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Computeraided Architecture Design and Optimized Implementation of Distributed Automotive EE Systems

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Basic Software (BSW) implementation of the AUTOSAR infrastructure (nearly 40 ... Basic AUTOSAR concepts (Cont. ... Instantiation of basic elements of the ... – PowerPoint PPT presentation

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Title: Computeraided Architecture Design and Optimized Implementation of Distributed Automotive EE Systems


1
Computer-aided Architecture Design and Optimized
Implementation of Distributed Automotive EE
Systems
  • Ajay Kumar, Antal Rajnak
  • Automotive ProgramsSystem Level Engineering
    Division

June 06, 2007 DAC 07, Paper 31.4
2
Presentation Outline
  • Problem statement
  • Basic AUTOSAR concepts
  • Proposed Tool Flow
  • Experience thus far
  • Suggested improvements / future work
  • Summary

3
Current Design Environment
  • Manual process with inadequate tool support
  • Insufficient data to support early decision
    making, leading to early binding and late
    verification.
  • ECU-focused rather than system-level
  • Validation on physical prototypes
  • Distributed, multi-company, modular supply chain
  • Few if any widely-accepted standards
  • The resulting architectures are seldom optimal in
    terms of
  • Performance
  • Flexibility / Scalability
  • Reliability
  • Life-cycle Cost

4
Industry trends
  • Increasing use of model-based function
    development
  • 20-25 of all EE functions covered today
  • Used for
  • Functional verification
  • Executable specification OEM -gt Tier1
  • Major standardization effort - AUTOSAR
  • Version 2.1 of specs released matured
  • Use gaining momentum in Europe
  • US and Japan watching closely
  • Step towards development and validation in a
    virtual environment, using Systems Engineering
    principles

5
Basic AUTOSAR concepts
  • AUTomotive Open System ARchitecture
  • Layered software architecture, with clearly
    defined interfaces
  • Applications implemented as atomic or composed
    Software Components (SWC)
  • Virtual Function Bus (VFB) abstraction of all
    interconnected SWCs, communicating exclusively
    through ports independent of underlying hardware
  • Run Time Environment (RTE) implementation of
    the VFB on a particular ECU
  • Basic Software (BSW) implementation of the
    AUTOSAR infrastructure (nearly 40 different
    modules)

6
AUTOSAR ECU sw structure source www.autosar.org
7
Basic AUTOSAR concepts (Cont.)
  • AUTOSAR systems are described by a set of XML
    based Description Files
  • Derived from a defined UML metamodel
  • Whats described ECUs, SWCs, their mapping to
    ECUs, ECU interconnections etc.
  • Whats missing Methodology to create these
    description files

8
The Implementation Abyss
  • Model based function design a widely
    accepted,and used technique
  • AUTOSAR brings new level of abstraction to
    function implementers
  • But
  • The task to translate a model based design into
    a robust, and efficient system, in a highly
    distributed environment remains a challenge.
  • How to bridge the implementation abyss?

9
Proposed SLD methodology
  • Architecture Design
  • Topology definition
  • SWC to ECU Vehicle function creation
  • mapping
  • VFB-level simulation
  • Bus scheduling
  • Initial ECU Scheduling
  • Metrics generation
  • ECU configuration
  • Runnables to task mapping
  • OS task scheduling
  • Configuration of remaining BSW modules

10
Proposed System Level Tool Chain
  • Implemented as a set of well connected
    point-tools.
  • Vehicle System Architect for the OEMs
  • Function Editor
  • Topology Editor
  • Function Mapper
  • VFB-level Simulator
  • Network Cluster Builder
  • ECU Scheduler
  • Harness Design Tool (Capital Harness)
  • Metrics Generator
  • Vehicle System Builder for the Tier 1s

11
Proposed Tool Flow
12
Tool Implementation Challenges
  • Support for concept evaluation for EE-systems in
    early phases of the design process, when the
    available level of detail is minimal
  • Connectivity to legacy OEM environments
  • Scalable tool functionality, depending on OEM
    preferences
  • Manual / Interactive use mode
  • Analysis
  • Synthesis requirements based design

