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MS Thesis Defense:An Intelligent Valve Framework for Integrated Systems Health Management on Rocket Engine Test Stands
Michael Russell
Advisor:Dr. Shreekanth Mandayam
August 30, 2010
3
Introduction
B-1/B-2 Test StandA-2 Test Stand
A-1 Test Stand
E-2 Test Stands E-1 Test StandsE-3 Test Stands
NASA Stennis Space Center, Mississippi
Introduction Background Approach Results Conclusions
4
Introduction
• Over 1,500 sensors in a rocket engine test stand
• This results in an enormous volume of sensor information
• Utilize health analysis algorithms to reduce the amount of information for operators
• Predict anomalous conditions before they occur
Introduction Background Approach Results Conclusions
5
IntroductionTest Stand Instrumentation • Large linear actuated valve• High-geared ball valves• Multi-sensor measurements –
Pressure, Temperature, Control, Feedback
Introduction Background Approach Results Conclusions
6
IntroductionSmart Instrumentation Framework for NASA-SSC Ball Valves and Large Linear Actuator Valves
Introduction Background Approach Results Conclusions
7
Objectives To design a framework for the detection of faults and failure
modes in the large linear actuated valve that are used on the rocket engine test stands at NASA-SSC.
To develop a diagnostic process that – Receives and stores incoming sensor data; Performs calculation of operating statistics; Compares with existing analytical models; and, Visualizes faults, failures and operating conditions in a 3D GUI
environment. To develop a suite of health analysis algorithms that can
detect anomalous behavior in the valve and other system components of the rocket engine test stand.
To expand the capability of the diagnostic algorithm to perform prognosis in specific contexts.
9
Background - FMECA Failure Modes Effects and Criticality Analysis
Background Approach Results ConclusionsIntroduction
11
Background - DiagnosticsAuthors Title Area of ResearchV. Puig, J. Quevedo, T. Escobet, F. Nejjari, and S. de las Heras, Automatic Control Department-Campus de Terrassa, Spain
Passive Robust Fault Detection of Dynamic Processes Using Interval Models
Model-based fault detection based on interval models that generate adaptive thresholds using three schemes (simulation, prediction, and observation)
H. Bassily, R. Lund, and J. Wagner,Clemson University
Fault Detection in Multivariate Signals With Applications to Gas Turbines
Compares multivariate autocovariance functions of two independently sampled signals in order to create a model-based algorithm to detect faults in a gas turbine
C. H. Lo, Eric H. K. Fung, and Y. K. Wong,Hong Kong Polytechnic University
Intelligent Automatic Fault Detection for Actuator Failures in Aircraft
Utilizes fuzzy-genetic algorithm to detect different types of actuator failures in a nonlinear F-16 aircraft model
G. Spitzlsperger, C. Schmidt, G. Ernst, H. Strasser, and M. Speil,Renesas Semiconductor Europe
Fault Detection for a Via Etch Process Using Adaptive Multivariate Methods
Uses an adaptive method to overcome false alarms in slowly degrading manufacturing processes that use Hotelling T2 and squared prediction errors.
W. R. A. Ibrahim, M. M. Morcos,Kansas State University
An Adaptive Fuzzy Self-Learning Techniquefor Prediction of Abnormal Operationof Electrical Systems
Details an intelligent adaptive fuzzy system with self-learning functions that monitors electrical equipment
S. Huang and K. K. Tan,National University of Singapore
Fault Detection and Diagnosis Based onModeling and Estimation Methods
Uses multiple Radial Basis Functions to estimate both the unknown nonlinear dynamics as well as the fault characteristics of a simulated system
J. Yun, K. Lee, K. Lee, S. B. Lee, J. Yoo,Electric Power Machinery Research Department, Hyundai Heavy Industries
Detection and Classification of Stator Turn Faultsand High-Resistance Electrical Connectionsfor Induction Machines
Proposes a stator-winding turn-fault detection algorithm using sensorless zero-sequence voltage or negative-sequence current measurements.
