基于流入角实时变化的气动性对操纵稳定性的影响

为研究汽车受侧风影响时风压中心线位置对整车操纵稳定性的影响,在CCM+软件中计算不同风速和不同流入角下的气动力,获得气动力与风速和车速的合速度以及流入角的初始关系曲线.利用MATLAB和Adams/Car联合仿真,搭建空气动力学和车辆动力学的双向耦合模型,以风压中心线与质心的距离为变量进行仿真分析.结果 显示,随着风压中心线由质心前方移动到质心后方:在开环仿真工况中,车辆的侧向位移会减小,但是如果风压中心线位于车辆后方超过一定的距离,车辆会在气动力产生的横摆力矩作用下向另外一侧偏移;闭环仿真工况中,当风压中心线穿过车辆质心时,由于侧向力的存在,方向盘依然需要一个很小的转角以维持直线行驶,风压中心线需要继续后移以保证方向盘稳态时的回正.     

非线性油气悬架的平顺性仿真研究

该文针对某工程车辆油气悬架系统建立了单气室油气弹簧的非线性刚度模型，在传统的定刚度车辆两自由度振动模型中加入了非线性的因素，使计算机仿真更接近工程实际。在Maflab／Simulink的环境下，对油气弹簧的刚度非线性、D级随机路面输入以及在随机路面输入下的车辆平顺性进行了计算机仿真。最后将油气悬架平顺性仿真结果和线性二次型最优主动控制悬架以及钢板弹簧被动悬架进行了比较，证明了油气悬架在降低车身加速度、改善轮胎接地性等方面具有显著的优越性和工程应用价值。     

基于虚拟样机技术的车辆平顺性研究

研究某轿车动力学模型优化,多体动力学理论,采用虚拟样机技术,对车辆行驶的平顺性,建立包含前后悬架、转向系统、车轮、制动系统、车身等在内的整车多体动力学虚拟样机模型,依据国家标准,在ADAMS/Car Ride中成功地对轿车进行脉冲输入和随机路面输入的平顺性仿真,得到的数据输入到MATLAB编制的平顺性评价程序中。对比结果表明,车平顺性较好。在此基础上,并将整车模型简化为二自由度1/4车辆模型,在Matlab/Simulink上建立振动模型,分析了悬架刚度、阻尼比、轮胎刚度对车辆平顺性的影响,得出车身加速度随悬架刚度、阻尼比及轮胎动载荷变化的规律。     

多轴越野车辆的行驶平顺性

以多轴越野车为研究对象,应用机械系统动力学仿真分析软件MSC Adams建立一、二、三桥悬架,轮胎及整车的多体系统模型. 进行整车脉冲输入及随机输入平顺性仿真分析,实现了在车辆设计阶段对其进行平顺性预测与分析的目标.     

汽车钢板弹簧非线性有限元分析

为在汽车动力学特性设计中准确计算汽车悬架的作用力,用HyperMesh建立钢板弹簧的有限元模型,并在钢板弹簧的接触面中添加接触单元模拟板间摩擦.利用Abaqus计算钢板弹簧刚度,考虑中心螺栓和U形螺栓的预紧力,分析不同摩擦因数对钢板弹簧迟滞特性的影响.计算结果表明该模型可用于分析考虑钢板之间摩擦作用时钢板弹簧的受力情况,探讨非线性有限元分析过程中钢板弹簧的刚度和迟滞特性.     

混合动力车辆转矩控制策略研究

在履带车辆行驶稳定性能的研究中,对比传统履带车辆结构形式,串联混合动力履带车辆的结构系统存在非线性特点,稳定性能很难保证.为了优化串联混合动力履带车辆的直驶稳定性能和转向性能,提出转矩调节控制策略;建立了驾驶员模型(包括加速踏板模型、制动踏板模型、方向盘模型)和整车动力学模型.根据驾驶员模型和整车动力学模型,采用转矩调节控制策略,在直驶加速、转向等工况下,进行了计算机仿真,结果表明转矩调节控制策略能有效的满足串联混合动力履带车辆的动力学需求.     

基于ADAMS/MATLAB联合仿真的LuGre动态轮胎模型研究

轮胎作为车辆与路面接触的唯一载体,其力学特性是车辆动力学响应分析和控制的重要基础.目前仿真研究中所使用的轮胎模型多为稳态模型,不能精确地描述轮胎的动态特性.因此,将动态轮胎模型应用于车辆动力学仿真软件中,对于整车动力学仿真和研究具有重要的作用.多体动力学软件Adams中自带的轮胎摩擦模型为静态模型,它将摩擦系数视为一个静态值,而实际轮胎与路面之间的摩擦是动态变化的,应为相对速度和位移的动态函数,所以本文以基于Lu Gre动态轮胎模型,应用Matlab/Simulink软件构建动态轮胎模块,通过接口与Adams/Car连接,进行整车模型与Simulink轮胎模型的同步联合仿真,实现轮胎与路面动态接触的历程的模拟,提高车辆系统仿真的精度.     

