【作者】 付饶；

【导师】 阮祥发；

【作者基本信息】 武汉理工大学 ， 机械制造及其自动化， 2007， 硕士

【摘要】 汽车四轮转向是汽车研究与应用的新技术。与二轮转向汽车相比，四轮转向汽车有如下优点：低速转弯时，转向半径小，汽车的灵活性高；高速行驶时，能迅速改变车道，而车身又不致产生大的摆动，减少了摆尾产生的可能性，使司机更容易控制汽车的姿态。本文在四轮转向(Four Wheel Steering，4WS)系统的动力学特性和控制研究上进行了一些探索，取得了以下成果：首先系统地介绍4WS的系统组成，并对4WS的转向过程进行了研究，分别分析了4WS在高速和低速下的转向特性，得出了其与普通2WS的区别和优势所在，及其在故障处理方面的优势策略。分析了4WS实际运行中的非线性因素，其中着重研究了轮胎非线性对汽车四轮转向系统的转向特性及行驶稳定性影响，介绍了一些常见的轮胎模型，并分别对其特点进行了介绍，最终设计了基于立方非线性轮胎侧偏公式的四轮转向二自由度模型，并对模型的合理性和缺陷进行了分析。分析了一些常用的控制方案，结合混杂控制的研究结果和前面设计的二自由度非线性模型，设计了4WS控制系统的实现方案，对二自由度模型的稳态响应和稳定性因素以及瞬态响应进行了分析，并在Matlab下对侧偏角响应、横摆率响应和横向加速度响应进行了仿真，验证了控制结果，得出了4WS系统可以很大程度上改善各种响应的结论。运用现代非线性动力学理论，结合非线性轮胎侧偏公式，建立了4WS的非线性动力学模型，研究了其稳定性，进行了数值模拟，证明了本文提出的动力学模型的合理性，并基于模拟结果对以后的设计工作提出了一些合理化建议。最后对本文的研究成果和不足进行了分析总结，并对4WS以后的研究和发展方向进行了展望。更多还原

【Abstract】 4WS (four wheel steering) is a new technology in vehicle systems. Compared with the current 2WS (two wheel steering), 4WS has such advantages: when the vehicle turns at low velocity, it provides more smaller steering radius and improves the flexibility; when the vehicle turns at high speed, it improves the operation stability.This thesis has the research contents as following:Analyzed on the steering process of 4WS, the characteristic in high speed andlow speed, the different and advantage compare with common 2WS, and theadvantage strategy on breakdown manage.Analyzed the nonlinear factors on 4WS, especially the tyre nonlinear model affects the steering characteristics and stability of the vehicle. A tyre cube nonlinear model is used in robust control of 4WS system. The nonlinear controller is gained, and the rationality and the blemish analyzed too.Based on the hybrid controller of 4WS system and the 2DOF model designed, an implementation scheme is put forward. Analyzed the stable state response and the stabilize factors and the transient state response of 2DOF model. Furthermore, the simulation based on Matlab is done to validate the accuracy of the identification, comes to the conclusion that 4WS can improve the response much.Analyzed some common control models, combined the nonlinear tyre model, a nonlinear 4WS model is put forward. Its stability is analyzed and the result is verified by simulation, and then gave some rationalization advises to later design based on the result of simulate.The last chapter summarizes the research work in this dissertation, and lists the future works in the area.更多还原