The current BMW 7 series is equipped with the first electronic stability program (ESP) featuring a FlexRay data bus interface. Via this new kind of data bus, the ESP system, developed by Bosch, communicates with the corresponding sensors, the adaptive cruise control (ACC), the integrated chassis management (ICM) system, as well as with the engine and transmission control units.
Compared with the CAN bus system usually used in cars today, FlexRay delivers a higher data transfer rate with much larger data packets, and is also fail-safe. Like the CAN bus system, FlexRay is also capable of transmitting event driven information and additionally provides the option to transmit real-time signals deterministically.
The task of the electronic stability program (ESP) is to stabilize the vehicle in critical driving situations by braking individual wheels. This possibility of electronically controlled braking is also used by assistance systems such as the Stop&Go function of the ACC adaptive cruise control. In combination with the passenger restraint system control unit, the ESP sensor signals also assist processes such as faster airbag deployment.
Real-time exchange of increasingly large amounts of data is an absolutely vital requirement for these and all future safety systems. FlexRay provides fast, fail-safe data communication with transmission options in up to two channels.
These channels can be scaled flexibly and used either for redundant, error-tolerant data transfer at up to 10 Megabits per second or for high data-transfer performance at up to 20 Megabits per second. The high-speed variant of the CAN bus, which has commonly been used up to now, only achieves 1 Megabits per second.