| Electric power steering (EPS) system is a new type of vehicle steering control system which can provide appropriate power steering according to to the driver's steering needs. Compared with the hydraulic steering system, it has advantage of low oil consumption,high safety and environmental protection etc. In recent years, the automotive steering system has switched from mechanical style into electric style,and most of high-graded cars had been equipped with electric power steering.The research of EPS is actively started at home and abroad, it has become a hot research topic which has great research significance and value in automotive industry.An controller based on DSP is developed in this paper by applying advanced and function powerful 32-bit fixed-point DSP chip TMS320F2812 in international market. Firstly, analysis of structure,working principle and composition of electric power steering system provide the basis for EPS system development and each component selection.At the same time,the control algorithm is determined by expatiating control strategy of EPS.Then, EPS system dynamics model is established, and simulation experiment of system control performance is made by applying MATLAB/SIMULINK.Good control effect based on selected PID control algorithm is verified through simulation experiment.Through analyzing the function of control unit in EPS system, a control system is developed by selecting DSP2812 as main control unit and selecting 89C52 microcontroller of STC company as sub control unit. The design of electric control hardware circuit is composed of power module,driving circuit module of implement machine,sensor processing circuit module,CAN bus master control module and subsystem control circuit module.Steering function is realized based on H bridge type circuit by controlling current and steering of motor.The according software program is writted by applying modular design method based on interrupt.Finally, a self-developed experimental board is introduced,and simulated experimentation is performed on the hardware and software system.The experimental results show that the stable performance of designed EPS system controller basically meet subject requirement. |
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