基于ADAMS的脉冲路面输入平顺性仿真分析

以某皮卡车为研究对象。利用ADAMS／VIEW软件建立了包括前后悬架、轮胎、车身、转向系和人-椅系统等在内的整车多刚体动力学模型，并对建模中的若干关键问题进行了详细的论述。运用ADAMS软件对建立的整车多体动力学模型成功地实现了脉冲路面输入下的平顺性仿真分析。将仿真所得结果与该车试验所得结果进行了对比，结果表明数据吻合较好，从而认为整车模型建立准确。并为进一步对该车做设计分析打下了良好的基础。     

基于RecurDyn的滑转对履带车辆加速性能影响研究

采用多体动力学仿真软件RecurDyn的履带车辆子系统Track(HM),建立履带车辆多体动力学模型,并在MATLAB/Simulink下建立了整车动态系统仿真模型。对履带车辆在硬、软两种地面的加速过程进行动力学仿真和对比分析,着重讨论在不同滑转的条件下履带车辆的加速性能以及滑转率对加速性能的影响,为履带车辆加速性能的研究与滑转的控制提供指导。     

基于多体动力学的车辆道岔通过性能研究

道岔复杂的轮轨关系及其变截面特性是车辆通过道岔时引起振动甚至脱轨的关键因素.根据60kg/m钢轨18号可动心轨道岔设计布置图,在多体动力学软件中建立车辆—道岔耦合系统模型,在此基础上对车辆—道岔系统模型进行验证,仿真计算车辆侧向和直向通过道岔的动力学响应.结果表明转辙器区、辙叉区轨道截面变化和轮轨型面匹配是影响车辆动力学性能的主要因素.最后,对车辆侧向通过离散轨道模型工况下的动力学响应进行仿真计算,讨论道岔轨下整体刚度和阻尼对模型动力学性能的影响,为改善车辆通过道岔时的动力学性能、道岔轨下刚度与阻尼参数匹配提供理论基础.     

Adaptive steering control without using measurements of lateral velocity of vehicles

In this paper, we propose an adaptive steering controller without using measurements of lateral velocity of vehicles. At first, we show a new dynamic expression suitable for the design of a stable adaptive steering controller without using the lateral velocity. Next, we develop an ideal vehicle model. In the designed ideal vehicle model, a good steering performance can be achieved even if the drivers’ steering characteristics vary. Finally, an adaptive steering controller is developed, so that the actual vehicles can track ideal vehicle model and realize good steering performance.     

四轮转向车辆操纵稳定性仿真分析

对四轮转向车辆的转向特性进行了理论分析,并对某控制策略的四轮转向车辆为例进行了仿真.建立了四轮转向车辆操纵动力学模型,分析了前轮角阶跃输入下四轮转向车辆的稳态响应和瞬态响应与传统前轮转向车辆的主要区别;在四轮转向车辆状态方程的基础上二求解出横摆角速度和侧向加速度与前轮转角的传递函数,与前轮转向车辆对比分析了传递函数零、极点位置对响应特性的影响.借助Matlab/Simulink,对四轮转向车辆进行仿真,发现仿真结果与理论分析吻合.将仿真结果与前轮转向车辆进行比较,阐明了四轮转向车辆的性能优势.研究结果可为评价四轮转向车辆的系统设计提供理论依据.     

整车建模和转向性能分析

转向性能研究中一般会更多地关注方向盘力矩的变化。所以,转向系统对分析精度起决定性影响,必须建立详尽的模型来描述其内部特性,如惯性、刚度、摩擦、阻尼和助力曲线,这些因素对方向盘力矩变化有非常显著的影响,以致影响转向性能。本文阐述了在AMESim软件中建立液压助力转向系统和整车模型的过程。首先提出了一种新的计算转向阀过流面积的方法,以获得真实的转向助力特性,然后建立了包含这个比较详尽的转向系统的整车动力学模型,用于转向性能研究,最后选用了几种实车道路试验结果来验证此模型的准确性。     

Mechanical-Hydraulic Co-Simulation of Full Hydraulic Articulated Steering System

With the development and improvement of the hydraulic steering system, the articulated steering system became the research focus of numerous domestic and foreign scholars. The full hydraulic steering system with a compact structure and ease of operation, is widely used in articulated steering mode. Furthermore, its performance can directly impact the steering sensitivity and stability. This paper studies the working principle and actual structure of the priority valve and the steering control valve, which are very important. By setting up a mathematic model, the system’s load-sensing characteristics and the impact of steering control valve bypass throttle damping on steering stability can be analyzed. The Hydraulic Components Design (HCD) model was established for the hydraulic part of this system. It is proved that the model can reflect the system’s actual properties by comparing simulation and experimental results. The dynamic model is based on its actual prototype parameters by taking the tire and ground forces into account. The steering process’s dynamic characteristics are co-simulated in the 1D+3D system model by combining AMESim and Virtual.Lab Motion. The simulation results show that the system’s load-sensing characteristics ensure the sensitivity of the steering operation, and the bypass throttle damping has significantly improved the operation stability and lowered down the cylinder pressure fluctuations. This can improve the system performance by appropriate optimization.

