
B-65150E/04 4. SERVO FUNCTION DETAILS
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4.6.5 Two-stage Backlash Acceleration Function
(1) Overview
When the machine reverses the direction of feed, two types of delay are
likely to occur; one type due to friction in the motor and the other due to
friction in the machine.
The two-stage backlash acceleration function compensates for two
types of delays separately, thus enabling two-stage compensation.
Stage 1: The friction torque is canceled when the
motor reverses.
Stage 2: The friction torque in the machine is
canceled.
Furthermore, optimum compensation can be performed at all times for
stage 1 against changing speed and load.
The two-stage backlash acceleration function performs compensation
as shown below:
Fig. 4.6.5 (a) Backlash acceleration under control of the two-stage
backlash acceleration function
Two-stage
compensation
Start
End
Time
The stage 1 compensation value is determined automatically.
Specify the parameter to determine how much of the estimated
friction is to be reversed.
Stage 1 acceleration coefficient (normally set to 100%)
Stage 2 acceleration amount
(if this is 0, stage 2 does not occur.)
Stage 2 acceleration
offset
(Normally, 0 is set.)
Stage 2 start and end parameters (detection unit)
The start point of stage 2 is specified as a distance relative to the start
of stage 1.
The end point is determined automatically. Normally, if the setting is
positive, the end point is set at a distance two times greater than the
start point distance. If the setting is negative, the end point is set at a
distance three times greater than the start point distance. An arbitrary
end point can also be set by setting the end scale factor parameter.