Mitsubishi Electric M700V Series Programming Manual page 426

13. Program Support Functions
(2) Reduction of arc radius reduction error amount using feed forward control
With the high-accuracy control, the arc radius reduction error amount can be greatly reduced
by combining the pre-interpolation acceleration/deceleration control method above-mentioned
and the feed forward control/SHG control.
The logical radius reduction error amount ΔR in the high-accuracy control mode is obtained
with the following expression.
Feed forward control
By setting Kf to the following value, the delay elements caused by the position loop in the
servo system can be eliminated, and the logical ΔR can be set to 0.
Kf = 1 (Feed forward gain 100%)
The feed forward gain can be set independently for G00 and G01.
(Note) If the machine vibrates when Kf is set to 1, Kf must be lowered or the servo system must
be adjusted.
13.15 High-accuracy Control ; G61.1, G08
SHG control + Feed forward control
1
2 ( 1 − K f
Δ R ≤
{ T p
2 R
R : Arc radius (mm)
F : Cutting feedrate (mm/min)
Tp : Position loop time constant (s)
Kf : Feed forward coefficient (fwd_g/100)
The equivalent feed forward gain to set Kf to 1 can
be obtained with the following expression.
⎧
− −
⎨
100 1 1
⎪
⎩ ⎪
F
Δ
R
R
414
F
2 2
) } ( )
6 0
⎫
2
⎛
⎛ ⎞ ⎪
fwd g _
PGN1 for conventional control
⎜
⎜ ⎟ ⎬
⎝ ⎠
⎝
50 ⎭ ⎪
2 × PGN1 for SHG control
Path for pre-interpolation
acceleration/deceleration control method (Kf = 1)
Path for pre-interpolation
acceleration/deceleration control method (Kf = 0)
Path for post-interpolation
acceleration/deceleration control method
2
⎞
⎟
⎠