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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
OBD & NOx anti-tampering system architecture
experiences & lessons learned
BRACE Automotive
Marcel Romijn
Competences coordinator
OBD & Emission specialist
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Introduction
o
Often overlooked are consequences of OBD and NOx anti-tampering legislations to system
architectures.
o
Also how unclear boundaries of the OBD system can generate problems.
o
Even more valid for heavy-duty on- and off-highway.
o
This presentation aims to discuss these potential problems and the lessons to learned.
Agenda:
o
Vehicle Diagnostics overview
o
Legislation requirements impacting system architecture
o
Diagnostic Master & Slave
o
Use of “off-the-shelf” smart sensors & actuators from suppliers
o
Architecture consequences on legislation compliance, required service information &
emissions warranty
o
Concluding
2
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Vehicle Diagnostics overview
Engine
• OBD (emissions)
• NOx inducements
• (EGAS) Functional Safety
• Safety (e.g. fire risk)
• Service
Transmission
• OBD (emissions)
• Functional Safety
• Service
Driver assistence systems
• Functional Safety
• Service
Comfort systems
• Functional Safety
• Service
Brakes & Vehicle dynamics
• Functional Safety
• Service
Supplier to Vehicle OEM  OEM is the responsible coordinator
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Vehicle Diagnostics overview
Engine (by Engine OEM)
Driver assistence systems
•
•
•
•
•
•
•
OBD (emissions)
NOx inducements
(EGAS) Functional Safety
Safety (e.g. fire risk)
Service
Comfort systems
•
•
Functional Safety
Service
Functional Safety
Service
“Work” application (by Bodybuilder)
•
•
Functional Safety
Service
Brakes & Vehicle dynamics (by supplier)
Transmission (by supplier)
•
•
Functional Safety
Service
•
•
Functional Safety
Service
Engine OEM & suppliers to Vehicle OEM to Bodybuilder  Responsible coordinator?
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5
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Vehicle Diagnostics overview
Engine (by Engine OEM)
•
•
•
•
•
OBD (emissions)?
NOx inducements
(EGAS) Functional Safety
Safety (e.g. fire risk)
Service
Comfort systems (by supplier)
•
•
Functional Safety
Service
Transmission (by supplier)
“Work” application
•
•
•
•
Functional Safety
Service
Driver assistence systems
•
•
Functional Safety
Service
Functional Safety
Service
Brakes & Vehicle dynamics (by
supplier)
•
•
Functional Safety
Service
Engine OEM & suppliers to Machine OEM  Responsible coordinator?
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Legislation requirements impacting system architecture
Concept of OBD & Emissions domain
o
Concept to clarify the legal requirements
o
Legislation requirements can define the
domain
o
Engine & Aftertreatment are always in
o
An engine-dyno certification means
transmission is not part of the domain
o
Hybrids are a difficult exemption
o
Special domains, responsibilites &
certification procedures for Hybrids
o
OBD & NOx warning system may be part of
domain
o
Engine
o
Driver interface (warnings)
o
Transmission
o
Aftertreatment
6
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Legislation requirements impacting system architecture
Concept of OBD & Emissions domain
o
US legislation is very strict, while EU & others only so-so
o
Any input to an OBD diagnostic = OBD & Emissions domain
E.g. switch off Misfire diagnostic with low fuel tank level or when Traction Control (via CAN)
requests torque limitation
o
Signals to domain
X
Domain
Any input to Emissions controls = OBD & Emissions domain
E.g. adapt EGR rate on Ambient temperature or the vehicle air pressure system as actuating
medium for Urea injector
X
Commands from domain
o
Any system/component possibly impacting emissions or OBD =
OBD & Emissions domain
E.g. Arctic Start Ether Support System, Wait-to-Start or Glow-plug light Systems,
Start-Stop, Cooling Systems, Driver modes (ECO, Sport), Cruise Controls
Arctic Ether start
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Legislation requirements impacting system architecture
Signals to domain
When inside the OBD & Emissions domain
o
X
Full-blown OBD monitoring on sensor signals
E.g. Electrical, Ranges, Plausibility, CAN-bus
o
Full-blown OBD monitoring on actuators & commands
Domain
E.g. Electrical, Commands Response (whole actuator system), CAN-bus
o
Possibility of being a DECECU (Diagnostic or Emission Critical ECU)
E.g. ECU OBD monitoring (Processor, Memory, Supply Voltage), Support CAL-ID (SW and Cal.
part number) & CVN (SW and Cal. verification calculation)
X
Commands from domain
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Diagnostic Masters & Slaves
Many control units possibly in OBD & Emissions domain
o
Should they all communicate individually to OBD Scantool?
o
Should they all keep their own storage of faultcodes and related information?
