Dynamic Feedforward Control (Following Error Compensation); General Properties - Siemens SINUMERIK 840D sl Function Manual

Loss of the referenced status of the basic axis
If the referenced status of the active measuring system of the basic axis changes from
"Referenced/synchronized" to "Not referenced/synchronized" (DB31, ... DBX60.4 or .5: 1→0),
then the MSEC and/or sag compensation is deactivated in the corresponding axis (basic/
compensation axis).
If the referenced status of the active measuring system of the basic axis then changes from
"Not referenced/synchronized" to "Referenced/synchronized" (DB31, ... DBX60.4 or .5: 0→1),
then the MSEC and/or sag compensation is reactivated in the corresponding axis (basic/
compensation axis).
Controller enable signals
If a compensation relationship is active, then the controller enable (DB31, ... DBX2.1) should
always be set the same for the basic and compensation axes.
Traversing signal output
The traversing signals of the compensation axis are only when the compensation function is
activated/deactivated and when the number of active compensation tables changes.
Traversing motion of the compensation axis, resulting from motion of the basic axis, does not
result in the output of traversing signals in the compensation axis.
5.5

Dynamic feedforward control (following error compensation)

5.5.1

General properties

Axial following error
The remaining system deviation of the position controller when traversing a machining axis is
known as axial following error. Expressed in another way, the axial following error is the
difference between the setpoint position and the actual position of the machine axis.
Effects
Particularly during acceleration in contour curvatures, e.g. circles and corners, this following
error leads to undesirable, velocity-dependent contour violations.
Compensation
The axial following error can be reduced almost to zero with the help of the "dynamic
feedforward control". The function is therefore also called "following error compensation".
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
5.5 Dynamic feedforward control (following error compensation)
K3: Compensations
313