National Instruments Order Analysis Toolset User Manual
  1. Manuals
  2. Brands
  3. National Instruments Manuals
  4. Software
  5. Order Analysis Toolset
  6. User manual
National Instruments Order Analysis Toolset User Manual

National Instruments Order Analysis Toolset User Manual

Order analysis toolset
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
LabVIEW
TM
Order Analysis Toolset

User Manual

LabVIEW Order Analysis Toolset User Manual
August 2003 Edition
Part Number 322879B-01

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the Order Analysis Toolset and is the answer not in the manual?

Questions and answers

Subscribe to Our Youtube Channel

Related Manuals for National Instruments Order Analysis Toolset

Summary of Contents for National Instruments Order Analysis Toolset

  • Page 1: User Manual

    LabVIEW Order Analysis Toolset User Manual LabVIEW Order Analysis Toolset User Manual August 2003 Edition Part Number 322879B-01...
  • Page 2 Thailand 662 992 7519, United Kingdom 44 0 1635 523545 For further support information, refer to the Technical Support and Professional Services appendix. To comment on the documentation, send email to techpubs@ni.com. © 2001–2003 National Instruments Corporation. All rights reserved.

  • Page 3: Important Information

    The reader should consult National Instruments if errors are suspected. In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.

  • Page 4: Table Of Contents

    How to Use This Manual ...vii Conventions ...vii Related Documentation...viii Chapter 1 Introduction to the LabVIEW Order Analysis Toolset Overview of the LabVIEW Order Analysis Toolset...1-1 Overview of the LabVIEW Order Analysis Start-Up Kit...1-1 Important Considerations for the Analysis of Rotating Machinery...1-2 System Requirements ...1-3...
  • Page 5 Displaying Spectral Maps... 3-8 Calculating Waveform Magnitude ... 3-10 Chapter 4 Resampling-Based Order Analysis LabVIEW Order Analysis Toolset Resampling Method... 4-1 Determining the Time Instance for Resampling ... 4-2 Resampling Vibration Data ... 4-4 Slow Roll Compensation... 4-5 Chapter 5 Calculating Rotational Speed Digital Differentiator Method...

  • Page 6: About This Manual

    For information about individual VIs, refer to the Order Analysis Toolset Help, available in LabVIEW 6.1 by selecting Help»Order Analysis. In LabVIEW 7.0 and later, Order Analysis Toolset Help is part of the LabVIEW Help, which is available by selecting Help»VI, Function, &...

  • Page 7: Related Documentation

    The following documents contain information that you might find helpful as you read this manual: • • • • LabVIEW Order Analysis Toolset User Manual LabVIEW Order Analysis Toolset Help Getting Started with LabVIEW LabVIEW User Manual LabVIEW Help viii...

  • Page 8: Introduction To The Labview Order Analysis Toolset

    Overview of the LabVIEW Order Analysis Toolset The LabVIEW Order Analysis Toolset is a collection of virtual instruments (VIs) for LabVIEW. These VIs help you measure and analyze noise or vibration signals generated by rotating machinery by enabling you to perform the following analysis operations: •...

  • Page 9: Important Considerations For The Analysis Of Rotating Machinery

    Do not use the LabVIEW Order Analysis Toolset for analysis of frequencies that are not excited by a fundamental frequency, such as the modes encountered in modal analysis.

  • Page 10: System Requirements

    (Windows Me/98) installation CD and follow the instructions that appear on the screen. If the startup screen does not appear, select Start»Run, navigate to the folder on the LabVIEW Order Analysis Toolset 2.0 installation CD, and double-click © National Instruments Corporation...

  • Page 11: Example Vis

    • • • • The example VIs use VIs found on the LabVIEW Order Analysis Toolset palettes and illustrate the basic capabilities of the LabVIEW Order Analysis Toolset. Acquiring Data for Example VIs For most of the example VIs, you can use prerecorded data or data you acquire with data acquisition (DAQ) hardware.

