IMV K2 Manuale utente
Non-Gaussian Random Vibration Control System
K2/ NON-GAUSSIAN
K2Sprint/ NON-GAUSSIAN
Instruction Manual
IMV CORPORATION
ULimitation of K2Sprint/NON-GAUSSIAN
･Maximum numbers of usable input channel are ‘2’ channels.
･Option of LIMIT CONTROL can not be added.
Type of Document : Instruction Manual
System Applied : K2/K2Sprint
Software < NON-GAUSSIAN > Later than Version 14.6.0
Japanese Edition
Version Date Contents
10.0.0 2016.02.29 First edition
10.0.1 2016.03.02 Correction of a misprint
13.0.0 2016.04.28 Correction of a misprint
14.3.0 2019.04.19 Modified description of Data save condition, correction of misprints
14.6.0 2020.04.15 Correction of a misprint
English Edition
Version Date Contents
13.0.0 2016.04.28 First edition
13.0.1 2017.09.28 Correction of misprint
14.3.0 2019.04.19 Modified description of Data save condition, correction of misprints
14.6.0 2020.04.15 Correction of a misprint
CONTENS
Chapter 1 Outline of the System........................................................... 1-1
1.1 Outline ........................................................................... 1-1
1.1.1 Index indicating characteristics of random vibration ........................ 1-1
1.1.2 Amplitude probability density ............................................... 1-2
1.1.3 Kurtosis .................................................................... 1-3
1.1.4 Skewness .................................................................... 1-4
1.1.5 Non-Gaussian random control ................................................. 1-5
1.1.6 Non-Gaussian characteristic type ............................................ 1-6
1.2 Specifications .................................................................... 1-7
1.2.1 NON-GAUSSIAN ................................................................ 1-7
Chapter 2 Operation System of K2 Application .............................................. 2-1
2.1 Outline ........................................................................... 2-1
2.2 Test File ......................................................................... 2-2
Chapter 3 Basic Operation................................................................. 3-1
3.1 Break point PSD ................................................................... 3-1
3.2 Measured PSD ...................................................................... 3-24
3.3 Measured waveform ................................................................. 3-47
Chapter 4 Test Definition................................................................. 4-1
4.1 Outline ........................................................................... 4-1
4.2 Fundamental/Control Condition ..................................................... 4-2
4.2.1 Frequency range fmax ........................................................ 4-2
4.2.2 Control frequency lines ..................................................... 4-3
4.2.3 Max. Observation Frequency (Max. Observation Freq.) ......................... 4-3
4.2.4 Controlled variable ......................................................... 4-4
4.2.5 Averaging Parameters ........................................................ 4-4
4.2.6 Equalization Mode ........................................................... 4-5
4.2.7 Loop check .................................................................. 4-6
4.2.8 Test time ................................................................... 4-7
4.2.9 Initial output level ........................................................ 4-7
4.2.10 Level increment ............................................................ 4-8
4.2.11 Auto-start ................................................................. 4-8
4.2.12 Shutdown time .............................................................. 4-8
4.2.13 Level Scheduling ........................................................... 4-9
4.2.13.1 Level ................................................................ 4-10
4.2.13.2 Time ................................................................. 4-10
4.2.13.3 Tolerance enlarge .................................................... 4-10
4.3 Waveform control condition ........................................................ 4-11
4.3.1 Specify the time of XFR measurement excitation .............................. 4-11
4.3.2 （This section is left blank intentionally.） ............................... 4-12
4.3.3 Control strategy ............................................................ 4-12
4.3.4 Drive saving ................................................................ 4-13
4.3.5 Control speed ............................................................... 4-15
4.3.6 Control sharpness ........................................................... 4-16
4.3.7 Cross-talk control loop open ................................................ 4-17
4.3.8 Cross-talk information averaging times ...................................... 4-18
4.3.9（This section is left blank intentionally.） ................................ 4-18
4.4 Excitation System Setting ......................................................... 4-19
4.4.1 Initial output voltage ...................................................... 4-19
4.4.2 XFR Measure output voltage .................................................. 4-19
4.4.3 Clipping.................................................................... 4-20
4.4.3.1 Clipping of drive waveform............................................ 4-20
4.4.3.1.1 Clipping by crest factor ....................................... 4-20
4.4.3.1.2 Allowable voltage .............................................. 4-20
