Mitsubishi Electric M700V Series Programming Manual page 109

6. Interpolation Functions
Designating intermediate point and end point
When using the 3-dimensional circular interpolation command, an arc that exists over the
3-dimensional space can be determined by designating the intermediate point and end point in
addition to the start point (current position). (Refer to following figure) So according to the
command format, it is necessary to designate an intermediate point in the 1st block and an end
point in the 2nd block. If only one block is designated, a program error (P74) will occur.
Liner interpolation is applied when the end point match the start point in the 3-dimensional circular
interpolation command. (Refer to "When liner interpolation is applied") Thus, a true circle
(360-degree rotation) cannot be designated in the 3-dimensional circular interpolation.
In addition, designate that an intermediate point is located in the middle of a start point and an end
point. If the intermediate point is near the start point or the end point, arc accuracy may fall.
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Designation of arc in 3-dimensional space
As shown in the above figure, when three points (start point, intermediate point, end
point) are specified on 3-dimensional space, arc center coordinates can be obtained.
An arc center cannot be obtained if only two points are specified, and a liner
interpolation is applied. If the intermediate point is near the start point or the end point,
an error may occur when calculating arc center.
6.14 3-dimensional Circular Interpolation; G02.4, G03.4
Plane including start point,
intermediate point and end point
Center
Start point
(Current position)
97
Intermediate point
End point