  • Page 12: Acquire Data (Analog Tach) Vi

    Settings section of the Configuration tab, use Tachometer for the © National Instruments Corporation Chapter 1 Introduction to the LabVIEW Order Analysis Toolset Acquire Data (Analog Tach) VI Acquire Data with PXI 4472 and TIO VI section for information about the Acquire Data with PXI 4472 Figure 1-1.

  • Page 13: Acquire Data With Pxi 4472 And Tio Vi

    Chapter 1 Introduction to the LabVIEW Order Analysis Toolset tachometer signal and S&V for the sound or vibration sensor. After choosing data acquisition settings, enter the number of pulses you want the tachometer to generate per revolution in the Tach Pulse/Rev text box.
  • Page 14 Chapter 1 Introduction to the LabVIEW Order Analysis Toolset Figure 1-3. Acquire Data with PXI 4472 and TIO VI Configuration Tab Use the Configuration tab of the Acquire Data with PXI 4472 and TIO VI, shown in Figure 1-3, to configure the DAQ devices. Use one of the counters on a TIO device to receive TTL-compatible tachometer pulses.
  • Page 15 Chapter 1 Introduction to the LabVIEW Order Analysis Toolset The Acquisition tab, shown in Figure 1-4, allows you to acquire and observe data. Click the Acquire button to acquire data. Continue to configure the data acquisition and acquire data until you acquire the data you want.

  • Page 16: Order Analysis

    Parts associated with rotating components include bearings, gears, and blades. Vibration of the rotating components creates noise and vibration signals. The machine rotational speed is the source of the noise and © National Instruments Corporation LabVIEW Order Analysis Toolset User Manual...
  • Page 17 Figure 2-1. The frequency domain and order domain plots of the signal are shown in the third and fourth graphs, respectively, in Figure 2-1. LabVIEW Order Analysis Toolset User Manual 1.7E+4 0.0E+0 –1.9E+4...
  • Page 18 4 Coils 7 Blades 10.0 Orders Figure 2-2. Order Spectrum of a PC Fan with Seven Blades and Four Coils Chapter 2 Order Analysis × Order ------------ - × ------------ - 12.0 14.0 16.0 LabVIEW Order Analysis Toolset User Manual...

  • Page 19: Effect Of Rotational Speed On Order Identification

    At a constant rotational speed, you can identify orders from both the conventional power spectrum and the frequency-time spectral map. Figure 2-3 illustrates the analysis of a vibration signal acquired from a PC fan running at a constant speed. LabVIEW Order Analysis Toolset User Manual ni.com...
  • Page 20 The peaks indicate different orders and appear in the frequency-time spectral map as white lines. © National Instruments Corporation STFT 31.9 31.9 Figure 2-3. PC Fan Running at Constant Speed Chapter 2 Order Analysis 31.9 LabVIEW Order Analysis Toolset User Manual...

  • Page 21: Variable Rotational Speed

    Spectrum In Figure 2-4, the overall frequency bandwidth is proportional to the change in frequencies. When the frequency and amplitude are constant over LabVIEW Order Analysis Toolset User Manual Frequency-Time Spectral Map Time Waveform –0.5 –1.0 Time Figure 2-4.
  • Page 22 When the © National Instruments Corporation Frequency-Time Spectral Map Time Waveform –0.5 –1.0 Time Figure 2-5. Frequency Changes Over Time Chapter 2 Order Analysis Overall Bandwidth Becomes Wide as the Frequency Changes LabVIEW Order Analysis Toolset User Manual...
  • Page 23 When the change of speed is large enough, the spectra of orders eventually overlap. When the spectra of LabVIEW Order Analysis Toolset User Manual STFT 31.9 31.9...

  • Page 24: Harmonic Analysis

    Thus, in the spectrum domain, the focus is on orders instead of frequency components. © National Instruments Corporation Chapter 2 LabVIEW Order Analysis Toolset User Manual Order Analysis...

