Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual - Manual (Page 342)

Publication 1784-UM003A-EN-P – June 2003
334 Motion Object Attributes
Maximum Bandwidth
There are limitations to the maximum bandwidth that can be achieved for the
velocity loop based on the dynamics of the torque loop of the servo drive and
the desired damping of the system, Z. These limitations may be expressed as
follows:
Bandwidth (Velocity) = 0.25 * 1/Z
2
* Bandwidth (Torque)
For example, if the bandwidth of the drive’s torque loop is 100 Hz and the
damping factor, Z, is 0.8, the velocity bandwidth is approximately 40 Hz.
Based on this number the corresponding gains for the loop can be computed.
Note that the bandwidth of the torque loop includes feedback sampling delay
and filter time constant.
The velocity loop in the motion controller is not used when the servo module
is configured for a velocity loop servo drive. Establishing the Velocity
Proportional Gain is not required in this case.
The typical value for the Velocity Proportional Gain is 250.