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| A Demonstration of
Technology for the
Jeffrey Banks, Brian Murphy and Karl Reichard, Penn State
This article describes the development and im-
plementation of a prototype embedded health
management system for the U.S. Army HEMTT
M1120A2+ vehicle. Diagnostic, advanced diag-
nostic and prognostic technologies were devel-
oped and implemented for four of the vehicle's
subsystems. A centralized vehicle health infor-
mation analyzer and server was developed and
resides in a hardened on-board computer. All of
the sensors and devices are networked into this
computer, which stores and processes the data for
display to the graphical user interface. This inter-
face was developed to provide vehicle operational
status data and sub-system health information in
an actionable format that is simple to understand
and intuitive to operators and maintainers.
The Heavy Expanded Mobility Tactical Truck
(HEMTT) and similar logistic support vehicles
are critical assets for the continued support of op-
erations in extreme and hazardous environments
throughout the world. When logistic support
vehicles have higher reliability levels the increased
availabilityratesdirectlyaffectwhetherornotmis-
sionscanbesuccessfullycompleted.Akeycontrib-
utor to achieving vehicle reliability and availability
is the ability to conduct vehicle maintenance effec-
tively and efficiently. This becomes increasingly
difficult to accomplish with vehicles that have a
high level of complexity to meet broad functional-
ity requirements. Conducting maintenance well
is even more difficult to achieve with maintainers
and operators who have rudimentary experience
with complex mechanical, hydraulic and electri-
cal systems. Efficient and effective maintenance
involves the capability to quickly and accurately
detect, diagnose, and localize faults to critical line
replaceable units (LRUs). It also involves provid-
ing replacement part information to the logistic
system to expedite the acquisition of the correct
LRU by the appropriate maintenance personnel.
This facilitates the part replacement process and
gets the vehicle back in service more quickly. The
enabling technologies that provide this capability
are referred to as health management technolo-
gies. Health management technologies that are
integrated into the vehicle can provide a wealth of
information to a variety of information customers
including: operators, maintainers, supply, logisti-
cians, mission planners ,etc. The technology pro-
vides the capability to more efficiently and effec-
tive manage a fleet of vehicles with the on-board
capability to continuously monitor and assess the
condition of critical components that contribute
to vehicle reliability and availability.
The Oshkosh Truck Company HEMTT
M1120A2+vehicleisalogisticsupportvehiclethat
is propelled by a diesel engine with 8 wheel drive
that allows the vehicle to operate in extreme field
environments.
The HEMTT has the ability to load and unload
up to 11 tons of payload in the field with the use
of the integrated hydraulic load handling system
(LHS). TheLHSiscomprisedof4hydrauliccyl-
inders,controlmanifolds,filters,reservoirtankand
pump. TheA2+versionofthevehicleisequipped
with a J-1939 controller area network (CAN) bus
thatallowsforlowbandwidth(~1Hz)digitaldata
to be transferred continuously throughout the ve-
hicle. The CAN bus provided us with a conduit
to collect raw and processed data from the engine
and transmission as well as raw data from 15 pres-
suresensors,2temperaturesensorsand1levelsen-
sor located in the hydraulic system. We used the
data from these sensors to develop the hydraulic
diagnostic capability for the vehicle.
In order to gain a better understanding of the hy-
draulicsystemandtofacilitatethedevelopmentof
the system diagnostics a hydraulic system model
was developed. The hydraulic system dynamic
model was developed by Penn State ARL to
represent the interactions of the hydraulic system
componentsingeneralterms. Eachcomponentof
the hydraulic system was modeled on the top level
ofthesimulationasitwouldappearinthevehicle's
hydraulic schematic as shown in Figure 1.
