IMPORTANT LEGAL NOTICE - The information on this site is subject to a disclaimer and a copyright notice
Banner Research
  European Commission   > Research > Growth
Homepage Competitive and Sustainable Growth - Making the European Research Area a Reality
Graphic element
Graphic element
Graphic element
Graphic element Research > Growth > Research projects > Land & marine transport projects > Driving by wire
Graphic element Driving by wire

Imagine 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 and Time-triggered architecture (TTA) projects to develop a highly dependable architecture and protocols for electronic systems in cars.

Car manufacturers 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.

Fault-tolerant control

Key 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 back-up
  • 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.

Both 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.

Benefits for car users

The 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.

Participants 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.

  Implications for the European vehicle industry

The 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.

The projects have spawned a new start-up company which is seeking to exploit commercially the TTA and related time-triggered protocol technologies. TTTech 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.

Thomas 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.

  Spreading the word

EU 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.

The 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.

Fault-tolerant control
Benefits for car users
Implications for the European vehicle industry
Spreading the word

Key data

The 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.

X-by-Wire - Safety-related fault tolerant systems in vehicles (BE95/1329)

TTA - 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.


Homepage Graphic element Top of the page