Fiat/Unito: Generation of Diagnostic Trees for On-board Diagnosis
Goals for on-board diagnosis:
y (Quick) selection of the correct
recovery action in order to:
- Guarantee passenger safety
- Avoid damage
- Avoid vehicle stop if possible
y Example: stop engine
- if “injector blocked open” is
suspected
- but try to rule out this hypothesis
- to avoid unnecessarily restrictive
action
y Provide good starting point for offboard diagnosis
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
Heller AG 17.4.97Struss Auto 2 − 1
The Common Rail System
Low Pressure
High Pressure
Sensor
Pump
FILTER
High Pressure Line
Pressure
Sensor
Low pressure
Line
P
RAIL
Pressure
Regulator
EFP
Electric Fuel
Pump
PR
PHASE
(N/2)
Back Flow Line
Fuel Tank
SPEED
(N)
ETK
Electronic
Control Unit
Injector
Engine speed / Torque Evaluation
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
Heller AG 17.4.97Struss Auto 2 − 2
Faults and Recovery Actions
Component
Low Pressure Circuit
Fault Mode
Insufficient
Recovery action
Performance limitation
Pressure regulator
blocked open
blocked closed
Leakage
Performance limitation
Stop
Limp home
Pressure Sensor
Blocked
insufficient
Low
Performance limitation
Performance limitation
Open loop
Injectors
Sensor blocked
Blocked
Recycle high
Open loop
Open loop
Performance limitation
Blocked open
Blocked closed
Sensor low
Stop
Go
Open loop
Recycle low
Go
High Pressure pipes
and Rail
High pressure Pump
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
Heller AG 17.4.97Struss Auto 2 − 3
Low pressure
Line
Fault Scenarios
Low Pressure
High Pressure
Sensor
Pump
High Pressure Line
FILTER
P
Pressure
Regulator
EFP
Electric Fuel
Pump
RAIL
Pressure
Sensor
PR
PHASE
(N/2)
Back Flow Line
Fuel Tank
•
y
y
y
Electric fuel pump does not convey
Pressure regulator blocked open
No injection at one cylinder
Injector blocked open
(permanently injection in one cylinder
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
SPEED
(N)
ETK
Electronic
Control Unit
Injector
Engine speed / Torque Evaluation
Heller AG 17.4.97Struss Auto 2 − 4
Diagnosis Results
Diagnoses
Observations
Actions
∆lowp_obs
∆p_obs
∆tm
-
-
0
lp_system insuff
Performance limitation
0
-
0
Pressure_regulator blocked_open
Performance limitation
Hp_pipes_and_rail leak
Limp home
Hp_pump blocked
Performance limitation
Hp_pump insuff
Performance limitation
Sensor low
Open loop
Sensor blocked
Open loop
Injectors recycle_high
Performance limitation
0
-
+
Injectors blocked_open
Stop
0
0
-
Injectors blocked_closed
Go
0
+
0
Pressure_regulator blocked_closed
Stop
Sensor high
Open loop
Sensor blocked
Open loop
Injectors recycle_low
Go
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
selected
action
Heller AG 17.4.97Struss Auto 2 − 5
The Demonstrator Architecture
PC
ETK
MAC
Parallel
Port
INCA
Software
Low Pressure
Sensor
HD FILES
Serial
Port
CoRa On-Board
Diagnostic
System
FILU
y For each scenario:
- electric circuit injecting the fault
y Each fault actuated for a fixed time
(for safety reasons)
Centro Ricerche Fiat
Electronic Systems
EDS Software
Acquisition
Dipartimento di Informatica
Università degli Studi di Torino
DISPLAY
Heller AG 17.4.97Struss Auto 2 − 6
Applying the Diagnostic Trees for Recovery Selection
-
∆lowp_obs
0
∆p_obs
perf_limit
-
lp system insuff
0
∆tm
0
limp_home
preg blocked open
hp pipes and rail leak
hp pump blocked/insuff
sensor low/blocked
inj recycle high
Centro Ricerche Fiat
Electronic Systems
Dipartimento di Informatica
Università degli Studi di Torino
+
go
+
stop
inj blocked closed
stop
inj blocked open
preg blocked closed
sensor high/blocked
inj recycle low
Heller AG 17.4.97Struss Auto 2 − 7