Modeling components as they appear makes the
model more intuitive to users as well as allowing
the model to be easily altered to reflect compo-
nents that might be added to the hydraulic system
at a later date. These modeled components repre-
sent the basis for a simulation library of hydraulic
components. At the lower level of each hydraulic
component is the underlying mathematics of each
component as shown in Figure 2. For instance,
the RESERVOIR of Figure 1 is governed by
the functional model shown in Figure 2. It is this
HEMTT LHS model that facilitated the devel-
opment of the hydraulic fault detection, isolation
and diagnostic reasoning for the health manage-
ment system.
iNTRODUCTION
HYDRAULIC DIAgNOSTIC
SYSTEM
HYDRAULIC SYSTEM MODEL
THE JOURNAL OF THE RELIABILITY INFORMATION ANALYSIS CENTER FIRST QUARTER - 2006
Embedded Health Management
HEMTT LHS Vehicle
Applied Research Laboratory and the RIAC
Figure 1 Dynamic HEMTT LHS Hydraulic Model
Modeling components as they appear makes the model more
intuitive to users as well as allowing the model to be easily
altered to reflect components that might be added to the
hydraulic system at a later date. These modeled components
represent the basis for a simulation library of hydraulic
components.
At the lower level of each hydraulic
component is the underlying mathematics of each
component as shown in Figure 2.
Probably the most impor
diagnostics for the HEMTT M
the diagnostics in a rigorou
vehicle validation was done o
data sets representing the span
at Penn State ARL. These
conditions available at the tes
were seeded on the vehicle
diagnostics developed when ap
5. HEALTH MANAGE
The vehicle health manageme
and software for convertin
information. An example of
the HEMTT vehicle health m
Figure 3.
Figure 3 Health Managem
Figure 1 - Dynamic HEMTT LHS Hydraulic Model
Figure 1 Dynamic HEMTT LHS Hydraulic Model
Modeling components as they appear makes the model more
intuitive to users as well as allowing the model to be easily
altered to reflect components that might be added to the
hydraulic system at a later date. These modeled components
represent the basis for a simulation library of hydraulic
components.
At the lower level of each hydraulic
component is the underlying mathematics of each
component as shown in Figure 2.
Figure 2 Reservoir System Logic and Reasoning Model
For instance, the RESERVOIR of Figure 1 is governed by
the functional model shown in Figure 2. It is this HEMTT
LHS model that facilitated the development of the hydraulic
fault detection, isolation and diagnostic reasoning for the
health management system.
4. DIAGNOSTIC DEVELOPMENT
Probably the most import
diagnostics for the HEMTT M
the diagnostics in a rigorous
vehicle validation was done o
data sets representing the span
at Penn State ARL. These
conditions available at the test
were seeded on the vehicle
diagnostics developed when ap
5. HEALTH MANAGE
The vehicle health managemen
and software for convertin
information. An example of
the HEMTT vehicle health ma
Figure 3.
Figure 3 Health Managem
The hardware architecture is b
including: sensor, data acqu
information server levels. The
the sensors installed on the h
the left side of the figure.
processing level consists of
maintenance information m
information monitor (VIM)
engine
electrical
control
Figure 2 - Reservoir System Logic and Reasoning Model
The diagnostics for the HEMTT LHS were de-
veloped and implemented in a four-step process:
1. Designing diagnostics on the simulation model
2. Checkingthemwithdatatakenfromthevehicle
3. Implementing them on the vehicle
4. Testing them on the vehicle
Indevelopingthehydraulicdiagnostics,eachcom-
ponent was examined for the effect of unmodeled
or undermodeled occurrences. This procedure
helps avoid avalanche faults (one fault lighting off
every indicator) and false positives/negatives.
Probablythemostimportantaspectindeveloping
diagnostics for the HEMTT M1120A2+ vehicle
was testing the diagnostics in a rigorous and re-
alisticmanner. On-vehiclevalidationwasdoneon
recorded data sets and live data sets representing
the span of time the HEMTT has been at Penn
State ARL. These tests represented all climatic
conditions available at the test site. Safe and pru-
dent faults were seeded on the vehicle to check
the validity of the diagnostics developed when
appropriate.
Thevehiclehealthmanagementsystemconsistsof
hardware and software for converting sensor data
into health information. An example of the hard-
ware architecture for the HEMTT vehicle health
management system is shown in Figure 3.
