LSIS XBF-PN04B, Руководство пользователя

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Chapter 9 Functions
9-16
Remark
1. When operation method is continuous, before reaching the amount of movement set by target
position, sometimes its speed changes to next operation step speed.
That is operating the remaining amount of movement less than operation speed at the next step to
control the operation speed continuously
(The remaining distance less than operation speed is less than distance the object can move
within one control cycle (0.8 (less than 2 axes)~2.4ms (8 axes) with the speed of the object before
reaching the target.
2. If control method is linear or circular interpolation and operation method is continuous, positioning
speed control will be different according to “Interpolation continuous operation type” of the
extended parameter. For more information, refer
to “Interpolation control continuous operation”.
(b) Look Ahead
1)
During “Continuous” operation, if the moving amount of next operation step is smaller than the distance
needed to decelerate the current operation speed, “Look Ahead” control is used to avoid to stop immediately
while operation speed
≠ 0
2) Look Ahead means is control that it calculates the permissible entry speed available for the next step by
using current operation step data and target position of the next step previously and uses that as the speed
of the end point of the current step. When target position (moving amount) of the next operation step is small,
it makes the step speed as 0 by reducing the permissible entry speed available for the next step.
3) The positioning module calculate the speed of the end point using total 3 steps including current step for
Look Ahead.
Next figure will explain the difference between general continuous operation using Look Ahead and not using
Look Ahead.
End point speed = Operating speed
Speed
Time
Operation step no. : 1
Operation step no. : 2
Operation step no. : 3
Speed
Time
Operation step no. : 1
Operation step no. : 2
Operation step no. : 3
ON
Start
command
In
operation
ON
Start
command
In
operation
ON
ON
Calculates the
end point speed
with Look Ahead
Calculate the
end point speed
with Look Ahead
*1
*2
Normal continuous operation Continuous operation with Look Ahead
*1 : Moving amount of step 2 and step 3 is more than the distance needed to decelerate step 1 operation speed. So,
endpoint speed = operation speed.
*2 : Since moving amount of step 3 is less than distance needed to decelerate step 2 operation speed, it calculates
the speed that makes the stop speed of step 3 as 0 and uses that as the end point speed of step 2.