Architectural Simulation of Distributed ECU Systems
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Motivation Definition Abstraction Classification Sample Usage Summary
Architectural Simulation ofDistributed ECU Systems
Joachim Schlosser
16. Dezember 2005
Motivation Definition Abstraction Classification Sample Usage Summary
Why Architectural Simulation?Context & Motivation
• Increasing complexity of automotive systems
• Highly interconnected controller and control loop systems
• Complicated integration of functions
⇒ Support the development of the technical architecture:
• Flexible validation
• earlier, well-founded assertions on temporal and functionalbehavior
• Recognize HW/SW integration issues earlier
Task of the thesis: define, classify, assess
Motivation Definition Abstraction Classification Sample Usage Summary
Terms of Architectural Simulation
Architectural simulation:execute behavioral models +architecture effects
(Technical) architecture:hardware platform + system platform
Behavioral model:functional behavior of components
⇒ Architectural simulation is a test method.⇒ Architectural simulation serves validation.
Motivation Definition Abstraction Classification Sample Usage Summary
Related Work
• Functional simulation, e. g. Matlab/Simulink, ASCET-SD
• Rapid prototyping, e. g. xPC, dSpace, ETAS
• Hardware simulation, e. g. VHDL, Verilog
• Static architecture analysis, e. g. function chains, WCETanalysis, scheduling analysis
Motivation Definition Abstraction Classification Sample Usage Summary
PrinciplePrinciple of Architectural Simulation
Example: safety critical, redundant systemfA Signal1
fBSignal2
fC
VerhaltenArchitektur
Mem
OSEK
CPU
BusCtrl BusCtrl BusCtrl
ECU1
Mem
OSEK
CPU
BusCtrl BusCtrl BusCtrl
ECU2
BusA
BusB
BusC
Motivation Definition Abstraction Classification Sample Usage Summary
Reflection of AbstractionWhy a Taxonomy?
• Discussions on abstraction dissatisfying
Solution: use abstraction taxonomy
⇒ Improve discussion
⇒ Ensure consistency of models
⇒ Detect model disharmony and put in metric
⇒ Benchmark modeling and simulation tools
Motivation Definition Abstraction Classification Sample Usage Summary
VSI TaxonomyVirtual Socket Interface Alliance: System Level Model Taxonomy
Time 1
Gateaccurate
2
Cycleaccurate
3
Cycleapprox.
4
Instructioncycles
5
Datacycles
6
Systemevents
7
Partialorder
Data 1
Bit
2
Data type
3
Abstract type
4
Property
5
Token
Function 1
Digital logic
2
Implementation
3
Algorithm
4
Mathematical
Structure 1
Structure
2
Block diagram
3
Black box
Program 1
Object code
2
Mikro code
3
Assembler
4
High levellanguage
5
DSPprimitive
6
Statemachine
Motivation Definition Abstraction Classification Sample Usage Summary
NotationSimplification
VSI Taxonomy, displayed as vector:
a =
(aZaDaFaSaP
)( TimeData
FunctionStructure
ProgrammingModel
)
• disuse of axis expressed by ⊥• abstraction ranges written as intervalls, e. g.
aV =
[4,7][2,4]
22⊥
Motivation Definition Abstraction Classification Sample Usage Summary
Dependencies betweeen Abstraction AxesCorrelations
Abstraction axes are not orthogonal.
Time
Data Function
Structure
ProgrammingModel
Why important?
• Consistency of models ("‘model harmony"’)
Motivation Definition Abstraction Classification Sample Usage Summary
Dependencies betweeen Abstraction AxesSample Relation, Sample Usage
Sample: RZP = Time× ProgrammingModel
Time 1 2 3 4 5 6 7Program 2 2 3 3 4 5 6
Sample usage:
• CPU modell for run time estimation
• Estimates generated C code (level P = [4, 6])
• To deliver instruction cycles (level Z = 4)
• Relation states: RZP(4) = 3
⇒ Model cannot meet requirements
Motivation Definition Abstraction Classification Sample Usage Summary
Dependencies between Types of ModelsWhy?
