Siemens SINUMERIK 840Di Function Manual page 74

Detailed Description
2.1 Motion monitoring functions
2.1.2 Following Error Monitoring
Function
In control engineering terms, traversing along a machine axis always produces a certain
following error, i.e. a difference between the set and actual position.
The following error that arises depends on:
• Position control loop gain
• Maximum acceleration
• Maximum velocity
• With activated feedforward control: Precision of the path model and the parameters:
In the acceleration phase, the following error initially increases when traversing along a
machine axis. After a time depending on the parameterization of the position control loop,
the following error then remains constant in the ideal case. Due to external influences, more
or less large fluctuations in the following error always arise during a machining process. To
prevent these fluctuations in the following error from triggering an alarm, a tolerance range
within which the following error may change must be defined for the following error
monitoring:
MD36400 $MA_CONTOUR_TOL (Contour monitoring tolerance range)
Fig. 2-1
2-2
MD32200 $MA_POSCTRL_GAIN (servo gain factor)
MD32300 $MA_MAX_AX_ACCEL (Maximum axis acceleration)
MD32000 $MA_MAX_AX_VELO (Maximum axis velocity).
MD32610 $MA_VELO_FFW_WEIGHT
(Factor for the velocity feedforward control)
MD32800 $MA_EQUIV_CURRCTRL_TIME
(Equivalent time constant current control loop for feedforward control)
MD32810 $MA_EQUIV_SPEEDCTRL_TIME
(Equivalent time constant speed control loop for feedforward control)
Following Error Monitoring
Axis Monitoring, Protection Zones (A3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0