Imagine if a supplier executive proposed a new way of controlling a vehicle requiring:
It's likely that any supplier executive who approached an automaker with such a system would be thrown out of purchasing so fast that his suit would get friction burns. But that's exactly the mix of parts that control brakes and steering today.
No more jumble
By-wire systems can eliminate some of the jumble of hydraulic and mechanical links in the car, replacing them with an electric architecture controlled by microprocessors. A big benefit is that by-wire requires fewer mechanical parts. That gives automakers greater flexibility in a vehicle's design.
For example, the driver could be anywhere inside the car, even in the back seat.
Here's why: Drive-by-wire technology uses sensors to translate steering and braking movements by the driver into electronic signals.
On-board computers interpret the movements and relay them to electric motors and actuators connected to the moving parts of the car. The systems respond more quickly than today's controls and can give feedback to the computer as they operate, allowing the car to deliver precise performance.
By-wire systems already have replaced direct links in one area.
"Most cars nowadays don't have a mechanical linkage between the accelerator pedal and the fuel injection system. It's done electronically, and most people don't even realize there's no mechanical linkage," says Steven Brown, director of North American Programs for SKF Automotive Division's Drive-By-Wire business unit.
While General Motors demonstrated drive-by-wire on its AUTOnomy and Hy-wire fuel cell concept cars in 2002 and 2003, more progress has happened with less fanfare in recent years -- especially in vehicles built in Europe. Brakes, transmissions and safety systems are bringing by-wire technology into the vehicle in small steps.
Electronic parking brakes such as those on the BMW 7 series, Audi A8, Renault Vel Satis and Lincoln LS are one example.
Hybrid vehicles, including the Toyota Prius and Honda Civic Hybrid, have introduced drivers to the advantages of regenerative braking, a kind of brake-by-wire system that converts forward motion into stored battery energy.
Shift-by-wire technology also is available on high-end autos such as the Aston Martin DB9 and Rolls-Royce Phantom, as well as models from BMW, Mercedes-Benz and Lexus.
Also, comfort and safety systems such as adaptive cruise control, automated parallel parking and steering intervention for lane-keeping rely on by-wire control of some steering and braking functions. Continental Teves showed such systems at the Frankfurt motor show last month.
Any supplier working on by-wire will tell you there are obstacles to mass adoption of the technology. The auto industry is accustomed to the highly refined technology now in place. Also, car buyers are not clamoring for a change, and some early by-wire technology features haven't sold well. Until by-wire systems combine more advantages into a single system, adoption of the technology will be gradual.
By-wire adaptation stumbled when 42-volt electrical systems failed to become an industry standard, but new dual-voltage systems offer the promise of enough power for high-force uses such as braking and steering.
A European consortium called SPARC -- for Secure Propulsion using Advanced Redundant Control -- and organized by DaimlerChrysler AG and Fiat is working on by-wire accident-avoiding demonstration vehicles.