Abstract:
A method and apparatus identifies a region of interest of transient vibration data needing analysis and provides context and construction for analytical plots. The method comprises providing transient data and determining a region of interest of the transient data, specifying a construction mode corresponding to a derived graphical display of the transient data and specifying a construction parameter corresponding to the specified construction mode. The method also comprises processing the transient data to produce at least one derived plot based on the transient data, the region of interest, the specified construction mode, and the specified construction parameters. This method may be performed by a graphical tool having a hardware module and a software module. The hardware module including a processor, a memory, a display, and a communicator, and the software module including a plotting module and a plotcontrol module.

Description:
FIELD 
       [0001]    The present invention relates to the field of machine vibration analysis. More particularly, it relates to a method and apparatus for identifying a region of interest of transient vibration data requiring analysis. 
       BACKGROUND AND SUMMARY 
       [0002]    Historically, vibration data analysis in evaluating machinery health is a daunting task. First, only relevant sections of the vibration data require analysis. It may be desirable in some limited cases to analyze steady-state vibration data in order to confirm a minimal level of vibration. However, the relevant sections generally are the transient vibration data sections. Unfortunately, the volume of transient vibration data available for analysis may be unmanageable. For example. one transient analysis system can collect 32 channels of vibration data 5,120 times per second for over 48 hours. An effective analysis of data collected from such a system may necessitate analysis of a single, continuous time waveform containing over 800 million data points. 
         [0003]    In order for such a data waveform to be analyzed sufficiently, it must be broken into smaller components or regions. Several different processing methods for sections of vibration data may be used in order to provide diagnostic benefits beyond viewing conventional waveforms and trend data (spectral-based parameter data plotted against time). Also, the different processing methods provide several display opportunities not available with plotted waveforms and trends. The processing and display methods available for vibration analysis include cascade/waterfall plots, average shaft centerline plots and Bode/Nyquist plots. 
         [0004]    In order to effectively use the vibration analysis plotting tools discussed above, a user must be able to provide a data context for these alternative displays—that is, to identify the portion of the data to be processed. Additionally, parameters used to construct the plots must also be specified. For these reasons, a method and graphical tool to help users identify the portion of the transient data requiring analysis is needed. Also, construction parameters associated with the graphical tool are needed to help determine how the portion of transient data is sampled in order to populate any derived analysis plots including cascade/waterfall plots, average shaft centerline plots and Bode/Nyquist plots. 
         [0005]    A method and apparatus for identifying a region of interest of transient vibration data requiring analysis solves the aforementioned and other problems. In one method for processing and displaying data, transient data is provided and a region of interest leading edge and trailing edge are determined, which together define the portion of transient data requiring analysis. A construction mode is specified corresponding to a derived graphical display of the transient data, and a construction parameter is also specified corresponding to the specified construction mode. The transient data is processed to produce at least one derived plot. The construction mode may be selected from; delta time construction mode, delta rpm construction mode, and fixed number construction mode. The derived plot may be selected from; cascade plots, average shaft centerline plots, and Bode/Nyquist plots. 
         [0006]    In one embodiment, a graphical tool is provided for identifying a region of interest representing transient data chosen by a user. The graphical tool also derives and displays an analytical plot from the region of interest. The transient data is collected by a vibration sensing instrument and represents the vibration of a machine, and the transient data is communicated to the graphical tool by the vibration sensing instrument. The graphical tool may include a hardware module and a software module. The hardware module has a processor, a memory, a display, and a communicator. The memory is connected to the processor and stores the software module. The display is also connected to the processor and displays the transient data, the region of interest, and the analytical plots. The communicator is connected to the processor and communicates with the vibration sensing instrument. The software module has a plotting module and a plotcontrol module having a tools module containing tools used by the plotting module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]    The preferred embodiments of the invention will now be described in further detail with reference to the drawings wherein like reference characters designate like or similar elements throughout the several drawings as follows: 
           [0008]      FIG. 1A  is a screenshot of the display of a region of interest of a collection of vibration time data. 
