The Time Synchronization Technology Based On IEEE 802.1 AS Research

With the fierce development of intelligent network-linked automotive technology,the traditional in-vehicle networks CAN,LIN and FlexRay bus have been unable to meet the requirements of Advanced Driver Assistant Systems(ADAS),automotive network convergence and other new technologies on the on-board network bandwidth requirements.Therefore,there is an open,high-speed,and easy to integrate with other electronic systems or equipment Car Ethernet technology came into being.However,Ethernet is lacking in real-time communication performance.For applications such as automotive network trunks with high real-time performance requirements,further development and research are needed.At present,the IEEE has expanded the original AVB(Audio/Video Bridging)to form a TSN(Time Sensitive Network)working group to develop the vehicle Ethernet.This article focuses on the precise timing method of IEEE 802.IAS from the perspective of communication time synchronization.And the research will be conducted as following:1.This paper focuses on the time synchronization process of the time-aware system,ana-lyzes the IEEE 802.IAS precise clock protocol,and studies the time synchronization technology.The time-aware system of key concepts such as network architecture based on time-aware system in the protocol is described.The time synchronization model is given and optimized.The structure of the time-aware system is analyzed.The time synchronization model of the time-aware system is analyzed from several aspects of system port,network topology,protocol state machine and data set.Theoretically analyzed and proposed two compensation mechanisms of time synchronization principle and time accuracy.2.The best master clock selection algorithm(BMCA)in the protocol is optimized.Firstly,according to the principle of algorithm,the data set and state decision are elaborated;and in the gPTP domain,the algorithm of time-aware system is a network node,and the composition function and important variables of the state machine are designed,and the state flow chart is used.The form describes the state machine function and its state transitions.Then CANoe is used as the simulation software to establish the network node of the time-aware system.The master control module,the clock module,the message module and the protocol state machine module are completed within the network node to verify the time synchronization process.3.The simulation software CANoe was used to simulate the time-aware network node.The program design of main control module,clock module,message module and protocol status module was completed in the network node.The data file was built and the time synchronization process was verified.4.Based on the TMS320C665x development board and the self?designed signal acquisition board,the network node program design was completed through Coder Composer Studio(CCS)integrated development environment,and the hardware and software development of the physical node was completed.Through the analysis of the physical test process,the results show that the designed network node can meet the requirements under the laboratory conditionsThe research of the IEEE 802.IAS protocol precision timing related technology will improve the accuracy of time synchronization.The research not only built up a good theoretical foundation for the practical application of time-sensitive networks,but also provided a positive reference for the time synchronization technology in vehicle electrical control systems and perceptual systems.