Background Approach Results ConclusionsIntroduction
13
Background - PrognosticsAuthors Title Area of ResearchF. Peysson, M. Ouladsine, R. Outbib, J.B. Leger, O. Myx, C. Allemand,University of Paul Cézanne
A Generic Prognostic Methodology Using Damage Trajectory Models
Presents a prognostic framework then decomposes a system into three levels: environment, mission, and process. Decision and data fusion between the three levels is used to create predictions.
Z. Sun, J. Wang, D. How, G. Jewell,The University of Sheffield
Analytical Prediction of the Short-Circuit Current in Fault-Tolerant Permanent-Magnet Machines
Describes an analytical technique to predict short-circuit current in a fault-tolerant permanent-magnet machine under partial-turn short-circuit fault conditions.
Y. Zhang, G. W. Gantt, M. J. Rychlinski, R. M. Edwards, J. J. Correia, C. E. Wolf,GM Research & Development,
Connected Vehicle Diagnostics and Prognostics, Concept, and Initial Practice
Presents a complete end-to-end framework of diagnostics and prognostics of General Motors vehicles. Presents initial result.
M. Baybutt, C. Minnella, A. E. Ginart, P. W. Kalgren, M. J. Roemer,Impact Technologies, LLC
Improving Digital System DiagnosticsThrough Prognostic and HealthManagement (PHM) Technology
Integrates prognostics and diagnostics from engineering disciplines to provide minimally invasive onboard monitoring of digital systems.
P. Lall, M. N. Islam, M. K. Rahim, J. C. Suhling,Auburn University
Prognostics and Health Management of Electronic Packaging
Investigates methods to determine material state in complex systems and subsystems to determine RUL.
S. K. Yang,Chin Yi Institute of Technology
A Condition-Based Failure-Prediction and Processing-Scheme for Preventive Maintenance
Uses an application-specific integrated circuit (ASIC) to perform preventive maintenance using Petri nets and Kalman filter prediction.
A. H. Al-Badi, S. M. Ghania, E. F. EL Saadany,University of Waterloo
Prediction of Metallic Conductor Voltage Owing to Electromagnetic Coupling Using Neuro Fuzzy Modeling
Presents a Fuzzy algorithm that can predict the level of a metallic conductor voltage. Provides simulation results and validation for three scenarios.
Background Approach Results ConclusionsIntroduction
16
Background – LLAV
BonnetBonnetPacking
StemValve Plug Seating
Body
Background Approach Results ConclusionsIntroduction
Approach – Faults and failure modes
18
Function Failure Mode EffectsController for cryogenic fluid tank
Seat Wear cause leaking fluid Fluid can enter system during a test causing catastrophic failure
Monitor the feedback of the valve and downstream pressure
Faulty pressure sensor falsely indicate valve failure
Incorrect valve maintenance may be performed
Packing at the top of the valve prevents leaks and allows for balanced pressure
When frozen, the packing can crack and break apart, degrading the performance of the valve
Valve may not function properly or be able to maintain needed pressure for test
Actuator must transition from fully open to fully closed in a consistent amount of time.
If the valve does not open or close at consistent timings, valve maintenance must be performed
The valve’s remaining useful life without maintenance is reducing.
The controller of the valve sends a valve to full close.
If the PID controller is unstable or telling the valve to get to a value it cannot reach, the actuator may “bounce” on the seat causing degradation in the soft metal.
Seat wear (described above) can occur more quickly resulting in delays and increased maintenance costs.
The valve feedback must respond to the control signal in an appropriate time for effective test operations.
Excessive “deadtimes” create poor timing in test operations and can cause pressure or flow mixture errors.
If the mixture is not precise is certain test articles, undesired results can occur.