13
Vehicle Function Editor
  • Users create atomic or composed SWCs representing
    vehicle functions
  • Method
  • Manual graphical entry
  • Import from function modeling tools(e.g.
    Matlab/Simulink)
  • Envelope of function is adequate
  • Interface consistency is checked

14
Vehicle Topology Editor
  • Instantiation of basic elements of the physical
    architecture (ECU-s, sensors, actuators, buses
    etc.)
  • Allows creation of soft (only partially
    defined) components in the early phases of
    design.
  • Import
  • Individual components
  • Pre-existing message matrix
  • Pre-existing topology
  • Graphically arrange components to form desired
    physical architecture.

15
Topology editing Function mapping
16
Vehicle Function Mapper
  • Function
  • Mapping of vehicle functions to logical ECUs
  • Check of resource demand vs. availability
  • Soft ECUs allocated to real ECUs from library
  • Split of end to end timing requirements btw ECUs
    and buses
  • Automatic gateway configuration
  • Output
  • System Configuration Description file
  • ECU extract of SCD
  • Export to Harness design tool

17
VFB-level Simulation
  • VFB-level view network of SWCs connected through
    ports
  • This network can be simulated
  • Appropriately compiled SWCs with behavior
    required
  • Verify desired functionality across single, as
    well as multiple ECUs

18
Network Scheduling the Cluster Builder
  • Basic Functionality
  • Produces schedule tables
  • Creation/modification of frames (PDU-s) and
    related parameters (ID, period time, x-fer mode
    etc.)
  • Interactive signal packing and editing of
    schedule tables
  • Cluster schedulability analysis
  • Expanded functionality
  • Automatic frame compilers (AFC-s) for
    CAN/LIN/FlexRay
  • Fully automatic scheduling and frame packing

19
ECU Scheduler
  • Runnables to tasks mapping
  • Manual configuration and schedulability analysis
    based on available timing information
  • Configuration of OS and BSW schedulers
  • Tightly coupled to network scheduling.

20
Unified Timing Model
21
Metrics generation
  • Compares and ranks a set of alternative
    architectural solutions in relative terms
  • Component cost is only one aspect - scalability,
    flexibility and extensibility will heavily
    influence the results.
  • Scenario based sensitivity analysis is essential
    to identify decision points
  • Simplified analysis running in the background
    provides live feedback to user

22
Vehicle System Builder
  • Function
  • Create/edit all AUTOSAR-relatedconfiguration
    files
  • Intelligently merge partial configuration
    filesfrom multiple sources
  • Generate a downloadable binary image of the
    complete software (AppsBSWConfig) for the
    selected ECU.

23
Vehicle System Builder
24
Correctness by Design
  • Vision
  • Requirements based Systems Engineering Process
  • Holistic, top-down approach, supported by well
    connected high-level tools.
  • Development and validation in a virtual
    environment
  • Values
  • Reduced cost
  • Shortened lead-times
  • Improved Reliability Quality

25
Experience thus far
  • Tool-set for requirements based synthesis of
    complex CAN and LIN networks and gateways
    successfully deployed and used in production
    since 1998 (Volcano Network Architect tool).
  • Users are enthusiastic!
  • But...
  • Timing analysis is not widely used in current
    automotive design flows.

26
Suggested improvements / future work
  • Enhanced AUTOSAR Timing Model to cover
    important concepts, i.e. jitter, phasing, or
    precedence required to deal with complex systems
  • Coordinated AUTOSAR Metamodel extensions
  • Evaluation metrics refinement
  • Define objective metrics and evaluationalgorithms
    to judge
  • Scalability
  • Flexibility

27
Summary
  • Bridging the implementation abyss between model
    based function design and creation of efficient
    AUTOSAR implementations calls for new methods,
    and advanced tool support.
  • Challenges
  • Usability in early project phases, when only
    limited amount of data is available
  • Need to support a flexible set of usage
    models(interactive, analytic or full synthesis)
  • The required technology is readily available
  • The AUTOSAR Timing model needs major re-work

28

QA...
  • Thank you!
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