Newport MM4006, User Manual

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MM4006 S e r v o Tuning
If intolerable overshoot develops, increase the Kd factor. Continue increas-
ing Ki and Kd alternatively until an acceptable loop response is obtained. If
oscillation develops, immediately reduce the Ki.
Remember that any finite value for Ki will eventually reduce the error at
stop. It is simply a matter of how much time is acceptable for your applica-
tion. In most cases it is preferable to wait a few extra milliseconds to stop
in position rather than have overshoot or run the risk of oscillations.
Following Error During Motion
This is caused by a Ki value that is too low. Follow the steps in the previous
paragraph, keeping in mind that it is desirable to increase the integral gain
factor as little as possible.
7.2.3 P o i n t s to Remember
• T h e MM4006 controller uses a servo loop based on the PID with velocity
feed-forward algorithm.
• Special servo design makes the velocity feed-forward only motor-depen-
dent, not load-dependent. It is factory-set and not accessible to the user.
• U s e the lowest acceleration the application can tolerate. Smaller accel-
eration generates less overshoot.
• U s e the default values provided with the system for all standard motion
devices as a starting point.
• U s e the minimum value for Ki that gives acceptable performance. The
integral gain factor can cause overshoot and oscillations.
EDI-10181En 1020 — 03/03
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