Background Approach Results ConclusionsIntroduction
Approach – FMECA
19
0 1 2 3 4 5 6 7 8 9 10 110
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
Criticality
Ris
k P
riorit
y N
umbe
r
Seat boucing
Transition Times
Sensor Failures
Extended Deadtimes
Frost Point
Seat Wear
Background Approach Results ConclusionsIntroduction
21
Approach – Failure modes
Failure mode Fault Detection algorithmSeat Wear Operating StatisticsSensor Failures AANNFrost Point Thermal modelExtended Deadtimes Adaptive Threshold
Operating StatisticsTransition Times Adaptive Threshold
Operating StatisticsSeat bouncing Operating Statistics
Background Approach Results ConclusionsIntroduction
22
Approach – Sensor Validation Pressure and temperature sensors are vital to the operations
of the test stands at NASA-SSC Specific mixtures of fluids and gas Chilldown
Failure modes in the sensors Characterized against faults found in frost line
Autoassociative neural networks Nonlinear principal component analysis Finds correlations of subsystem components Find faults based on residual values
Background Approach Results ConclusionsIntroduction
23
Approach – Sensor Validation Nonlinear principal component analysis (NPCA)
PCA: where P is the eigenvectors of the covariance matrix,Y is the sample set, and T is the transformed data
NPCA : Replace P by nonlinear vector function
In order to restore data, another nonlinear vector function is needed:
Cybenko (1989) showed that functions of the following form are capable of fitting any nonlinear function :
A sigmoid satisfies this
24
Approach – Sensor Validation
𝜎
𝜎
𝜎
𝜎
y1
y2
y3
T1
T2
𝜎
𝜎
𝜎
𝜎
y1'
y2’
y3’
T1
T2
G(Y) H(T)G(Y) H(T)
𝜎
𝜎
𝜎
𝜎
y1
y2
y3
𝜎
𝜎
𝜎
𝜎
y1’
y2’
y3’
T1
T2
Mapping Layer
InputLayer
BottleneckLayer
DemappingLayer
OutputLayer
Background Approach Results ConclusionsIntroduction
27
Approach – Sensor Validation Data
Methane Thruster Testbed Project Trailer
Background Approach Results ConclusionsIntroduction
28
Approach – Sensor Validation Metrics
Background Approach Results ConclusionsIntroduction
Sensitivity – Measure of the amount of fault data points correctly identified
Sensitivity – Measure of the amount of nominal data points correctly identified
Positive Predictive Value – Measure of the fault data points correctly identified
Negative Predictive Value – Measure of the nominal data points correctly identified
F-measure – Measure of a tests accuracy
29
Approach – Adaptive Threshold PID controllers are used to operate valves
Stroke timings, input delays and gain factors can be contribute to failing health
A method to detect anomalous behavior of the valve A bank of ARMA filters can be used to create an
adaptive threshold based on the input of the set points and PID controller
ARMAX:
Background Approach Results ConclusionsIntroduction
30
Approach – Adaptive Threshold
𝐹𝑖𝑡=100∗(1− 𝑛𝑜𝑟𝑚 ( h𝑦 − 𝑦 )𝑛𝑜𝑟𝑚 ( 𝑦−𝑚𝑒𝑎𝑛 ( 𝑦 ) ) )
Background Approach Results ConclusionsIntroduction
32
Approach – Adaptive Threshold Data
Forward analytical model to simulate valve transfer function in Simulink with PID controller:
𝑉 𝑝𝑟𝑜𝑐𝑒𝑠𝑠=𝑔∗𝑒−𝑇 𝑠∗𝑠
𝑠2+2∗𝜁 ∗𝑇𝑤∗𝑠+𝑇𝑤2
: Gain: Unit delay: Natural frequency: Damping ratio: Valve response
Background Approach Results ConclusionsIntroduction
0 10 20 30 40 50 600
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Time (s)
Per
cent
age
open
(%
)
Transfer function with changing values of : damping coefficient
Step Signal = .2 = .4 = .6 = .8 = 1 = 1.2
33
Approach – Adaptive Threshold Data
Parameter Nominal Low Abnormal High Abnormal
Gain
Natural
Frequency
Damping Ratio
Delay
Background Approach Results ConclusionsIntroduction
34
Approach – Diagnostic Process Requirements
