电动汽车多自由度整车建模与仿真分析

多自由整车动力学模型是开发电动汽车虚拟样机的核心技术。为研究不同自由度整车动力学模型的适用工况,文章根据经典的汽车动力学思想,利用Matlab/Simulink分别建立了整车动力学模型DOF_2、DOF_7和DOF_10,并进行了单移线工况的仿真实验。实验结果表明,2自由度和7自由度整车模型可适用于模拟低速转弯的行驶工况,10自由度整车模型可适用于模拟低速转弯和高速转弯等多种工况。综上,文章所建模型可为不同工况下整车控制和自适应巡航等项目提供研发平台。     

ADAMS在汽车动力学仿真中的应用研究

运用ADAMS软件建立了C型车多自由度整车多体动力学仿真近似模型，详细考虑了前悬架系统、后钢板弹簧系统和轮胎模型，并对不同方向盘转角及改变整车质心位置下的操纵稳定性进行了动力学仿真。     

汽车高速振动仿真与试验研究

系统介绍应用ＡＤＡＭＳ软件建立多自由度汽车振动模型的方法，并且建立与实际悬架系统和转向系统结构相对应并考虑内外激励的４３自由度整车动力学模型，研究汽车高速行驶时影响平顺性、操纵稳定性的主要原因。     

基于ADAMS-Car的汽车建模与仿真研究

为了有效应用多体动力学软件ADAMS/Car进行车辆动力学研究,介绍并建立了包括汽车底盘、车身、转向、前后悬架、轮胎、动力总成等分系统的汽车整车模型,将整车系统简化为单自由度的质量-刚度-阻尼系统,建立微分方程,分别应用Matlab/Simulink和ADAMS/Car两种仿真方法,对整车模型进行了正弦激励输入下的仿真,比较计算结果可知达到稳态后的车身响应曲线非常吻合。研究表明:基于ADAMS/Car建立的整车多体动力学模型准确,可以用于实际车辆的仿真研究。     

遗传算法优化的整车7自由度EPS控制仿真

根据EPS的结构和动力学特性,建立EPS动力学方程,采用PID控制和基于遗传算法优化的BP神经网络控制策略,并结合7自由度的整车模型和魔术轮胎模型建立整车EPS仿真模型。文中使用了一种含有3个参数的双指数形式的道路附着系数与滑移率关系计算模型,分析了PID控制和优化神经网络控制对EPS整体系统的影响。     

汽车动力传动系实时动力学仿真模型

将动力传动系视为刚体系统,建立适用于开发型驾驶模拟器的动力传动系4自由度实时动力学仿真模型,输入驾驶员的点火开关信号、油门踏板信号、离合器踏板信号及挡位信号,在一定的传动系各部件及驱动轮的运动状态下,传动系模型可向整车动力学模型输出驱动轮上的驱动力矩,从而完成车辆的实时动力学仿真,并进一步向驾驶模拟器输送整车的实时运动状态。仿真与动力性试验的对比结果表明,该模型不但具有实时性,而且可通过整车模型使开发型驾驶模拟器为驾驶员提供逼真的整车运动响应。     

面向结构的汽车齿轮齿条式转向系仿真模型

针对齿轮齿条式转向系统建立了面向结构的转向系统模型,包括转向齿条动力学和转向横拉杆以及转向立柱的弹性特性、转向减振器阻尼力、转向干摩擦、液压助力特性等。所建模型具有完备的动力学自由度,能准确地反映路面激励对转向轮运动状态地影响。并将该模型嵌入到整车动力学模型中,对两种典型工况进行了仿真计算。通过仿真结果与道路试验结果的对比,验证了该模型的正确性。     

车辆横向稳定性自适应预测控制

为解决利用车辆机理模型设计控制器时的自适应问题,针对非线性车辆动力学系统,提出一种基于数据驱动的横向稳定性控制策略。利用递推子空间模型辨识算法设计预测器,根据预测器的形式并结合车辆横向稳定性控制提出一种具有模型自适应特性的预测控制器。利用MATLAB/Simulink建立7自由度整车动力学仿真模型,结合国际标准ISO/DIS 7401:2000以及ISO 3888:1999进行实车道路试验,并对仿真模型进行了数值验证,基于整车动力学模型,对自适应预测控制器的控制效果进行了数值仿真验证,证明了算法的有效性和鲁棒性。     

基于Matlab／simulink的汽车整车模型非线性仿真

随着汽车动态仿真的发展。产生了不同复杂程度的动力学仿真模型。通过将汽车车身看作是一个刚体,忽略悬置的发动机和驾驶员以及座椅。建立了一个非线性七自由度的立体模型,在正弦路面激励下运用Matlab／simulink软件对汽车整车系统进行仿真计算。仿真结果表明,该模型可能存在混沌现象。     

