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。     

基于近似模型的车辆操纵稳定性及平顺性的优化研究

简述了基于近似模型的车辆操纵稳定性及平顺性的优化设计方法.利用多体动力学软件ADAMS/Car建立了某轿车整车多体动力学模型,并确定了车辆操纵稳定性及平顺性的评价目标.以悬架弹簧刚度、减振器阻尼特性和横向稳定杆刚度为设计变量,利用近似优化数学模型对该轿车进行了操纵稳定性和行驶平顺性的多目标优化计算.结果表明,近似模型技术对于汽车性能的平衡优化是一种十分有效的方法.     

多刚体系统动力学在汽车操纵动力学建模中的应用

Ｒ－Ｗ方法是一种适用于建立多刚体系统模型的普遍性方法，具有推导准确、通用性好、推导出的模型便于用计算机求解等优点。本文应用该方法建立了多自由度汽车操纵动力学模型，给出了有模型对北京１２１轻型货车进行汽车操纵稳定性动态模拟的实例。     

基于UniTire模型的平顺性和操纵稳定性协同研究

为考虑平顺性和操纵稳定性两者之间的联系和相互影响,本文中对两者进行了协同研究。首先基于UniTire模型,结合前后轮路面激励的滤波白噪声模型、平顺性4自由度平面模型和操纵稳定性2自由度平面模型,采用状态方程构建了平顺性和操纵稳定性的协同模型,提出了协同仿真算法。然后在常用路面等级和车速下,对某轿车进行了平顺性和操纵稳定性协同仿真。结果表明,采用平顺性和操纵稳定性协同模型,可同时实现两个性能的协同仿真,而由线性UniTire模型仿真得到的操纵稳定性参数大于非线性UniTire模型仿真的对应结果,说明采用线性轮胎模型研究操纵稳定性偏于保守。     

基于VC++的汽车操纵稳定性模拟计算系统设计

本文基于汽车操纵动力学理论,针对中型客车建立了汽车动力学模型——二自由度模型,通过动力学微分方程求解评价汽车操纵稳定性的评价参数等。又以中型客车为对象和VC++为平台开发了汽车操纵稳定性模拟计算系统软件,并以转向盘角阶跃输入为例进行操纵稳定性计算,获得其特征曲线和评价指标对其操稳性进行评价分析。     

汽车7自由度振动模型建模及在汽车平顺性能仿仿研究中的应用

本文叙述了采用多刚体系统动力学建立汽车７自由度振动模型的方法。并利用该模型对某汽车的平顺性进行了研究。结果证明了该建模方法的正确性和数值计算的稳定性，同时也证明了设计结果的可行性 。     

汽车动理学模型综述

随着汽车动态仿真的发展，产生了不同复杂程度的汽车动理学模型，主要分为集中参数模型和多体模型。在简要说明汽车动理学发腰过程的基础上，介绍了用集中参数模型法建立的动力传动系模型、路面模型以及研究汽车平顺性和操纵稳定性的整车模型，技术介绍了多体模型以及用有限元法和动态子结构法建立的仿直模型，最后提出了汽车动理学模型的发展趋势。     

半主动悬架模糊控制仿真

为缓和路面传递给车身的冲击,改善汽车行驶的平顺性和操作稳定性,文章建立了二自由度1／4车体半主动悬架非线性动力学模型,利用MATLAB模糊逻辑控制工具箱设计半主动悬架的模糊控制器,通过运用MATLAB／SIMULINK,对悬架系统进行了仿真分析。结果表明,该控制方法能有效地降低车身垂直加速度、悬架的动挠度和车轮动载荷,提高了汽车的平顺性和操纵稳定性。     

公路卧铺客车人体平顺性响应分析

建立了“人-卧具”的六自由度振动力学模型和公路卧铺客车的13自由度振动力学模型。应用随机振动理论和汽车平顺性理论，详细讨论在路面随机激励下人体的平顺性响应及在各种影响因素作用下平顺性的变化趋势。     

车辆操纵稳定性及平顺性的协同优化研究

利用车辆多体动力学模型与多目标优化工具,对悬架弹簧、减振器及横向稳定杆特性进行操纵稳定性与行驶平顺性的协同优化仿真.结果表明汽车的操稳性和行驶平顺性的各项性能指标均得到了改善.     

