a car where vital functions like steering or braking are controlled by
onboard electronic systems. Gone are mechanical and hydraulic components
connecting gears, pedals and steering wheel to the steering column and
drive shaft, replaced instead by embedded computers, cables, optical fibres,
sensors and actuators. This vision of motoring could soon be a reality
building on ground-breaking work by the X-by-wire
architecture (TTA) projects to develop a highly dependable architecture
and protocols for electronic systems in cars.
are increasingly looking to on-board electronic systems to provide the
next breakthroughs in improving car safety and functionality. However,
in the past, the goal of replacing mechanical, hydraulic or pneumatic
systems with computerised ones to control driving functions such as braking
or steering has foundered on cost and reliability. The X-by-wire and TTA
projects aimed to develop enabling technologies for electronic driver
assistance systems appropriate for the mass production environment of
car manufacture. This meant systems had to be low cost, reliable and easy
to maintain in the field.
elements of the two projects involved:
developing an architecture for fault-tolerant electronic systems
in vehicles capable of controlling car functions like steering
or braking without mechanical
developing a prototype implementation of the architecture for
a steer-by-wire application
making recommendations for the design process and rules for the
certification and maintenance of x-by-wire systems.
projects were co-ordinated by Daimler-Benz,
and included other major car manufacturers and their component suppliers.
The partners are confident that their research efforts have produced
an electronics architecture and protocols for driver-assistance
systems which are so secure, or fault tolerant, that no mechanical
back-up would be required. The X-by-wire project developed a prototype
steer-by-wire system without mechanical back-up, which demonstrated
the feasibility and scalability of the architecture.
for car users
projects should lead to long term benefits for drivers and the vehicle
industry. By-wire systems should enhance safety by liberating drivers
from routine tasks and assisting the driver to respond to critical
situations. The on-board intelligence should allow driver instructions
such as steering in a particular direction or accelerating at a
given point to be translated into the optimum manoeuvre for the
prevailing driving conditions or environmental influences.
The technology also has the potential to make cars more environmentally
friendly and less expensive. Dispensing with mechanical parts should
mean better use of materials, more freedom of design in the interior
of the vehicle, while the greater precision and accuracy of the
intelligent systems should mean less engine wear, better fuel economy
and easier maintenance.
concluded that steer-by-wire systems offer a number of specific
benefits. Being able to dispense with a steering column means car
manufacturers will have new design options in the engine compartment
and be able to adapt left hand/right hand steering systems more
easily. For drivers the risk of injury from the steering column
in the event of a collision is eliminated and noise and vibration
should be reduced. The project participants also envisage a situation
where systems can be easily improved by downloading a software upgrade.
for the European vehicle industry
success of the projects has put the European automotive, subsystem
supplier and semiconductor industries in a pole position in an important
emerging high technology market. The technology leadership gained
could also bring benefits to other industry sectors such as aeronautics,
railways or nuclear industry.
projects have spawned a new start-up company which is seeking to
exploit commercially the TTA and related time-triggered protocol
was formed in 1998 by a research team from the Vienna
University of Technology, which had been one of the project
partners. TTTech has since launched TTP hardware and software products.
Thurner, the project co-ordinator for Daimler Chrysler, says partners
have now all set up internal projects in the field of X-by-wire,
and the issue has become more competitive. He has no doubt that
the EU-backed projects have given European manufacturers a lead
in this important technology. "European industry has the key
role in driving this technology. A lot of spin-offs of the project
will be introduced in vehicles during the normal continuous improvement
of existing systems. I expect a slow and evolutionary introduction
and not a revolutionary step," he says.
funding, in the form of an accompanying measure, is also helping
to promote the technology and facilitate its transfer and exploitation
with the establishment of the TTPforum.
The TTPforum aims to bring together the pacesetters in the field
of Time-Triggered Technology so they can share news and latest developments.
The first meeting was held in Munich, Germany and attracted over
70 attendees from 30 companies covering the automotive, railway,
aerospace and semiconductor industries, all supporting TTP as a
standard for dependable real-time systems.
TTP community made its first ever presentations in the US in March
2000 when the fourth TTPforum meeting was held in Detroit - the
home of the US car industry. The meeting attracted 100 delegates
from 50 organisations including most of the big car manufacturers.
EU-funded X-by-Wire and TTA projects within the Land
and Marine Transport key action have laid the basis for a
major leap forward in on-board driver-assistance systems for cars.
As a result, Europe now leads the field in highly dependable electronic
control technology for vehicles. Through an accompanying measure
aimed at promoting and exploiting research results, the EU is
also helping to spread the word to Detroit - the headquarters
of the US car industry.
- Safety-related fault tolerant systems in vehicles (BE95/1329)
- Time-triggered architecture (ESPRIT 4 23396)
The electric brakes on the
test vehicle can be operated by the normal brake pedal or by a
manually operated potentiometer for test purposes.
The TTP module on this circuit
board is the heart of the electronics innovation. Its functions
will be integrated into a computer chip as the development continues.