
B–63503EN–1/01
7. FEEDRATE CONTROL/ACCELERATION
AND DECELERATION CONTROL
314
NOTE
1 If linear acceleration/deceleration after interpolation for
cutting feed is enabled, linear acceleration/deceleration is
executed during cutting feed and during a dry run. Linear
acceleration/deceleration can also be executed during jog
feed if the JGL bit (bit 4 of parameter No. 1610) is specified
accordingly.
2 In circular interpolation especially when circular cutting is
executed at high speed, the actual path of the accelerated
or decelerated tool deviates from the specified arc in the
direction of the radius.
The maximum error in the radial direction (Dr) can be
approximated by the following expressions:
If the error caused by the time constant of the servo loop is
excluded, the error cause by linear acceleration/
deceleration or bell shaped acceleration/deceleration after
interpolation is 1/12 of that caused by exponential
acceleration/deceleration.
3 Linear acceleration/deceleration can be executed both for
cutting feed and for jog feed along a PMC axis.
Acceleration/deceleration for cutting feed is executed even
if acceleration/deceleration for jog feed is selected. In jog
feed along the PMC axis, the time constant for cutting feed
is used instead of that for jog feed.
Dr :Maximum radius error (mm)
v :Feedrate (mm/s)
r :Radius of arc (mm)
T
1
:Acceleration/deceleration time constant (s)
T
2
:Time constant of servo loop (s)
(Reciprocal of position loop gain)
Y
X
r
Dr
Specified path
Actual path
D r= ( T
1
2
+ T
2
2
) …Exponential acceleration/deceleration
D r= ( T
1
2
+ T
2
2
) …Linear acceleration/deceleration or bell
shaped acceleration /deceleration
after interpolation
2
24
1
2
1
2
11
v
2
r
v
2
r
Note