  • Page 25: Gabor Transform

    1. The ratio between the length of the analysis window and the window shift step determines the time overlap. By default in the LabVIEW Order Analysis Toolset, the ratio is set to 4. For example, if the window length is 2,048, the window shift is 512.
  • Page 26 You also can wrap data blocks backward from the beginning of the data sample to the end. 2-11 Chapter 2 Order Analysis Data Blocks Zeros Data Blocks LabVIEW Order Analysis Toolset User Manual...
  • Page 27 Refer to Appendix A, information about the Gabor transform and the Gabor expansion. Refer to Chapter 3, information about how the LabVIEW Order Analysis Toolset uses a method based on the Gabor transform for order tracking. LabVIEW Order Analysis Toolset User Manual Figure 2-8 shows two examples of padding.

  • Page 28: Resampling

    Calculates the sampling time at the desired shaft-angular increment. Uses interpolation to obtain new samples at the desired time. 2-13 Chapter 2 Order Analysis Frequency Order LabVIEW Order Analysis Toolset User Manual...
  • Page 29 STFT on the angle samples, where an order axis is used instead of a frequency axis. Each horizontal white line in the Order vs. Rev plot indicates the strong power at an integer order. LabVIEW Order Analysis Toolset User Manual Order vs. Rev Angle Samples –0.5...

  • Page 30: Adaptive Filter

    After the resampling process takes place, recovering a time waveform at a specific order might be difficult. Refer to Chapter 4, about how the LabVIEW Order Analysis Toolset uses software-based resampling for order analysis. Adaptive Filter Although the frequencies of the order components change as the rotational speed changes, you can consider the rotational speed and the frequency of order components to remain constant in a relatively short time interval.

  • Page 31: Gabor Transform-Based Order Tracking

    Gabor Transform-Based Order Tracking This chapter discusses a new order analysis method based on the Gabor transform and provided by the LabVIEW Order Analysis Toolset that enables you to complete the following tasks: • • Overview of Gabor Order Analysis The Gabor transform can give the power distribution of the original signal as the function of both time and frequency.
  • Page 32 Figure 3-2 illustrates the Gabor order analysis process provided by the LabVIEW Order Analysis Toolset. Vibration Signal Step 1: Data Acquisition Tachometer Signal LabVIEW Order Analysis Toolset User Manual Gabor Step 5: Step 2: Coefficients Mask Gabor Operation Transform Step 4:...

  • Page 33: Extracting The Order Components

    Acquire data samples from the tachometer and noise or vibration sensors synchronously at some constant sample rate. Use the LabVIEW Order Analysis Toolset VIs to complete the following steps. Perform a Gabor transform on the noise or vibration samples to produce an initial Gabor coefficient array.
  • Page 34 RPM is the averaged instantaneous rotational speed in the time interval, N is the number of frequency bins, and f frequency. In the LabVIEW Order Analysis Toolset, the number of frequency bins N equals the length of the window.

  • Page 35: Masking

    ------------ - ------------ - -- - – -- -    varies in time, the order bandwidth TRUE m n , FALSE m n , c ˆ is the masked coefficient m n , LabVIEW Order Analysis Toolset User Manual...

  • Page 36: Extracting Orders

    (a) Original Signal 500– 400– 300– 200– 100– 0– Time (s) (c) Masked Coefficients Figure 3-4(a) shows a frequency-time spectral map after the Gabor transform. LabVIEW Order Analysis Toolset User Manual 500– 400– 300– 200– 100– 0– 500– 400– 300– 200–...

  • Page 37: Reconstructing The Signal

    Gabor © National Instruments Corporation Chapter 3 1.0– Original Signal 0.5– 0.0– –0.5– –1.0– Figure 3-5. Original Signal and Extracted Order Component Gabor Transform-Based Order Tracking Extracted 4th Order 10.0 12.0 Time (s) LabVIEW Order Analysis Toolset User Manual 14.6...

