Research On Application Of FlexRay Bus Technology In Automotive Steering-by-Wire System

With the development of the level of the automotive industry,automotive control systems have evolved towards electronic integration and intelligence.The increase in the number of electronic control units in automobiles has led to an increase in electrical signals,complexity in the construction of automotive networks,and signal reliability issues.It is an urgent problem for the current automotive manufacturers to solve.The requirements of the new generation of automotive electronic control systems are that the vehicle-mounted network has a flexible structure,a high message transmission rate,and a certain fault-tolerant bus network in an internal environment with electromagnetic interference.FlexRay is an in-vehicle network protocol based on the application of a line-by-wire system.Its functional safety and reliability studies are crucial.Relevant research shows that FlexRay bus message packaging has a direct impact on the security and reliability of the system operation,and is an important issue of the on-board communication mechanism.First of all,to discuss the reliability of the SBW communication system,taking into account the failure probability of FlexRay bus message transmission,the FlexRay bus lacks an active retransmission mechanism at the application level to improve message transmission reliability.Based on the static frame retransmission,this paper defines the transmission reliability and time slot utilization of FlexRay network,and establishes mathematical model and problem abstraction.The derivation formula yields message reliability contributions at the expense of slot utilization.The dissertation pays attention to two indicators of retransmission reliability contribution and retransmission time slot consumption,and proposes to use the reliability requirements as constraints to make the optimization of the FlexRay frame packing model into a generalized integer linear programming.According to the reliability contribution rate,the first use The descending adaptation algorithm(FFD)establishes a retransmission sequence to improve the efficiency of frame transmission retransmission and the reliability enhancement.Message packaging is performed on the premise of meeting message reliability and static segment message scheduling.A FFD-fpbor frame packing algorithm based on transmission reliability is proposed.The system’s global success rate is defined with the time-out period as the unit of calculation.It is calculated to meet the upper and lower limits of the number of retransmissions in the success rate of the system.Experiments show that the algorithm can improve the utilization of the network bandwidth by increasing the utilization of the time slot when the specified reliability is met.The rate helps improve the real-time transmission of messages.Finally,build the SBW system hardware experiment platform,establish the FlexRay bus type communication network,and apply the improved static frame packing method proposed in this paper.The results show that the proposed method improves the utilization of the bandwidth of the static segment and improves the utilization of the network bandwidth.The experimental results show that the message-reliability and real-time transmission of the line-by-wire system are improved.The research results have theoretical reference and engineering value for the application of FlexRay bus technology in SBW.