The X-by-Wire Project
The objective of this project is to achieve a framework for the
introduction of safety related fault tolerant electronic systems without
mechanical backup in vehicles (so-called "x-by-wire systems"). The "x" in
"x-by-wire" represents the basis of any safety related application,such as
steering, braking, power train or suspension control or multi-airbag
systems. These applications will greatly increase overall vehicle safety
by liberating the driver from routine tasks and assisting the driver to
find solutions in critical situations.
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Project Summary
Constraints of Mass Production
The severe constraints of mass production and easy maintenance require
manufacturable cost effective solutions for safety increasing driver
assistance applications. Solutions which rely on complex mechanical
backups will not meet the cost requirements. With no mechanical backup
available, x-by-wire system have to be used. Therefore, reliability and
demonstration of the safety of these new systems becomes crucial.
Project Goal
Within this project an architecture for fault tolerant electronic
systems in vehicles, capable of steer-by-wire, will be worked out and
implemented in a prototype. The resulting architecture will meet
automotive requirements including the safety analysis. Results will be
submitted as draft standards to appropriate standardisation bodies (ISO,
SAE). The project addresses Brite-EuRam 111, technical areas 3B.5 and
3B.6.
For this purpose, existing approaches (aeronautic, railway, nuclear,
ships) will be investigated concerning their suitability for vehicles.
Especially, work which has already been done in other EC-Projects will be
taken into account in order to realise a technology transfer from research
status into production.
Safety Certification with a European Dimension
Because of big expenditure and outlay in advance, no single vehicle
manufacturer has up to now introduced really fault tolerant safety related
x-by-wire systems without mechanical backup. In order to share research
effort and to make mass production possible, the European vehicle industry
has to offer European wide accepted solutions, and to set standards for
x-by-wire systems to remain competitive. A common approach towards safety
certification and clear legal requirements is necessary to avoid European
fragmentation and uncoordinated and parallel research.
Benefits
A common European x-by-wire development, which has the potential to
become a European or even a world-wide standard, accompanied by broad
and fast dissemination of the results, translates into a significant
strategic advantage for the European automotive, supplier and
semiconductor industry. The success of this project will put the
European Industry in a pole position in an important emerging high
technology market. A direct benefit will be given to the vehicle
customer. Safe intelligent driver assistance systems based on
x-by-wire solutions will make affordable safety for everybody
possible. Gaining the technological leadership, will also bring a
number of benefits to other industry sectors.
The Consortium
The consortium came together as the result of the EUCAR masterplan. Driven
by EUCAR, all the interests in the field of x-by-wire of the European
automotive industry were focused and harmonised. The consortium is,
therefore, well suited for the work and very powerful for exploitation and
enforcement of standardisation.
The consortium consists of
Industrial Objectives and Expected Achievements
Introduction
Highly sophisticated future vehicle applications such as driver
assistance or autonomous driving need computerised control of the
driving dynamics. This requires that driver requests be sensed and
interpreted appropriately so as to take proper account of the current
driving conditions and environmental influences. These requests have
to be translated into optimum steer, brake, and acceleration
manoeuvres. The advantages of such safety and comfort increasing
applications are well known. They have been demonstrated in the
Prometheus project (CED 3), that has also established the appropriate
functionality required of such a computerised control system.
However, with present implementation strategies this functionality, or
even just a subset thereof, cannot be realised within the typical
constraints of mass production: low costs, reliability, system
modularity, maintainability in the field, whilst meeting the
requirements for safety certification. At the moment it can't be
expected that cost-effective manufacturable x-by-wire solutions will
rely on expensive mechanical backup. Today's fail-safe systems have in
general a reduced limp-home and a driver dependent functionality in
case of one significant failure. A fault-tolerant system, on the
other hand, guarantees the whole functionality even after a major
failure has occurred.
Objectives
This project has the following objectives:
- Specification and design of a fault tolerant electronic architecture
which is suitable to be the basis for any safety related intelligent
driver assistance application onboard a vehicle. The architecture
will cover x-by-wire applications which do not rely on mechanical
backup. It will meet all vehicle requirements such as costs,
manufacturability, and easy maintenance.
