mI-DEAS Vold-Kalman Tracking Filter SoftwareFor Tracking Responses and Loads

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The I-DEAS Vold-Kalman TrackingFilter software is used for high perfor-mance tracking of harmonic respons-es, or orders, of periodic loads inmechanical and acoustical systems.Closely spaced and crossing orderscan be extracted from systems withmultiple shafts, and possess a finerfrequency and order resolution thanmore conventional techniques. Thesetracking capabilities are independentof slew rates. Harmonic amplitudeand phase are functions of the loadand the transfer characteristics of thesystem, and are called the complexenvelope. The filter tracks the com-plex envelope as a function of timeand is symmetric in time, such thatthere is no phase bias. Becausetachometer information is used forthe estimation, the complex envelopemay also be expressed as a functionof axle speed or rpm. The harmonicwaveform may be generated from thecomplex envelope and the tachome-ter information for synthesis and edit-ing purposes.

Applications� Accurate determination of phaseand amplitude of first axle order for multiplane balancing and trou-bleshooting of industrial rotatingmachinery foundations.

� Separating drive shaft orders fromwheel orders in suspension tuning.

� Isolating order interaction phenomenain subjective sound quality studies.

� Sound quality synthesis studies.� Tracking dopplerized orders in pass-by tests.

Order tracking with the filter is a post-processing operation, which shouldbe used in conjunction with waterfalland spectrogram visualization foroptimal insight in the data. Becauseof the resolution of the filter, thetachometer analyses must be precise,such that an inspection of the rawand fitted rpm estimates is recom-mended. An inspection of waterfallsor spectrograms of the original andmasked data to verify choice of band-width and decoupling options shouldaccompany the extraction of orders.

Comparisons� Versus all previous methods, Vold-Kalman offers beat-free decou-pling of close and crossing orders as well as advanced tachometer processing including automaticwild point rejection.

� Versus FFT-based Order Cuts, Vold-Kalman offers no leakage, finer reso-

Typical data for which Vold-Kalman filtering is required.

lution, complex envelope, as well aswaveform and no slew rate limitation.

� Versus computed order tracking,Vold-Kalman offers finer resolution,complex envelope, as well as wave-form and no slew rate limitation.

� Versus digital tracking filters, Vold-Kalman offers much shorter transients,no phase bias (unless digital filter isFIR or filtered in both directions), com-plex envelope in addition to wave-form, and no slew rate limitation.

� Versus previous Kalman tracking fil-ters, Vold-Kalman offers explicitbandwidth specification, multiple filters for flat pass-band, directextraction of the complex envelope,and one half the computationalcomplexity.

PrerequisiteI-DEAS Core Test™ or I-DEAS SoundQuality Engineering™

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MTS Systems Corporation14000 Technology DriveEden Prairie, MN 55344-2290612-937-4555, Fax 612-937-4515E-mail: info@mts.comwww.mts.com

ISO 9001 CERTIFIED

Specifications subject to change without notice.© 1998 MTS Systems CorporationMTS is a registered trademark of MTS SystemsCorporation. I-DEAS Vold-Kalman Tracking Filter, I-DEAS, and I-DEAS Master Series are trademarks ofStructural Dynamics Research Corporation.300217-01 I-DEASVOLD-01 Printed in U.S.A. 1298

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1st Generation FFT Based Computed Digital Vold-Kalman Kalman Order Cuts Order Track Track Filters

Beat-free decoupling of Yes No No No Noclose and crossing orders

Leakage Yes No No No No

Phase bias No No N/A N/A Yes(unless filtered in both directions)

Transients No No N/A N/A Yes

Complex envelope Yes Yes Yes Yes No(after demodulation)

Waveform Yes Yes No No Yes

Explicit bandwidth Yes No Yes Yes Yesspecification (Harmonic confidence factor)

Slew rate limitation No No Yes Yes Yes

Multiple filters Yes No N/A N/A Yes