Development Of Automotive Power Liftgate Control Logic

The continuous development and perfection of automotive electronics technology makes the automobile gradually develop in the direction of comfort and intelligence.The power liftgate module has received more attention,and the security problems of tailgate software caused by the defects of electronic and electrical systems have become one of the most concerned hotspots.In order to solve the problem of automobile electronic and electrical failure caused by power liftgate module system,ISO 26262 is an important technical index,and its development process is regulated and guided.Among them,the model-based design has been widely used in this field.The graphical design model is directly related to the requirements and can be traced,which is more convenient for maintenance and high efficiency.Under the guidance of the functional safety standard,this thesis analyzes the complex functions and safety technical requirements of the control system of the power liftgate module,and the control logic of the application layer of the power liftgate module controller is designed by using the model-based design,aiming at improving the ability of automotive power liftgate to avoid unexpected failure of functions and promoting the reusability and development efficiency of software.It has practical application significance to software development of controllers.The main work completed in this thesis is as follows:(1)In accordance with the requirements of the third part of the functional safety concept design of ISO 26262,the relevant items of the electric tailgate system are first defined at the whole vehicle level,then hazard analysis and risk assessment are carried out to determine the functional safety objectives and define the safety integrity level.Based on the safety objective,fault tree analysis is carried out,and the functional concept requirements are refined to the functional safety requirements and technical safety requirements at the software level of the development system.Taking these requirements as guidance and referring to the E-Gas three-layer software architecture concept,the software security architecture of the power liftgate module control system is researched and designed.(2)The control logic analysis of each sub-functional module of the power liftgate module controller is carried out to clarify the development requirements.At the same time,according to the specification of test cases,the test cases of the power liftgate module control system are reasonably designed according to the functional requirements,so as to test whether the design requirements are met or not.(3)The structure of power liftgate module system is analyzed in detail and the MATLAB/Simulink model of the controlled object of power liftgate module system is established.(4)The application layer of power liftgate module controller is developed by model-based design.According to the functional requirements and designed software architecture,Simulink/Stateflow tool is used to build the control logic model of the controller application layer hierarchically.The established application layer control policy model is checked and verified to ensure that it conforms to the requirements,the modeling specification of the functional security standards and Embedded Coder code generation is satisfied.(5)The software model of the application layer of the power liftgate module controller was tested in three stages: model in loop,software in loop and processor in loop,which verified the accuracy and reliability of the system model and program and met the design requirements.