• Harmony of interacting models
• Discrepancy of abstraction admissible according toindividual dependency
• Consistency of abstraction of whole system
Motivation Definition Abstraction Classification Sample Usage Summary
Types of Models with Abstraction and Dependencies
KomponentenimplementierungKomponentenverhalten
Funktionsnetzstruktur
Betriebssystem
Middleware
Stimulation Simulation
Architektur
Prozessor
Abbildung
Verhalten
Nachricht
Speicher
Signal
Prozess Task
FeldbusAnalyse
Fehler
1
1..*
1
1..*
0..11..*
0..*
1..*
1..*
1
0..11..*
0..1
1..* 1 1
1
1
0..1
1..*
0..1
1..*
0..1
0..*
0..*
1
1
1..*
[2,5]
2[2,3]
3[1,4]
[4,6][2,4]
33
[1,5]
221∞2
Motivation Definition Abstraction Classification Sample Usage Summary
Types of Models with Abstraction and Dependencies
KomponentenimplementierungKomponentenverhalten
Funktionsnetzstruktur
Betriebssystem
Middleware
Stimulation Simulation
Architektur
Prozessor
Abbildung
Verhalten
Nachricht
Speicher
Signal
Prozess Task
FeldbusAnalyse
Fehler
1
1..*
1
1..*
0..11..*
0..*
1..*
1..*
1
0..11..*
0..1
1..* 1 1
1
1
0..1
1..*
0..1
1..*
0..1
0..*
0..*
1
1
1..*
[2,5]
2[2,3]
3[1,4]
[4,6][2,4]
33
[1,5]
221∞2
Motivation Definition Abstraction Classification Sample Usage Summary
Types of Models with Abstraction and Dependencies
Postulation:[4,6][2,4]
33
[1,5]
≤( 2
21∞2
)+
[2,5]2
[2,3]3
[1,4]
Motivation Definition Abstraction Classification Sample Usage Summary
Architectural Simulation in the Development Process(extremely simplified, no iterations)
Motivation Definition Abstraction Classification Sample Usage Summary
Example of Usage Brake-by-Wire
• Simulation and architecture modeling withCadence VCC/SysDesign
• Function modeling with ETAS ASCET-SD
Sensor vRR
Sensor vRL
Sensor vFR
Sensor vFL
Bremsaktor RR
Bremsaktor RL
Bremsaktor FR
Bremsaktor FLBremspedal
Sensor
FeststellbremseSchalter
Motivation Definition Abstraction Classification Sample Usage Summary
Simulation ResultsScheduling 1
0
0,02
0,04
0,06
0,08
0,10
3,500 3,505 3,510 3,515 3,520 3,525 3,530 3,535 3,540 3,545
q q q q q q
q q q q q q q q q
+ + +
+ +
r r r r r r r
r r r r r r r r
r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r
r r r r r r r r r r r r r r r r r r r r r r r
u u u u u u u u
u u u u u u u
Task 3.50 3.51 3.52 3.53 3.54
Arch/MCU1Arch/MCU2Arch/MCU3Arch/WCU_FLArch/WCU_FRArch/WCU_RLArch/WCU_RR
MCU1 OSEK::Archi...Behav/Fehlerbeh.Behav/Kraft_rlBehav/Kraft_frBehav/ÜberwachungBehav/SensorsignalBehav/Kraft_rrBehav/Signalverarb.Behav/Kraft_flBehav/Längskraft
0 1 2 3 4 5 6 7
20 ms 10,6 ms
Gesamtlatenz 43,5 ms
busallocation
{
prozessorutilization
{
(a) q Pedalpos. Sens. MCU2
(b) r Pedalpos. Sens. MCU2 auf MCU2
(c) + Pedalpos. Sens. MCU2 auf MCU1
(d) u normalisierte Klemmenkraft fl lokal
(e) r normalisierte Klemmenkraft fl MCU2 auf WCU fl
Motivation Definition Abstraction Classification Sample Usage Summary
Simulation ResultsScheduling 2
0
0,02
0,04
0,06
0,08
0,10
3,500 3,505 3,510 3,515 3,520 3,525 3,530 3,535 3,540 3,545
q q q q q q
q q q q q q q q q
+
+ + +
r r r r r r
r r r r r r r r r
r r r r r r r r r r r r r r r r r r r r r r r r r r r r
r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r
u u u u u u
u u u u u u u u u
Task 3.50 3.51 3.52 3.53 3.54
Arch/MCU1Arch/MCU2Arch/MCU3Arch/WCU_FLArch/WCU_FRArch/WCU_RLArch/WCU_RR
MCU1 OSEK::Arch...Behav/Fehlerbeh.Behav/Kraft_rlBehav/Kraft_frBehav/ÜberwachungBehav/SensorsignalBehav/Kraft_rrBehav/Signalverarb.Behav/Kraft_flBehav/Längskraft
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8
4,5 ms 4,3 ms
Gesamtlatenz 21,0 ms
Motivation Definition Abstraction Classification Sample Usage Summary
Advantages of Architectural SimulationComparison to other test methods
• Better test depthsome properties hard or impossible to reproduce with realhardware
• Better test coverageautomated tests, simulation computers easier scale betterthan HiL/RP systems
Motivation Definition Abstraction Classification Sample Usage Summary
Disadvantages
• Problem of test coverage
• In early phases no detailed models⇒ limited simulation accuracy
• Limited accuracy of software run time estimation
• Effort for assembly, analysis, model adation
• Complexity of tool chain and models
Motivation Definition Abstraction Classification Sample Usage Summary
Summary and PerspectiveArchitectural Simulation
• Architectural simulation defined, classified, benchmarked
• Metrics for abstraction review
⇒ Earlier disclosure of inconsistencies in design andimplementation
⇒ Project dependent balancing of effort to expected benefit
⇒ Architectural simulation as project stopped
⇒ Use of static architecture analysis instead of/ ahead ofarchitectural simulation