Mitsubishi Electric CR750-Q Instruction Manual page 279

(13) This instruction cannot be used in a constantly executed program.
Precautions for registration of position data after execution of linear (circular arc) interpolation for
vertical 5-axis robots
In the linear (circular arc) interpolation, the posture data at the operation start position and the posture
data at the movement target position are different by +180 degrees or -180 degrees or more, the robot
performs shortcut operation. For vertical 5-axis robots (RV-F series), the registered posture data is shown
at the movement target position, but the actual posture is deviated by +360 degrees or -360 degrees.
For example, when linear interpolation is performed from the 0-degree position to the +200-degree posi-
tion of the A axis, the posture data at the current position is shown as +200 degrees, but the robot oper-
ates to the -160-degree position.
When the position data is registered under such a condition, the posture data deviated by +360 or -360
degrees from the actual position is registered. Be careful when the position data is compensated after lin-
ear (circular arc) compensation movement for debugging operation (step feed, MS position movement) of
the program.
This phenomenon can be avoided by specifying the roundabout operation in the argument type of the lin-
ear (circular arc) interpolation, or by the servo OFF operation before the position data is registered.
MVR3 P1, P2, P3
Moves by XYZ
interpolation (3-axis
XYZ interpolation)
P_CURR
Fig.4-26:Example of circular interpolation motion path 3
P2
P1
P3
Detailed explanation of command words 4-259
4MELFA-BASIC V