Servo system principles
Section 1-4
14
1-4-3
Motion control algorithm
The servo system controls the motor by continuously adjusting the speed
reference to the Servo Driver. The speed reference is calculated by the motion
control algorithm of the CJ1W-MCH72, which is explained in this section.
The motion control algorithm uses the demand position (A), the measured
position (D) and the Following Error (B) to determine the speed reference. The
Following Error is the difference between the demanded and measured
position. The demand position, the measured position and the Following Error
are represented by the axis parameters
MPOS
,
DPOS
and
FE
. Five gain
values have been implemented for the user to be able to configure the correct
control operation for each application.
C is the output signal.
• Proportional gain
The proportional gain
K
p
creates an output
O
p
that is proportional to the
Following Error E.
O
p
= K
p
· E
All practical systems use proportional gain. For many just using this gain
parameter alone is sufficient. The proportional gain axis parameter is called
P_GAIN
.
• Integral gain
The integral gain
K
i
creates an output
O
i
that is proportional to the sum of
the Following Errors that have occurred during the system operation.
O
i
= K
i
·
Σ
E
Integral gain can cause overshoot and so is usually used only on systems
working at constant speed or with slow accelerations. The integral gain axis
parameter is called
I_GAIN
.
• Derivative gain
The derivative gain
K
d
produces an output
O
d
that is proportional to the
change in the Following Error
E
and speeds up the response to changes in
error while maintaining the same relative stability.
O
d
= K
d
·
∆
E
Derivative gain may create a smoother response. High values may lead to
oscillation. The derivative gain axis parameter is called
D_GAIN
.
• Output speed gain
The output speed gain
K
ov
produces an output
O
ov
that is proportional to
the change in the measured position
P
m
and increases system damping.
O
ov
= K
ov
·
∆
P
m
A
B
C
D
∑
∑
K
p
K
i
K
d
K
vff
K
ov
∆
∆
Summary of Contents for SYSMAC CJ Series
Page 2: ......
Page 70: ...Specifications Section 2 4 58...
Page 84: ...FINS commands Section 3 4 72...
Page 148: ...All BASIC commands Section 4 2 136 AXIS 1 AXIS 0...
Page 370: ...Section 358...