大客车操纵稳定性模拟计算系统开发

文章基于汽车动力学原理,以Visual C++为平台开发了汽车操纵稳定性模拟计算系统。探讨当前汽车操纵稳定性研究的现状、方法和适用于操纵稳定性分析的二自由度和四自由度整车动力学模型及轮胎模型。最后给出了动力学微分方程的求解方法及编程实现技术。     

Development of a generalised equivalent estimation approach for multi-axle vehicle handling dynamics

This paper devotes analytical effort in developing the 2M equivalent approach to analyse both the effect of vehicle body roll and n-axle handling on vehicle dynamics. The 1M equivalent vehicle 2DOF equation including an equivalent roll effect was derived from the conventional two-axle 3DOF vehicle model. And the 1M equivalent dynamics concepts were calculated to evaluate the steady-state steering, frequency characteristics, and root locus of the two-axle vehicle with only the effect of body roll. This 1M equivalent approach is extended to a three-axle 3DOF model to derive similar 1M equivalent mathematical identities including an equivalent roll effect. The 1M equivalent wheelbases and stability factor with the effect of the third axle or body roll, and 2M equivalent wheelbase and stability factor including both the effect of body roll and the third-axle handling were derived to evaluate the steady-state steering, frequency characteristics, and root locus of the three-axle vehicle. By using the recursive method, the generalised 1M equivalent wheelbase and stability factor with the effect of n-axle handling and 2M equivalent generalised wheelbase and stability factor including both the effect of body roll and n-axle handling were derived to evaluate the steady-state steering, frequency characteristics, and root locus of the n-axle vehicle. The 2M equivalent approach and developed generalised mathematical handling concepts were validated to be useful and could serve as an important tool for estimating both the effect of vehicle body roll and n-axle handling on multi-axle vehicle dynamics.     

Lateral dynamics of single unit skid-steered tracked vehicle

In the design and development of high-speed tracked vehicles, it is necessary to have an understanding of the interrelationship between the terrain factors and the vehicle characteristics during steering. The handling behavior of skid-steered tracked vehicles is more complex than that of wheeled vehicles because of non-linear characteristics arising from the sliding interface between the track and the ground. In the present work, a five degree-of-freedom (DOF) steering model of a tracked vehicle is developed, and the handling behavior during non-stationary motion is studied when operating at high and low speeds. It is demonstrated that the inclusion of roll and pitch DOF changes the steering response when compared to the response from three DOF models proposed earlier by several researchers. This is due to the strong coupling between the pitch and yaw motions. The effect of the initial forward velocities on the trajectory of the vehicle during non-stationary motion is also studied. It is observed from the results that the stability is influenced by the type of steering input, steering ratio and vehicle forward speed.     

智能车辆转向变结构控制方法的研究

从车辆的转向动力学和预瞄运动学特性出发，结合转向系统的系统辨识，建立了车辆转向系统的线性模型。运用变结构滑模控制理论和多模型切换，使车辆转向控制具有良好的跟踪性能和鲁棒性。     

Modeling and control of an anti-lock brake and steering system for cooperative control on split-mu surfaces

The brake and steering systems in vehicles are the most effective actuators that directly affect the vehicle dynamics. In general, the brake system affects the longitudinal dynamics and the steering system affects the lateral dynamics; however, their effects are coupled when the vehicle is braking on a non-homogenous surface, such as a split-mu road. The yaw moment compensation of the steering control on a split-mu road is one of the basic functions of integrated or coordinated chassis control systems and has been demonstrated by several chassis suppliers. However, the disturbance yaw moment is generally compensated for using the yaw rate feedback or using wheel brake pressure measurement. Access to the wheel brake pressure through physical sensors is not cost effective; therefore, we modeled the hydraulic brake system to avoid using physical sensors and to estimate the brake pressure. The steering angle controller was designed to mitigate the non-symmetric braking force effect and to stabilize the yaw rate dynamics of the vehicle. An H-infinity design synthesis was used to take the system model and the estimation errors into account, and the designed controller was evaluated using vehicle tests.     

