| Environmental protection and energy saving, adjustable dynamical characteristics and security, and so on, its has been researched in one of the key research projects by many automobile enterprises and research institutes ,besides, electronic controller hardware and software development is one of the core technical of its.Firstly, all kinds characteristics of steering system were analysed in this paper, electric power steering system structure and dynamics model were mainly researched, and proposed control strategy base on PID, steering shaft dynamics, rack dynamics and motor mathematical model of the electric power steering system were established by using Matlab/Simulink tool box, and established the dynamical characteristics curve, at the same time, no power, have power and PID control power were simulated and analysed, through the contrast and analysis, the PID control mechanism can accurately control power size, and have good control effect.In this paper, controller hardware and software of electric power steering system are mainly designed and developed. Hardware design mainly includes: selecting the freescale MC9S12 series microcontroller as EPS system CPU, design the smallest CPU system circuit (including clock circuit, filter circuit, the power circuit, reset circuit, etc.); The Power circuit is designed by the chip of LM2576; the steering wheel torque sensor signal and speed signal circuit, drive circuit of motor and communication circuit, etc. Drive circuit of motor is drived by the chip of TD340, communication circuit consists mainly of serial and CAN bus communication, which can communicate with the PC and vehicle. In software, A/D conversion program is mainly compiled, PWM module and pulse capture program and related registers configurations process emphatically.System of PC monitoring program is designed by using the LabVIEW software, realizing the communication between computer and EPS controller, and can be data display, drawing graphic, data storage and dynamic contrast, and completing the automatic process of data acquisition.In order to verify the reliability of the controller hardware and software, and carry through experimental study on test-bed, including the contras of without power and have power, the influence of electric current of motor to torque, and speed of vehicle to electric current of motor, and steering returning control etc, the experimental results show that the controller hardware performance is good, stable and reliable; Software control effect is good, dynamical characteristics comply with the design requirements. Steering system stability is good, and the steering wheel without obvious jitter, steering feel is good, and getting ready for the loading test of the next. |
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