           [0009]      FIG. 1B  is a screenshot of the display of a cascade or waterfall plot representing the region of interest shown in  FIG. 1A . 
           [0010]      FIG. 1C  is a screenshot of the display of a Bode/Nyquist plot representing the region of interest shown in  FIG. 1A . 
           [0011]      FIGS. 2A  is a screenshot of a display of two regions of interest synchronized with one another. 
           [0012]      FIG. 2B  is a screenshot of a display of an average shaft centerline plot representing the region of interest shown in  FIG. 1A . 
           [0013]      FIG. 3A  is a screenshot of the display of the settings dialogue. 
           [0014]      FIG. 3B  is a diagram of the settings including construction modes and associated construction parameters. 
           [0015]      FIG. 4A  is a screenshot of a display of a region of interest showing steps in a delta time construction mode. 
           [0016]      FIG. 4B  is a screenshot of a display of a region of interest showing steps in a delta rpm construction mode. 
           [0017]      FIG. 4C  is a screenshot of a display of a region of interest showing steps in a fixed number construction mode. 
           [0018]      FIG. 5  is a flowchart of graphical tool analysis of data samples from two companion channels. 
           [0019]      FIG. 6  is a diagram of the graphical tool including the hardware module and its components and the software module and its components with the hardware module connected to the vibration sensing instrument. 
       
    
    
     DETAILED DESCRIPTION  
       [0020]    The following paragraphs disclose a method for identifying a region of interest of transient machine vibration data facilitating analysis using context and construction parameters for analytical plots. 
         [0021]    Referring now to  FIG. 1A , a screenshot of the region of interest  10  of a collection of time-series vibration data  12  is shown. Such time-series vibration data  12  may result from a variety of sources including machine vibration. Furthermore, time-series vibration data  12  may be collected in several ways including collection by vibration transducers. The time-series vibration data  12  is communicated to a computer or other processing device where it is graphically displayed as the dependent variable versus the independent variable—such as time as shown in  FIG. 1A . This graphical tool  14  allows a user to visually inspect the time-series vibration data  12  over a specified period of time in order to determine the areas where data analysis may be necessary. Alternatively, tachometer data may be collected by a tachometer and communicated to the computer or other processing device where it is graphically displayed by the graphical tool  14 . 
         [0022]    The region of interest  10  is positioned by a user in order to provide context for displays derived from the transient waveform and transient trend data such as cascade or waterfall, average shaft centerline and Bode/Nyquist displays. The user chooses a leading edge  16  for the region of interest  10  by using the graphical tool  14 . The leading edge  16  of the region of interest  10  provides the starting time for the data to be used to derive analytical plots such as those discussed above. The user also chooses a trailing edge  18  for the region of interest  10  using the graphical tool  14 . The trailing edge  18  provides the ending time for the data to be used to derive analytical plots. 
         [0023]    The user selects the region of interest  10  by visually inspecting the vibration data  12  in search of a section of transient data and chooses a leading edge  16  and a trailing edge  18 , which together surround the section of transient data chosen. The user also chooses settings  35  ( FIG. 3 ) associated with the derived plots. Alternatively, the user may select the region of interest  10  after having chosen settings  35 . Once such settings  35  are chosen as discussed below, plots such as those shown in  FIGS. 1B and 1C  are derived by the graphical tool  14 .  FIG. 1B  shows a cascade plot  20  depicting spectra versus machine speed, which is represented by z-axis  24  of  FIG. 1B . A graph similar to that shown in  FIG. 1B , but wherein the z-axis  24  represents time is a waterfall plot. In other words, a waterfall plot shows spectra versus time. The cascade plot  20  is a three dimensional derivation of the region of interest  10  in the frequency domain, which is represented by the x-axis  22 , with respect to vibration amplitude, which is represented by the v-axis  26 .  FIG. 1C  shows a Bode/Nyquist plot derived from the region of interest  10  shown in  FIG. 1A . The Bode plots, on the lower half of  FIG. 1C , show peak vibration amplitude at a particular frequency versus machine speed (FIG.  1 Cii) and also show phase of the same peak vibration versus machine speed (FIG.  1 Ciii). The Nyquist plot, on the upper half of  FIG. 1C , shows peak vibration amplitude at a particular frequency along with associated phase in a polar display (FIG.  1 Ci). 
