Copley Controls Corp. 167
APPENDIX
C: VELOCITY LOOP FILTERS
C.1: Advanced Velocity Loop Filter
C.1.1: Filter Overview
CME 2 supports 2 classes of filters: the Low-Pass and the Custom Bi-Quad. The Low-Pass filter
class includes the Single-Pole and the Two-Pole Butterworth filter types.
The default filter settings (2-Pole Butterworth with 200 Hz Cut Off Frequency) suit the needs of
most applications.
C.1.2: Filter Instructions and Details
C.1.2.1 Click V Loop ( ) to open the Velocity Loop screen.
C.1.2.2 Click Filter ( ) to open the Velocity Loop Output Filter screen.
C.1.2.3 Adjust the filter settings described below.
Filter
Class/Type
Description
Low-Pass/
Single Pole
The single-pole low pass filter is the simplest filter. The value entered in the Cut-off
Frequency field provides the -3 db point. The filter will attenuate at -20 db/decade
past the cut-off frequency, reducing excitation of high frequency resonance.
Low-Pass/
2 Pole Butterworth
The Butterworth filter is a maximally flat low pass filter. This second order two-pole
filter has a damping ratio of 0.707 and produces no peaking in the Bode plot. The
value entered in the Cut off Frequency field provides the -3 db point. The filter
attenuates at -40 db/decade past the cut off frequency. The phase-lag at lower
frequencies is greater than the phase lag of other second order filters that exhibit
more peaking.
Custom Bi-Quad The Bi-Quadratic filter has two quadratic terms: one in the numerator, and one in the
denominator. The numerator affects the filter’s two zeros and the denominator
affects the filter’s two poles. Many filter classes and types can be expressed in the
Bi-Quad form by entering the coefficients. The coefficients can be calculated using
any commercially available math software package and entered as floating point
numbers. However, due to the fixed-point representation, the numbers may be
rounded.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
