Software Design Of Vehicle Terminal Based On Embedded Linux

With the rapid development of the internet of vehicles technology and the electric vehicle industry,vehicles are gradually developing in the direction of networking,intelligence,electrification,and sharing.As a network communication device between the vehicle and the outside world,the vehicle terminal is related to the enterprise’s supervision of vehicles and information sharing between vehicles and the outside world,which indirectly affects the safety of vehicles and drivers.Although 5G and C-V2X communication technologies are developing rapidly,the vehicle terminals at home and abroad are still more frequently obtaining life entertainment,road rescue,operation monitoring,and other vehicle networking services via the 4G network.There are few vehicle terminals with 5G and V2X communication functions,so it is necessary to design a new generation of vehicle terminals with 5G and C-V2X communication functions.This thesis takes Huawei MH5000-871 5G module as the development platform and uses the embedded Linux system operating system to design vehicle remote service and management module,V2X business module,and OTA upgrade module.To solve the problem that the real-time performance of the Linux system is difficult to meet the demand for V2X communication,the real-time optimization is carried out in terms of scheduling strategy,interrupt management,memory management,communication protocol stack,etc.,and the real-time performance is quantitatively analyzed.The research contents of this thesis are as follows:Firstly,the overall design of the vehicle terminal is determined.This thesis combines the research background,development status,and trend of the vehicle terminal,analyzes the requirements of the remote service and management system and the V2X system,determines the business functions of the vehicle terminal,and selects the software and hardware platforms.Secondly,the vehicle terminal software is designed and tested.The vehicle terminal software is divided into the business layer and the function module layer.The function module includes network registration,data storage,data encryption,data collection,V2X,positioning,and other function modules.The business layer includes the remote service and management module,the V2X business module,and the OTA upgrade module.The remote service and management module has functions of network connection,time data sending and calibration,vehicle data collection,transmission and storage,parameter query and setting,terminal control,etc.The V2X business module has functions of network connection,real-time control data collection,V2X data frame transmission and reception,control decision analysis,etc.The OTA upgrade module uses A/B mode and has a function of the online differential upgrade.Then,the vehicle terminal software is compiled,and the business functions are tested in the laboratory environment.The results show that the designed vehicle terminal software operates normally.Finally,the real-time performance of Linux system based on Xenomai/RTnet is analyzed.To solve the problem that the real-time performance of the Linux system is difficult to meet the demand for V2X communication,this thesis analyzes the real-time optimization methods of the dual-kernel strategy which combines the real-time kernel and the Linux kernel,resetting the interrupt routing to ensure that interrupts are prioritized by the real-time kernel,using the static memory mechanism in the real-time subsystem,and using the clock synchronization and priority queue mechanism in the Ethernet communication.This thesis selects the Xenomai dual-kernel system and the RTnet protocol stack to construct the real-time Linux system and quantifies the realtime performance of the solution by using the log-normal distribution.The results show that the solution has better real-time performance and meets the requirements of 1 ms task response latency and 1ms in-vehicle network transmission latency for V2X business,which can reduce the target value by 80%.