Some automakers are using brake-by-wire systems in their latest vehicles. Jason Fenske at Engineering Explained has the details on how these systems work.
Brake-by-wire systems insert electronics into the mechanism. In a car with brake-by-wire, pressing the brake pedal sends a signal to a brake control unit that then actuates the brakes. Computers determine, based on pedal position and pressure, how much braking the driver wants. An electric pump then pushes hydraulic fluid through brake lines, much like conventional braking systems.
It may not sound like a good idea to cut the direct connection between the pedal and brakes, but these systems have redundancies. For example, Audi’s system includes a path for pedal pressure to act directly on the brakes as a backup.
2019 Audi e-tron prototype drive, Pikes Peak
This technology has a few advantages. Because the pedal isn’t directly connected to the braking system, pedal feel is artificially generated. That means engineers have complete control over how pedal feel is tuned, Fenske noted.
In hybrids and electric cars (like the Audi E-Tron Sportback Fenske used in this video), which use both regenerative braking and friction braking, brake-by-wire offers more flexibility in how the two braking methods are deployed. In all cars, brake-by-wire also gives the car more control, aiding the effectiveness of driver-assist systems, Fenske said.
By-wire controls also offer designers more flexibility when combined with battery-electric or hydrogen fuel-cell powertrains. They could allow future cars to be designed by simply placing new bodies atop a common “skateboard” chassis. That idea was first proposed by General Motors in the early 2000s with its Autonomy and Hy-Wire concepts, and is now being put into practical use by startup Canoo, which designed a complete chassis that can be driven without a body.