- A prototype implementation of this fault tolerant architecture
covering a steer-by-wire application without mechanical backup. The
prototype will be a laboratory demonstrator.
- Recommendations for the design process and rules for certification
and maintenance of x-by-wire systems. Drafts will be submitted to
standardisation bodies (ISO, SAE ...)
Approach
The project will establish a common set of automotive industry requirements
for safety critical electronic onboard systems (x-by-wire systems) under
the constraints of mass production. The approach includes investigation
of existing solutions and necessary improvements concerning their
suitability for vehicle requirements and manufacturability. An
architecture, based on the world-wide state of the art in ultra dependabie
system design, which will meet these requirements will be defined. Work
already done in other EC-Projects concerning fault tolerant systems will be
taken into account in order to realise a technology transfer from research
status into production. The results will be disseminated to the European
automotive industry and to other interested European industries such as
semiconductor, automatisation, and aircraft industry, and to
standardisation committees.
Expected Achievements
An architecture for safety related x-by-wire applications in vehicles under
the special constraints of mass-production will be worked out, as well as
recommendations for certification and for standardisation.
This architecture will be the framework for highly reliable and
manufacturable cost effective systems and components, linked by a network
and adequate development and maintenance processes. The development of
special driver assistance applications which base on this architecture,
such as autonomous driving, is not part of this project.
In the automotive industry the lead-time for an entirely new model is
approximately five years. If a highly reliable microelectronics
architecture for vehicles is successfully established by the end of this
project, i.e. in the year 1999, the basic technologies will be available
and proven. It then can be expected that affordable safety increasing
driver assistance systems for everybody will hit the market by the year
2004.
State-of-the-Art and Degree of Innovation
The long-term needs of the European automotive industry in the field of
microelectronics are described in the EUCAR masterplan. The availability
of a highly dependable distributed electronic system onboard a car for
x-by-wire applications has been identified as a key element for the future
competitiveness of the European automotive industry.
Similar activities take place in the USA within the SAE (Society of
Automotive Engineers), particularly-in the SAE Committee on
multiplexing onboard a car. In 1993 this SAE committee published a
document [SAE 94b] on the requirements of safety critical control
applications onboard vehicles. In this document the topics of temporal
performance, dependability and implementation constraints of safety
critical automotive networks are established and a typical benchmark
problem of a safety critical application is defined. In a companion
document [SAE 94c] the SAE came to the conclusion that none of the surveyed
protocols (J 1850 [SAE94a], CAN [SAE90], VAN, AUTOLAN, etc.) satisfies the
requirements of distributed safety critical applications onboard vehicles.
In parallel, work has already started in Europe on applying safety critical
software principles to automotive applications. The PROMETHEUS software
dependability subgroup have produced guidelines [PROM94], and in the UK, a
consortium of twelve companies forming The MOTOR Industry Software
Reliability Association, has produced Development Guidelines for Vehicle
Based Software [MIRA94].
In the aerospace industries the topic of dependable electronics system has
been the subject of intensive investigations over many years. In 1993 the
FAA published the well known RTCA/DO-178/B [RTCA92] document on
guidelines for the design of safety critical systems and software onboard
airplanes. The architectures of the AIRBUS A320 fly-by-wire system is
contained in [Trav88]. A seminal document [Rush931 on the issues of
"Formal Methods and the Certification of Critical Systems" has been written
by John Rushby, SRI International in the context of an FAA project on
system validation. Communication systems standards for aerospace
applications are established by ARINC, e.g., the ARINC 629 bus [ARIN91 ]
used on the Boeing 777 airplane, and the SAFEBUS developed jointly by
Boeing and Honeywell.
Other solutions are available in transportation in general, e.g. military
vehicles, ships, trains, as well as in safety critical industrial
applications like nuclear power plants.