     

考虑高速公路横向坡道转向行驶操纵稳定性的汽车轴距和轮距分析

为分析汽车轴距和轮距设计对操纵稳定性的影响,建立高速公路横向坡道转向行驶的汽车转向动力学模型,并在MATLAB/Simulink软件中建立相应的仿真模型.采用某型汽车设计轴距和轮距进行仿真,得到以不同速度在不同横向坡度道路上转向行驶时的横摆角速度、侧向加速度和质心侧偏角.根据该型汽车的转向特性和侧翻阈值评价其在高速公路横向坡道转向行驶时的操纵稳定性,结果表明该型汽车的设计轴距和轮距满足操纵稳定性要求.计算方法和仿真结果对整车设计具有指导意义.     

Hybrid attitude control in steering maneuver using ARC Hil setup

This paper presents the design of an active roll controller for a vehicle and an experimental study using an electric actuating roll control system. Firstly, based on a three degrees of freedom linear vehicle model, the controller is designed using lateral acceleration and rollrate feedback. In order to investigate the feasibility of an active control system, experimental work is carried out using a hardware-in-the-loop (Hil) setup which has been constructed using the devised electric actuating system and the full vehicle model including tire characteristics. The performance is evaluated by an experiment using the Hil setup in which steering maneuvers are carried out. Finally, in order to enhance the control performance in a transient region, the hybrid control strategy is proposed and evaluated.     

横摆力矩和主动前轮转向结合的车辆横向稳定性模糊控制仿真

提出一种基于横摆力矩和主动前轮转向相结合的车辆横向稳定性控制方法,以横摆角速度和侧偏角为控制目标,利用前馈补偿和模糊控制产生横摆力矩和附加的前轮转角,通过控制制动力的分配以及对转向角的修正,使车辆转向行驶时的横摆角速度和侧偏角很好地跟踪参考模型.对转向轮阶跃输入和正弦输入两种工况分别进行了仿真研究,采用横摆力矩和主动前轮转向相结合控制方法,车辆转向时的瞬态及稳态响应优于单独的横摆力矩控制,表明该方法能有效地控制车辆横摆角速度和侧偏角,提高车辆转向时的横向稳定性,同时能有效地减轻驾驶员操纵负担.     

基于整车动力学模型的EPS预测控制策略仿真研究

为了提高车辆的转向性能,基于整车动力学模型,研究电动助力转向系统(EPS)控制策略;针对PID控制参数固定不变,无法实时控制EPS动态响应的问题,提出了一种滚动优化的预测控制策略,并运用CarSim整车模型与Matlab软件相结合,实现了EPS控制仿真;通过对比仿真结果中横摆角速度和质心侧偏角等转向性能参数表明:用预测控制算法对EPS实施控制,比传统控制方法更精确,可有效提高车辆的转向性能和操纵稳定性,使EPS操控更加精准和轻捷。     

Stability enhancement and traction control of road vehicles

An algorithm that enhances the stability and traction of a road vehicle (which may be steering) during ‘acceleration’ (meaning either braking or accelerating) is presented. This algorithm has two domains: partial-effort acceleration and maximum-effort acceleration. During partial-effort acceleration, stability enhancement requires only proper distribution of longitudinal traction forces. During maximum-effort acceleration, stability enhancement requires distribution and reduction of longitudinal traction forces. The algorithm attempts to provide the desired levels of acceleration while it simultaneously constrains trajectory disturbance of the vehicle. The algorithm uses total information about the road surface characteristics, the driver's actions, and the vehicle's design and dynamic states. It fully accommodates non-linear vehicle dynamics and tyre force characteristics. The algorithm has the form of a linear program and its operation is traced in a series of graphs where the geometry of linear programming is used as a setting.     

Disturbance Observer Based Control for Four Wheel Steering Vehicles With Model Reference

This paper presents a disturbance observer based control strategy for four wheel steering systems in order to improve vehicle handling stability. By combination of feedforward control and feedback control, the front and rear wheel steering angles are controlled simultaneously to follow both the desired sideslip angle and the yaw rate of the reference vehicle model. A nonlinear three degree-of-freedom four wheel steering vehicle model containing lateral, yaw and roll motions is built up, which also takes the dynamic effects of crosswind into consideration. The disturbance observer based control method is provided to cope with ignored nonlinear dynamics and to handle exogenous disturbances. Finally, a simulation experiment is carried out, which shows that the proposed four wheel steering vehicle can guarantee handling stability and present strong robustness against external disturbances.