ElmoMC SimplIQ Digital Servo Drives-Bell Getting Started - Manual (Page 70)

The SimplIQ for Steppers Getting Started & Tuning and Commissioning Guide
MAN-BELGS (Ver. 1.1)
70
KP KI Velocity +Displ. -Displ. Rec. T. Rec. Res Profile
30 Marked
On Plot
12000 5000 5000 0.48 sec 400 musec off
Figure 62: Test results for several KI and fixed KP. The test with KI=8000 has an
overshoot of 30% with negligible undershoot and can be considered a good choice
3. The final step is performing small iterations on KI and KP (a 10% parameter
change in each test) and testing in order come up with the best solution defined
by the user. However, the user must be careful to preserve the gain margin as
explained in Section
A.4
We are now ready to give the first guidelines for what to look for when searching
for a good controller:
Guideline 1: When searching for good controllers try to increase KI in order to
improve the closed loop performance of the system. However, increasing KI too
much creates unacceptable oscillations as shown in Figure 63.
Guideline 2: Never allow an overshoot of more than 40%. A typical overshoot
selection is 25%.
The example in Figure 63 reflects a non-robust controller with
poor properties such as a large settling time.
0.1 0.12 0.14 0.16 0.18 0.2
-1.5
-0.7
0.1
0.9
1.7
2.5
x 10
4
C
ount
s
/s
e
c
.
Tim e (sec.)
K I=8000
K I=6000
K I=4000
K I=2000
K I=1000
K I=500
Reference
0.1 0.12 0.14 0.16 0.18 0.2
-0.5
-0.1
0.3
0.7
1.1
1.5
Am
p
e
re
Tim e (sec.)
K I=8000
K I=6000
K I=4000
K I=2000
K I=1000
K I=500