  • Page 38: Displaying Spectral Maps

    The LabVIEW Order Analysis Toolset provides several methods of obtaining a 2D spectral map over the whole signal in the frequency-time, frequency-rpm, and order-rpm domains.
  • Page 39 1500 1000 Figure 3-7. 2D Spectral Maps Gabor Transform-Based Order Tracking 10.0 15.0 20.0 25.0 30.0 Time (s) (b) RPM vs. Time 1250 1500 1750 2000 2250 2500 2774 (d) Order-RPM Spectral Map LabVIEW Order Analysis Toolset User Manual 36.0...

  • Page 40: Calculating Waveform Magnitude

    In practical applications such as product testing for comparison with reference curves, calculating the waveform magnitude as a function of rpm is useful. The LabVIEW Order Analysis Toolset uses the root mean square (RMS) of the time waveform to calculate the waveform magnitude and correlate the sine waveform with the tachometer pulses to obtain the waveform phase.

  • Page 41: Resampling-Based Order Analysis

    Resampling-Based Order Analysis This chapter describes the resampling method provided by the LabVIEW Order Analysis Toolset, determining the time instance for resampling, resampling vibration data, and slow roll compensation. LabVIEW Order Analysis Toolset Resampling Method With software resampling, the LabVIEW Order Analysis Toolset enables you to complete the following tasks: •...

  • Page 42: Determining The Time Instance For Resampling

    LabVIEW Order Analysis Toolset User Manual Acquire data samples from tachometer and noise or vibration sensors synchronously at some constant sample rate. Use the LabVIEW Order Analysis Toolset VIs to complete the following steps: Determine the pulse edges from the tachometer signal and interpolate the pulse edges to get the time instance for resampling.
  • Page 43 When you interpolate the time sequence for a smaller angle interval, you need a constant rate integer factor interpolation filter. The LabVIEW Order Analysis Toolset uses a cascaded integrator-comb (CIC) filter when interpolating the time sequence for a smaller angle. The transfer function of the CIC filter is given by the following equation.

  • Page 44: Resampling Vibration Data

    T LabVIEW Order Analysis Toolset User Manual Figure 4-2. Original Time Sequence and CIC Interpolation Filter with an Interpolation Factor of Eight samples/second yields a discrete sample...

  • Page 45: Slow Roll Compensation

    The LabVIEW Order Analysis Toolset uses a digital adaptive-interpolation filter to complete the entire resample process. The bandwidth of the adaptive-interpolation filter automatically changes according to the new sampling rate to prevent the aliasing phenomenon.
  • Page 46 Rolling Center Shaft Center The LabVIEW Order Analysis Toolset can perform the vector-based slow roll compensation on order magnitudes and phases. The toolset performs slow roll compensation subtracting a slow roll vector from the measured magnitude and phase.

  • Page 47: Calculating Rotational Speed

    Calculating Rotational Speed This chapter describes the digital differentiator method used by the LabVIEW Order Analysis Toolset to calculate rotational speed and describes averaging pulses to smooth noisy calculated rotational speed results. Digital Differentiator Method To successfully extract order components, create spectral maps, and calculate waveform magnitudes, you need rotational speed as a function of time during the data acquisition process.
  • Page 48 θ(t) usually involves step-by-step polynomial curve fitting, which requires multiple computations in each iteration. Instead of observing θ(t) directly, the LabVIEW Order Analysis Toolset observes t(θ), which is the inverse function of θ(t), because calculating the first derivative...

