Rockwell Automation 8720MC Drives Integration Manual - Manual (Page 54)

Publication 8720MC-IN002A-EN-P — December 2002
2-22 Commissioning Your 8720MC Analog Drive
Optimizing the Motor Orient Procedure
This section provides the information you need to optimize your
motor’s orientation: Usually motor orient cycle time is a critical issue.
It is therefore important to adjust the parameters to get the most out of
the drive and motor. The 8720MC is capable of high accelerations,
speeds and torques therefore the mechanical systems usually become
the limit. To achieve maximum performance it is desirable to get the
maximum orient speed and acceleration the mechanical system can
support.
The key parameters in achieving this are Parameter 222, “Spin Orient
Spd”; Parameter 260, “Posn Accel Rate”; Parameter 157, “At Spd
Window” or Parameter 272, “Speed Window%” and Parameter 100,
“Vel Prop Gain” assuming Servo Loop Parameter Group 0.
In general the optimizing procedure is to:
1. First auto tune the motor with the orient load, such as a spindle or
indexing mechanism, connected. Refer to Performing the Auto
Tune.
2. Next gradually increase the orient speed and orient acceleration in
unison.
3. After each change in Parameters 222 and 260 execute an orient.
Continue to do this until the desired cycle time is achieved or the
maximum capability of the mechanical system is realized.
It may be necessary to increase the “At Spd Window” via Parameter
157 or 272 to avoid missing a marker and taking an extra revolution to
achieve the orient position. Also, if the motor and load mechanism are
overshooting the orient angle, it may help to increase the velocity
proportional gain, Parameter 100, “Vel Prop Gain 0” assuming Servo
Loop Parameter Group 0. It may also be necessary to increase the plus
and minus torque limits via Parameters 82 and 83 assuming Servo
Loop Parameter Group 0.