Task 1: Development of the valve sensor interface to ActiveX controller
Task 2: Development of prototype immersive user interface for intelligent valve
Background Approach Results ConclusionsIntroduction
35
Approach – Diagnostic Process
Background Approach Results ConclusionsIntroduction
DDE Client
Virtual Reality Environment
G2 Diagnostic Environment
WonderWare .NET Plugin
NASA Data Acquistion
System (DDE Server)
Health Data
Health Data
Measurement Data
36
Approach – Diagnostic Process MS-SQLCE was used for database management and
persistent data storage
Background Approach Results ConclusionsIntroduction
38
Approach – Prognostics Goal of prognostics: Determine remaining
useful life (RUL) of a component or system Prognostic techniques are mathematical
predictions based on previous inputs and outputs AR and ARMA – Linear predictors Kalman Filter - State-space model
Prognostics rely heavily on diagnostic information as well as parameter calculation of key state variables
Background Approach Results ConclusionsIntroduction
39
Approach – Prognostics Kalman Filter:
Time Update:
Measurement update:
−
Background Approach Results ConclusionsIntroduction
Time(Predict)
Measurement(Correct)
40
Results – Sensor Validation
Failure mode Fault Detection algorithmSeat Wear Operating StatisticsSensor Failures AANNFrost Point Thermal modelExtended Deadtimes Adaptive Threshold
Operating StatisticsTransition Times Adaptive Threshold
Operating StatisticsSeat bouncing Operating Statistics
Background Approach Results ConclusionsIntroduction
41
Results – Sensor Validation
2.75 2.8 2.85 2.9 2.95
x 105
0
100
200
300
400
Elapsed Time (s)
Pre
ssu
re (
PS
IG)
Simulated data for sensor validation
Measured Data
Simulated Fault DataEstimated AANN Data
2.75 2.8 2.85 2.9 2.95
x 105
0
0.2
0.4
0.6
0.8
1
Elapsed Time (s)
Fa
ult
De
tect
ed
Fault region detection
Background Approach Results ConclusionsIntroduction
42
Results – Sensor Validation
2.75 2.8 2.85 2.9 2.95
x 105
0
100
200
300
400
Elapsed Time (s)
Pre
ssu
re (
PS
IG)
Simulated data for sensor validation
Measured Data
Simulated Fault DataEstimated AANN Data
2.75 2.8 2.85 2.9 2.95
x 105
0
0.2
0.4
0.6
0.8
1
Elapsed Time (s)
Fa
ult
De
tect
ed
Fault region detection
Background Approach Results ConclusionsIntroduction
43
Results – Sensor Validation
2.82 2.84 2.86 2.88 2.9 2.92 2.94 2.96
x 105
100
150
200
250
300
350
400
Elapsed Time (s)
Pre
ssu
re (
PS
IG)
Simulated data for sensor validation
Measured Data
Simulated Fault Data
Estimated AANN Data
2.82 2.84 2.86 2.88 2.9 2.92 2.94 2.96
x 105
0
0.2
0.4
0.6
0.8
1
Elapsed Time (s)
Fa
ult
De
tect
ed
Fault region detection
Background Approach Results ConclusionsIntroduction
44
Results – Sensor Validation Failure
0 1 2 3
x 104
0
200
400
600
AANN estimation for PE-1134-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
100
200
300
Error signal and threshold for PE-1134-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
50
100
150
200
AANN estimation for PE-1140-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
50
100
150
200
Error signal and threshold for PE-1140-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
200
400
600
AANN estimation for PE-1143-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
100
200
300
Error signal and threshold for PE-1143-GO
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
50
100
AANN estimation for PC1
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
0 1 2 3
x 104
0
5
10
15
20
Error signal and threshold for PC1
Elapsed Time (ms)
Pre
ssur
e (P
SIG
)
Background Approach Results ConclusionsIntroduction
45
Results – Sensor Validation Failure
0 1 2 3
x 104
0
20
40
60
AANN estimation for VPV-1139-FB
Elapsed Time (ms)
Perc
ent
Open (
%)
