1 GMU – GM PROJECT Model-Based On-Board Fault Diagnosis of Emission Control Components in Automotive Engines “FaultFinder”

2 The emission control problem Main pollutants in automotive tailpipe emissions: Hydrocarbons (un-burnt fuel) Carbon monoxide (partially burnt fuel) Nitrous oxides (compounds arising from high-pressure combustion) Single catalytic converter for the three pollutants

3 Catalyst efficiency for three pollutants

4 Basic fuel-control system driver THROTTLE ENGINE FUEL INJECTOR CONTROLLER POSITION SENSOR OXYGEN SENSOR airexhaust fuel feed-forward feedback

5 driver Exhaust gas recirculation (EGR) THROTTLE ENGINE EGR VALVE CONTROLLER MAP SENSOR RPM SENSOR airexhaust

6 On-Board Diagnosis (OBD) – II Regulation (Mid-nineties) Any fault of an emission control component causing any of the three main pollutants to exceed its legal limit by 50% must be detected/diagnosed within three driving cycles. Warning light must illuminate. Driving cycle: 25 min highway/city

7 Car engine model MANIFOLD SUBSYSTEM INERTIAL SUBSYTEM AIR-FUEL SUBSYSTEM Thr Egr Fuel Load Map Oxygen Rpm Thr: throttle Egr: exhaust gas recirculation Map: Manifold absolute pressure Rpm: Revolutions per minute

8 Car engine model MANIFOLD SUBSYSTEM INERTIAL SUBSYTEM AIR-FUEL SUBSYSTEM Thr Egr Fuel Load Map Oxygen Rpm

9 Car engine model MANIFOLD SUBSYSTEM AIR-FUEL SUBSYSTEM Thr Egr Fuel Map Oxygen Rpm

10 Work-plan Data-collection from vehicle (idle, city, highway, hill) Model identification (direct identification of each equation) Algorithm design Coding (HC11; assembly code, memory-limited system) Building fault-emulators (hardware on vehicle) Road testing (fault free/faulty)

11

12

13

14

15 Six-variable system Thr Egr Fuel Rpm Map VO 2 Thr Egr Fuel Map Rpm VO VO 2 : Oxygen sensor voltage

16 Four-variable system MANIFOLD SUBSYSTEM Thr Iac Egr Map Maf Thr/Iac Egr Map Maf Iac: Idle air control Maf: Mass air flow

17 The four subsystems THROTTLE BODY INTAKE MANIFOLD Thr/Iac Egr Maf Map Maf

18 Residual generation MODEL EXCEPTIONS MapThr Iac Egr Map^ raw residual Thr Rpm - +

19 A “typical” equation Map^(t) = constant *Thr(t) *Iac(t) *Egr(t) *Map(t-1) autoregressive term – *Thr 2 (t) – 0.001*Iac(t)*Egr(t) linear terms nonlinear terms

20 Residual processing LOW-PASS FILTER THRESHOLD TESTING UP/DOWN COUNTER THRESHOLD TESTING raw residual filtered residual 0/+1/-1 count (periodically reset ) one bit of the fault-code

21 Residual and counter – no fault

22 Residual and counter – high noise

23 Residual and counter – with fault

24 System report – no fault

25 System report – MAF fault

26 System report – EGR or MAP fault

27 25-car fleet experiment Fleet of “identical” vehicles (Chevy Blazer) available at GM Collect data from 25 vehicles Identify models from combined data from 5 vehicles Test on data from 25 vehicles Residual means and variances vary  increase thresholds (sacrifice sensitivity) Only a 50% increase is necessary

28 Fault sensitivities Critical fault sizes for detection and diagnosis (fleet experiment) ThrIacEgrMapMaf detection 2%10%12% 5% 2% diagnosis 6%20%17% 7% 8%

29 Contributors At GMU At GM Ron HiraMan-Feng Chang Xiaowen FangMark Costin Qiang Luo Derong Liu Moid KunwerTom Ting Ramin MonajemyJohn Van Gilder Zdzislaw Kowalczuk Jim Heron Bill Hunter Yong Li Jason Peng

30 Epilogue May 26, 2004 DETROIT, Michigan - General Motors honors its top innovators of 2003 at the 28th annual "Boss" Kettering Awards ceremony today. The "Boss" Kettering Award is GM’s highest award for recognizing GM technical inventions and innovations.

31 FaultFinder: Model-Based Approach for Advanced Engine Diagnostics This model-based approach for advanced engine diagnostics … requires no additional sensors or other hardware, reduces false-alarm rates, improves vehicle repair rates and dealership effectiveness.

32 This innovation has been implemented in the 2004 Chevrolet Malibu featuring ECOTEC 2.2-LITER 4- cylinder engines; Cadillacs featuring the Northstar 4.6-liter V-8 engines; and Chevrolet Colorado and GMC Canyon mid-size trucks. The FaultFinder team includes Thomas Ting and Dr. Man-Feng Chang of GM R&D; John Van Gilder and Dr. Mark Costin of GM Powertrain Division.

33 Janos, While celebrating this recognition, we would like to acknowledge your invaluable contributions as a Principal Investigator of a five-year joint project between GM and George Mason University. The project resulted in the first General Motors experimental demonstration of model-based diagnostics for the detection of faults in an engine emission system. This is an important step and set the stage for further research in this area. Thank you again. Man-Feng