         [0024]    Referring now to  FIG. 2A , two transient signal channels  30  and  32  are shown. The user may select to display the data from two channels simultaneously in the graphical tool  14 . If the vibration data  12  collected on the two channels  30  and  32  had been collected simultaneously (or nearly so), the graphical tool  14  will automatically synchronize the regions of interest  10  for comparative analysis 
         [0025]    In the embodiment shown in  FIG. 2B , an average shaft centerline plot  34  is shown. The average shaft centerline plot  34  is calculated from the vibration data  12  collected simultaneously (or nearly so) on channels  30  and  32 , contained within the synchronized regions of interest  10  shown in  FIG. 2A . The average shaft centerline plot  34  may be calculated from the vibration data  12  from channels  30  and  32  stored in the memory  86  of the hardware module  76  for subsequent analysis ( FIG. 6 ). Alternatively, the average shaft centerline plot  34  may be calculated from the vibration data  12  collected on channels  30  and  32  for real-time analysis. 
         [0026]    The average shaft centerline plot  34  shown in  FIG. 2B  may be populated in real time as data is collected over the region of interest  10  of the two channels  30  and  32 . That is, as the vibration data  12  is collected, or as soon thereafter as a user can choose the leading edge  16  and trailing edge  18  of the region of interest  10  and the settings  35  ( FIG. 3 ), the average shaft centerline plot  34  may be created. 
         [0027]    Referring now to  FIGS. 3A and 3B , the settings dialog  36  and a flowchart representing the selection of settings by a user are shown. In this embodiment of the graphical tool  14 , Bode/Nyquist  28 , cascade  20 , and average shaft centerline  34  plots are available as illustrated by the header  37 . In order to program the graphical tool  14  to use the region of interest  10  of a collection of vibration data  12  in analysis, a user initially must choose several settings  35  from the settings dialog  36 . First, the user must select a construction mode  38  from the group of delta time construction mode  40 , delta rpm construction mode  42 , and fixed number construction mode  44 . In  FIG. 3A , the delta time construction mode  40  has been selected. 
         [0028]    Once the construction mode  38  has been selected, the user must determine construction parameters  46  associated with the selected construction mode  38 . The construction parameters  46  may include only one criterion or in other embodiments may include several criteria. If delta time construction mode  40  is the selected construction mode  38 , the delta time criterion  48  construction parameter  46  must be selected. In the figure, a time of 5 seconds has been chosen as the delta time criterion  46 . The delta time criterion  46  is a time value which the graphical tool  14  uses to step through the vibration data  12  from the leading edge  16  of the region of interest  10  to the trailing edge  18  of the region of interest  10  in its analysis. Each step  54  ( FIG. 4A ) has a time width equal to the value of the delta time criterion  48 . 
         [0029]    Referring back to  FIGS. 3A and 3B , if the delta rpm construction mode  42  is chosen, the delta rpm criterion  50  construction parameter  46  must be selected. The delta rpm criterion  50  is a value representing a change in machine rotations per minute. The delta rpm criterion  50  is used by the graphical tool  14  to select a sample of the vibration data  12  at each instance where the machine speed changes by an amount equal to the delta rpm criterion. Thus, the delta rpm criterion  50  of the delta rpm construction mode  42  serves a similar function as the delta time criterion  48  of the delta time construction mode  40 . However, if the fixed number construction mode  44  is selected, the user must enter a fixed number criterion  52 . The fixed number criterion  52  is a number indicating to the graphical tool  14  the number of time intervals into which the region of interest  10  should be equally divided. 