0 1 2 3
x 104
0
20
40
Error signal and threshold for VPV-1139-FB
Elapsed Time (ms)
Perc
ent
Open (
%)
0 1 2 3
x 104
0
20
40
AANN estimation for VPV-1139-CMD
Elapsed Time (ms)
Perc
ent
Open (
%)
0 1 2 3
x 104
0
10
20
30
40
Error signal and threshold for VPV-1139-CMD
Elapsed Time (ms)
Perc
ent
Open (
%)
Background Approach Results ConclusionsIntroduction
46
Results – Sensor Validation Average Metrics
Sensitivity 99.89%
Specificity 74.76%
Positive Predictive Value 97.89%Negative Predictive Value 96.11%F-Measure 98.84%
Background Approach Results ConclusionsIntroduction
47
Results – Adaptive Threshold
Failure mode Fault Detection algorithmSeat Wear Operating StatisticsSensor Failures AANNFrost Point Thermal modelExtended Deadtimes Adaptive Threshold
Operating StatisticsTransition Times Adaptive Threshold
Operating StatisticsSeat bouncing Operating Statistics
Background Approach Results ConclusionsIntroduction
48
Results – Adaptive Threshold Setpoints
0 1000 2000 3000 40000
20
40
60
80
100
Samples
Ope
n P
erce
ntag
e (%
)
Setpoint transition 1
0 1000 2000 3000 40000
20
40
60
80
100
Samples
Ope
n P
erce
ntag
e (%
)
Setpoint transition 2
0 1000 2000 3000 40000
20
40
60
80
100
SamplesO
pen
Per
cent
age
(%)
Setpoint transition 4
0 1000 2000 3000 40000
20
40
60
80
100
Samples
Ope
n P
erce
ntag
e (%
)
Setpoint transition 5
0 1000 2000 3000 40000
20
40
60
80
100
Samples
Ope
n P
erce
ntag
e (%
)
Setpoint transition 6
0 1000 2000 3000 40000
20
40
60
80
100
Samples
Ope
n P
erce
ntag
e (%
)
Setpoint transition 7
Background Approach Results ConclusionsIntroduction
49
Results – Adaptive Threshold Setpoints
1500 2000 2500 3000 3500 4000
60
80
100
Sample
Perc
ent
Open (
%)
G: 0.98 Tw
: 0.98 : 0.98 Ts: 2
Measured Values
Upper ThresholdLower Threshold
1500 2000 2500 3000 3500 4000
-1
0
1
Sample
Fault D
ete
ction:
Fault identification: 0 faults
Nominal operating conditions for Setpoint #1
Background Approach Results ConclusionsIntroduction
50
Results – Adaptive Threshold Setpoints
1500 2000 2500 3000 3500 4000 450060
80
100
Sample
Per
cent
Ope
n (%
)
G: 0.9 Tw
: 0.85 : 0.85 Ts: 4
Measured Values
Upper Threshold
Lower Threshold
1500 2000 2500 3000 3500 4000
-1
0
1
Sample
Fau
lt D
etec
tion:
Fault identification: 276 faults
Abnormal operating conditions for Setpoint #1:Low Damping coefficient
Background Approach Results ConclusionsIntroduction
51
Results – Adaptive Threshold Setpoints
Abnormal operating conditions for Setpoint #3:High input delay
1500 1600 1700 1800 1900 2000 2100 2200 2300
0
20
40
60
Sample
Per
cent
Ope
n (%
)
G: 0.9 Tw
: 0.9 : 0.95 Ts: 5
Measured Values
Upper ThresholdLower Threshold
1500 1600 1700 1800 1900 2000 2100 2200 2300-1
-0.5
0
0.5
1
Sample
Fau
lt D
etec
tion:
Fault identification: 776 faults
Background Approach Results ConclusionsIntroduction
52
Results – Adaptive Threshold Setpoints
Abnormal operating conditions for Setpoint #5:Low gain
100 200 300 400 500 600 700 800 900
0
50
100
Sample
Per
cent
Ope
n (%
)
G: 0.9 Tw
: 1.15 : 0.85 Ts: 5
Measured Values
Upper Threshold
Lower Threshold
100 200 300 400 500 600 700 800 900
-1
-0.5
0
0.5
Sample
Faul
t Det
ectio
n:
Fault identification: 2864 faults
Background Approach Results ConclusionsIntroduction
53
Results – Adaptive Threshold Metrics
0.9 1 1.1 1.2 1.3100
150
200
250Gain
Avg
. N
umbe
r of
Fau
lts
Parameter value0.8 1 1.2 1.40
200
400
600Natural Frequency
Avg
. N
umbe
r of
Fau
lts
Parameter value
0.8 1 1.2 1.4120
140
160
180
200Damping Coefficient
Avg
. N
umbe
r of
Fau
lts
Parameter value2 3 4 5
100
150
200
250Input Delay
Avg
. N
umbe
r of
Fau
lts
Parameter value
Background Approach Results ConclusionsIntroduction
54
Results – Adaptive Threshold on LLAV
0 50 100 150-20
