
B-63943EN-1/02 4.REFERENCE POSITION ESTABLISHMENT
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- Absolute command and incremental command
After the reference position has been established, positioning to a
specified end point is performed. This operation is explained below.
(1) When an absolute command is specified
Movement to the end point in the new coordinate system that has
been established in step <3> is made. For example, when G90
G00 Xxx.Yyy.; is specified, the tool moves as indicated with the
bold line in the figure below. Note that, however, the figure
shows the positional relationship among points and that the
intermediate tool path is not always of the linear interpolation
type.
Specified end point (xx,yy)
Position at which the reference
position is established
Machine coordinate system before the reference position is
established (inaccurate coordinate system)
Workpiece origin offset
Workpiece coordinate system before the reference position is
established (inaccurate coordinate system)
(New) machine coordinate system (accurate coordinate
system) after the reference
Workpiece origin offset
(New) workpiece coordinate system (accurate coordinate
system) after the reference
ctual end point ((xx,yy) in the coordinate system after the reference position is established)
Difference between the machine coordinate system at power-on and the machine
coordinate system after the reference position is established (
α
,
β
)
Start point
Fig. 4.9.1 (d) Operation when an absolute command is specified
(2) When an incremental command is specified
Movement is made along each axis by a specified distance.
(The movement is indicated with the bold line in the figure
below. Note that the intermediate tool path is not always of the
linear interpolation type.) The coordinates at the end point are
those in a newly established coordinate system. When there is a
difference (α, β) between the newly established coordinate
system and the old coordinate system, the coordinates at the end
point are shifted by (α, β). For example, when G91 G00
X100.Y30.; is specified from the position of which absolute
coordinates are (0,0), the distance of movement along each axis
is (100,30), and the coordinates of the end point are (100-α,
30-β).