全文总字数：12959字

1. 研究目的与意义（文献综述）

1. aim and significance ( recent researchstatus )

1.1 the background andsignificance of the subject research

in recent years, with the increasing complexityof the traffic environment, especially with the continuous expansion ofpeople's driving range, there are more and more situations that need to driveunder adverse conditions, which increases the operating frequency of thedriver's steering wheel, which needs to reduce driving fatigue and improve theportability and flexibility of operation, so the requirements for steeringsystem are getting higher and higher. it is not only necessary to assistthe driver in steering operation (to provide power and feedback road sense),but also to actively intervene the vehicle steering when the driver has atransition operation, so as to improve the handling and stability of thevehicle. the basic function of the steering system is to change andrestore the driving direction of the vehicle, and to provide the driver with asuitable sense of road; the two basic contradictions to be solved by thesteering system are light steering and sensitive steering, light steering atlow speed and stable steering at high speed; to ensure that the car can turnaccording to the will of the driver.

2. 研究的基本内容与方案

2.the basic contents,objectives, technical schemes and measures to be adopted

the purpose ofthis paper is to design a steering system mechanical components and powerassist system for medium-sized cars (this paper mainly takes therack-and-pinion electric power steering system as the researchobject). the following requirements need to be met: 1) when the car turns,all wheels should rotate around the instantaneous steering center. 2) thesteering wheel has the ability of automatic steering. 3) in the drivingstate, the steering wheel shall not produce natural vibration and the steeringwheel does not wobble. 4) the movement caused by the steering transmissionmechanism and the suspension guide device is not coordinated, and the swing ofthe wheel should be minimized. 5) the steering is sensitive and theminimum turning diameter is small. 6) easy to operate.

themain content of this paper and the technical scheme to be adopted include thefollowing four parts:

3. 研究计划与安排

3.schedule

1-2 (18-19 weeksof 7 semesters) determine graduation project topics, improve graduation projectassignments (relevant parameters), and collect data inside and outside theschool

3 (the first weekof 8 semesters) scheme idea, literature search, and completion report

4. 参考文献（12篇以上）

4.reference

[1]陈家瑞.汽车构造(下).北京：机械工业出版社，2000。

[2]王望予.汽车设计.北京：机械工业出版社，2006.