Innovation: Electronic exit from spaghetti junction: Controller area networks will cut car wiring to one cable

CAR ENGINES are about to become simpler - not like the old days when anyone could tinker under the bonnet, but in a hi-tech development that will turn the car into a high-volume, electronic product, as important to semiconductor manufacturers as the personal computer.

The emerging technology of controller area networks (CAN) will reduce the amount of wiring required in vehicles and other products, from the current sea of multicoloured spaghetti to a two-way wire controlled by a computer. Rather than each bit of a car having its own length of cable, all sections will share the CAN wire.

'The complex wiring needed on modern systems is bulky and heavy. Most will benefit from a CAN replacement, which is both lighter and cheaper and takes only a quarter of the space,' says Richard McLaughlin, who runs a user group at the University of Warwick for companies that want to adapt the technology for their products.

Assessments carried out by Mr McLaughlin and his colleagues for the Rover Group show that CAN costs pounds 15 less per car than conventional wiring. 'That may not seem much, but it adds up if you are producing 30,000 cars per year.'

Using CAN also reduces the power consumption and the time taken to assemble products. 'Installing the existing wiring harness in a car is like wrestling with a boa constrictor. In comparison, controller area networks are much easier to route through a car,' Mr McLaughlin says.

CAN technology was developed by Bosch, the German engineering company. There are competing variants of the technology. For example, SGS Thomson, the French electronics company, developed vehicle area networks in collaboration with Renault and Peugeot. However, Bosch has promoted widespread use of controller area networks by licensing semiconductor manufacturers to produce CAN computer chips.

To date, the only production cars to use CAN are BMW and Mercedes-Benz. Jaguar expects to use the technology from next year. CAN also appears in a few other products: the marine engineering company Navico of Portsmouth has used it to wire up the navigation systems for ships; Philips Medical Systems, in the Netherlands, is adopting the technology for its products; and Class, the German manufacturer, is using it in combine harvesters.

The attractions of CAN go much further than its appeal as a simple replacement for existing wiring.

Work at Warwick has shown, for example, that if Range Rovers were fitted with controller area networks, then adding all the extra lights needed to adapt them for the police would cost a few pounds, compared with the hundreds it costs now to install the extra wiring needed.

CAN also opens up the possibility of developing much more sophisticated controls. Because the wiring system is integrated and intelligent, it can recognise failures in one electrical system and implement measures to compensate - so if the brake lights fail, for example, the fog lights will respond to the brake pedal.

In the US, it is proposed that such car networks could be linked to sensors to monitor engine performance and exhaust emissions. These would feed a dashboard display that allowed motorists to prove they were complying with pollution laws.

Last month, Mercedes- Benz announced the introduction of an intelligent car- handling system. This is a dynamic control that employs electronic sensors to feed a stream of information from the engine, gearbox, accelerator pedal, steering, brakes and wheels to the vehicle's central computer via the controller area network.

Instant calculations are made on all the forces acting on the wheels, and if the car 'thinks' driving conditions could be dangerous, it automatically applies extra braking pressure to one or more wheels. Mercedes-Benz says it can correct both understeer and oversteer in critical situations such as fast cornering. The driver is unaware of the split-second intervention.

'The system enhances safety, mainly in those critical situations where the driver would hardly have a chance to bring the vehicle back to a safe course by steering or braking manoeuvres,' the company claims.

Six semiconductor manufacturers, including Intel, NEC and Motorola, have now licensed the technology and this is beginning to bring the price down. Mr McLaughlin says the evidence from the user group is that the technology will soon be in widespread use.

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