It's getting more and more

How does “drive by wire” actually work?

Yokes are not only available from Tesla - and not without steer by wire.

(Bild: Lexus)

Throttle commands and gear selection are already transmitted by cable to the engine and transmission in a large proportion of new cars. Brakes and steering will follow: The so-called by-wire technology saves space, money and weight - and also enables a few new functions.

"By wire" means by cable. This means that the driver's wishes are no longer transmitted mechanically via shafts, cables and linkages, as was originally the case, but electrically. A sensor constantly monitors the position of the accelerator pedal and steering wheel and transmits this information electronically to a control unit. This first checks the plausibility of the instructions and then uses an electric motor (actuator) to control, for example, the gear selection elements in the gearbox or the throttle valve on the petrol engine.

The Honda NSX already had electronic throttle control and fully electric power steering in 1995.

(Bild: 100yen)

This means that the mechanical connection can be dispensed with. The by-wire technology is designed redundantly so that this does not lead to problems if the technology fails. Sensors, cables and, in some cases, the actuators are therefore on board twice. Nevertheless, the whole thing is lighter, cheaper and takes up less space than the classic solution. In the future, safety-relevant systems such as steering ("steer-by-wire") and braking systems ("brake-by-wire") will increasingly be controlled via by-wire technology in addition to the transmission ("shift-by-wire") and engine.

The switch to electrical command transmission has other advantages as well. For example, the individual systems of the car can be better and more independently controlled electronically, for use in new assistance systems through to autonomous driving.

In this context, the industry is also working on new steering systems whose controls no longer have to be round, but can take the form of joysticks, for example. For electronic steering to work, however, a more powerful electronic architecture is required. The current combination of relatively slow CAN bus transmission and a large number of individual control units is now reaching its limits. (Holger Holzer/SPX)