Sigma II User’s Manual
Chapter 6: Servo Adjustment
6-10
n
Methods for Using Proportional Control
Proportional control can be used in the following two ways.
•
When operation is performed by sending speed references from the host control-
ler to the servo amplifier, the host controller can selectively use P control mode
for particular conditions only. This method can suppress overshooting and
shorten setting time. Refer to 6.2.5 Using Mode Switch for particular conditions.
•
If PI control mode is used when the speed reference has a reference offset, the
motor may rotate at a very slow speed and fail to stop even if 0 is specified as a
speed reference. In this case, use P control mode to stop the motor.
6.2.4
Setting Speed Bias
The settling time for positioning can be reduced by assigning bias to the speed refer-
ence block in the servo amplifier. To assign bias, use the following constants.
Set the parameters to shorten the time required for positioning according to the
application.
The bias increment width (Pn108) is expressed as an error pulse width that deter-
mines the time in which bias input (Pn107) takes effect. The bias input is ON if the
error pulse width exceeds the value set in Pn108.
Pn000.1
Setting
Control Mode
0
Speed
Control
Usual speed control or position con-
trol is selected.
Input signal /P-CON (CN1-41) is used
to select PI control or P control.
1
Position
Control
Parameter
Signal
Setting
Application
Pn107
Bias
Setting Range: 0 to 450
rpm
Default Setting: 0
rpm
Position Control
Pn108
Bias Addition Width
Setting Range: 0 to 250
Default Setting: 7
Position Control
CN1-41
is open.
PI control
CN1-41
is 0V
P control
P or PI
control
selection
CN1-41
/P-CON
Servo amplifier
Error pulse
Internal speed reference
Pn107
Bias increment width
Pn108
