Acceleration/Deceleration Before Interpolation - Mitsubishi Electric MELSEC iQ-R16MTCPU Programming Manual

Acceleration/deceleration before interpolation

In order to control the impact on the machine when starting/stopping, acceleration/deceleration control is performed for
movement commands and the speed curve is smoothened. However, because the acceleration/deceleration processing
when high-accuracy control is disabled is performed after interpolation, corners at block joints become rounded and
deviations from the commanded shape occur. In high-accuracy control mode, these problems are solved by acceleration/
deceleration control before interpolation. With acceleration/deceleration before interpolation, a working path that is consistent
with the commanded shape in the G-code program is possible. Moreover, because acceleration/deceleration before
interpolation uses the constant inclination acceleration/deceleration method, the acceleration/deceleration time can be
shortened.
Basic patterns for acceleration/deceleration control in linear interpolation commands
Control mode Acceleration/deceleration curve pattern
Normal mode
Composite speed
(Acceleration/
deceleration after
interpolation)
clamp:Cutting feed clamp speed
G1tL: G1 time constant (linear)
High-accuracy • When interpolation distance is long and the speed reaches the feed speed
control mode
Speed
(Acceleration/
deceleration before
interpolation)
• When interpolation distance is short and the speed does not reach the feed
speed
Speed
T = 2 ×
F:
T:
Ts:
L:
:
clamp: Cutting feed clamp speed for high-accuracy control mode
G1bF: Acceleration/deceleration before interpolation - maximum speed
G1btL: Acceleration/deceleration before interpolation - time constant
6 AUXILIARY AND APPLIED FUNCTIONS
226
6.7 High-Accuracy Control
G1tL
F1
G1bF
L
F2
G1bF/2
θ
Ts2=G1btL/2
Ts1=G1btL Ts1=G1btL
T
L Ts1 × F1
-1
T = + θ = tan
F1 G1bF
clamp=G1bF
F
L
θ
Ts
Ts=G1btL
T
F × G1btL
TS =
Ts × L/G1bF
Feed speed
Interpolation time
Acceleration/deceleration time to reach the feed speed
Interpolation distance
Acceleration/deceleration inclination
clamp
Time
clamp=G1bF
Time
G1bF
Ts1
Time
G1bF
-1
θ = tan
2R G1btL
Operation
• Because the acceleration time to reach the
command speed is fixed (time constant acceleration/
deceleration), the slower the command speed, the
more gradual the acceleration/deceleration becomes
(acceleration/deceleration time does not change).
• The time to reach the command speed (G1 time
constant (linear)) is set for each axis. However, when
the time constant for the base axis is different, arcs
can become warped.
• Because the acceleration time until the maximum
speed set in the parameters (acceleration/
deceleration before interpolation) is fixed (constant
inclination acceleration/deceleration), the slower the
command speed, the shorter the acceleration/
deceleration time.
• There is one value (common value for all axes) for
the acceleration/deceleration time constant for a line.
*: Acceleration/deceleration before interpolation -
maximum speed and acceleration/deceleration
before interpolation - time constant are for defining
the inclination of acceleration/deceleration. The
actual cutting feed maximum speed is clamped by
the G-code control axis parameter "cutting feed
clamp speed for high-accuracy control mode".