09.95
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9–48

SINUMERIK 840C (IA)

9.5.3.2 Installation with adaptation characteristic

If the compensation is acceleration dependant, a characteristic must be determi-
ned in a second stage.
The required compensation amplitudes for different radii and velocities are deter-
mined, the effect of the compensating amplitudes checked in a circularity test and
the optimum compensation amplitudes logged.
The following characteristic is used for the adaptation:
Dn

t

Dnmax
Dnmin
12 3 4
a3a’3
a1a2
Acceleration
NC MD 12480 NC MD 12520
Minimum amplitude
NC MD 12400
NC MD 12440
Max. amplitude NC MD 12320
Fig. 9.25
A distinction is made between four ranges in the characteristics:
for a < a1
for a1 a a2
for a2 < a < a3
for a3 a
Dn = Dnmax
Dnmax
Dnmax
Dnmin
a
a1
1 – a– a 2
a3– a2
The characteristics in Fig. 9.25 are used for the following examples. It is defined
by the values “Maximum compensating amplitude”, “Minimum compensating am-
plitude” and the three acceleration values a3, a2 and a1. Considerably more mea-
sured values should be determined as a control, must importantly there should
be a sufficient number of points for high velocities with small radii. The characteri-
stic values are most easily derived from a graphic representation.
The acceleration values are derived from a = v2/r from the radius and travel
velocity. The acceleration value can easily be varied using the override switch.
Before entering these acceleration values a3, a2 and a1 in machine data 1244*,
1248* and 1252*, it may be necessary to convert to the input format of the ma-
chine data ([mm/s2] [100 units MS/s2] or [10000 units MS/s2]).
A monitoring function in the control ensures that incorrect parameterization of the
characteristics for the friction feedforward control are avoided.
The following conditions must be met when entering accelerations a3, a2 and a1
for the characteristic.
a1 < a2 < a3
If this condition is not met, parameter error 328 is output. The user should there-
fore follow the input sequence a3, a2 and then a1 when entering the acceleration
values. Parameter error 328 is also output if internal formats are exceeded as a
result of calculation errors when determining the accelerations from inputs a3, a2
and a1 . If this happens, the user must check whether the break points in the
9 Drive Servo Start-Up Application (as from SW 3)
9.5.3 Conventional quadrant error compensation (as from SW 2)