15. Measurement Support Functions
15.2 Skip Function; G31
550
Detailed description (Skip coordinate readout error)
(1) Skip signal input coordinate readout
The coasting amount based on the position loop time constant Tp and cutting feed time
constant Ts is not included in the skip signal input coordinate values.
Therefore, the workpiece coordinate values applying when the skip signal is input can be read
out across the error range in the following formula as the skip signal input coordinate values.
However, coasting based on response delay time t1 results in a measurement error and so
compensation must be provided.
R
ead
out error
ε
(
μ
m
)
Readout error of skip signal input coordinates
Readout error of skip input coordinates
Readout error with a 60mm/min feedrate is:
ε
=
±
×
0.001 =
±
0.001 (mm)
Measurement value is within readout error range of
±
1
μ
m.
ε
=
±
×
t
2
+1
0
-1
Measurement value comes
within shaded section.
60
Feedrate (mm/min)
60
60
F
60
ε
: Readout error (mm)
F
: Feedrate
(mm/min)
t
2
: Response error time 0.001 (s)
(2) Readout of other coordinates
The readout coordinate values include the coasting amount. Therefore, when coordinate
values are required with skip signal input, reference should be made to the section on the G31
coasting amount and compensation provided. As in the case of (1), the coasting amount
based on the delay error time t2 cannot be calculated, and this generates a measuring error.
