Delta RMC101 - Manual (Page 48)

Appendix B: Tuning RMC100 Startup Guide
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• If a following error occurs during acceleration and deceleration and
adjusting the Gains and Acceleration Feed Forward does not help, the
Acceleration and Deceleration ramps are too steep for the response of the
system.
• If the actual position lags or leads the target position during the entire
constant velocity section of the move, adjust the Feed Forwards.
• Should the system seem a little sloppy, try adjusting the Proportional Gain.
• If the Drive is not high, the gains can probably be increased for better
control. If the Drive is too high, or an overdrive error occurs, the system is
not capable of performing the requested move. The Speed, and/or
Accelerations may need to be decreased.
• If the system vibrates while in position, the Dead Band value may need to
be increased. However, if the oscillation is not caused by a deadband in
the system then this will not help! A rule of thumb is to set the Dead Band
Eliminator value to half of the peak-to-peak oscillation of the drive output
while in position.
The final tuning of the system should be made at the speed of intended
operation.
Tuning a Torque Motor
The following procedure may be used to tune motors running in torque mode.
1. Set all Gains and Feed Forwards to zero.
This is done by editing the values in the main RMCWin window. Then click
the to initialize the RMC100.
2. Set the Null Drive
The drive it takes to hold the axis in position is referred to as the Null drive. If
the axis tends to drift significantly when you give it an Open Loop drive of 0,
you should set the null drive. This drive is then always added to the total drive
output and helps the RMC100 accurately follow the motion profile. To set the
null drive, issue a P command to hold the axis in position in closed loop, then
issue the N command.
3. Check Dead Band
If your system has a large dead band, you will need to set the Dead Band
Eliminator value. To find your dead band, give increasing amounts of drive to
the system with the Open Loop command. The value of drive at which the
system starts to move is your dead band. If this value is approximately 400 or
greater, the Dead Band Eliminator should probably be used. If it is less, it is
left to the discretion of the designer.
4. Adjust the Differential Gain
Torque motors generally do not have much damping. Damping must be
provided for the system, or it will be difficult to control. Providing some
Differential Gain will effectively dampen the system. Do the following:
a) Set all the gains to zero. Issue an Open Loop (O) command of zero.
b) Increase the Differential Gain. Issue a Set Parameters (P) command to put
the axis in closed loop control.