Rockwell Automation 2094-xMxx-S Kinetix 6000 Multi-axis Servo Drives User Manual - Manual (Page 235)

Rockwell Automation Publication 2094-UM001H-EN-P - June 2013 235
Appendix
D
Configure the Load Observer Feature
The load observer feature is a control loop inside the drive 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 235
How it Works 235
Configuration 236
Setting Gains with Sercos IDN Write Messages 246
Compensate for High Frequency Resonances 247