1. 研究目的与意义（文献综述）

the car steering system is an important component of the car. it is a very important safety device to ensure the safe driving of the car. its function is to control the driving direction of the car according to the driver's intention. it directly affects the overall maneuverability and driving stability of the car. in the history of automobile development, the steering system has gone through four stages, they are: manual steering (ms), hydraulic power steering (hps), and electric hydraulic power steering power steering (ehps) and electric power steering (eps)^[18].

the first application of electric power steering was in japan. in february 1988, japan's suzuki motor company first applied the eps system to cervo mini cars^[1], and later also used it on alto cars. after that, eps technology has been favored by major car manufacturers and has been innovated and improved step by step. in 1993, honda motors of japan installed eps on the premium sports car acuransx, and daihatsu and mitsubishi corporation installed eps systems on their branded cars respectively^[14]. some european and american automobile companies have also developed their own eps systems and installed them on different cars and mini cars, such as zf in germany, lucas in the united kingdom, and trw and delphi in the united states^[2]. subsequently, opel's 3l8i and volkswagen's polo immediately deployed the delphi eps system.

with the continuous development and progress of the eps system, the eps system has gradually changed from being mainly used in mini-cars to being deployed in mid-size cars and medium-large trucks, gradually replacing hydraulic power steering systems^[3]. the eps system has a wide range of applications, high efficiency, and strong adaptability. because of these characteristics, commercial vehicles and large cars have gradually begun to apply the pes system. many auto parts suppliers in europe, america, japan and south korea are developing eps systems for different types of cars. while expanding the scope of applicable models, eps is also improving its functions step by step. a full-speed power-assisted eps system developed by delphi has for the first time been equipped with two function transfer switches to provide corresponding assistance for urban and suburban driving. this can not only ensure the portability of the vehicle when driving at low speed (driving in urban areas), but also provide a suitable road feel for driving at high speed (driving in suburbs). japan's suzuki company's eps system equipped on wagonr can automatically adjust the assistance size according to the relationship between load, road surface and vehicle speed^[4].

2. 研究的基本内容与方案

the basic content

(1) analysis of the composition and function of the electric vehicle steering system.

(2) establish a mathematical model for each part of the electric power steering system.

3. 研究计划与安排

4. 参考文献（12篇以上）

[1] nakayama t, suda e. the present and future of electric power steering[j]. int.j.of vehicle design, 1994,15(3,4,5):243-254.

[2] jin bingying，ning guangqing，shi guobiao.overview of the development of automobile electric power steering system[j].tractors and farm transporters.vol.37 no.1,2010:1,2,5.

[3] herkommer, r. steering the right way-steering the economic way: energy saving concepts in hydraulic steering(10) systems. fisita congress helsinki, june 2002.