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ESTRATTO DOCUMENTO

Modalità di Esame

Progetto + Discussione Orale (15/30)

2 Prove Scritte

• Prima parte - sviluppo di hw/sw per sistemi

embedded (7/30)

• Seconda parte – progetto di controllori embedded

“correct-by design” (11/30)

Con votazione > 30 si ottiene 30 e lode

Materiale didattico

• Paulo Tabuada, Verification and Control of

Hybrid Systems, A symbolic approach, Springer,

2009

• Articoli di ricerca

Sito della didattica e sito dell’Ing. Giordano Pola

www.diel.univaq.it/people/pola/

Embedded Systems

• Computational systems, but not stand alone computers

• Computation interfacing sensors and actuators

• Reactive to physical environment stimuli

• Networked and distributed information processing

Correct-by-design methodology for

embedded systems design

Embedded system’s design

Decomposition of concerns:

Systems and control engineers design controllers

 assuming fast sampling rates for correct operation Design

Software engineers design real-time operating

 systems and high level code assuming correct

operation of controllers Integration

Different teams design different modules that

 coordinate through digital as well as physical

communication

The integrated product is then tested and/or verified

 Testing/

to determine correctness verification

Embedded system’s design Conservative design

Decomposition of concerns: Simulation/Verification is

Systems and control engineers design controllers

 currently the only available

assuming fast sampling rates for correct operation method to “prove” correctness

of embedded systems.

Software engineers design real-time operating

 It is time and cost demanding

systems and high level code assuming correct

operation of controllers When a bug is found the

system has to be redesigned,

Different teams design different modules that

 which may introduce new bugs

coordinate through digital as well as physical

communication Formal verification is only

possible for systems with very

The integrated product is then tested and/or verified

 simple continuous dynamics,

to determine correctness e.g. timed automata,

rectangular hybrid systems, ...

Embedded system’s design

Powertrain Unit

by Magneti-Marelli

Decomposition of concerns:

Systems and control engineers design controllers

 assuming fast sampling rates for correct operation

Software engineers design real-time operating

 systems and high level code assuming correct Memory 256 Kb

operation of controllers Lines of C code 50 000

6

Productivity Lines/Day

Different teams design different modules that

 Changing rate 3 years

coordinate through digital as well as physical Development 40 man-

communication effort year

Validation time 5 months

The integrated product is then tested and/or verified

 Time to market 24 months

to determine correctness *Fabio Romeo, Magneti-Marelli Design

Automation Conference, Las Vegas,

June 20th, 2001

Correctness is essential in Safety Critical Applications …

 Ariane 5 was launched on 4th June 1996. It exploded 37s after launching due to software error

 The program had been running for 10 years, costing $7 billions

The rocket and its cargo itself cost $500 millions

 The same software worked perfectly on Ariane 4 and it was then used in Ariane 5

What had changed, was the physical system around the software

Power-Train Embedded Controller

• Electronic device controlling an internal combustion

engine and a gearbox

• The goal

– offer appropriate driving performance (e.g. torque,

comfort, safety)

– minimize fuel consumption and emissions

• Relevant characteristics

– strictly coupled with mechanical parts

– hard real-time constraints

– complex algorithms for controlling fuel injection,

spark ignition, throttle position, gear shift …

– Heuristic algorithms and simplistic average-value

models used in the past

Challenges

• Increasing complexity

• New safety, quality and emission requirements

• New System-on-Chip architectures

• Shorter time to market

• NEED more rigorous approach with

– More accurate models

– Clear partition between algorithms and

implementation

– Formal proofs of correctness

– Successive refinement from specifications to

implementation

– Executable Specifications

Engine and Power-train model

Simple?

Throttle Manifold

opening angle (continuous system)

Manifold

pressure Gear

Clutch

Insertion/ change

Engine sub- Release

system

Spark timing Vehicle

Drive-line Speed

Torque (continuous system with

changing dynamics)

Injection Engine and Drive-line



 

Engine and Drive-line

Combustion Process

INTAKE COMPRESSION EXPANSION EXHAUSTED

570°

320°

CRANKSHAFT

ANGLE 120° 440°

FSM for a single cylinder

positive

negative spark

spark advance:

advance:

the spark is given before

after

the TDC between C and E


PAGINE

33

PESO

1.08 MB

AUTORE

Atreyu

PUBBLICATO

+1 anno fa


DESCRIZIONE DISPENSA

Embedded Systems:
- computational systems, but not stand alone computers;
- computation interfacing sensors and actuators;
- reactive to physical environment stimuli;
- networked and distributed information processing.


DETTAGLI
Corso di laurea: Corso di laurea magistrale in ingegneria delle telecomunicazioni
SSD:
Università: L'Aquila - Univaq
A.A.: 2011-2012

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher Atreyu di informazioni apprese con la frequenza delle lezioni di Sistemi embedded e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università L'Aquila - Univaq o del prof Pomante Luigi.

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