Mitsubishi Electric MELDAS C6 Programming Manual page 318

15. Measurement Support Functions
Detailed description (G31 coasting)
The amount of coasting from when the skip signal is input during the G31 command until the
machine stops differs according to the parameter "#1174 skip_F" or F command in G31.
The time to start deceleration to a stop after responding to the skip signal is short, so the machine
can be stopped precisely with a small coasting amount
F
δ 60 × Tp +
=
0
δ
: Coasting amount (mm)
0
F : G31 skip speed (mm/min.)
Tp : Position loop time constant (s) = (position loop gain)
t : Response delay time (s) = (time taken from the detection to the arrival of the skip
1
signal at the controller via PC)
t : Response error time (0.001 s)
2
When G31 is used for calculation, the value calculated from the section indicated by δ1 in the
above equation can be compensated, however, δ2 results in calculation error.
The relationship between the coasting amount and speed when Tp is 30ms and t
in the following figure.
Relationship between coasting amount and feedrate (example)
(Note) When the base specification parameter "#21101 add01/bit3" is set to "1", the automatic
acceleration/deceleration becomes valid for the deceleration at skip signal input.
Thus, the coasting amount from the skip signal input to stop may be larger than when the
automatic acceleration/deceleration is invalid.
F F
60 × ( t ± t 60 × ( Tp + t
) =
1 2
Skip signal input
F
t
1
Stop pattern with skip signal input
0.050
0.040
0.030
0.020
0.010
0 10 20
Feedrate F (mm/min)
F
) ± 60 × t
1 2
δ
δ
2
1
− 1
Area inside shaded section
denotes coasting amount δ
± t
Tp
2
Tp = 0.03
t = 0.005
1
30 40 50 60
310
15.2 Skip function
0
Time (S)
is 5ms is shown
1
Max. value
Average
Min. value
70