4.4.3.1.3 Allowance clipping ratio ....................................... 4-21
4.4.3.2 Clipping of control response waveform ................................. 4-21
4.4.4 High Pass Filter(HPF) ....................................................... 4-22
4.5 Control Reference ................................................................. 4-23
4.5.1 PSD definition .............................................................. 4-23
4.5.1.1 Non-Gaussian characteristic........................................... 4-23
4.5.2 PSD definition type ......................................................... 4-25
4.5.2.1 Break point PSD definition............................................ 4-26
4.5.2.1.1 Outline ........................................................ 4-26
4.5.2.1.2 Frequency ...................................................... 4-27
4.5.2.1.3 Level .......................................................... 4-27
4.5.2.1.4 Slope .......................................................... 4-27
4.5.2.1.5 rms change ..................................................... 4-28
4.5.2.1.6 Non-Gaussian control ........................................... 4-29
4.5.2.2 Measured PSD definition............................................... 4-30
4.5.2.2.1 Outline ........................................................ 4-30
4.5.2.2.2 PSD Data File loading .......................................... 4-32
4.5.2.2.3 Data edit ...................................................... 4-34
4.5.2.2.3.1 LPF (low pass filter) .................................... 4-34
4.5.2.2.3.2 HPF (high pass filter) ................................... 4-35
4.5.2.2.3.3 Level Change ............................................. 4-36
4.5.2.2.3.4 rms change ............................................... 4-37
4.5.2.2.4 Non-gaussian control ........................................... 4-37
4.5.2.2.5 CSV data file .................................................. 4-38
4.5.2.3 Measured Waveform definition.......................................... 4-39
4.5.2.3.1 Outline......................................................... 4-39
4.5.2.3.2 Waveform Data File loading ...................................... 4-40
4.5.2.3.3 Data edit....................................................... 4-43
4.5.2.3.3.1 Filtering................................................. 4-43
4.5.2.3.3.2 Edging ................................................... 4-45
4.5.2.3.3.3 Scalar calculation........................................ 4-48
4.5.2.3.3.4 Data length change........................................ 4-50
4.5.2.3.4 CSV data file................................................... 4-53
4.5.3 Tolerance Definition ........................................................ 4-54
4.5.3.1 Tolerance ............................................................. 4-55
4.5.3.2 Define the alarm line ................................................. 4-55
4.5.3.3 Use the lower limit line .............................................. 4-55
4.5.4 RMS Check ................................................................... 4-56
4.6 Input Channel ..................................................................... 4-57
4.6.1 Outline ..................................................................... 4-57
4.6.2 Input channel configuration ................................................. 4-58
4.6.3 Input channel element ....................................................... 4-59
4.6.3.1 （This section is left blank intentionally.） ......................... 4-60
4.6.3.2 Specify the abort level of XFR measurement ............................ 4-60
4.6.3.3 Averaging weighting factor ............................................ 4-60
4.6.3.4 Maximum Value Control ................................................. 4-61
4.6.3.5 Minimum Value Control ................................................. 4-62
4.6.3.6 Specify the averaging parameters to each ch. .......................... 4-63
4.6.3.7 Monitoring RMS observing .............................................. 4-64
4.6.3.7.1 Abort Check / Alarm Check ....................................... 4-64
4.6.3.8 Use the observation profile ........................................... 4-65
4.6.3.8.1 Profile definition .............................................. 4-66
4.6.3.8.2 Tolerance definition ............................................ 4-66
4.6.3.8.3 Limit by observation profile .................................... 4-67
4.7 Analysis condition ................................................................ 4-68
4.7.1 Outline ..................................................................... 4-68
4.7.2 Analysis condition .......................................................... 4-68
4.8 Data Save Condition ............................................................... 4-70
4.8.1 Outline ..................................................................... 4-70
4.8.2 Saving Condition ............................................................ 4-70
4.9 Operation Status .................................................................. 4-72
Chapter 5 Message and Meanings............................................................ 5-1
5.1 K2Non-Gaussian Error Message ...................................................... 5-1
Chapter 6 Supplemental Explanation........................................................ 6-1
6.1 Set Up ............................................................................ 6-1
6.2 Manual Operation .................................................................. 6-2
1 - 1
Chapter 1 Outline of the System
1.1 Outline
K2/NON-GAUSSIAN is an option of K2/RANDOM.
