Hypertherm V9 Series Phoenix Rev.11 - Manual (Page 213)

Phoenix 9.76.0 Installation and Setup Manual 806410 213
9 – Motion Control
After the system has been successfully tuned, adjust the servo error tolerance to equal twice the normal following error
for the axes.
 This is a common approach to setting the servo error tolerance but is up to the discretion of the service technician.
This adjustment allows the system to operate without the nuisance faults that are caused by temporary resistance to
the motion, such as dirt on motion rails or temporary tension from motor cabling.
Tuning for Current Drives
Tuning for current drives is similar to tuning for velocity drives because the recommended tuning procedure focuses on
the response of the motion. The process begins with low initial values that are increased to get the necessary response.
If the axes start to vibrate or oscillate, this indicates the selected gain value is too high and should be lowered. Basic
tuning should start with the motors disengaged from the machine to allow you to confirm the controlled motion and
response of the motion axes. Motors can then be engaged for fine tuning their performance.
Set up the Watch Window to display position and following error for the selected axes. Load and automatically cut the
Test Pattern simple shape from the shape library in trial mode. You can follow the response of the system by watching the
performance of the Motor/Encoder feedback and its ability to maintain path in the preview window.
Systematically increase the velocity gain until it has little or no effect on the following error or until instability becomes
noticeable. Proportional gain can then be used to increase the “stiffness” of the response. Integral gain can be used to
improve the steady-state performance. Derivative gain can be used to provide a dampening effect.
After tuning for the best response, increase feed forward gain systematically to further reduce following error if necessary.
You do not have to eliminate following error but it is wise to ensure that following error for each axis is similar.
 Feed forward gain reduces steady state following error, but may cause overshoot.
Note that some following error is desirable. Following error terms should be nearly the same from one axis to another, and
the polarity of the following error term must be the same as the direction of travel.
Finally, check the system tuning by placing a pen on the system. Draw the test pattern provided in the simple shape library
and observe the cornering capability, arc/ circle contouring and the ability to position at the center crossings. When
troubleshooting tuning issues, varying the size and trial speed can often provide valuable information by observing the
pen marks.
After the system has been tuned successfully, adjust the servo error tolerance to equal twice the normal following error
for the axes.
 This is a common approach to setting the servo error tolerance but is up to the discretion of the service technician.
This adjustment allows the system to operate without nuisance faults caused by temporary resistance to the motion,
such as dirt on motion rails or temporary tension from motor cabling.