Mitsubishi Electric MELSEC-L LD75D, User Manual

Page: 399 / 818

397
CHAPTER 9 MAJOR POSITIONING CONTROL
9
9.
2 Set
ting t
he Pos
itioning
D
at
a
(2) 2-axis circular interpolation control with center point designation (ABS
circular right, ABS circular left)
(a) Operation chart
In the absolute system, 2-axis circular interpolation control with center point designation, positioning is carried
out from the current stop position (start point address) to the address (end point address) set in " Da.6
Positioning address/movement amount" in an arc path having as its center the address (arc address) of the
center point set in " Da.7 Arc address".
Positioning of a complete round with a radius from the start point address to the arc center point can be carried
out by setting the end point address (positioning address) to the same address as the start point address.
In circular interpolation control with center point designation, an angular velocity is calculated on the
assumption that operation is carried out at a command speed on the arc using the radius calculated from the
start point address and center point address, and the radius is compensated in proportion to the angular
velocity deviated from that at the start point. Thus, when there is a difference (error) between a radius
calculated from the start point address and center point address (start point radius) and a radius calculated
from the end point address and center point address (end point radius), the composite speed differs from the
command speed as follows.
• Start point radius > End point radius: As compared with the speed without error, the speed becomes slower
as end point address is reached.
• Start point radius < End point radius: As compared with the speed without error, the speed becomes faster
as end point address is reached.
Radius
Movement by circular interpolation
Forward direction
Reverse direction
End point address
Start point address
(current stop position)
Arc address
Forward direction Reverse direction
(positioning address)
Arc center point
Reverese direction
Forward direction
(Arc address)
(current stop position)
Start point address
=
Reverese direction
Forward direction
End point address
(positioning address)