0
20
40
60
80
100
120
Time (s)
Perc
enta
ge C
losed (
%)
Adaptive Threshold Training Data
Upper Values
Lower ValuesActual Values
Background Approach Results ConclusionsIntroduction
55
Results – Adaptive Threshold on LLAV
0 50 100 150
0
20
40
60
80
100
Elapsed Time (s)
Per
cent
age
Clo
sed
(%)
Valve Feedback with Simulated Obstruction
Upper Threshold
Lower TresholdMeasured Valve Feedback
0 50 100 150-0.2
0
0.2
0.4
0.6
0.8
1
Upper Faults
Elapsed Time (s)
Fau
lt D
etec
ted
0 50 100 150-0.2
0
0.2
0.4
0.6
0.8
1
Lower Faults
Elapsed Time (s)
Fau
lt D
etec
ted
Background Approach Results ConclusionsIntroduction
61
Results – Prognostics for LLAV
0
10
20
30-50-40-30-20-10010
500
1000
1500
2000
2500
3000
3500
4000
4500
SNR
Prediction performance of Kalman model for LLAV signal
Prediction Steps
RM
SE
Background Approach Results ConclusionsIntroduction
62
Contributions Validation of a thermal model for the determination of the
frost line on the LLAV. The development of an auto-associative neural network
algorithm for validation of sensors. An adaptive threshold algorithm for fault detection and
trending of degradation in the LLAV. A survey of AR, ARMA and Kalman filter techniques for the
prediction of time series data. Operating statistic algorithm that provides historical context
for maintenance personnel. Development of a diagnostic process for data acquisition,
data storage and visualization of the LLAV.
Background Approach Results ConclusionsIntroduction
Conclusions
An intelligent valve framework has been designed and implemented that gives NASA-SSC test operators ability to diagnosis key faults and monitor a valve’s health degradation at the E complex test stands.
Three diagnostic algorithms assist in detecting and diagnosing the faults outlined in the FMECA
A diagnostic process was developed that acquires, stores and analyzes data from the valves on the E complex test stands
Background Approach Results ConclusionsIntroduction
64
Future Work
Further develop the diagnostic process Complete prognostics section of the
framework to provide maintenance personnel with three types of data: Determination of remaining useful life (RUL) of a
valve for predictive maintenance Initiation of “what if?” queries Comprehensive risk analysis of every test
procedure
Background Approach Results ConclusionsIntroduction
65
Acknowledgements
The support of my MS program by the NASA Graduate Student Researchers Program (GSRP) award No. NNX07AO92H in 2008 and 2009 is gratefully acknowledged. The research work presented in this thesis was also supported by NASA Stennis Space Center under Grant/Cooperative Agreement No. NNX08BA19A
Background Approach Results ConclusionsIntroduction
69
Approach – Operational Statistics Seven key statistics were identified that
provide historical context for the valve’s health: Transitions - The amount of times the valve has
traveled from a completely open to a completely closed with non-cryogenic fluid flow.
Cryogenic Transitions - The amount of times the valve has traveled from a completely open to a completely closed with cryogenic fluid flow.
Background Approach Results ConclusionsIntroduction
70
Approach – Operational Statistics Distance Traveled - The linear distance the valve has
traveled in inches. Last transition time - The time it took for a valve to
go from completely open to completely closed. Average transition time - The average of the last ten
transitions from completely open to completely closed.
Direction changes - The amount of times the valve has changed motion from either opening to closing or closing to opening.
Number of closings - The amount of times the valve has come to a completely closed state.