  • Page 49: Averaging Pulses

    θ θ represents the differentiator coefficients. dθ ω t ----- - Chapter 5 Calculating Rotational Speed , you can use a digital k i – – ------------------- - ----- - dθ θ θ LabVIEW Order Analysis Toolset User Manual (5-1)
  • Page 50 The solid line in Figure 5-2 represents the results of calculating the rotational speed averaged by five. As Figure 5-2 shows, the averaged rotational speed is smoother than the non-averaged rotational speed. LabVIEW Order Analysis Toolset User Manual 19.3 19.4 Time (s) Figure 5-2.
  • Page 51 Gabor Expansion and Gabor Transform This appendix presents an overview of the Gabor expansion and the Gabor transform methods used in the LabVIEW Order Analysis Toolset. This appendix also describes application issues associated with using the discrete Gabor-expansion-based time-varying filter.
  • Page 52 L of the sequence to L given window h[k] that always has unit energy, you can compute the LabVIEW Order Analysis Toolset User Manual – ∑ s ˜ k [ ]γ ∗ k m∆M m n , s ˜...
  • Page 53 ≤ < ≤ < ≤ < 2L N – γ ---- - h – γ ⁄ j2πnk – – a ˜ k [ ] is simply LabVIEW Order Analysis Toolset User Manual (A-4) ----- - 1 – γ ≈ (A-5)
  • Page 54 To overcome the problem of the reconstructed time waveform not equaling the selected Gabor coefficients, use an iterative process. Complete the following steps to perform the iterative process. LabVIEW Order Analysis Toolset User Manual c ˆ m n , denotes a binary mask function whose elements are either m, n –...
  • Page 55 Repeat steps 1 through 4 until the time waveforms converge. C ˆ C ˆ ΦGH Gabor Expansion and Gabor Transform ≠ ΦC C ˆ ΦC ΦC C ˆ ΦC Φ … – Φ LabVIEW Order Analysis Toolset User Manual...
  • Page 56 The amount of redundancy causes slow computation speed and huge memory consumption, making γ[k] = h[k] an impractical Gabor transform method. Usually, the LabVIEW Order Analysis Toolset uses the orthogonal-like representation introduced at the end of the Transform Basics the Gaussian and Hanning windows, the difference between the analysis and synthesis windows is negligible when the over sampling rate is four.
  • Page 57 Brüel & Kjær Sound & Vibration Measurement A/S, 1999. Hewlett Packard Application Note 243-1. Effective Machinery Measurements using Dynamic Signal Analyzers. Qian, Shie, and Dapang Chen. Joint Time-Frequency Analysis. Upper Saddle River, NJ: Prentice Hall PTR, 1996. LabVIEW Order Analysis Toolset User Manual...

  • Page 58: Technical Support And Professional Services

    Technical Support and Professional Services Visit the following sections of the National Instruments Web site at ni.com • • • If you searched your local office or NI corporate headquarters. Phone numbers for our worldwide offices are listed at the front of this manual. You also can visit...
  • Page 59 That is, you can use either of the dual functions for a Gabor transform while using the other dual function for a Gabor expansion. © National Instruments Corporation Nyquist frequency. Nyquist frequency. equals m, n LabVIEW Order Analysis Toolset User Manual...
  • Page 60 Nyquist frequency. See also filter. order A harmonic related to the rotational speed of a machine. order analysis The analysis of harmonics related to rotational speed. The application of harmonic analysis to rotating machinery LabVIEW Order Analysis Toolset User Manual aliasing anti-aliasing ni.com...
  • Page 61 Analysis Toolset, it is always equal to a quarter (0.25) of the window length. For example, if the window length is 2,048, the window shift is 512. © National Instruments Corporation found by each method are the projection of the m, n LabVIEW Order Analysis Toolset User Manual Glossary m, n...
  • Page 62 3-5 extracting orders, 3-6 reconstructing a signal, 3-7 order tracking, 3-1 getting started, vii help professional services, C-1 technical support, C-1 how to use this manual, vii installing the toolset, 1-3 instrument drivers, C-1 LabVIEW Order Analysis Toolset User Manual...
  • Page 63 2-1 Gabor transform method, 2-10 methods of, 2-9 resampling method, 2-13, 4-1 Order Analysis Start-Up Kit, 1-1 Order Analysis Toolset, using in analysis of rotating machinery, 1-2 orders, definition of, 2-2 over sampling, definition of, A-2 phone technical support, C-1...

This manual is also suitable for:

Labview

Table of Contents