−EN en 0908NH
After completion of a positioning task, position control is
switched to force control to keep the drive at a standstill.
Reversing does not occur at the time of reaching the standstill
condition, but:
200 ms later or
when the change in the actual force after reaching the
standstill condition is more than 25% of the friction hys
teresis.
The standstill condition has been reached if
the tolerance has been reached once and
the position error is within 70% of the permissible toler
ance window and
the speed is less than 4 mm/s and
the chamber pressures are smaller than the supply pres
sure (especially in vertical operation with large masses,
chamber pressures that are larger than the supply pres
sure may briefly occur).
If the drive leaves its tolerance window for standstill position
during standstill control or if the speed exceeds 4 mm/s, then
the position controller is activated to move the drive back to
its target position. If the drive has reached the target position
and the standstill conditions, standstill control is re−activated,
provided one of the stated conditions for the delay time or
force control is fulfilled.
B−43