The hardware architecture is broken down into
threelevelsincluding:sensor,dataacquisitionand
processing, and information server levels. The
sensor level consists of all of the sensors installed
on the hydraulic system as shown on the left side
ofthefigure. Thedataacquisitionandprocessing
level consists of the Oshkosh Truck Corp main-
tenance information monitor (MIM) and vehicle
information monitor (VIM) modules, the Detroit
continued on page 22
HEALTH MANAgEMENT
ARCHITECTURE
DIAgNOSTIC DEVELOPMENT
PAGE 21
Diesel engine electrical control unit (ECU) and
Allison transmission ECU and the Penn State
ARL battery prognostic modules. Above this
layer is the vehicle information server that consists
of an on-board semi-ruggedized computer and in-
formation display, which can either be a DT-3000
truck computer or a wireless tablet. The health
informationcanalsobedisplayedoffplatformona
website operated by Penn State ARL.
The development and implementation of health
management technology to the HEMTT
M1120A2+ vehicle provides the ability to quickly
and reliably detect, diagnose and isolate faults
to specific line replaceable units (LRU), which
contributes to decreased maintenance time and
increased vehicle availability. In order to achieve
this capability the health information must be dis-
played to the operator and maintainer in a manner
that is simple, intuitive and information rich with-
out being too complex and overwhelming.
The first display is the Asset Visibility display that
is essentially a map with various vehicles repre-
sented by icons as shown in Figure 4.
This display leverages from existing Force XXI
Battle Command, Brigade-and-Below (FBCB2)
vehicle interface technology that enables Blue
Force Tracking for the U.S. Army field units.
Our intention was not to replicate this technology
but show how the health management technol-
ogy could be integrated into an existing advanced
technologythathasbeenpreviouslyimplemented.
The display shows location information for the
vehicle both graphically and with text as well as a
high level indication of vehicle sub-system health
status for the LHS hydraulics, batteries, engine
and transmission. The five sub-system indicators
willbegreyfornohealthissues,yellowforahealth
caution indication or red for a health warning
indication.
The second display is the battery display that
shows battery health information for the four ve-
continued from page 21
A Demonstration of Embedded Health Management Technology
for the HEMTT LHS Vehicle
5. HEALTH MANAGEMENT ARCHITECTURE
The vehicle health management system consists of hardware
and software for converting sensor data into health
information. An example of the hardware architecture for
the HEMTT vehicle health management system is shown in
Figure 3.
Figure 3 Health Management Hardware Architecture
The hardware architecture is broken down into three levels
including: sensor, data acquisition and processing, and
information server levels. The sensor level consists of all of
the sensors installed on the hydraulic system as shown on
the left side of the figure.
The data acquisition and
processing level consists of the Oshkosh Truck Corp
maintenance information monitor (MIM) and vehicle
information monitor (VIM) modules, the Detroit Diesel
engine
electrical
control
unit
(ECU)
and
Allison
transmission ECU and the Penn State ARL battery
prognostic modules.
Above this layer is the vehicle
information server that consists of an on-board semi-
ruggedized computer and information display, which can
either be a DT-3000 truck computer or a wireless tablet.
The health information can also be displayed off platform on
a website operated by Penn State ARL.
6. HEALTH INFORMATION DISPLAY
The development and implementation of health management
technology to the HEMTT M1120A2+ vehicle provides the
ability to quickly and reliably detect, diagnose and isolate
faults to specific line replaceable units
(LRU), which
contributes to decreased maintenance time and increased
vehicle availability. In order to achieve this capability the
Figure 3 - Health Management Hardware Architecture
health information must be displayed to the operator and
maintainer in a manner that is simple, intuitive and
information
rich
without
being
too
complex
and
overwhelming.
The first display is the Asset Visibility display that is
essentially a map with various vehicle represented by icons
as shown in Figure 4.
Figure 4 HEMTT Asset Visibility Display
This display leverages from existing Force XXI Battle
Command, Brigade-and-Below (FBCB2) vehicle interface
technology that enables Blue Force Tracking for the U.S.
Army field units. Our intention was not to replicate this
technology but show how the health management technology
could be integrated into an existing advanced technology
that has been previously implemented. The display shows
Figure 5 HEMTT Battery Health Display
The battery health page shows health information
four vehicle batteries. Each of the four smaller gau
the left side of the display shows state of charge d
each battery. The large gauge shows the system lev
of charge for all four batteries because a fault in one
can adversely affect the entire group of batteries. Bel
gauges are two battery prognostic indications includ
estimated remaining vehicle starts and the remaining a
of time that the vehicle can run on battery power (i.e.
watch) and still start the vehicle.
