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Gemini GV Hardware Installation Guide
Position Mode Tuning Procedure
Primary Tuning Procedure
1.
Disable the drive.
2.
Configure the drive for
position tuning mode (DMODE17). In this mode, the drive
commands an alternating 1/4 revolution step change in position 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 position loop bandwidth is too
high. To eliminate oscillations:
• decrease bandwidth using the DPBW command.
A sluggish response indicates that position loop bandwidth is too low. To improve
the response:
• increase bandwidth by using the DPBW 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 position
mode (DMODE6, DMODE7, or DMODE8). 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
position tuning mode (DMODE17). In this mode, the drive
commands an alternating 1/4 revolution step change in position at a one second
repetition rate.
(In some applications a different move 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.
3.
Configure ANALOG MONITOR A to show position error (DMONAV3).
4.
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).
5.
Adjust your oscilloscope to display position error. (The analog monitor can be
scaled, in percent, with the DMONAS command.)
6.
Enable the drive and observe your system’s response. Position error will increase
during acceleration, but should decay smoothly to near zero without significant
ringing or instability.
Ringing or an oscillating response indicates that the position loop bandwidth is too
high, or the position loop damping is too low. To eliminate ringing or oscillations:
• decrease bandwidth using the DPBW command; then, if necessary:
• adjust damping by using the SGPRAT command. Use the value that
gives the best performance.
• in applications with backlash or high static friction, disabling the velocity
integrator (SGINTE0) can help improve stability.
• NOTE: In position mode, the velocity loop bandwidth tracks changes in
position loop bandwidth by a ratio set by the SGPSIG command. In
position mode, the DVBW command is ignored.
A sluggish response indicates that position loop bandwidth is too low, or position
loop damping is too high. To improve the response:
• increase bandwidth by using the DPBW command; then, if necessary:
• adjust damping by using the SGPRAT command. Use the value that
gives the best performance.
NOTE: Ringing or a sluggish response can also indicate inaccurate drive settings
for LJRAT or LDAMP.
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