The solutions mentioned do not meet the vehicle requirements. Aerospace
solutions for example are functionally adequate, but economically far too
expensive for the automotive market because of the different world-wide
production volumes (1 000 versus 60 000 000 units/year). The cost
constraints of the-automotive industry coupled with the potential of a
mass-market require innovative system solutions that, if proven successful,
will be picked up by the aerospace community, but not vice versa.
There is a visible trend in the automobile industry for an increasing
number of safety related electronic systems directly responsible for active
and passive driver, passenger and environmental safety. Electronic
driver assistance systems with direct control of the steering, braking, and
powertrain functionality, partly based on route image processing, were
demonstrated successfully last year at the end of the PROMETHEUS project
(e.g. CED3, Collision Avoidance).
Because of big expenditure and outlay in advance, no single car
manufacturer has introduced really fault tolerant safety related x-by-wire
systems up to now without mechanical backup, e.g. for braking or steering.
Exceptions are some applications which have the fail safe state defined as
"no functionality" in case of one major error (e.g. airbag). However, this
local fail safe state is from the drivers point of view insufficient. An
airbag system is useless if during an accident the airbag remains in the
"no functional"-state because of a previous error.
Considering these facts there is at the moment a window of opportunity for
the development of a standard for dependable microelectronic systems
onboard mass produced vehicles. This project tries to take advantage of
this opportunity and to establish an industrial European leadership in this
important new field.
In the-academic community the field of fault-tolerant system research is
well established. This year the 25th symposium on Fault-Tolerant
Computing will take place in Los Angeles. More than 2000 papers on
fault-tolerant system research have been published in the 25 proceedings of
this most prestigious world-wide conference on dependable systems,
sponsored by the IEEE computer society [FTCS88]. The International
Federation of Information Processing (IFIP) has started a Working Group on
Dependable Computing (IFIP WG 10.4) in 1979. Within this working group
scientists from all around the world meet to discuss the latest advances in
the field of dependable system research. Members of this consortium are
also members of this working group.
The European Commission has supported the basic research on fault-tolerant
distributed systems by a number of projects (ESPRIT project 818/2252 DELTA
4 [Powe91], BRA 6362 PDCS 2, BRA 7071 PROCOS 11 and BRA6360 BROADCAST).
The technology transfer from the mentioned projects to this consortium will
take place by two members of this consortium who are also active members of
the PDCS project.
In a recent book on "Advances in Ultra-Dependable System" [Suri95] the
world-wide literature on dependable systems has been surveyed and 34
relevant publications of this field have been selected for inclusion in
this book. The papers refer to MARS [Kope89], DELTA 4 [Powe88], FTPP
[Harp88], MAFT [Kiec88], and ERICA [vanD90]. They are well known to this
consortium.
The National Swedish research during the last six years carried out by
Chalmers, Mecel, Volvo, SAAB, SCANIA, concerning distributed systems for
safety critical applications in cars, has shown the importance of an
appropriate development process for such systems [Bri94a] [Bri94c],
[Tom94], [Witt]. The requirements derived from the safety critical closed
control loop applications conceding dependability, computing and
communication jitter and delay, general performance, gives the important
system architecture parameters. A functionally verified distributed
architecture, which is able to close control loops over the network, was in
a second step enhanced with the fault tolerance properties. The Basement
concept (Mecel) and the DACAPO concept (Chalmers) are both an important
input for the x-by-wire project.
The consortium will especially take into account
- the work done on the MARS architecture refined in PDCS and all the
additional work already done or planned contributing to this
architecture including the time-triggered communication protocol TTP
[Kope94] that has been developed in the context of the MARS project
(for which a number of international patents have been granted).
- the BASEMENT concept, which is an architecture for in-vehicle
distributed real-time systems. It covers application development, as
well as hardware and software which provides execution and
communication support.
- the work done at Chalmers concerning distributed control systems for
safety critical applications in cars, covering the DACAPO concept
regarding the development process, system architecture, OS,
communication, ...
Public Project Documents
This page was last updated on Oct 1 1997 by webmaster@vmars.tuwien.ac.at