摘要随着当今社会的发展、技术的进步，道路安全得到了人们更高的重视，为了保证行车安全，汽车的操纵稳定性也受到了重视。四轮转向技术是一种可以使前后轮同时改变方向的技术，后轮可以独立进行转向。低速时，前后轮异相转向，可以减小汽车的转弯半径，提高汽车的机动性和灵活性；高速时，前后轮同时相转向，可以提高汽车的循迹能力，提高汽车的行驶稳定性。

首先，简要介绍了本文的选题的背景及意义，概括了近年来汽车四轮转向系统的国内外研究现状及发展趋势，matlab/simulink平台下，建立了线性二自由度四轮转向车辆模型。再次，介绍了四轮转向车辆的特性，对四轮转向车辆的操纵稳定性评价指标进行了分析，包括四轮转向车辆对前轮角阶跃输入的瞬态及稳态响应，又对四轮转向车辆与前轮转向车辆运动进行比较，结果表明四轮转向的操纵稳定性比前轮转向好很多。63526

毕业论文关键词：四轮转向  线性二自由度四轮转向车辆模型  操纵稳定性

 毕业设计说明书（论文）外文摘要

Title     The Research of the Commercial Vehicle Four Wheel Steering System              

Abstract  With the development of modern society and technology, people attach importance to road safety. In order to guarantee safety, auto control stability should also be valued. Four-wheel steering technology is a kind of technology which can change the direction both front and rear wheel, rear wheel can turn independently. At low speed, front and rear wheel turn out-of-phase, which can reduce automobile turning radius, improve the mobility and flexibility of car; At high speed, t front and rear wheel turn in-phase, which can improve the car comprehensively tracking ability, improve the car driving stability.

First, this paper briefly introduced the background and significance，summarizes the car four-wheel steering system in recent years both at home and abroad present research situation and development trend, this paper expounds the main research work. Second, set a linear 2-d four-wheel steering model, establish the tire cornering characteristics of nonlinear model, in matlab/simulink flat, we established the nonlinear second freedom four-wheel steering vehicle model. Third, this paper introduces the characteristics of the four-wheel steering vehicles, evaluation index of four-wheel steering control stability are analyzed, including four-wheel steering vehicle on the front step input Angle of transient and steady response, and the four-wheel steering vehicle and front wheel steering vehicle are compared, the result shows that four-wheel steering control stability is better than the front wheel steering.

Key Words: Four Wheel Steering; The vehicle model of two degrees of freedom linear four wheel steering；control stability

 目  次1.绪论 2

1.1.论文研究的背景和意义 2

1.2.四轮转向技术国内外研究现状及发展趋势 3

1.3.本论文的主要研究工作 6

2. 车辆动力学系统建模 7

2.1.线性二自由度四轮转向车辆模型 7

3. 四轮转向系统转向特性研究 13

3.1.四轮转向车辆转向特性分析 13

3.2.四轮转向车辆操纵稳定性的理论推导及分析 17

3.3.四轮转向汽车对前轮角阶跃输入的瞬态响应 19

4. 二自由度四轮转向系统控制策略研究