Background Approach Results ConclusionsIntroduction
72
175”
11”
Approach – Frost Line Packing at the top the LLAV is used to keep
offset pressures for pneumatic and hydraulic valves Freezing the packing causes degradation Valve length is increased to prevent
freezing Every inch added to these valves
increases cost Performed test to analyze frost
line
Predicted Locationfor 32° F
Actual Frost Line
Background Approach Results ConclusionsIntroduction
73
Approach – Frost LineThe test was completed with the following protocol: A simulated valve was programmed into the WonderWare
control environment When the simulated valve opened, liquid nitrogen (LN) was
poured into the box containing the valve. During the next several hours, the liquid nitrogen was kept at a
constant level in order to simulate the passing of fluid through an open valve.
The temperature and frost line was monitored after the body reached a steady state temperature of -322oF (boiling point of LN).
There was a thermocouple at the base of the valve and a thermocouple about 3 inches up the stem of the valve, both were monitored and stored in a data file.
Background Approach Results ConclusionsIntroduction
75
Approach – Frost LineThe following sensor faults were injected into the DAQ system: Faulty connection in amplifier input Amplifier power down Tustin input disconnect Input disconnection on the digitizer Frost insulation Temperature junction reference Thermocouple and power disconnection Thermocouple disconnections and shorts Transmitter power and failure Unaccounted thermocouple junction
Background Approach Results ConclusionsIntroduction
76
Approach – Frost Line AlgorithmUse physical model to estimate base and stem temperatures:
Estimated base temperatureAmbient Temperature
𝑇 𝑓𝑙𝑢𝑖𝑑:Boiling temperature of fluid𝑡𝑜𝑝𝑒𝑛 :Time the valvehas beenopen𝑚 : Steady state time
𝐿𝑇𝐶 :Distanceof thermocouple ¿ base
𝑇 𝑒𝑠𝑡 :Estimated temperature of thermocoupleat LtcLength of the stem of the valve𝑇 𝑎𝑚𝑏: Ambient temperature𝑚𝑡 : material constant
Background Approach Results ConclusionsIntroduction
Approach – Frost Line Algorithm
77
Used least squares curve fitting on base run to determine and :
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
x 104
-350
-300
-250
-200
-150
-100
-50
0
50
Time (s)
De
gre
ss (
F)
Base Run
Top ThermocoupleTop SimulationBottom ThermocoupleBottom Simulation
M – Chill Down M – Warm Up mt – Chill Down mt – Warm up
659.80s 4672s .36 .32
Background Approach Results ConclusionsIntroduction
78
Results – Prognostics
0 10 20 30 40 50 60 70 80 90 1000
20
40
60
80
100
120Time series with 0 mean and 1 variance
Time (s)
Am
plitu
de
Background Approach Results ConclusionsIntroduction
79
Results – Prognostics
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plitu
de
AR prediction at 1 prediction step and SNR = 25dB
AR Prediction
Actual Signal
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plitu
de
AR prediction at 5 prediction steps and SNR = 25dB
AR Prediction
Actual Signal
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plit
ude
AR prediction at 5 prediction steps and SNR = -5dB
AR Prediction
Actual Signal
Background Approach Results ConclusionsIntroduction
80
Results – Prognostics
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plit
ude
ARMA prediction at 1 prediction steps and SNR = 25dB
ARMA Prediction
Actual Signal
0 20 40 60 80 100-20
0
20
40
60
80
100
120
Time (s)
Am
plit
ude
ARMA prediction at 1 prediction steps and SNR = -5dB
ARMA Prediction
Actual Signal
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plitu
de
ARMA prediction at 5 prediction steps and SNR = -5dB
ARMA Prediction
Actual Signal
Background Approach Results ConclusionsIntroduction
81
Results – Prognostics