整车多体动力学模型的建立、验证及仿真分析

利用多体动力学方法建立了某轿车的整车非线性多体动力学模型,模型中考虑了前后悬架、转向系统的详细几何结构参数,以及连接处的橡胶衬套、阻尼器的非线性特性,轮胎采用M agic Formu la模型。对所建模型进行了多种试验验证,并分析了该样车的操纵稳定性等相关特性,仿真结果表明所建整车多体模型有较高的精度。     

Effects of FTP-75 mode vehicle fuel economy improvement due to types of power steering system

This paper focuses on fuel economy improvement according to the type of power steering system. Usually, a conventional power steering system is directly driven by the crankshaft of the engine with a belt, known as HPS (hydraulic power steering). However, there is some inefficiency with this system at high engine speeds. To improve this inefficiency, automobile makers have developed two power steering systems: EHPS (electro-hydraulic power steering) and MDPS (motor-driven power steering) or EPS (electric powered steering). However, there has been insufficient study of effects of the type of power steering system on fuel economy. In this paper, the effect of the type of power steering system on fuel economy is studied experimentally, and calculations of the effect on vehicle fuel economy are presenting using computer simulation with AVL cruise software. The results demonstrate that a 1% vehicle fuel economy improvement can be achieved in a vehicle with an electro-hydraulic power steering system compared to a vehicle with a hydraulic power steering system. In addition, a 1.7% vehicle fuel economy improvement can be achieved using a full electric power steering system in a FTP-75 driving cycle. These results could be used to choose a power steering system.     

电动客车稳态转向特性仿真研究

利用虚拟样机分析软件ADAMS建立了整车多体动力学模型,并进行了仿真分析。研究了由电池布置带来的前后轴载荷变化(整车质心位置变化)和横向稳定杆对转向性能的影响。结果显示,整车在空载和满载时均为不足转向;后轴载荷比例增加对稳态转向不利;加装横向稳定杆可以大大改善车厢侧倾,对稳态转向有一定改善。     

Simulation of Vehicle and Power Steering Dynamics Using Tire Model Parameters Matched to Whole Vehicle Experimental Results

This paper uses simulation to investigate how vehicle loading conditions (driver only, passengers, cargo, and fuel) affect power steering system and overall vehicle dynamics. Our purpose of the study was to evaluate the power steering system model for possible use in the National Advanced Driving Simulator (NADS). The effects of changing loading conditions on inertial properties of passenger cars have been found experimentally using a Vehicle Inertia Measurement Facility (VIMF). This paper presents simulation results using a vehicle handling model combined with a power steering system model and a nonlinear tire model. A crucial part of this project was the adjustment of certain parameters of Pacejka's tire model in order to match simulation results with experimental measurements of vehicle and power steering variables in transient maneuvers.     

智能汽车自动紧急转向避撞的跟踪控制方法对比研究

为了提高智能汽车的主动安全性,提出3种不同的自动紧急转向避撞跟踪控制方法。首先建立汽车避撞简化模型,对制动、转向及两者相结合的3种不同避撞方式进行对比分析。其次,为深入研究汽车避撞过程中的实际响应,建立包含转向、制动及悬架3个子系统耦合特性的底盘18自由度统一动力学模型,并进行相关试验验证。随后构建智能汽车自动紧急转向避撞控制框架,对五次多项式参考路径和七次多项式参考路径的横摆角速度和横摆角加速度进行对比分析。接着以线性2自由度转向动力学模型为参考对象,对最优控制四轮转向、最优控制前轮转向、前馈与反馈控制相结合的前轮转向3种不同的跟踪控制系统分别进行设计。最后,以汽车底盘18自由度统一动力学模型为研究对象,对上述3种避撞控制系统进行仿真试验对比分析。研究结果表明：与制动避撞相比而言,转向避撞所需的纵向距离有较大降低,随着车速的增加和路面附着系数的越低,效果越明显;七次多项式参考路径比五次多项式参考路径的避撞过渡过程更为平缓,当实际车速与控制器所用车速不一致时,前者避撞性能表现更优;最优四轮转向控制系统在高、低2种不同附着路面都具有较好的避撞效果,最优前轮转向控制系统次之,而前馈与反馈相结合的前轮转向控制系统在低附着路面上则表现出严重的失稳。     

Vehicle systems: coupled and interactive dynamics analysis

This article formulates a new direction in vehicle dynamics, described as coupled and interactive vehicle system dynamics. Formalised procedures and analysis of case studies are presented.

An analytical consideration, which explains the physics of coupled system dynamics and its consequences for dynamics of a vehicle, is given for several sets of systems including: (i) driveline and suspension of a 6×6 truck, (ii) a brake mechanism and a limited slip differential of a drive axle and (iii) a 4×4 vehicle steering system and driveline system.

The article introduces a formal procedure to turn coupled system dynamics into interactive dynamics of systems. A new research direction in interactive dynamics of an active steering and a hybrid-electric power transmitting unit is presented and analysed to control power distribution between the drive axles of a 4×4 vehicle. A control strategy integrates energy efficiency and lateral dynamics by decoupling dynamics of the two systems thus forming their interactive dynamics.