         [0030]    An additional criterion required for cascade or waterfall plots  20  is a block size parameter  68 , which is shown in the settings dialog  36  of  FIG. 3A . The block size parameter  68  is used to construct spectral data  70  ( FIG. 5 ) necessary for cascade plotting. Furthermore, for an average shaft centerline plot  34 , trend data from two separate, companion monitoring channels—for example  30  and  32  of FIG.  2 —is required. The trend data from the two channels must correspond to the same period of time. In alternate embodiments other types of analytical plots requiring additional or different construction parameters  46  may be used. Further, depending on the construction mode  38 , in conjunction with the type of analytical plot chosen, specific construction parameters  46  may be necessary. The construction parameters  46  described herein are the minimum necessary construction parameters  46  for using each of the described construction modes  38  and associated analytical plots. 
         [0031]    Referring now to  FIG. 4A , a block of vibration data  12  with a selected region of interest  10  being analyzed with the delta time construction mode  40  is shown. The delta time construction mode  40  requires a delta time criterion  48  as discussed above. As shown in  FIG. 4A , each step  54  is spaced apart from the previous step  54  by a time equal to the delta time criterion  48 . Thus, in other embodiments of the delta time construction mode  40 , a step  54  does not necessarily fall on the trailing edge  18  of the region of interest  10 , However, in this exemplary embodiment, a step  54  does fall on the leading edge  16  of the region of interest  10  and each successive step  54  is spaced a distance equal to the delta time criterion  48  from the previous step  54 . At the end of each step  54 , a block of waveform data  60  and a gross scan DC trend point  62  are used to provide an additional sample used by the graphical tool  14  in deriving a plot. 
         [0032]    Referring now to  FIG. 4B , a block of vibration data  12  with a selected region of interest  10  being analyzed with the delta rpm construction mode  42  is shown. The delta rpm construction mode  42  requires a delta rpm criterion  50  as discussed above. FIG.   4 Bi shows the RPM or the speed of the machine on its y-axis  51  versus time on its x-axis  53 . In this example, the RPM of the machine increase at a constant rate and FIG.  4 Bi therefore shows a linear curve. In other examples and embodiments, however, the RPM of the machine do not increase at a constant rate and the RPM versus time curve may be very different. FIG.  4 Bii shows the vibration amplitude of the machine on its y-axis  55  versus time on its x-axis  53 . 
         [0033]    In this example many of the steps  54  are equal in time, but in other examples and embodiments, for example those in which the RPM curve is non-linear, the steps may be unequal. In fact, they may be significantly different. In this example step  54   a  is on the leading edge  16  of the region of interest  10 . The region of interest  10  is analyzed through the time domain and when the delta rpm criterion  50  is achieved, a new sample of data for derived plots is taken. The delta rpm criterion  50  is met when the RPM has changed an amount equal to the value of the delta rpm criterion  50  entered by the user. In this example, the RPM has increased by an amount equal to the delta rpm criterion  50  as of the time represented by step  54   b . Therefore, at the time associated with step  54   b , a data sample is taken. Continuing to move through the vibration data versus time, the RPM has changed an amount equal to the delta rpm criterion  50  next at the time associated with step  54   c . Therefore, another data sample is taken. This procedure is continued for the remaining time within the region of interest  10  until the trailing edge  18  of the region of interest  10  is reached. 
         [0034]    The RPM or speed of the machine may be determined, for example, by analyzing tachometer data once for every tachometer pulse. This speed is constantly analyzed in order to determine the instant at which the speed has changed an amount equal to the delta rpm criterion as discussed above. At such instant, a data sample is taken for derived plots. 
         [0035]    Referring now to  FIG. 4C , a block of vibration data  12  with a selected region of interest  10  being analyzed with the fixed number construction mode  44  is shown. The region of interest  10  selected is from the leading edge  16  to the trailing edge  18 . The steps  54  shown on the bottom of the figure divide the region of interest  10  into equal sections as described above. In this case, the fixed number criterion  52  is equal to six, that is, the region if interest is divided into six equal divisions of time. In the fixed number construction mode  44 , a step  54  will never extend further in time that the trailing edge  18  of the region of interest  10  as was possible with the delta time construction mode  40  and the delta rpm construction mode  42 . 