The state of
information on the right side of the display will indic
fault exists and whether a specific battery sho
replaced.
The third display is the engine display that shows
status information for the Detroit diesel engine as sh
Figure 4 - HEMTT Asset Visibility Display
HEALTH INFORMATION DISPLAY
THE JOURNAL OF THE RELIABILITY INFORMATION ANALYSIS CENTER FIRST QUARTER - 2006
hicle batteries as shown in Figure 5.
Each of the four smaller gauges on the left side
of the display shows state of charge data for each
battery. The large gauge shows the system level
state of charge for all four batteries because a fault
inonebatterycanadverselyaffecttheentiregroup
of batteries. Below the gauges are two battery
prognostic indications including the estimated re-
maining vehicle starts and the remaining amount
of time that the vehicle can run on battery power
(i.e., silent watch) and still start the vehicle. The
state of health information on the right side of the
display will indicate if a fault exists and whether a
specific battery should be replaced.
The third display is the engine display that shows
engine status information for the Detroit diesel
engine as shown in Figure 6. The engine gaug-
es on the left of the display show general engine
operational parameters including: engine speed,
coolant temperature, oil temperature, oil pres-
sure and remaining oil life (indication of when oil
should be changed). The lights on the right side
of the display indicate engine faults for coolant
temperature, oil temperature, oil pressure, oil life
and engine overspeed.
The fourth display is the transmission display
that shows transmission status information for
the Allison transmission as shown in Figure 7.
The transmission gauges on the left of the display
show general transmission operational param-
eters including: oil temperature and remaining
oil life (indication of when oil should be changed).
The lights on the right side of the display indicate
transmission faults for oil temperature and oil life.
The fifth display is the hydraulic display that
shows hydraulic system health information for the
load handling system as shown in Figure 8. The
hydraulic gauges on the left of the display show
general hydraulic operational parameters includ-
ing: fluid pressure, reservoir temperature, main
control manifold temperature and remaining fluid
life (indication of when fluid should be changed).
tion must be displayed to the operator and
a manner that is simple, intuitive and
ich
without
being
too
complex
and
lay is the Asset Visibility display that is
ap with various vehicle represented by icons
ure 4.
4 HEMTT Asset Visibility Display
leverages from existing Force XXI Battle
gade-and-Below (FBCB2) vehicle interface
t enables Blue Force Tracking for the U.S.
its. Our intention was not to replicate this
show how the health management technology
rated into an existing advanced technology
reviously implemented. The display shows
ation for the vehicle both graphically and
ll as a high level indication of vehicle sub-
status for the LHS hydraulics, batteries,
nsmission. The five sub-system indicators
r no health issues, yellow for a health caution
d for a health warning indication.
play is the battery display that shows battery
ion for the four vehicle batteries as shown in
Figure 5 HEMTT Battery Health Display
The battery health page shows health information for the
four vehicle batteries. Each of the four smaller gauges on
the left side of the display shows state of charge data for
each battery. The large gauge shows the system level state
of charge for all four batteries because a fault in one battery
can adversely affect the entire group of batteries. Below the
gauges are two battery prognostic indications including the
estimated remaining vehicle starts and the remaining amount
of time that the vehicle can run on battery power (i.e., silent
watch) and still start the vehicle.
The state of health
information on the right side of the display will indicate if a
fault exists and whether a specific battery should be
replaced.
The third display is the engine display that shows engine
status information for the Detroit diesel engine as shown in
Figure 6. The engine gauges on the left of the display show
general engine operational parameters including: engine
speed, coolant temperature, oil temperature, oil pressure and
remaining oil life (indication of when oil should be
changed). The lights on the right side of the display indicate
engine faults for coolant temperature, oil temperature, oil
pressure, oil life and engine overspeed.
