Rockwell Automation Publication 2094-UM001J-EN-P - March 2017 237
Appendix D
Configure the Load Observer Feature
The load observer feature is a control loop inside the Kinetix® 6000 drive
(firmware revision 1.124 or later) that estimates the mechanical load on the
motor and compensates for it, thereby forcing the motor to behave as if it is
unloaded and relatively easy to control. As a result, load observer automatically
compensates for disturbances and load dynamics, such as sudden inertia/
torque changes, compliance, backlash, and resonances.
Benefits
You can use load observer with out-of-box controller gains, where the load is
unknown and thus the Load Inertia Ratio = 0, or with auto-tuned controller
gains, where the Load Inertia Ratio is known or calculated by performing an
auto-tune procedure.
When used with out-of-box controller gains, load observer does the following.
• Provides relatively high-performance motion control without tuning
• Automatically compensates for load resonances and machine wear over
time
When used with auto-tuned controller gains, load observer does the following.
• Increases controller bandwidth
• Reduces tracking errors, so line speeds can be increased
• Provides tighter control of moving parts, reducing wear and saving
material costs
How it Works
Load observer acts on the acceleration signal within the control loops and
monitors the Acceleration Reference and the Actual Position Feedback. Load
observer models an ideal unloaded motor and generates a load Torque
Estimate, in torque units, that represents any deviation in response of the actual
motor and mechanics from the ideal model. This deviation represents the
reaction torque placed on the motor shaft by the load mechanics. It is
estimated in real time and compensated by closed loop operation.
Topic Page
Benefits 237
How it Works 237
Configuration 238
Setting Gains with Sercos IDN Write Messages 250
Compensate for High Frequency Resonances 251
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