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A DaimlerChrysler Company
Model-Based Transient Calibration Optimization
for Next Generation Diesel Engines
Chris Atkinson, Atkinson LLCand
Marc Allain & Craig Savonen,Detroit Diesel Corporation
August 200511th Annual Diesel Engine Emissions Reduction (DEER) Conference
©2005 Detroit Diesel Corporation. All Rights Reserved. 211th Annual DEER Conference August 2005
Presentation Topics
Diesel Engine Technology Trends Calibration RequirementsModel-Based Calibration Transient Engine Model DevelopmentRapid Transient Calibration OptimizationResultsModel-Based Control and DiagnosticsSummary
©2005 Detroit Diesel Corporation. All Rights Reserved. 311th Annual DEER Conference August 2005
Diesel Engine Technology Trends
Ever Decreasing Emissions RequirementsEver Increasing Fuel Economy DemandsIncreasing Mechanical and Electronic Complexity of EnginesCost Reduction DemandsReduced Product Engineering Development CyclesIncreasing Demands on Transient Test Facilities
©2005 Detroit Diesel Corporation. All Rights Reserved. 411th Annual DEER Conference August 2005
Technical Challenges
Rapidly Increasing Complexity of Engine ControlIntegration of Aftertreatment ControlNew Low Temperature Combustion RegimesEmissions Testing – FTP, In-Use, NTE435,000 Mile Useful Life RequirementsHD OBD Requirements
All Of These Lead To A Significantly Increased Calibration Burden.
©2005 Detroit Diesel Corporation. All Rights Reserved. 511th Annual DEER Conference August 2005
Diesel Engine ComplexityYear Engine Technologies Number of Calibrateable
Parameters1998 Injection Timing 3
Injection Pressure2004 Injection Timing 4 - 5
Injection PressureEGRTurbocharging Control
2007+ Injection Timing (multiple) 11 - 15+Injection PressureEGRTurbocharging Control Aftertreatment Control
©2005 Detroit Diesel Corporation. All Rights Reserved. 611th Annual DEER Conference August 2005
Increasing Calibration Complexity
YEAR Actuators Sensors Control Outputs
1998 2 8 32002 4 10 32004 8 15 52007 10 19 112010 12 22 15
©2005 Detroit Diesel Corporation. All Rights Reserved. 711th Annual DEER Conference August 2005
Full Factorial Calibration Space
Year Engine Control Parameters Number of Discrete Test Setpoints
1998 Speed, Load, Injection Timing & Pressure 10,0002002 Speed, Load, Injection Timing & Pressure, EGR 100,0002004 Speed, Load, Injection Timing & Pressure,
EGR, Turbocharging Control1,000,000
2007 Speed, Load, Multiple Injection Timing, Injection Pressure, EGR, Turbocharging Control, Particulate Filter Regeneration
1,000,000,000
2010 Speed, Load, Multiple Injection Timing, Injection Pressure, EGR, Turbocharging Control, Aftertreatment Controls
10,000,000,000
©2005 Detroit Diesel Corporation. All Rights Reserved. 811th Annual DEER Conference August 2005
The Challenge for Calibration
The Curse of Dimensionality – a 2007 specification diesel engine might have 109 test points if tested in a full factorial experimentCalibration requirements may increase by 2-3 orders of magnitude by 2010-2014 due to new engine technologiesDesign of Experiments can reduce the overall engine mapping burden significantly (perhaps by a factor of 100), but this still results in huge experimental matricesAnd, steady state engine mapping not well suited to
TRANSIENT emissions regulations, fuel economy reduction, driveability and aftertreatment regeneration.
©2005 Detroit Diesel Corporation. All Rights Reserved. 911th Annual DEER Conference August 2005
Steady-State Degrees of Freedom
Tailpipe-outNOxPMHCCO
Engine-outNOx / PM / HC / CO
Catalystefficiency
Engine-outNOxPMHCCO
Fuelingconditions
Intake charge
Intakecharge
Fresh air
EGRrate
Fuelingconditions
Quantity
Timing
Fuelingconditions
Rate shape
Pressure
Catalystefficiency
Operatingtemperature
Duty cycle
Steady-State Calibration Is handled adequately through widely accepted Design of Experiment (DoE) Methods
©2005 Detroit Diesel Corporation. All Rights Reserved. 1011th Annual DEER Conference August 2005
Steady-State Performance Mapping
BSFCBSFCBSFCBSFC
NO
xN
Ox
NO
xN
Ox
For Steady-State Calibration, Static Engine Performance Mapping Is Sufficient
Time-Consuming Process
Results Not Directly Applicable to Transient Calibration
©2005 Detroit Diesel Corporation. All Rights Reserved. 1111th Annual DEER Conference August 2005
Transient Degrees of Freedom
Tailpipe-outNOx / PM / HC / CO
Engine-outNOx / PM / HC / CO
Catalystefficiency
Engine-outNOx / PM / HC / CO
Fuelingconditions
Intake charge
Intakecharge
Fresh air
EGRrate
Fuelingconditions
Quantity
Timing
Fuelingconditions
Rate shape
Pressure
Catalystefficiency
Operatingtemperature
Duty cycle
Time
Time
Time
Time
Time
Time
Transient Engine Calibration must account for an additional Degree of Freedom: Time
©2005 Detroit Diesel Corporation. All Rights Reserved. 1211th Annual DEER Conference August 2005
Competing & Overlapping Time Scales
Closed-loop response
Time - sec
Time - sec Time - sec
Time - sec
VGT
EGR Rate
NOx Aftertreatment
DPF InletTemperature Control
Common RailPressure
Time - sec
Boost Control
Step Response Of Individual Engine Systems
Orders of Magnitude Difference in Transient Response
Including Time as an integral part of the Setpoint Definition Process enables optimum Transient Calibration
Transient Engine Performance Mapping corresponds to a Transient Design Of Experiment
©2005 Detroit Diesel Corporation. All Rights Reserved. 1311th Annual DEER Conference August 2005
Engine Operating Modes
Calibration Requirements are increased further due to Multiple Engine Operating Modes including
Steady-stateTransientColdAltitudeSmoke ControlAftertreatment Regeneration
(predominantly transient or dynamic phenomena)and varying ambient or exhaust conditions
©2005 Detroit Diesel Corporation. All Rights Reserved. 1411th Annual DEER Conference August 2005
Model-Based Calibration
Problem: How can engine calibration be performed quicker, better
and cheaper?
Solution: Transfer the majority of the calibration burden out of the
Engine Test Cell and onto the engineer’s desktop, using
MODEL-BASED Rapid Transient Calibration Methods.
©2005 Detroit Diesel Corporation. All Rights Reserved. 1511th Annual DEER Conference August 2005
Model-Based Methods
A definition of model-based methods, relevant to engine calibration, is
“a combination of first principles, equation-based modeling and data-based techniques used to develop high fidelity, real-time dynamic models, suitable for predicting engine emissions, performance and operating states over highly transient operating cycles”.
©2005 Detroit Diesel Corporation. All Rights Reserved. 1611th Annual DEER Conference August 2005
Modeling Approach
Dynamic (transient) models use a combination ofPhysical Modeling
First principlesEquation-basedPhenomenological
Heuristic ModelingData-drivenLearningData from actual engine operation (real time emissions, performance, fuel consumption and operating states).
©2005 Detroit Diesel Corporation. All Rights Reserved. 1711th Annual DEER Conference August 2005
Example of a Transient Engine Model
Composite Model made up of Interacting Sub-models:Air Flow Model
Volumetric EfficiencyEGR Flow Model
Charge EstimationFuel Injection and Combustion Model
Air-Fuel Ratio EstimationThermal EffectsNOx and PM Formation Sub-models
©2005 Detroit Diesel Corporation. All Rights Reserved. 1811th Annual DEER Conference August 2005
COMMANDSdriver input
or driving cycle
Equation-Basedand Data-Driven
Engine Model
Transient Model Development
Engine Control Unit(ECU) Engine
∑+
–
COMMANDS
Dynamic cycle speed and load
requirements
Engine Control Unit(ECU)
Calibration Maps and Lookup Tables
ACTUALOUTPUTSEmissions
PerformanceFuel Economy
PREDICTEDOUTPUTSEmissions
PerformanceFuel Economy
Map and Lookup TablePerturbations usingRapid Prototyping
Engine Control System
©2005 Detroit Diesel Corporation. All Rights Reserved. 1911th Annual DEER Conference August 2005
Diesel Engine Modeling
Equation-Basedand
Data-DrivenEngine Model
INPUTS
Engine SpeedFuel Injection Quantity
Injection TimingInjection Pressure
Exhaust Gas RecirculationVariable Geometry Turbocharger Setting
OUTPUTSTorque
Emissions•HC•CO•NOx•CO2•PM
Exhaust TemperatureExhaust Pressure
Turbo SpeedCombustion Pressure
Direct Injection Diesel Engine
©2005 Detroit Diesel Corporation. All Rights Reserved. 2011th Annual DEER Conference August 2005
Transient Design Of Experiment
BTRQNOxHCCOPM
RPMFresh air setpointEGR setpointInjection parameters(timing & pressure)
Offline Equation and Data-based Transient Engine
Model
Transient Engine Model
BTRQNOxHCCOPMBSFC
Optimization scheme
RPMFueling rateFresh air setpointEGR setpointInjection parameters(timing & pressure)
Air
EGR
Inj.