         [0036]    The fixed number step duration  64  is the length of time of each step  54  in the fixed number construction mode  44 . This value  64  is calculated by determining a region of interest time duration  66 , which is the difference of the time associated with the trailing edge  18  and the time associated with the leading edge  16 . The fixed number step duration  64  is the region of interest time duration  66  divided by the fixed number criterion  52 . In the fixed number construction mode  44  a block of waveform data  60  and a gross scan DC trend point from each step  54  is used to provide an additional sample for each of the derived plots. 
         [0037]      FIG. 5  shows a flowchart of the progression of data samples  59   a  and  59   b  collected from the regions of interest  10  of two, synchronized channels  30  and  32 . The arrows in  FIG. 5  represent processing steps performed by the graphical tool  14 . As illustrated in  FIG. 5 , the cascade/waterfall plots  20  and the Bode/Nyquist plots  28  may be derived and displayed by use of a single source of vibration data  12  ( FIG. 1 ). However, as discussed above, the average shaft centerline plot  34  requires two, companion sources of vibration data  12 , represented in this figure as channels  30  and  32 . Regarding the cascade plot  20 , the graphical tool  14  first determines spectrum data  70  from a data sample  59   a  and then populates the cascade plot or display  20  from several spectral data  70 . Similarly, the graphical tool  14  first determines a peak/phase data point  72  for each data sample  59  and combines several peak/phase data points  72  to derive a Bode/Nyquist plot or display  28 . However, the graphical tool  14  must process two data samples  59   a  and  59   b  collected from two, companion channels  30  and  32  to determine a shaft centerline data point  74 . Several data points  74  are combined to derive an average shaft centerline plot or display  34 . 
         [0038]    Referring now to  FIG. 6 , a schematic diagram of the graphical tool  14  is shown. The graphical tool  14  includes both a hardware module  76  and a software module  78  that interact with one another. The hardware module  76 , in one embodiment, includes a processor  84 , a memory  86 , a display  88 , and a communicator  90 . Preferably, the communicator  90  communicates with a vibration sensing instrument  92  engaging a machine  94 . The machine  94  is the subject of the vibration analysis and the source of the vibration data  12 . The vibration sensing instrument  92  is preferably one or more accelerometers and a tachometer but may be any vibration sensing instrument  92 . The vibration sensing instrument  92  communicates the vibration data  12  to the communicator  90  of the hardware module  76  preferably in a format where the independent variable is time and the dependent variable is displacement or vibration distance. The vibration data  12  is stored in the memory  86 , which is accessed by the processor  84  as directed by the software module  78  of the graphical tool  14 . 
         [0039]    The software module  78  is preferably stored in the memory  86  of the hardware module  76  and controls the processor  84  of the hardware module  76 . In one embodiment, the software module  78  includes plotcontrol module  80  and plotting module  82 . Plotcontrol module  80  and plotting module  82  are preferably library files with a “.dll” file extension. Plotcontrol module  80  is a library containing tools represented by the tools module  96  and is used by the plotting module  82 . Plotcontrol module  80  also draws the region of interest  10  on the display  88 , represented by graphics module  98 , allowing the user to resize the region of interest  10 , that is, to set the leading edge  16  and the trailing edge  18 . This is done by the user making a simple selection such as by mouse, keyboard, or other input commands. 
         [0040]    Additionally, movement of the region of interest  10  may be automated so that derived plots  20 ,  28 , and  34 , automatically step through time as represented by automation module  102 . Plotcontrol module  80  also raises events, represented by the raise events module  100 , when the size or position of the region of interest  10  changes such as by user input commands. Plotting module  82  responds to such events, represented by event response module  102 , by calculating the data required for populating derived plots  20 ,  28 , and  34 . Plotting module  82  also manages the construction modes  38  and construction parameters  46  associated with the region of interest  10  as represented by managing module  104 . 
         [0041]    The foregoing description of preferred embodiments for this invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the invention and its practical application, and to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.