Siemens SINUMERIK 840D sl Function Manual page 426

K3: Compensation
5.6 Friction compensation (quadrant error compensation)
● $AA_QEC_TIME_2
● $AA_QEC_MEAS_TIME_1/_2/_3
Parameter acceptance
The QEC system variables are stored in the non-volatile user memory after the NC program
is started where they remain unchanged until the memory is erased or reformatted or until a
new learning or relearning process takes place or until they are written by the NC program.
Before the learning cycle is called, all system variables must be assigned valid values for the
learning process. This can be done, for example, in a subroutine. After this NC program has
run and a reset has been performed, the QEC data are active.
Characteristic data
The characteristic data determined during the learning process are stored as system
variables in the user memory reserved for this purpose.
Format: $AA_QEC[n] Range of n: 0 ... 1024
These values write the learned characteristic in internal formats and must therefore not be
changed!
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"Compensation time constant for adaptation of compensation value decay time"
At a value of zero of less than or equal to $AA_QEC_TIME_1, no adaptation is
performed.
The decay time is usually constant over the entire working range. In rare cases however,
it can be advantageous to raise the decay time in the very small acceleration range, or to
lower it at high accelerations. For further information, please refer to Section "Further
optimization and intervention options".
Range of values: ≥ 0; recommended value: 0.015s (identical to $AA_QEC_TIME_1)
"Measurement time for calculating the error criterion in acceleration range 1/2/3"
The measurement time is started, as soon as the criterion for injection of the
compensation value is fulfilled (i.e. the set speed changes sign). The end of the
measurement time is defined by the set parameter values.
Different measuring times are required for each characteristic range.
Recommended values for
– $AA_QEC_MEAS_TIME_1: 0.090s (= 6 *$AA_QEC_TIME_1)
– $AA_QEC_MEAS_TIME_2: 0.045s (= 3 * $AA_QEC_TIME_1)
– $AA_QEC_MEAS_TIME_3: 0.030s (= 2 * $AA_QEC_TIME_1)
The recommended values must only be changed if the compensation is insufficient in
these acceleration ranges or if $AA_QEC_TIME_1 is changed. For further information,
please refer to Section "Further optimization and intervention options".
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions