Vehicle Simulation for Engine Calibration to Enhance RDE Performance

Vehicle Simulation for Engine Calibration to Enhance RDE Performance IPG Apply & Innovate 2018 11st and 12nd of September, Karlsruhe, Germany Dr. Yutaka Murata Yui Nishio Dr. Yukihisa Yamaya Masato Kikuchi Honda R&D Co., Ltd. Automotive R&D Center 1

Contents Background Concept of model based simulation environment Vehicle simulation model - Vehicle model - Driver model - Route model - Traffic model Application results in RDE-compliant powertrain development Summary 2

New Civic diesel Fuel economy (CO 2 ) Modified NEDC 1.6L diesel engine 91 g/km (6MT, Sedan) 93 g/km (6MT, Hachback) 109 g/km (9AT) Exhaust emissions Euro6d-TEMP Civic 3 Passed RDE regulation and achieved 91 g/km

RDE definition Chassis dynamometer RDE Vehicle speed profile Fixed Depends on vehicle, driver, route, and traffic Environment (Ta, Pa) Fixed Depends on season, weather, wind, and altitude Road load force Straight, w/o gradient (w/o PEMS) Repeatability with w/o Depends on curves, altitude, road surface, passengers, and baggage (with PEMS) 4 Difficulty to check RDE performance at all conditions during development

Method for RDE simulation and calibration Validation in real world Tests on road Chassis dynamometer (vehicle) + vehicle simulation Engine test bed (engine) + vehicle simulation EiL (Engine in the loop) Easy to simulate and calibrate Model (engine) + vehicle simulation MiL (Model in the loop) PEMS Vehicle simulation: consideration of road load force change due to curves, altitude, road surface (weather, wind), driver behavior, and traffic conditions 5 Necessity of model utilization for efficient development

Contents Background Concept of model based simulation environment Vehicle simulation model - Vehicle model - Driver model - Route model - Traffic model Application results for RDE compliant powertrain development Summary 6

Engine calibration timeline RDE-compliant engine development method First engine First vehicle Engine hardware fix Engine software fix Validation phase SOP Engine bench tests (EiL: Engine in the loop) Vehicle tests on road with PEMS Vehicle tests in (environmental) chassis dynamometer Vehicle model (virtual) Target vehicle speed - Fixed (NEDC, WLTC, etc) profile - Vehicle simulation output profile Model based simulation (MiL: Model in the loop) Engine simulation environment - ECU model - Combustion model - Catalyst model Vehicle simulation environment - Vehicle model - Driver model - Route model - Traffic model Vehicle simulation for engine hardware/calibration fix and RDE validation 7

Flowchart of model utilization Vehicle simulation simulation (NEDC, WLTC, RDE) Vehicle model Driver model Route model Traffic model Ne, Te, etc. Experiment definition Boundary finder Dynamic DoE Transient measurement (environmental engine bench) Dynamic statistical combustion model Engine simulation ECU model Catalyst model Synthetic gas flow test bed Calibration target Base maps, environmental corrections, controllers, aftertreatment control etc. Simulation and optimization Verification Vehicle test Coupling of vehicle simulation and engine simulation 8

gfuel (g/s) Soot (mg/s) NOx (mg/s) Vehicle speed Predictive accuracy of engine model Urban Rural Motorway NOx (mg/s) Measurement Simulation Engine outlet Tailpipe Soot (mg/s) Measurement Simulation Model input: engine speed, brake torque, coolant temp., ambient temp., and ambient pressure gfuel (g/s) Measurement Simulation 9 Achievement of quantitative emissions prediction at RDE

Contents Background Concept of model based simulation environment Vehicle simulation model - Vehicle model - Driver model - Route model - Traffic model Application results in RDE-compliant powertrain development Summary 10

Coasting time (sec) Road load force (N) Road load force of vehicle model Model input: Vehicle specification (F0, F1, F2) Vehicle simulation Vehicle simulation Vehicle speed (km/h) Vehicle speed (km/h) 11 Confirmation of the road load force accuracy by coasting simulation

Predictive accuracy of NEDC simulation Measurement Vehicle simulation. Target vehicle speed Simulated vehicle speed Upper limit Lower limit Model input: Vehicle specification (F0, F1, F2) Target vehicle speed and gear shift profile. Measurement Vehicle simulation 12 Engine speed and torque are well simulated (gear shift profile is given)

Predictive accuracy of WLTC simulation Measurement Vehicle simulation. Target vehicle speed Simulated vehicle speed Upper limit Lower limit Model input: Vehicle specification (F0, F1, F2) Target vehicle speed profile. Measurement Vehicle simulation 13 Engine speed and torque are well simulated (gear shift position is calculated)

Statistical analysis with big driving data Vehicle speed distribution Acceleration / deceleration distribution Maximum Center Gear shift up timing distribution Center Gear 5th->6th Gear 4th->5th Gear 3rd->4th Gear 2nd->3rd Gear 1st->2nd Center Minimum 14 Extraction of driver behavior to reproduce real driving

Influence of driver model parameter on dynamic behavior Max. acceleration Too aggressive Max. shift up engine speed Max. acceleration & shift up engine speed Urban Rural Motorway Urban Too smooth Rural Motorway V*a pos: Vehicle speed multiplied by maximum positive acceleration RPA: Relative positive acceleration Succeed in targeting assumed driver characteristics 15

Route models for RDE performance validation n1 n2 n3 Simulation 16 Introduction of detailed digital map information (traffic sign, curve, altitude)

Traffic flow model Standard traffic Heavy traffic Simulation Standard traffic Heavy traffic 17 Utilization of stochastic based traffic model to reproduce real driving

Contents Background Concept of model based simulation environment Vehicle simulation model - Vehicle model - Driver model - Route model - Traffic model Application results in RDE-compliant powertrain development Summary 18

Vehicle simulation for RDE route Route Rural Digital map Simulation Motorway Urban Altitude Urban Rural Motorway 19 Generation of vehicle speed by vehicle, driver, route, and traffic models

RDE measurement vs. simulation Urban Rural Motorway Real driving n1 n2 n3 Simulation 20 Vehicle speed profiles at RDE conditions are well expressed in simulation

Driving characteristics at RDE Real driving Too aggressive Urban Real driving Urban Rural Motorway Too smooth Rural Motorway Simulation Too aggressive Simulation Urban Rural Urban Rural Motorway Too smooth Motorway 21 Realization of vehicle simulation within RDE dynamic criteria regulation

9AT transmission model Simulation 9AT Simulink model 6MT 9AT 6MT 9AT 22 Introduction of automatic transmission logic in the vehicle simulation

Engine speed (rpm) Torque (Nm) Altitude (m) Vehicle speed (km/h) Model based RDE performance evaluation Vehicle, driver, route, and traffic models Vehicle simulation Vehicle speed, engine speed, brake torque, and gear shift position Engine simulation NOx, Soot, CO 2 etc. Altitude Rural Vehicle speed Tailpipe NOx Motorway Gear shift position Engine speed Brake torque Urban Time (sec) 23 Achievement of emission prediction with vehicle and engine simulation

Evaluation of emission robustness Simulation Total (Urban+Rural+Motorway) 6MT 9AT Total (Urban+Rural+Motorway) Urban 6MT 24 Validity confirmation of hardware selection and calibration data settings

Summary It is a challenge to sufficiently validate RDE performance under all conditions through road tests during vehicle development due to wide range of validating conditions. A model based development technology was established to simulate, verify and calibrate the emissions performance of a vehicle. RDE performance could be accurately predicted by coupling a vehicle driving simulation with an engine simulation that includes an ECU model, combustion model (dynamic data based statistical model), and exhaust aftertreatment catalyst model. Use of the simulation model enabled robust validation of RDE performance under various conditions that assume driving on actual roads. 25 Thank you very much for your kind attention.

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