Research On Modeling And Control Strategy Of Steering-by-wire System For Vehicle

Steering-By-Wire (SBW) syetem is a kind of brand-new technology for the design of steering system, as a new technology is much better than traditional steering system,which is incorporate with advanced electronic technology control theory and information technology.For it eliminated the mechanical connection between the steering wheel and the turning wheel(The connection between them by controlling the signal), and broke away from inherent restrictions of tradition steering system completely, which could not only design force transfer trait freely and angle transfer trait for vehicle steering, but change the characteristics of feedback from the road. Automotive SBWsystem is an important innovation which can improve handling stability, safety and comfortability of the vehicle and bring more design space for automotive steering.In this paper, it did a thorough research to traditional automotive steering system,and made the best use of automobile engineering, theoretical mechanics and embedded system based on the achievements of steering system. It made an thorough study from the dynamics of each module in the system, simulation model and control strategies for automotive SBW system form.Main contents:First, the thesis described the development history of traditional automotive steering system, discussed respectively research status of SBW system at home and abroad, the significance of developing SBW system and key technology of SBW; And it expounded basic structure and working principle of SBW system, and matching researched the main parts of SBW hardware system.Secondly, the vehicle, tires and return-to-center torque, road feeling modules, etc.of SBW system were conducted dynamics study,and Simulink models of corresponding module were established in Matlab/Simulink software function;Motor simulation model was established, the working principle and steering motor control method was analyzed,the relationship of the manipulation stability and SBW was studied, thus steering execution control strategy of SBW system were studied based on the dynamic analysis of road feeling simulation;Tire return-to-center torque control strategy was studied on the basis of motor model through the dynamics research of wheel, tires and return-to-center torque and the establishment of simulation model; The steering wheel force characteristics was described, the affect relations of steering wheel force characteristic to vehicle speed and lateral acceleration were analyzed, control validation of road feeling simulation was studied through PID control and fuzzy control two different controls, and compared their differences.Finally, the thesis constructed the function modules of SBW software system, including: initialization module, the main loop modules and interrupt service module.