MTS Series 793 - Manual (Page 115)

How to Perform Advanced Tuning Techniques
MTS Series 793 Tuning and Calibration Tuning Procedures 115
About Tuning Filters
Forward loop filters
The response of the mechanical system (valve, actuator, test specimen) limits the
amount of controller gain you can use before the system becomes unstable.
A filter in the forward path of the controller may be used to shape the system
response. This may make it possible to increase the controller gain, improving
command and feedback tracking while maintaining stability.
Forward loop filters are available for all control modes, and include:
• A Low-Pass filter that attenuates signals above a specified frequency.
• A Band-Stop filter that attenuates signals in a specified band around a
specified frequency.
• A Break-Recover filter that attenuates signals above the Break frequency.
Phase lag of the filter is reduced at higher frequencies by limiting the filter
attenuation at frequencies above the Recover frequency.
• A Lead-Lag filter that applies a lead-lag compensator with a maximum of 2
poles (lag) and 2 zeros (lead). Signals will be attenuated above the Pole 1
and Pole 2 frequencies. Phase lag of the filter can be reduced at higher
frequencies by limiting the filter attenuation at frequencies above the Zero 1
and Zero 2 frequencies.