THORLABS Kinesis PFM450E, Руководство пользователя

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Page 33 ETN018233-D03
PFM450E Piezo Focus Mount and Controller
5.2.3 Filters tab.
Fig. 5.3 Piezo Settings panel - Loop Tuning tab
When operating in Closed Loop mode, the proportional, integral and differential (PID)
constants can be used to fine tune the behaviour of the feedback loop to changes in
the output voltage or position. While closed loop operation allows more precise
control of the position, feedback loops need to be adjusted to suit the different types
of focus mount assemblies that can be connected to the system. Due to the wide
range of objectives that can be used with the PFM450 and their different masses,
some loop tuning may be necessary to optimize the response of the system and to
avoid instability, however the default parameters should offer stable operation for
most small and medium size objectives.
To adjust the PID constants, enter a value in the associated window as follows:
Proportional Gain - The Proportional parameter makes a change to the output which
is proportional to the current error value. A high proportional gain results in a large
change in the output for a given error. If set too high, the system can become
unstable.
It accepts values in the range 0 to 10000 (default 760)
Int
egral Gain - The Integral parameter accelerates the process towards the
demanded set point value, ensuring that the positional error is eventually reduced
to zero. If set too high, the output can overshoot the demand value.
It accepts values in the range 0 to 10000. (default 560).
Derivative Gain
- The Derivative parameter damps the rate of change of the
output, thereby decreasing the overshoot which may be caused by the integral
term. However, the differential term also slows down system response. If set too
high, it could lead to instability due to signal noise amplification.
It accepts values in the range 0 to 10000 (default 10,000).
Please see Fig. 5.4 for guidance on Proportional and Integral settings for different
loads. The Differential value does not normally need adjustment.