Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 233)

Servo Parameters
Chapter 7
7-87
The servo parameters in the sections that follow are available to configure
digital systems only. They specify important motor and machine
information necessary for proper motor commutation and digital drive
operation. These parameters become available when the servo loop type is
configured as “digital”.
Function
This parameter is not available on 9/230 analog systems or 9/260 and
9/290 systems that use the three axis analog servo card.
The load to inertia ratio is used in conjunction with the standard motor
parameters to choose the initial start up velocity loop gains (note typically
the gains must be changed once the servo is connected to a load). The
value entered here represents the ratio between the inertia of the motor and
the inertia of the load. If a standard motor has been selected, motor
inertias can be obtained from the standard motor tables in your integration
and maintenance manual.
If a nonstandard motor is to be used, motor inertias are generally included
with the motor specification literature.
The load inertia can be calculated using conventional equations of
mechanics. Calculations should consider drive train mass, and part mass
(if it is expected to be significant).
Important: Once you have powered up your system and confirmed wiring,
fine tuning of the servo gains is almost always required once the servo shaft is
coupled to a load. Using online AMP to adjust the velocity/position loop
gains will automatically reset the Standard Motor Table Values parameter
to “No” at the control. Once you finish tuning your servos we recommend
uploading the AMP from the control to store the new gain values and set this
parameter to “No”.
Axis Parameter
Number
Axis Parameter
Number
(1) [1017] (7) [7017]
(2) [2017] (8) [8017]
(3) [3017] (9) [9017]
(4) [4017] (10) [10017]
(5) [5017] (11) [11017]
(6) [6017] (12) [12017]
7.4
Digital Servo Parameters
7.4.1
Load Inertia Ratio