Control Techniques FM-3, Reference Manual

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Tuning Procedures
Initial Test Settings
When running the tests outlined in this section, the motor and drive must be operational so
you will need to enter starting values.
If your application has less than a 10:1 inertia mismatch, the default parameter settings will
be acceptable. If the inertial mismatch is greater than 10:1, use the following table for initial
parameter settings.
Determining Friction
This parameter represents friction that increases proportionally as motor velocity increases.
The viscous friction of your system can be determined by reading the percent of continuous
torque required to operate the loaded motor at two different speeds.
Consider the following before determining the Friction:
• The most consistent readings can usually be obtained at motor speeds higher than 500
RPM but lower test speeds can be used if necessary.
• If your application has travel limits, it may be helpful to use an external position controller
to prevent the axis from exceeding the machine limits. Set up a trapezoidal profile as
shown.
• In the procedure below, the Torque Command and Velocity Feedback parameters can be
measured using the drive’s analog outputs, PowerTools software or an FM-P.
• With vertical loads the test readings must be taken while traveling in the same direction.
• An oscilloscope may be needed for systems with limited travel moves to measure the
rapidly changing torque and velocity signals.
• If your system’s friction changes with operating temperature, perform this procedure at
normal operating temperature.
Procedure for Determining Friction:
1. Run the motor at the low test speed (at least 500 RPM).
2. While at speed, note the Torque Command Actual value (TCL).
Parameter Setting
Friction 0.00
Inertia Ratio 1/3 to 1/2 Actual
Response 500/Inertia Ratio
High Performance Gains Disabled
Feedforwards Enabled
Line voltage Actual Applied