Dependable and cost-effective architecture for X-by-wire systems with membership middleware

Balancing the trade-off across dependability and cost-effectivcncss is essential to promote the viability of X-by-Wire systems in mass market commercial vehicles. To achieve this goal, focusing on the electronic platform architecture, we have proposed a network centric architecture based on a concept of autonomous decentralized systems. In this architecture, if one electronic control unit (ECU) fails, the remaining normal ECUs autonomously execute a backup control to maintain at least minimal necessary functionality of the system. Thus, our architecture can tolerate the existence of the failed ECU and docs not require the high cost redundant ECUs. We have also proposed a membership middleware layer as a core element of the network centric architecture to ensure consistency of the ECU status information among all ECUs. In this work, we have implemented the membership middleware on a hardware and software platform equivalent to one assumed to be used in commercial X-by-Wire systems. Subsequently, we have developed a prototype FlexRay-bascd brake-by-wire system based on the proposed network centric architecture to evaluate a required overhead, especially CPU computational load of the membership middleware. This paper describes implementation details and performance evaluation results of the membership middleware. Furthermore, it proposes improved membership algorithms to reduce CPU computational load, which will be an inevitable constraint for practical X-by-Wirc systems.