
7.FEEDRATE CONTROL/ACCELERATION AND DECELERATION CONTROL B-63323EN-1/03
- 686 -
1636 Time constant for bell-shaped acceleration/deceleration for rapid traverse
along each axis (T2)
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Note
NOTE
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 (∆r) can be
approximated by the following expressions:
Exponential acceleration/deceleration
r
2
V
)
2
2
T
2
1
2
1
T
2
1
(r +=∆
Linear acceleration/deceleration
r
2
V
)
2
2
T
2
1
2
1
T
24
1
(r +=∆
Bell-shaped acceleration/deceleration
r
2
V
)
2
2
T
2
1
2
1
T
48
1
(r +=∆
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.
r : 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)
∆
0
Y
X
r