Distributed System Control with FlexRay Nodes in Commercial Vehicles

Abstract: Most vehicles today use some kind of hydraulic brake system in order to stop the vehicle. There are other techniques that will not only decrease the stop length, but also create a more stable vehicle; an example of such system is the Electromechanical braking system. The problem with such a system is that the requirements of data transmission and reliability are different from the system that is used today. To be able to implement such a system, a relatively new network protocol called FlexRay can be used. Different design alternatives will be introduced and one important subject is how the local nodes in the wheels can take over calculations, in a distributed way, from more central nodes. The best design was simulated using Matlab and a library called TrueTime to investigate if it is possible to implement such a system. The results from the simulation shows that it is possible to implement the system and that there is a lot of free space on the network for other tasks. An animation shows how the different nodes exchange redundancy responsibilities. One conclusion was that it is better to choose a simple design of the system instead of an advanced one where the nodes are connected to several networks to add redundancy. Once again the expression 'less is more' is valid!