| EPS is referred to electric power steering system, developed in recent years. Startedlate in domestic, but a huge market and good prospects make EPS research has a practicalsignificance and long-term development prospect.Key technology of column-EPS system was researched, including reducer andelectronic control unit parts, designed specific structure of reducer, hardware andsoftware of ECU. Specific studies are as follows:Column-EPS deceleration device was studied, including worm, planetary gearreducer and pulley type; cycloid steel ball planetary reduction was proposed asdeceleration devices, working principle, stress analysis, transmission ratio, mechanicalefficiency are the focus of analysis, put forward the realization of the basic structure.Decision process of control mode was analyzed; PID control was used as the controlmethod; assist characteristic curve was researched and the characteristics of curves wassummarized, advantages and disadvantages of them were analyzed. Mathematical modelof mechanical steering system and EPS system were separately established; self-diagnostic method was proposed for the electric power steering system and common faultand prepared fault code table were made. Assist motors, sensors and microprocessorswere selected; made EPS system core component electronic control unit as a key objectof study, hardware and software systems were designed, including a variety of controlcircuit and software process.By Matlab/Simulink software, mechanical steering system simulation model andEPS system simulation model were established, fuzzy controller was designed todetermine the target current, the controller and PID control were applied to EPS system,the correctness of the model and reasonable of control strategy selection were verified. |
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