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Gemini GV Hardware Installation Guide
Velocity Mode Tuning
For most applications, the default tuning parameters for velocity and position
modes are set to provide good, stiff motor shaft performance for a given load
setting. With the default tuning parameters set in the Express Setup procedure, you
need only set the system load-to-rotor inertia ratio and your system will be tuned.
If your system has significant mechanical damping, you may need to set the
system damping as well. Should you wish to modify the default values and fine
tune your system for velocity mode, use the following procedures.
WARNING
This procedure causes the motor shaft to move. Make sure that shaft motion will
not damage equipment or injure personnel.
Velocity Mode Tuning Procedure
Primary Tuning Procedure
1.
Disable the drive.
2.
Configure the drive for
velocity tuning mode (DMODE16). In this mode, the drive
commands an alternating 2 rps step change in velocity, at a one second repetition
rate.
3.
Enable the drive and observe your system’s response. (If necessary, you can
connect an oscilloscope as described in
Advanced Tuning below.)
Ringing or an oscillating response indicates that the velocity loop bandwidth is too
high. To eliminate oscillations:
• decrease bandwidth using the DVBW command.
A sluggish response indicates that velocity loop bandwidth is too low. To improve
the response:
• increase bandwidth by using the DVBW command.
NOTE: Ringing, oscillations, or a sluggish response can also indicate inaccurate
drive settings for LJRAT or LDAMP.
4.
After you achieve a satisfactory system response, reconfigure the drive for velocity
mode (DMODE4). This completes the primary tuning procedure.
If you are unable to achieve a satisfactory response, proceed to the advanced
tuning procedure below.
Advanced Tuning Procedure
1.
Disable the drive.
2.
Configure the drive for
velocity tuning mode (DMODE16). In this mode, the drive
commands an alternating 2 rps step change in velocity, at a one second repetition
rate.
(In some applications a different velocity profile may give better results. Choose a
move similar to that required by your application, but using fast acceleration and
deceleration rates. Be sure the maximum velocity of your move is well below the
rated speed of your drive/motor combination.
A square wave generator connected to the velocity input (in DMODE4) may also be
used.)
3.
Configure ANALOG MONITOR A to show velocity setpoint, which is
commanded
velocity (DMONAV4).
4.
Configure ANALOG MONITOR B to show
actual velocity (DMONBV5)
5.
Connect one channel of your oscilloscope to the drive’s ANALOG MONITOR A
(pin 21). Connect your oscilloscope’s ground to the drive’s ANALOG GROUND
(pin 25).
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