Efficient Utilization of FlexRay Network Using Parameter Optimization Method

Abstract—FlexRay is a high rate of bus communication standard in-vehicle network system, which takes time division multiple access (TDMA) and flexible time division multiple access (FTDMA) media mechanism to transmit messages flexibly, efficiently and reliably. However, due to protocol constraints and multiple design objectives, it is not an easy task to design a FlexRay schedule. In this paper, to achieve more efficient use of FlexRay network, an algorithm to obtain the optimal length of static messages is proposed, and the messages which are longer than the optimal length are assigned to dynamic segment. Then, according to the important level of dynamic messages, a frame ID allocation scheme by using optimal scheduling algorithm of dynamic programming and multi-stage decision for dynamic messages is proposed. After analyzing the worst delay time of the static and dynamic frames, the dynamic segment length optimization algorithm which aimed at minimizing the worst delay time of messages is put forward. Finally, according to the results which are the application of the algorithms to the FlexRay-based vehicle chassis control system, the static slot utilization rate reached 86.5%, the length of dynamic segment which transmits aperiodic messages is reduced by 43.4 %.