Post on 16-Jan-2016
transcript
Illustrative Examples, Two Different Machine Data
Illustrative Examples
• Machine Vibration
Moderate
Strong
Knock region
White Noise, Background Noise
0 2000 4000 6000 8000 10000 12000 140000
0.5
1
1.5
2
PS
D B
KG
No
ise
Freq Hz
0 50 100 150 200 250 300 350 400 450 500-0.2
-0.15
-0.1
-0.05
0
Eve
nt-
fre
e S
egm
ent
s
0 500 1000 1500 2000 2500 3000 3500-2
-1
0
1
2
Cy
cle
Dat
a
Acceleration Data, Single Cylinder Engine, Knock Condition
Background Noise Removal
0 500 1000 1500 2000 2500 3000 3500-10
-5
0
5
10
De
nois
ed
Signal with Backgroung Noise Removed
0 500 1000 1500 2000 2500 3000 3500-10
-5
0
5
10Cylinder Head Vibrations, Original and Denoised, Cycle #1
Ori
gin
al
Wavelet DecompositionMultiresolution
Wavelet Coefficients andDenoising
Residual( Noise Component)
Denoising, Another Example
Thresholded coefficients
Leve
l nu
mbe
r
1000 2000 3000
5
4
3
2
1
1000 2000 3000
-5
0
5
10
Original and de-noised signals
Original coefficients
Leve
l nu
mbe
r
1000 2000 3000
5
4
3
2
1
-5
0
5
d5
Original details coefficients
-5
0
5
d4
-5
0
5
d3
-5
0
5
d2
1000 2000 3000
-10
0
10
d1
Two Stage Denoising of Signals
0 100 200 300-2
-1
0
1
2No Knock Cycle #11
Ori
gin
al
0 100 200 300-2
-1
0
1
2
Den
Sta
ge
1
0 100 200 300-1
-0.5
0
0.5
1
1.5
Den
Sta
ge
2
0 100 200 300-4
-2
0
2
4
0 100 200 300-4
-2
0
2
4
0 100 200 300-4
-2
0
2
4
6 Hard Knock, Cycle #7
Signal component at WP No.38: a) Severe Faulty Condition, b), Mild Fault (b), Fault-free Condition (c).
WP node 38
-0.5
0
0.5
-0.5
0
0.5
1500 1550 1600 1650 1700 1750 1800 1850 1900 1950
-0.5
0
0.5
Sample point
Denoised Signal, WP Node
0 100 200 300-2
-1
0
1
2
Ori
gin
al
No Knock Cycle #6
0 100 200 300-1
-0.5
0
0.5
1
Den
Sta
ge
1
0 100 200 300-0.2
-0.1
0
0.1
0.2
Den
Sta
ge
2
0 100 200 300-2
-1
0
1
2D
en S
tag
e 2
0 100 200 300-4
-2
0
2
4
Den
Sta
ge
1
0 100 200 300-4
-2
0
2
4
Ori
gin
al
Hard Knock Cycle #7
Illustration of Sparsity of Wavelet Coeffs
0 10 20 30-10
0
10
Cy
cle
# 8
0 100 200 300-5
0
5
Mild
Kn
ock
0 100 200 300-1
0
1N
o K
no
ckSignal at High Freq.Band #36
0 100 200 300-5
0
5
Ha
rd K
no
ck
0 10 20 30-10
0
10
20
Cyc
le #
1
0 10 20 30-5
0
5
Cyc
le #
6
Coeffs
Variability of Cyclic Signals
Illustration of Variablity, Spectral Variability, 16 cycles
0 2000 4000 6000 8000 10000 12000 140000
200
4001
6 c
yc
les
Spectrum of Mclean Data, Cyl Head vibration, full cycle
0 2000 4000 6000 8000 10000 12000 140000
200
400
me
an
0 2000 4000 6000 8000 10000 12000 140000
50
100
std
0 2000 4000 6000 8000 10000 12000 140000
0.5
1
std/
me
an
Freq Hz
Spectrum of the vibration signal and its denoised version
Variability in Cyclic Runs
• Variation of vibrations in three consecutive cycles
Original Denoised
Analysis in Coefficient Domain