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Industrial Process

Driving by wire

 
 
The test vehicle has electrical brakes on all four wheels that are activated by the electronic system. The electric motors each build up a braking force of 40 kN within 150 milliseconds.

The test vehicle has electrical brakes on all four wheels that are activated by the electronic system. The electric motors each build up a braking force of 40 kN within 150 milliseconds.

Aeronautics technology sometimes produces innovations of particular interest to the car industry. European research projects are looking to the sky to develop new concepts in on?board electronics. One example is a fail?safe computer network with its own unique architecture and protocols to control and steer cars, just like aircraft.

     

"Electronic systems such as those for anti-lock braking (ABS) and traction control are already helping drivers to keep control of their vehicles even if they make a mistake. In the future we will see the introduction of much more active safety functions, based on electronic intervention in the main steering systems,' explains Michael Franck, Director of Research at DaimlerChrysler, who is coordinating two projects supported by the European Union, one on Time-Triggered-Architecture (TTA) and X-by-Wire, the other on Safety-related fault-tolerant systems in vehicles.

A new nervous system

In conventional transmission systems, the controls - steering wheel, pedals and gears - are connected to the drive system by means of mechanical and hydraulic links. Thanks to this project, within a few years vehicles coming off the production line will have a completely new nervous system. Cables will transmit data from electronic actuators and sensors to an on-board computer with a specially designed architecture and protocols. This network will process incoming data and outgoing commands with extraordinary precision and speed. As well as being safer, this innovation will make it possible to build cleaner cars with lower fuel consumption and cut production costs through better use of materials, simplification of production processes, etc.

Back-up system

'Drive-by-wire systems like this demand particularly robust and dependable on-board electronics. All the electronic controls must work together in a single network and exchange data with each other in real time,' adds Mr Franck. To meet these demands, research conducted mainly at the Technical University of Vienna has developed the time-triggered architecture (TTA) concept plus the time-triggered protocol (TTP) to implement it.

But what if an error were to occur despite all this? The architecture would contain it within a single subsystem and not allow it to spread to other parts of the network. Two computers calculate the same functions at the same time in a dual network. If one fails, the data from the other are available immediately.
This 'fail-silent' architecture makes a system-wide breakdown impossible. Each component knows what the other is doing and can react accordingly. The whole car is smart and the driver can leave the work to the central processing unit (CPU) controlling the computer and the network. The vehicle will adapt perfectly to weather and road conditions, etc. while also catering for the individual driver's special wishes.

Commercial prospects

The potential offered by these new designs could give European industry a flying start in this highly competitive sector. Because of their complexity and high cost, they could not have been developed without putting together a partnership of high-fliers. Leading carmakers - DaimlerChrysler, Ford Europe, Fiat and Volvo - joined forces with British Aerospace (a member of the Airbus consortium), electronic components producers (Robert Bosch, Mecel and Magneti Marelli) and academics, notably from the Technical University of Vienna, the University of York and the University of Ulm, to see through these two projects.

Once these basic mechatronic steering, braking, acceleration and suspension systems are on the market, new applications are sure to follow. The computer interface created will make it easy to add on new functions by combining intelligent software controlling existing base functions. Thanks to the common bus architecture, new smart sensors and actuators can easily be added to the system, bringing further safety improvements.

The benefits of real-time, fault-tolerant safety systems based on time-triggered architecture are not limited to the car industry alone. A demonstration unit using the ELEKTRA interlocking system developed by Alcatel-Austria has already been built for the railway industry. Wider use of TTA technology could also generate a market for tools in a variety of applications (emergency shutdowns for off-shore oil platforms, lift systems management in buildings, ventilation systems for tunnels, etc.) and create opportunities for small firms. This is already the case for TTTech Computertechnik GmbH, a spin-off company launched in 1997 after 15 years' research on TTA at the Technical University of Vienna, which is actively involved in the development and application of TTA components and tools.

 
Title
Time-triggered architecture (TTA)

Reference
23396

Programme
ESPRIT 4

Contact
Gunter Heiner
DaimlerChrysler
Fax : +49-3039982107
E-mail

Partners
-DaimlerChrysler, Stuttgart, Germany (coordinator)
-University of York, York, United Kingdom
-Austria Mikro Systeme Int., Unterpremstaetten, Austria
-Alcatel Austria Ag, Vienna, Austria
-Universität Ulm, Ulm, Germany
-Matra Mhs, Nantes, France
-Temic Telefunken Microelectronic Gmbh, Heilbronn, Germany
-British Aerospace Airbus Ltd, Bristol, United Kingdom
-Technische Universität Wien, Vienna, Austria
-Genias Software Gesellschaft Für Numerisch-Intensive Anwendungen Mbh, Neutraubling, Germany

Title
Safety-related Fault-tolerant Systems in Vehicles

Reference
BRPR950032

Programme
Brite-EuRam III

Contact
Thomas Thurner
DaimlerChrysler
Fax : +49-7111720745
E-mail

Partners
-DaimlerChrysler AG, Stuttgart, Germany (coordinator)
-AB Volvo Technological Development, Göteborg, Sweden
-Ford Motor Company Ltd, Basildon, United Kingdom
-Mecel AB, Göteborg, Sweden
-Chalmers University of Technology, Göteborg, Sweden
-Technische Universität Wien, Vienna, Austria
-Robert Bosch GmbH, Stuttgart, Germany
-Magneti Marelli SpA, Milan, Italy
-Centro Ricerche Fiat ScpA, Turin, Italy

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 electric brakes on the test vehicle can be operated by the normal brake pedal or by a manually operated potentiometer for test purposes.

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