Yaskawa DR2 Sigma Servo - Manual (Page 135)

APPLICATIONS OF Σ-SERIES PRODUCTS
3.6.6 Using Mode Switch
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3.6.6 Using Mode Switch
1) Use the mode switch for the following purposes:
a) To prevent overshoot during acceleration or deceleration (for speed control).
b) To prevent undershoot during positioning in order to reduce settling time (for position
control).
Speed
Overshoot
Actual motor
operation
Reference
Time
Undershoot
Settling time
2) In other words, the mode switch is a function that automatically switches the speed con-
trol mode inside the Servopack from PI control to P control while certain conditions are
being established.
NOTE The mode switch is used to fully utilize performance of a servo drive to achieve very high-
speed positioning. The speed response waveform must be observed to adjust the mode
switch.
For normal use, the speed loop gain and position loop gain set by autotuning provide suf-
ficient speed/position control.
Even if overshoot or undershoot occurs, they can be suppressed by setting the accelera-
tion/deceleration time constant for the host controller, the soft start time constants
(Cn-07, Cn-23), or position reference accel/decel time constant (Cn-26) for the Servo-
pack.
TERMS
From PI control to P control
PI control means proportional/integral control and P control means proportional control. In
short, switching “from PI control to P control” reduces effective servo gain, making the servo
system more stable.
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