0 20 40 60 80 1000
10
20
30
40
50
60
70
80
90
100
Time (s)
Am
plit
ude
Kalman prediction at 1 prediction steps and SNR = 25dB
Kalman Prediction
Actual Signal
0 20 40 60 80 1000
20
40
60
80
100
120
Time (s)
Am
plit
ude
Kalman prediction at 5 prediction steps and SNR = 25dB
Kalman Prediction
Actual Signal
0 20 40 60 80 100-20
0
20
40
60
80
100
120
Time (s)
Am
plitu
de
Kalman prediction at 5 prediction steps and SNR = -5dB
Kalman Prediction
Actual Signal
Background Approach Results ConclusionsIntroduction
82
Results – Prognostics
0
5
10
15
-50510152025
0
500
1000
1500
2000
2500
3000
3500
SNR (dB)
Prediction performance of AR model for = 0 and = 1 signal
Prediction Steps
MS
E
0
5
10
15
-100
1020
30
0
500
1000
1500
SNR (dB)
Prediction performance of ARMA model for = 0 and = 1 signal
Prediction Steps
MS
E
Background Approach Results ConclusionsIntroduction
83
Results – Prognostics
0
5
10
15
-50
510
1520
25
0
500
1000
1500
2000
SNR (dB)
Prediction performance of Kalman filter model for = 0 and = 1 signal
Prediction Steps
MS
E
Background Approach Results ConclusionsIntroduction
84
Results – Prognostics for LLAV
85 90 95 100 105 110 115 120 125 130
-20
0
20
40
60
80
100
120
Time (s)
Per
cent
age
Ope
n(%
)
30 step prediction of process variable using ARX model
Previous Process
Predicted ProcessActual Process
Control Input
85 90 95 100 105 110 115 120 125 130-20
0
20
40
60
80
100
120
Time (s)
Per
cent
age
Ope
n(%
)
30 step prediction of process variable using ARMAX model
Previous Process
Predicted ProcessActual Process
Control Input
Background Approach Results ConclusionsIntroduction
85
Results – Prognostics for LLAV
0
10
20
30
-50-40
-30-20
-100
10
0
2000
4000
6000
8000
10000
SNR
Prediction performance of ARMA model for LLAV signal
Prediction Steps
RM
SE
0
10
20
30
-50-40-30-20-10010
0
2000
4000
6000
8000
10000
12000
SNR
Prediction performance of AR model for LLAV signal
Prediction Steps
RM
SE
Background Approach Results ConclusionsIntroduction
86
Results – Thermal Modeling
0.5 1 1.5 2 2.5
x 104
-500
-400
-300
-200
-100
0
100
200
Time (s)
De
gre
ss (
F)
Amplifier Power Down and Tustin Input Disconnect
Top ThermocoupleTop SimulationBottom ThermocoupleBottom Simulation
0.5 1 1.5 2 2.5
x 104
0
0.2
0.4
0.6
0.8
1
Time (s)
Fa
ult
Cla
ssifi
catio
n
Top Thermocouple Fault Detection
0.5 1 1.5 2 2.5
x 104
0
0.2
0.4
0.6
0.8
1
Time (s)
Fa
ult
Cla
ssifi
catio
n
Bottom Thermocouple Fault Detection
Background Approach Results ConclusionsIntroduction
87
Results – Thermal Modeling
0 0.5 1 1.5 2 2.5 3 3.5 4
x 104
-350
-300
-250
-200
-150
-100
-50
0
50
Time (s)
De
gre
ss (
F)
Faulty Connection in Amplifier Input
Top ThermocoupleTop SimulationBottom ThermocoupleBottom Simulation
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 104
0
0.2
0.4
0.6
0.8
1
Time (s)
Fau
lt C
lass
ifica
tion
Top Thermocouple Fault Detection
0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 104
0
0.2
0.4
0.6
0.8
1
Time (s)
Fau
lt C
lass
ifica
tion
Bottom Thermocouple Fault Detection
Background Approach Results ConclusionsIntroduction
88
Results – Thermal Modeling
350 400 450 500 550 600 650
-3
0
3
5
7
9
11
13
X: 417.2Y: 3.006
Fro
st L
ine
(in
che
s)
Elapsed Time (s)
Frost line model comparison with actual thermocouple data
350 400 450 500 550 600 650
-20
-10
0
10
20
30
40
50
60
40
X: 359.8Y: 31.97
Te
mp
era
ture
(F
)
Thermocouple reading at 3 inches
Actual time of frost point at 3 inchesPredicted time of frost point at 3 inches
Predicted frost line
Background Approach Results ConclusionsIntroduction
89
Results – Thermal Modeling Average Metrics
Sensitivity 98.80%Specificity 81.07%Positive Predictive Value 86.13%Negative Predictive Value 91.39%F-Measure 89.32%
Background Approach Results ConclusionsIntroduction