Vibration test is conducted to verify that the designed performance and functions of a product can be
maintained until it is discarded by artificially giving it dynamic stress which is assumed to be given
during the life cycle of a product. The test result greatly depends on the type and method of artificial
stress to be given to the product. Therefore, vibration to be given artificially in the vibration test is
preferable to be similar to that in actual vibration environment. For these reasons, sinusoidal vibration
has been used for most of vibration tests for the last few decades. However, random vibration has
become mainstream recently, since it is closer to actual vibration.
In this random test, Gaussian random vibration in accordance with Gaussian distribution (normal
distribution) is used. However, analysis of measured vibration including vibration during transportation
often reveals the vibration to be non-Gaussian random vibrationwhich generates higher peaks, not
Gaussian random vibration.
Non-Gaussian random controller reproduces such non-Gaussian random vibrations more precisely. In
the non-Gaussian random test, higher peaks are generated than in the conventional random test.
Thoroughly understand the nature of non-Gaussian random test, review the protection of specimen and
vibration system, considering varied protective functions provided for this system, and conduct the test
carefully.
It should be noted that the reproduction of non-Gaussian random vibration having the same
characteristics as measured vibration is difficult in general. This is because there are many types of non-
Gaussian random vibration having varied characteristics while the characteristics of Gaussian random
vibration are uniquely defined.
1.1.1 Index indicating characteristics of random vibration
Following two types of indexes indicating characteristics of random vibration are used in normal
random test.
・Power spectral density (PSD)
・rms value
In non-Gaussian random test, following two parameters are added as indexes indicating non-
Gaussian.
・Kurtosis
・Skewness
‘Kurtosis and Skewness’, a kind of statistic, the same as rms value, is indicated by numerical
value as ‘5’. Although rms value is easy to understand immediately as a value to indicate
‘magnitude of vibration’, ‘Kurtosis and Skewness’ may be hard to be understood immediately. To
understand ‘Kurotosis and Skewness’, it is necessary to understand how characteristics of random
vibration are evaluated.
1 - 2
1.1.2 Amplitude probability density
Amplitude probability density (function) indicates the distribution states of random vibration
amplitude (magnitude) to evaluate the characteristics of random vibration.
In the graph below, normal waveform graph is turned clockwise by 90, and amplitude values are
on the horizontal axis, while time values are on the vertical axis.
Horizontal axis in this graph is divided into fixed intervals, like scales (grids), as shown below. In
the histogram shown below, the number of points counted on the waveform between the bins are
plotted for each amplitude level.
However, shape of histograms cannot be compared because the number of points is greater as the
waveform is longer (as the test time is longer). Amplitude probability density is the histogram that
the number of points at each amplitude level is normalized by using the total number of points. And
amplitude probability density facilitates the comparison of histograms.
-2 -1 0 1 2
Time [s]
Amplitude [m/s
2
]
0
-2 -1 0 1 2
Amplitude [m/s2]
0
Amplitude [m/s2]
Time [s]
Number of points
Number of points
between each bins
are counted.
Histogram
Waveform graph
1 - 3
1.1.3 Kurtosis
Kurtosis (peakedness) indicates the density extent of amplitude probability density in the vicinity
of zero (average value), and it also indicates the peakedness in the area close to zero.
As kurtosis is larger, the peakedness in the area close to zero is enhanced, and the tail is thicker.
As the tail is thicker, the peak of random vibration is higher. Kurtosis of Gaussian distribution is
“3”.
Amplitude probability density examples in the case of Gaussian distribution and, 6 and 10 of
kurtosis K are shown below.
Random vibration examples in the case of Gaussian distribution and, 6 and 10 of kurtosis K are
shown below. As kurtosis is larger, the peak of waveform is higher.
-4 -3 -2 -1 0 1 2 3 4
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Amplitude [m/s2]
Amplitude probability density
0
K = 10
K = 6
K = 3
(Gaussian distribution)
2 2.5 3 3.5 4
0
0.05
Zoom
0 1 0 2 0 3 0
-5
0
-5
0
5
-5
0
5
[s]
[m/s2]
[s]
[s]
K = 10
K = 6
K = 3 (Gaussian distribution)
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