Figure 5 - HEMTT Battery Health Display
Figure 6 - HEMTT Engine Display
3
4 HEMTT Asset Visibility Display
everages from existing Force XXI Battle
gade-and-Below (FBCB2) vehicle interface
t enables Blue Force Tracking for the U.S.
its. Our intention was not to replicate this
show how the health management technology
rated into an existing advanced technology
reviously implemented. The display shows
ation for the vehicle both graphically and
ll as a high level indication of vehicle sub-
status for the LHS hydraulics, batteries,
nsmission. The five sub-system indicators
no health issues, yellow for a health caution
d for a health warning indication.
play is the battery display that shows battery
ion for the four vehicle batteries as shown in
four vehicle batteries. Each of the four smaller gauges on
the left side of the display shows state of charge data for
each battery. The large gauge shows the system level state
of charge for all four batteries because a fault in one battery
can adversely affect the entire group of batteries. Below the
gauges are two battery prognostic indications including the
estimated remaining vehicle starts and the remaining amount
of time that the vehicle can run on battery power (i.e., silent
watch) and still start the vehicle.
The state of health
information on the right side of the display will indicate if a
fault exists and whether a specific battery should be
replaced.
The third display is the engine display that shows engine
status information for the Detroit diesel engine as shown in
Figure 6. The engine gauges on the left of the display show
general engine operational parameters including: engine
speed, coolant temperature, oil temperature, oil pressure and
remaining oil life (indication of when oil should be
changed). The lights on the right side of the display indicate
engine faults for coolant temperature, oil temperature, oil
pressure, oil life and engine overspeed.
continued on page 24
Figure 7 - HEMTT Transmission Display
Figure 6 HEMTT Engine Display
The fourth display is the transmission display that shows
transmission status information for the Allison transmission
as shown in Figure 7. The transmission gauges on the left of
the
display
show
general
transmission
operational
parameters including: oil temperature and remaining oil life
(indication of when oil should be changed). The lights on
the right side of the display indicate transmission faults for
oil temperature and oil life.
Figure 7 HEMTT Transmission Display
The fifth display is the hydraulic display that shows
hydraulic system health information for the load handling
system as shown in Figure 8. The hydraulic gauges on the
Figure 8 HEMTT LHS
The sixth display is the
shows hydraulic system
handling system as shown
The schematic display pro
vehicle LHS hydraulic sy
interactive and it display
(i.e. pumps, manifolds, ra
system but it also shows t
components during LHS
the user to look at the r
temperature or levels se
unload cycles. This facili
the system functions
interrogation and trouble
PAGE 2
continued from page 23
The lights on the right side of the display indicate
hydraulic faults for pump failure, oil temperature,
reservoir level, sensor failure, lift overload, high
pressure filter, return filter, relief valve, low pump
pressure, primary, secondary and tertiary hydrau-
lic loop faults, proximity probe 1,2 or 3 faults and a
main control manifold fault. These fault indicator
lights allow for the diagnosis and localization of a
fault to a specific LRU on the vehicle. All of these
hydraulicfaultindicatorsweredevelopedwiththe
use of the hydraulic model by Penn State ARL
The sixth display is the hydraulic schematic dis-
play that shows hydraulic system functional dy-
namics for the load handling system as shown in
Figure 9.
The schematic display provides a functional over-
view of the vehicle LHS hydraulic system. This
display is dynamic and interactive and it displays
not only all of the components (i.e. pumps, mani-
folds, ram cylinders, etc,) of the hydraulic system
but it also shows the dynamic fluid flow between
thecomponentsduringLHSoperation. Thisdis-
playallowsfortheusertolookattherawdatafrom
any of the pressure, temperature or levels sensors
from the previous load or unload cycles. This fa-
cilitates a better understanding of how the system
functionsandalsoallowsformanualinterrogation
and troubleshooting of the hydraulics by a system
level expert. This display would be very useful to
the original equipment manufactures (OEM) as a
field service tool and also at the school house for
training on the operation and maintenance of the
system.
The final display is the vehicle status display that
shows the location of faults for the hydraulic,
battery, engine and transmission sub-systems as
shown in Figure 10.
In an effort to keep the interface graphical, intui-
tive and not overly complex, a 3-D CAD model of
the Oshkosh palletized load system (PLS) truck
was acquired because a model of the LHS truck
was not available. The PLS truck model was
modified to match the LHS truck for this display.
This provided us with a way to show the location
Figure 8 - HEMTT LHS Hydraulic System Health Display
Figure 8 HEMTT LHS Hydraulic System Health Display
The sixth display is the hydraulic schematic display that
shows hydraulic system functional dynamics for the load
handling system as shown in Figure 9.
