【作者】 岑达希；

【导师】 胡树根； 王耘； 宋小文；

【作者基本信息】 浙江大学 ， 车辆工程， 2011， 硕士

【摘要】 随着汽车工业的迅速发展,公路网络建设的日益完善,汽车的行驶速度得到了极大地提高,与此同时,路上的汽车数量也越来越多,汽车的交通事故也就不断地增加。由汽车交通事故造成的生命财产损失日益严重,汽车的行驶安全性能,尤其是侧向安全性能越来越受到人们的重视。被动安全技术和主动安全技术成为了研究重点和热点。汽车侧翻由于其严重的危害性也得到了大家的重视,越来越多的学者和汽车制造商对汽车侧翻的形成机理和控制方法进行研究。而我国对于这一领域的研究处于起步阶段,进行汽车防侧翻控制的研究对进一步提高汽车的安全性能有着现实的意义和广阔的应用前景。轮胎的侧向力与制动力都与其垂直载荷有关,而垂直载荷的大小受到汽车侧倾运动的影响,而横向载荷转移率正是反映垂直载荷及其变化的重要参数,因此,建立了基于横向载荷转移率的非线性轮胎模型,并在此基础上建立基于横向载荷转移率并能够反映汽车运动状态的八自由度汽车系统动力学模型,并将该模型作为汽车防侧翻控制研究的基础。主动转向技术可以主动改变转向角的大小来调整汽车的运动姿态。本文通过深入分析转向角大小对汽车侧翻的影响,采用主动转向来进行防侧翻控制,并进行了数值仿真分析,分析结果说明主动转向能够通过改变汽车的横摆角速度和侧向加速度来降低汽车的横向载荷转移率,从而提高了汽车的防侧翻能力。同时该分析结果为主动转向防侧翻控制设计提供依据。差动制动能够通过改变汽车的动力学特性来改变汽车的行驶姿态。本文通过分析单轮差动制动对汽车动力学特性的影响以及差动制动防侧翻控制的基本原理,建立了基于横向载荷转移率的汽车差动制动防侧翻动力学模型,并在此基础上进行数值仿真研究。通过比较了差动制动与普通制动的防侧翻效果来说明差动制动的优越性,然后研究分析了差动制动时制动力大小对汽车运动姿态的影响,为防侧翻控制设计提供依据。最后,在上述的理论分析的基础上,本文提出一种联合主动转向和差动制动的汽车防侧翻的滑模控制策略及其控制器的设计方法。仿真结果表明该控制策略能够有效地提高汽车的防侧翻能力以及行车轨迹保持能力,增强了汽车的操纵稳定性。更多还原

【Abstract】 With the rapid development of the vehicle industry and the enhancement of the road condition, the vehicle speed has become higher and higher. Meanwhile, more and more traffic accidents occur after the number of automobiles increasing fast. Because of the loss of lives and property grows heavier caused by the traffic accidents, the vehicle security, especially the lateral security, has wined more and more attention. The Active Safety Technology and the Passive Safety Technology have become focus of the vehicle security research. Due to the serious harm of rollover, more and more researcher and auto manufacturers have been doing much research on the theory of rollover and the anti-rollover control methods. But in China, the research on this field is just in the initial stage. So, Studying on the anti-rollover control to enhance the vehicle security has practical significance and broad application prospects.For a tire, its lateral force and braking force are both related to its vertical load, and the vertical load is affected by the roll movement, moreover the Lateral-load Transfer Rate (LTR) is an important parameter to describe the change of the vertical load. By considering this, a nonlinear tire model and an 8-DOF vehicle dynamic model have been built based on the LTR, and the study on anti-rollover control is base on these models.Active steering theology can change the steering angle independently to change the movement of the automobile. Through analysis how the steering angle influences the roll movement, this paper uses active steering theology as an anti-rollover control method. During the simulation, the method is validated. The results show that active steering theology can improve the anti-rollover performance by reducing the LTR through change the yaw rate and the lateral acceleration.Differential braking technology can change the vehicle dynamic to improve the driving movement. After analyzing the differential braking effect on the dynamic and its fundamental for anti-rollover control, a special dynamic model has been built based on the LTR, and then, simulation has been done. Through compare the effect of differential braking and the common braking, differential braking was proved better. Furthermore, how the braking force yielded by differential braking do effect on the driving movement was discussed. All of these study provide theory for the anti-rollover controller design. Finally, based on the analysis above, a sliding mode control theory and its controller design method for anti-rollover by integrated active steering and differential braking was presented. During the simulation, the method works. The results show that this control method can not only enhance the anti-rollover ability but also keep the car driving on the right way.更多还原