Ambient
air T
ABS Vehicle
speed
PM sensor
Aftertreatment
ECU
Driver
interface
Glow plug
control
Engine ECU
Cooling fan
EGR valve
Urea pump
NH3 sensor
VGT
actuator
OBD
Scantool
NOx sensor
Swirl valves
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Diagnostic Masters & Slaves
o
Typically one or two Diagnostic Masters are assigned
o
Responsible for all fault code storages
-No synchronization needed for drive cycle definitions start/end & other cycles
-Prevent “stack-up” of fault codes by the same problem source
-Easy to allocate system overall diagnostics that monitor over several ECU’s functions
o
Supports all scan tool communication
o
Smart gateway
Experience: ~80 CAN messages
total for SAE J1939 scantool
E.g. Collects, stores, and updates CAL-ID/CVN’s, Smart gateway for Mode6 OBD, groups similar diagnostics under one monitor,
aligns and combines all info for Readiness and Monitor status, and aligns EI-AECD counters with NTE area reporting
o
Responsible for commands to driver interface
o
Requires lots of interface agreements; some of which do not fit in with current standards
o
Requires OBD expertise & preferably develop this only once!
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Diagnostic Masters & Slaves
Placement of diagnostics based on diagnostic levels and information need
System
interpretation of
sensor value
Environment in
which the sensor
measures
Electrical circuit
of the component
System
Plausibility
Range
Electrical
“Does the whole system act as it should?”
“Does the value make any sense?”
Exceeding normal measurement range; in unit of the sensor
Short/Open circuits; usually all the Volt, Amps, Ohms things
Every diagnostic needs information
Look at the source of the information
The “monitored value” and enabling conditions
No point in sending “engine speed” data to a NOx sensor, rules out the
possibility of diagnostics that require “engine speed” based enabling to be
founded in NOx sensor.
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Use of “off-the-shelf” smart
sensors/actuators from suppliers
Typical Heavy-Duty Diesels = large amount off-the-shelf parts
o
Economy-of-scales cost reduction reasons
o
Makes diagnostic responsibility a multi-company task
o
Many (sub)suppliers have little knowledge about i.e. OBD & NOx anti-tampering
o
Purchasing contracts often not technically deep enough
o
Lack of important details or even requesting only “OBD compliance” as a generic term
o
Makes all the ingredients for a disastrous development project!
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Use of “off-the-shelf” smart
sensors/actuators from suppliers
False PASS scenario with off-the-shelf part based on real-life experience
o
Smart valve (i.e. EGR) based on stepper-motor & butterfly valve; internally diagnosed for stuck
butterfly valve by means of internal control error
o
CAN communication consisted of 1 bit per internal fault.
If bit = FALSE; Then PASS status to fault code storage & scan tool info
If bit = TRUE; Then FAIL status set to fault code storage & scan tool info
o
Now ask yourselves; what is a scenario of a stuck valve?
Say the valve can not move to more than 50% opening due to blockage
Valve works fine below 50% opening
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Use of “off-the-shelf” smart
sensors/actuators from suppliers
Be
ingenious
Let’s imagine how does the diagnostic react?
Engine
Start / Running
FALSE PASS!
PASS
CAN bit =
FALSE
Yes
Set
point<
50%
No
CAN bit =
TRUE
o
First at start setpoint = 0; so PASS is set
o
Later during engine running setpoint = >50%; so FAIL is set
o
Fault is now self-healed at every engine start or when setpoint is <50%
FAIL
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Use of “off-the-shelf” smart
sensors/actuators from suppliers
False PASS issues with off-the-shelf parts; a real life experience cont’d:
o
Two solutions investigated:
1) Blame the new-to-OBD (sub)supplier: Modify the internal diagnostic by adding enabling conditions
2) Let the OBD engineers fix it: Don’t forward directly the (sub)suppliers internal status to fault handling
o
With 1, the supplier needed to wait for diagnosing unless the setpoint was at higher level
What to do with the 1 bit fault reporting in CAN? When not TRUE is that a PASS or just a “Don’t know yet”?