The schematic display provides a functional overview of the
vehicle LHS hydraulic system. This display is dynamic and
interactive and it displays not only all of the components
(i.e. pumps, manifolds, ram cylinders, etc,) of the hydraulic
system but it also shows the dynamic fluid flow between the
components during LHS operation. This display allows for
the user to look at the raw data from any of the pressure,
temperature or levels sensors from the previous load or
unload cycles. This facilitates a better understanding of how
the system functions and also allows for manual
interrogation and troubleshooting of the hydraulics by a
system level expert. This display would be very useful to
the original equipment manufactures (OEM) as a field
service tool and also at the school house for training on the
operation and maintenance of the system.
4
Figure 8 HEMTT LHS Hydraulic System Health Display
The sixth display is the hydraulic schematic display that
shows hydraulic system functional dynamics for the load
handling system as shown in Figure 9.
The schematic display provides a functional overview of the
vehicle LHS hydraulic system. This display is dynamic and
interactive and it displays not only all of the components
(i.e. pumps, manifolds, ram cylinders, etc,) of the hydraulic
system but it also shows the dynamic fluid flow between the
components during LHS operation. This display allows for
the user to look at the raw data from any of the pressure,
temperature or levels sensors from the previous load or
unload cycles. This facilitates a better understanding of how
the system functions and also allows for manual
interrogation and troubleshooting of the hydraulics by a
system level expert. This display would be very useful to
the original equipment manufactures (OEM) as a field
service tool and also at the school house for training on the
operation and maintenance of the system.
Figure 9 HEMTT LHS Hydraulic System Schematic
Display
Figure 9 - HEMTT LHS Hydraulic System Schematic Display
A Demonstration of Embedded Health Management Technology
for the HEMTT LHS Vehicle
THE JOURNAL OF THE RELIABILITY INFORMATION ANALYSIS CENTER FIRST QUARTER - 2006
of LRU faults in the most straightforward way
possible. The vehicle display provides a simple
and graphic display for showing the location of
LRU faults. This allows the maintainer to quick-
ly apply maintenance to the correct component,
where maintenance is needed. This display is also
dynamic in that the vehicle can be rotated to dif-
ferentviewsthatbestshowsaspecificcomponent.
The fault component can also been shown with
an animated zoom view to show the details of the
component.
The objective of this project was to design, devel-
op and implement prototype health management
technologytoprovidethecapabilitytofacilitateef-
ficientandeffectivemaintenanceontheHEMTT
M1120A2+ vehicle. During this project, a strong
emphasis was placed on the creation of actionable
the vehicle can be rotated to different views that best shows
a specific component. The fault component can also been
shown with an animated zoom view to show the details of
the component.
Figure 10 HEMTT Vehicle Health Display
.
8. CONCLUSIONS
The objective of this project was to design, develop and
implement prototype health management technology to
provide the capability to facilitate efficient and effective
maintenance on the HEMTT M1120A2+ vehicle. During
this project, a strong emphasis was placed on the creation of
actionable health information from the vehicle raw sensor
data and on the development of an intuitive and information
rich graphical user display.
This HEMTT M1120A2+ vehicle will serve as a platform
for showing how the health management technology can be
integrated into the vehicle to provide diagnostic and
prognostic information to operator and maintainers. It also
helps to create the `vision' for the implementation of health
management technology for legacy and future ground
vehicles. When the health information is put in the hands of
Figure 10 - HEMTT Vehicle Health Display
health information from the vehicle raw sensor
data and on the development of an intuitive and
information rich graphical user display.
This HEMTT M1120A2+ vehicle will serve as a
platformforshowinghowthehealthmanagement
technology can be integrated into the vehicle to
provide diagnostic and prognostic information to
operator and maintainers. It also helps to create
the `vision' for the implementation of health man-
agement technology for legacy and future ground
vehicles. When the health information is put in
thehandsofthewarfighter,inaformatthatiseasy
to understand, they can become more effective
and efficient in their critical jobs as operators and
maintainers.
This work was supported by PM Heavy at tank
automotivecommand(TACOM)underContract
Number N00024-02-D-6604. The content of the
information does not necessarily reflect the posi-
tion or policy of the Government, and no official
endorsement should be inferred.
CONCLUSIONS
ACKNOWLEDgEMENTS
PAGE 2
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