【作者】 朱明；

【导师】 邓兆祥；

【作者基本信息】 重庆大学 ， 车辆工程， 2004， 硕士

【摘要】 本文以国产某微型车为研究对象,研究了其动力学参数的提取,动力学模型的建立。基于磁流变减振器建立了汽车半主动悬架系统,并根据最优控制理论进行了控制仿真。主要研究工作包括以下几个方面。采用三种方法对汽车动力学参数进行提取。分别是试验法,三维建模法和图纸查阅。在试验法中设计了专用的双簧倒立摆试验台,对发动机,车门和车椅等复杂部件进行参数测试;利用UG的三维模型对白车身,前后桥作参数提取;根据试验报告获得了悬架的阻尼和刚度参数,以及轮胎的刚度参数。再根据空间力系质心坐标公式和力矩平移定理求得整车的动力学参数。最后针对二自由度1/4模型、四自由度1/2车模型和七自由度全车模型分别建立了相应的力学参数表。磁流变减振器理论建模和试验建模的研究。本文提出的磁流变减振器的工作模式为混合工作模式。基于平行板通道模型的流变学分析,提出了磁流变减振器阻尼力的理论模型。基于Bingham塑性模型提出了磁流变减振器阻尼力的实验模型。根据试验数据对低速和高速段采用分段非线性回归拟合,拟合的仿真数学模型能够比较真实的反映示功特性和速度特性。并对磁流变减振器的时滞现象进行了分析,得出由于LR电路的瞬态响应造成了时滞,可以采用电流驱动器的调节来缩短响应时间。引入磁流变减振器作为执行器,根据拉格朗日法建立了二、四、七自由度的汽车半主动悬架系统动力学方程,在此基础上根据状态空间方法写出了状态方程和输出方程。对不同模型的固有特性进行了分析比较。同时为了验证动力学参数和模型的正确性,利用实车进行了道路试验。对车身的垂直,俯仰和侧倾三种运动姿态进行了固有频率的参数识别。结果表明建立的整车动力学模型能反映真实情况。探讨了利用最优控制理论对基于磁流变减振器的半主动悬架系统进行控制仿真的问题。针对二自由度1/4车模型和七自由度整车模型,分别建立了随机最优控制仿真系统。仿真结果表明,在设计控制规律时,应综合考虑各方面因素,合理选择半主动悬架性能指标函数中的加权系数,控制运动响应,才能改善汽车平顺性和操纵稳定性。更多还原

【Abstract】 Based on one homemade mini-car, this paper researches the method getting the dynamics parameters of a car, and the way establishing the dynamics model. Moreover, this paper designs the semi-active suspension system based on magnetorheological (MR) fluid damper, and simulates it according to Linear-Quadratic (LQ) optimal control theory. The following four subjects are mainly studied.Adopting three methods to get the dynamics parameters of a car. There are test, 3D modeling and referring to drawings respectively. In the test method, a special double spring inverted-pendulum test rig is designed, which is used to test these parameters of engine, doors and seats; Using the 3D models of car-body, front axle and rear axle to get their parameters; According to the test report, getting the damping and stiffness of suspension and the stiffness of tyres. Then obtaining the whole car dynamics parameters based on mass center coordinates formula of space force system and torque translation theorem. Finally, respectively forming different dynamics parameters tables according to different degree of freedom (DOF) models. Study on the theoretic modeling and experimental modeling about MR fluid damper. In this paper, MR fluid damper work mode is mixed mode. Based on the rheology analysis about parallel-plate model, the damping force theoretic model of MR fluid damper is brought forward. Based on Bingham plasticity model, the damping force experimental model of MR fluid damper is put forward. Taking subsection nonlinear regress to fit test data under low and high speed. The result shows that the simulation model can reflect the force-displacement and force-velocity characteristic well. Furthermore, analyzing the time flag phenomena of MR fluid damper, and getting the conclusion that it results from the transient state response of LR circuit and the response time can be decreased by using the current driver.Using Lagrange method to construct 2, 4, and 7 DOF automobile semi-active suspension system based on MR fluid damper. On the basis of it, writing out the state equation and output equation according to state space method. Moreover, analyzing the inherent characteristics according to different DOF models. At the same time, the road test is carried through for validating the dynamics parameters and model. The natural frequencies of sprung mass heave, pitch and roll acceleration are identified. The result shows that the whole car dynamics model can reflect the real vehicle condition. <WP=7>Discussing the problem how to use LQ optimal control strategy for the automobile semi-active suspension based on MR fluid damper. Based on quarter-car and whole-car models, the stochastic optimal control systems are designed respectively. The simulation result shows that only comprehensively consider each factor and rationally select the weight parameters of the semi-active suspension performance target function, can the riding quality and steering controllability be improved.更多还原