Kollmorgen
Commissioning
SILVER
LINE
®
Product Family
5-12
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
0
0.0005
0.001
0.0015
0.002
Command
Feedback
Figure 5-6 -3dB Point: 70% Attentuation
5.4 PROBLEMS
The mechanical construction can limit the performance of your velocity loop. The problems caused by the mechanics
fall into three categories:
•
Compliance
•
Non-Linearities
•
Resonance
5.4.1 Compliance
In compliant systems, the load is not tightly coupled to the motor shaft. If you move the load by hand, you can feel
springiness. Compliant systems often are very stable when you tune with lower target bandwidths. However, they
oscillate vigorously at low frequencies when you try to tune them for higher bandwidths.
A compliant system has the following characteristics:
•
There is springiness between the motor and the load or at the motor mounting plate.
•
The frequency of oscillation is less than 100 Hz.
Compliance can be corrected by the following actions:
•
Reduce the bandwidth of the system.
•
Stiffen the machine so the load is not springy.
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