Limitless Movement Function - Yamaha DRCX User Manual

8-3 Program Function
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8-3-2 Limitless movement function

The limitless movement function allows multiple turns in the same direction along the robot axis.
The DRCX controller incorporates the soft limit function that prohibits any robot motion which
exceeds the soft limits specified by the parameters. This soft limit function is very useful for linear
movement type robots such as FLIP-X series. However, this function is sometimes undesirable for
rotary type robots such as FROP because it limits multi-turn movements in the same direction. In
such cases, the limitless movement function will prove useful.
To enable the limitless movement function, set the position data unit parameters (Setting PRM21 to
2 is suitable for applications using servo conveyors, and setting to 3 is suitable for applications using
FROP or index tables.) to 2 or 3. When these parameters are set to 0 or 1, the limitless movement
function does not work. In other words, the limitless movement function works only for the axis with
the position data unit parameter set to 2 or 3. It is therefore possible to allow limitless movement on
only one axis and perform normal movement on the other axis. Of course, two axes can be operated
with the limitless movement function. Setting the position data unit parameters to 2 is suitable for
applications using servo conveyors, and setting them to 3 is suitable for applications using FROP or
index tables.
■ When the position data unit parameter is set to 2:
When this parameter is set to 2, the current position is expressed in millimeters from 0 to the "plus
soft limit - 0.01mm" as a basic cycle. Therefore, even if the robot moves to the plus soft limit
point, that position sets to 0mm so that the robot can move continuously in the same direction.
In limitless movement, the movement direction can also be selected with a movement command
*1) such as MOVA which specifies a target position.
To select a movement direction opposite the return-to-origin direction, add 5000mm to the target
point for point setting. To select the same movement direction as when performing return-to-
origin, add 5000mm to the target point and give a minus sign to this value. When the movement
direction is not specified, the robot moves in the direction of shorter distance. For example, when
just 30mm is specified for the point setting, the movement direction differs depending on the
current position. However, when 5030mm is specified, the robot always moves in the direction
opposite the return-to-origin direction. In contrast, when -5030mm is specified, the robot always
moves in the same direction as when performing return-to-origin.
In the case of a movement command such as MOVI which specifies the amount of movement, the
movement direction is determined by the plus/minus sign of the point data, just as with normal
movement.
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CAUTION
• When the parameter is 2, set the plus soft limit to always be an integer multiple of the lead equivalent value.
If it is not a value multiplied by an integer, positioning at the desired point may sometimes be impossible. The +
soft limit setting range is 1 to 4999.
• The maximum distance of one movement is a distance equal to one cycle (+ soft limit). To move a distance
longer than one cycle, divide the movement distance into two or more portions.
• In limitless movement, @XINC (@XDEC) or @YINC (@YDEC) allows moving a distance equal to one cycle.
The movement speed setting and stop method are just the same as for normal movement.
• If the target point is the same as the current position on the program when executing a movement command
such as MOVA which specifies a position, the robot motion differs depending on whether the movement
direction is selected by point setting, as follows:
When the movement direction is selected: Moves a distance equal to one cycle in the selected direction and stops.
When no movement direction is selected: Does not move.
• Limitless movement cannot be performed in combination with the ACHA or ACHI statement.
• Use caution when operating the robot since the soft limits are disabled during limitless movement.
*1) These movement commands include MOVA, MOVF, MOVD, MOVM, DRVA and DRVD statements. The MOVD
and DRVD statements are provided only for communication commands and can directly specify the target point.
*2) The lead equivalent value can be checked with the lead length parameters (PRM60, PRM100). The lead length param-
eter indicates a distance the robot axis (or workpiece on the axis) moves while the motor makes one turn, in units of 1/
100mm.
*2)