Research Of Message Scheduling Optimization For Flexray Static And Dynamic Segments

As the rapid development of the modern automotive industry,automotive electronic systems will gradually replace mechanical and hydraulic control systems.The number of the electronic control unit and message transmissions between the electronic control unit has greatly increased,which puts higher requirements on the bandwidth and transmission capabilities of modern vehicle communication networks.FlexRay not only satisfies the needs of modern vehicle communication networks,but also has advantages such as high real-time and security.In order to meet the evolving of the vehicle communication network,FlexRay information scheduling fusion technology has become one of the key issues to improve the safety and reliability of the on-board bus network system.The main research contents are the FlexRay communication network scheduling algorithm,in order to optimize the performance of the vehicle communication network.According to the transmission characteristics of static segment and dynamic segment in FlexRay protocol,the efficient scheduling algorithms for the static segment and dynamic segment network are put forward.In the research of FlexRay static segment,the main contents are the FlexRay network static segment scheduling algorithm and optimization strategy,improve the scheduling efficiency of vehicle network and optimize the performance of communication network.The FlexRay static segment characteristic was first analyzed,then selected bandwidth utilization as the performance metrics to scheduling problem.A signal packing method is proposed with Next fit decreasing algorithm.Based on the signal-packing,FID multiplexing method was used to minimize the number of FIDs.In the research of FlexRay dynamic segment,the transmission characteristics of dynamic segments are analyzed,and a FID allocation scheme is proposed.In the case that all the dynamic messages satisfy the schedulability,the transmission priority of the message is allocated by using the ratio of the message deadline and the message length,so as to maximize the network utilization as a constraint,the message response time is minimized.In this paper,the simulation of the algorithm based on Matlab and the physical experimental analysis of based on CANoe.FlexRay are designed.The algorithm simulation mainly verifies the network performance of the static scheduling algorithm based on Next fit decreasing algorithm,and obtains the specific message packing combination.As well as the dynamic segment based on the complex deadline scheduling algorithm can effectively optimized the message response time.And the physical experiments are setting up a system communication network model based on the car bus development software Network Designer.FlexRay and CANoe.FlexRay.In the static segment,the simulation results show that the proposed algorithm could reduce the bus load by 16.3%,the bandwidth utilization by 32.8%,as well as,the number of FIDs decreased by 53.8%.The FlexRay static segment message improves the transmission efficiency.In the dynamic segment,the proposed complex deadline scheduling algorithm improves the bandwidth utilization of the dynamic segment by 5%,reduces message transmission time by 59%,and optimizes network performance.