The Basics of Positioning Control Positioning method type
1 - 8
MITSUBISHI ELECTRIC
● The moving part continues by a coasting distance until it completely stops, after the stop
command is given. The coasting distance is not controlled and it is represented as the shaded
part in the figure below.
● Dispersion in the stop distance changes as shown below. Dispersion is affected by the speed of
the workpiece when the stop command is given and the speed reduction time delay after stop.
● If the required stop precision is not satisfactory when stopping from the normal operation speed,
the most effective method to improve the stop precision is to reduce the operation speed.
However, if the operation speed is simply reduced, the machine efficiency may also be reduced.
Therefore, in actual operation, the motor speed can be reduced from a high speed to a low speed
before the motor is stopped, as shown below.
Fig. 1-10:
Positioning pattern
1200b0da.eps
Fig. 1-11:
Positioning pattern
1200c0da.eps
1200d0da.eps
Fig. 1-12:
Positioning pattern
Speed
Time
StopStop command
Coasting
distance
Speed
Time
Stop
Stop
command
Dispersion in
stop
Stop
Speed recuction start
Time delay
Speed
Time
Stop
Speed reduction
command
Improved stop
precision
Stop command
Low
speed
Speed
Time delay
Poor stop
precision
Stop
command
Stop
Time
High speed
High speed
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