o
With 2, make the OBD master handle the waiting for diagnosing until a relevant setpoint
In the meantime ignore whatever the smart valve was sending in fault reporting
o
This experience has come again and again in many situations and systems
Even outside OBD such as Safety related diagnostics
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Use of “off-the-shelf” smart
sensors/actuators from suppliers
DECECU (Diagnostic or Emission Critical ECU) in USA:
o
Check up-to-date legislation  boundary between “component” and “ECU”
o
Typical example: more then 2 Components (e.g. Sensors)  DECECU
o
Example: Smart valve
Components: Stepper motor (actuator), position sensor, and PCB electrical circuits temperature sensor (overheat protection)
o
Usually only first two used; thus not a DECECU
o
However, PCB temperature sensor can also be used by OBD master in assisting e.g. Engine Coolant
Temperature plausibility check
o
Now all three are used and therefore DECECU
o
Special Note:
The same component can be a DECECU in one application and not be a DECECU in another application
Makes for interesting discussions between OEMs, suppliers and sub-suppliers!
16
CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Architecture consequences on legislation compliance,
required service information, and emissions warranty
What are the consequences if we end up with a compliancy disaster?
o
False PASS or no-detections give rise to problems with legislator in USA
Many of these are found in required tests on series-production vehicles either performed by OEM or performed by legislator
o
False FAIL or non-existent failures give rise to problems with customers
Legislator is unhappy too because it generates a “bad image” regarding required OBD & NO x anti-tampering systems
o
Possible consequences
1. (Forced) recall & warranty costs
2. Exposure in news; (i.e. http://www.epa.gov/otaq/cert/eng-recall/recall.htm or http://www.nhtsa.gov/Vehicle+Safety/Recalls+&+Defects)
3. Possibly fines
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Architecture consequences on legislation compliance,
required service information, and emissions warranty
Emissions related warranty; an USA thing:
o
For items in the Emissions & OBD domain an extended warranty is required
Can last up to 10 years and depending on vehicle type varies from 180.000km to 750.000km
o
All warranty repairs must be reported to legislator; regardless of repairer
o
When a certain % of vehicles has gotten the same warranty repair  forced recall
o
A DECECU has a longer warranty term than a component
o
Thus domain creation can be driven by potential warranty costs and recalls
Many OEMs have a list of no-go signals as the associated sensor would be too expensive in warranty claims
Same component in a different application can make the difference of a 3 years B10 vs. a 10 year B1 reliability demand
o
Components that cannot comply may become maintenance items (e.g. NOx sensors)
Set a maintenance term on when to replace most of the components before they are broken
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Architecture consequences on legislation compliance,
required service information, and emissions warranty
Information exchange
o
A lot of information must be disclosed about the workings of Emissions system and OBD
During type-approval application and during the vehicle lifetime on a publicly available Service Information website
o
Includes also info from the off-the-shelf components internal workings
Again; great fun in discussions between OEMs, suppliers and sub-suppliers
o
Some examples of the public available information:
Detroit Diesel: https://ddcsn-ddc.freightliner.com/cps/rde/xchg/ddcsn/hs/5712.htm
Ford (incl. Heavy-duty): https://www.motorcraftservice.com/vdirs/retail/default.asp?pageid=diag_theory_retail&gutsid=diagsheet&menuIndex1=10
General Motors: https://service.gm.com/gmspo/mode6/index.html
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CTI 3rd International Conference Heavy-Duty Diesel Diagnostics – 9th October 2014
Be
ingenious
Concluding
OBD, NOx anti-tampering & other diagnostics are always challenging
o
Usage in Heavy-duty domain adds more challenges
o
Understanding responsibilities throughout the vehicle/machine is key
o
Create boundaries with clear and limited I/O interfaces
o
Just sourcing components already requires focus on many items unknown to many outsiders
o
Things that seem not important or were never important before can have the biggest financial impact
o
Knowledgeable (sub)suppliers can be of great help
o
(Sub)suppliers that are unaware can however create a nightmare scenario
o
(Sub)suppliers need to be prepared to see very different demands of their products depending on
application
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Be
ingenious
Questions?
www.brace-automotive.com
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