©2005 Detroit Diesel Corporation. All Rights Reserved. 2111th Annual DEER Conference August 2005
Transient Engine Test Cycles
Transient Engine Test Cycle
-250
250
750
1250
1750
2250
0 200 400 600 800 1000
Time (s)
Engi
ne S
peed
(rpm
) and
Tor
que
(Nm
)
©2005 Detroit Diesel Corporation. All Rights Reserved. 2211th Annual DEER Conference August 2005
Transient Engine Modeling Results -Torque
©2005 Detroit Diesel Corporation. All Rights Reserved. 2311th Annual DEER Conference August 2005
Transient Engine Modeling Results -NOx
NO
x
Time
©2005 Detroit Diesel Corporation. All Rights Reserved. 2411th Annual DEER Conference August 2005
Typical Model Emissions Prediction Accuracy
NOx, CO2 (instantaneous) 2-5%
CO, HC (instantaneous) 5-10%
PM (instantaneous) 5-10%
NOx, CO2 (integrated) 2-3%
CO, HC (integrated) 3-5%
PM (integrated) 5-6%
Fuel consumption 1-3%
©2005 Detroit Diesel Corporation. All Rights Reserved. 2511th Annual DEER Conference August 2005
Rapid Transient Calibration Optimization
Equation-Based and Data-Driven
Engine Model
PREDICTEDOUTPUTSEmissions
PerformanceFuel Economy
CalibrationOptimizer
COMMANDSEngine cycle
dynamicrequirements
Engine Control Unit(ECU)
Calibration Maps and Lookup Tables
©2005 Detroit Diesel Corporation. All Rights Reserved. 2611th Annual DEER Conference August 2005
Transient Calibration Optimization Functions
Cost function – minimize fuel consumption,Subject to the constraint of meeting NOx and PM emissions integrated across a transient cycle,While not exceeding certain engine operating state parameter levels, such as turbocharger speed, peak cylinder pressure and peak injection pressure,While also meeting NTE emissions levels.
©2005 Detroit Diesel Corporation. All Rights Reserved. 2711th Annual DEER Conference August 2005
Model-Based Technologies under Development
Closed-LoopControlSensors
Actuators
Non-LinearControl
Virtual Sensors
On-BoardAdaptation Diagnostics
Calibration Optimization
AutomatedCode Generation
Rapid ControlPrototyping
FuelEconomy
Cost
StabilityTransientResponse
DevelopmentTime
OfflineDevelopment
Fuzzy Logic
Neural-Net Control
PredictiveControl
EmissionsReduction
©2005 Detroit Diesel Corporation. All Rights Reserved. 2811th Annual DEER Conference August 2005
Model-Based Control Components
SetpointDefinition
ActuatorsSensorsControllers:FuelAirEGRAftertreatmentDiagnostics
Adaptation
ObserverModels
Setpoint Definition Modules (i.e. Calibration) Are Becoming Increasingly Dominant Within The Overall Engine Control Scheme
©2005 Detroit Diesel Corporation. All Rights Reserved. 2911th Annual DEER Conference August 2005
SummaryModel-based methods can transfer a significant portion of the engine calibration burden from the test cell to the desktop Transient engine models are the technology required to meet the transient emissions regulations and operating requirementsA combined equation-based and data-driven engine modeling approach offers high model fidelity and predictive capabilityCalibration optimization is well suited to the computational environmentAs engine mechanical and electronic complexity increases, so these methods will become more important and useful.
©2005 Detroit Diesel Corporation. All Rights Reserved. 3011th Annual DEER Conference August 2005
Acknowledgements• U.S. Department of Energy
• Gurpreet Singh• Roland Gravel
• National Energy Technology Laboratory• Carl Maronde• Jeffrey Kooser
• Detroit Diesel Corporation• Kuno Flathmann• Ping Ge• Min Sun
• Atkinson LLC•Greg Mott