BMW Brake system relies on FlexRay

In its current 7-series, BMW uses a FlexRay-equipped brake system. The high data transfer bandwidth for a FlexRay system is needed for the multiple communication tasks the brake controller has to master: The system communicates with the related sensors, the adaptive cruise control system, the integrated chassis management system (ICM) and the ECUs monitoring and controlling engine and transmission.

The electronic stability program (ESP) controls the brakes and stabilizes the vehicle by applying the brake at single dedicated wheels in critical situations. Several assistant systems such as the stop-and-go function of the adaptive cruise control have access to the ESP and can take control of the brakes in certain situations.

On the other hand, the signals provided by ESP sensors help to speed triggering occupant restraint systems. All these communication processes require high bandwidth, fault tolerance, real-time behavior, and scalability. FlexRay offers two independent data channels with a capacity of up to ten Mbit/s each. The CAN technology, typically used for this kind of applications in its high-speed flavor, offers only 1 Mbit/s.

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