GMU GM PROJECT

1
GMU GM PROJECT

• Model-Based On-Board Fault Diagnosis of
• Emission Control Components in
• Automotive Engines
• FaultFinder
• 1990-1996

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

air
exhaust
THROTTLE
ENGINE
fuel
FUEL INJECTOR
POSITION SENSOR
OXYGEN SENSOR
CONTROLLER
feed-forward
feedback
5

Exhaust gas recirculation (EGR)

• driver

air
exhaust
THROTTLE
ENGINE
EGR VALVE
MAP SENSOR
RPM SENSOR
CONTROLLER
6
On-Board Diagnosis (OBD) II Regulation(Mid-nine
ties)

• 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
Thr Egr Fuel
Load

MANIFOLD SUBSYSTEM
INERTIAL SUBSYTEM
AIR-FUEL SUBSYSTEM
Map Oxygen
Rpm
Thr throttle
Egr exhaust gas recirculation Map Manifold
absolute pressure Rpm Revolutions per minute
8
Car engine model

Car engine model
Thr Egr Fuel
Load

MANIFOLD SUBSYSTEM
INERTIAL SUBSYTEM
AIR-FUEL SUBSYSTEM
Map Oxygen
Rpm
9
Car engine model
Car engine model

Car engine model
Thr Egr Fuel

MANIFOLD SUBSYSTEM
AIR-FUEL SUBSYSTEM
Rpm
Map Oxygen
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
Thr Egr Fuel Map Rpm VO2
0 1 1 1 1
1 1 0 1 1
1 1 1 1 0
1 1 1 1 1
1 0 1 1 1 1
1 1 0 1 1
1 1 1 1 0 VO2
Oxygen sensor voltage
Map
Egr
Fuel
VO2
Rpm
16

Four-variable system

Thr
Map
Thr/Iac Egr Map Maf
0 1 1 1
1 0 1
1 1 1 0
1 1 1 1
0 Iac Idle air control Maf Mass air
flow
MANIFOLD SUBSYSTEM
Iac
Egr
Maf

17
The four subsystems
Thr/Iac
Egr

THROTTLE BODY
INTAKE MANIFOLD
Map
Maf
Map
Maf
18
Residual generation
Map
Thr Iac Egr

MODEL
-
Map
EXCEPTIONS
Thr Rpm
raw residual
19
A typical equation

• Map(t) 13.72 constant
• 0.78Thr(t)
• 0.049Iac(t)
• 0.22Egr(t)
• 0.66Map(t-1) autoregressive term
• 0.0085Thr2(t)
• 0.001Iac(t)Egr(t)

linear terms
nonlinear terms
20
Residual processing
raw residual

LOW-PASS FILTER
filtered residual
THRESHOLD TESTING
0/1/-1
UP/DOWN COUNTER
count (periodically reset)
THRESHOLD TESTING
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)
• Thr Iac Egr Map Maf
• detection 2 10 12 5 2
• diagnosis 6 20 17 7 8

29
Contributors

• At GMU At GM
• Ron Hira Man-Feng Chang
• Xiaowen Fang Mark Costin
• Qiang Luo Derong Liu
• Moid Kunwer Tom Ting
• Ramin Monajemy John 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 GMs 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
• RD 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