Safe-by-wire plus: bus communication for the occupant safety system

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Safe-by-wire plus: bus communication for the occupant safety system

Bührig, Peter

The occupant safety system in a passenger car includes a steadily increasing number of sensors and actuators that are placed throughout the car. They all need to be electrically connected to one or more control modules. In order to maintain some control on costs it is desirable to reduce the complexity of the wiring by application of a bus system. However, because of unique requirements associated with the occupant safety system, conventional in-vehicle networks like CAN, LIN or FlexRay are not the optimum choice. Consequently an industry consortium has been founded to create a bus standard that specifically targets the challenging requirements of occupant safety systems, but is flexible enough to support various system architectures. This paper discusses the properties of Safe-by-Wire Plus (SbW+) and gives examples of system architectures that are supported. Using the SbW+ bus gives a number of advantages over a traditional system with point-to-point wiring between ECU and each single satellite module: The number of sensors and/or actuators can be varied without having to change the hardware of the ECU. Even completely new modules for e.g. occupant classification or pre-crash sensing can be added to the bus. This universality of the bus ensures that it is future proof. Investment into know-how and tools will be negligible compared to the long time of usage. Number of ECU wires is much reduced. A smaller connector can be used reducing the size of the entire module. This saves cost, weight and space in the car. The total length of cables is reduced significantly.