A comprehensive study on the stability analysis of vehicle dynamics with pure/combined-slip tyre models

In this paper, a vehicle's lateral dynamic model is developed based on the pure and the combined-slip LuGre tyre models. Conventional vehicle's lateral dynamic methods derive handling models utilising linear tyres and pure-slip assumptions. The current article proposes a general lateral dynamic model, which takes the linear and nonlinear behaviours of the tyre into account using the pure and combined-slip assumptions separately. The developed methodology also incorporates various normal loads at each corner and provides a proper tyre–vehicle platform for control and estimation applications. Steady-state and transient LuGre models are also used in the model development and their responses are compared in different driving scenarios. Considering the fact that the vehicle dynamics is time-varying, the stability of the suggested time-varying model is investigated using an affine quadratic stability approach, and a novel approach to define the critical longitudinal speed is suggested and compared with that of conventional lateral stability methods. Simulations have been conducted and the results are used to validate the proposed method.     

Vehicle dynamics control using an active third-axle system

This paper introduces the active third-axle system as an innovative vehicle dynamic control method. This method can be applicable for different kinds of three-axle vehicles such as buses, trucks, or even three-axle passenger cars. In this system, an actuator on the middle axle actively applies an independent force on the suspension to improve the handling characteristics, and hence, its technology is similar to slow-active suspension systems. This system can change the inherent vehicle dynamic characteristics, such as under/over steering behaviour, in the linear handling region, as well as vehicle stability in the nonlinear, limit handling region. In this paper, our main focus is to show the potential capabilities of this method in enhancing vehicle dynamic performance. For this purpose, as the first step, the proposed method in both linear and nonlinear vehicle handling regions is studied mathematically. Next, a comprehensive, nonlinear, 10 degrees of freedom vehicle model with a fuzzy control strategy is used to evaluate the effectiveness of this system. The dynamic behaviour of a vehicle, when either uncontrolled or equipped with the active third axle is then compared. Simulation results show that this active system can be considered as an innovative method for vehicle dynamic control.     

Analysis of handling performance based on simplified lateral vehicle dynamics

In this article, the analysis methods for vehicle handling performance are studied. Using simple models, dynamic characteristic parameters such as yaw, natural frequency, and the damping coefficient of a vehicle can be theoretically formulated. Here, the vehicle is simplified by a bicycle (single-track) model, and the tire is modeled by an equivalent cornering stiffness and first order lag. From the experimental road data, the tire model parameters (equivalent cornering stiffness and time lag constant) are extracted. These parameters are then inserted into the theoretically formulated equations of dynamic characteristic parameters. For the purpose of validating the efficiency of the suggested methods, experimental road tests (where the cars have different handling performances) are performed. The results show that vehicle handling performance can be sufficiently represented by the suggested dynamic characteristic parameters. So, it is concluded that the proposed method has practical use for the development of new cars or for the comparison of similar cars since the evaluations of the vehicle handling performance can be efficiently determined by the suggested dynamic characteristic parameters.     

道路几何参数对车辆操纵稳定性影响

为研究道路几何参数对车辆操纵稳定性的影响,本文采用MATLAB/Simulink建立了3自由度整车动力学模型,通过数值仿真模拟,研究了车辆在不同超高、纵坡坡度以及合成纵坡下动力响应,在此基础上进一步分析了在不同车速以及前轮转角输入下,道路几何参数对车辆操纵稳定性的影响.结果表明:与水平路面相比,道路超高和纵坡坡度对车辆...     

Vehicle handling dynamics modelling by a data-driven identification method

Modelling of vehicle handling dynamics has received a renewed attention in recent years. Different from traditional vehicle modelling, a novel data-driven identification method for vehicle handling dynamics is proposed, which can avoid the problems of the under-modelling and parameter uncertainties in the first-principle modelling process. By first-order Taylor expansion, the nonlinear vehicle system can be linearised as a slowly linear time-varying system with fourth-order. In order to identify the derived identifiable model structure, a recursive subspace method is presented. Derived by optimal version of predictor-based subspace identification (PBSID_opt) and projection approximation subspace tracking (PAST), the identification method is numerical stability and gives an unbiased estimation for the closed-loop system. Based on standard road tests, the proposed modelling method is proven effective and the obtained model has good predictive ability. Additionally, it is noted that the model obtained from the initial phase of straight driving is just a mathematical model to describe the relationship between input and output. And when the vehicle is steering, the model can converge to a stable phase quickly and represent vehicle dynamic performance.     

Roll and pitch independently tuned interconnected suspension: modelling and dynamic analysis

In this paper, a roll and pitch independently tuned hydraulically interconnected passive suspension is presented. Due to decoupling of vibration modes and the improved lateral and longitudinal stability, the stiffness of individual suspension spring can be reduced for improving ride comfort and road grip. A generalised 14 degree-of-freedom nonlinear vehicle model with anti-roll bars is established to investigate the vehicle ride and handling dynamic responses. The nonlinear fluidic model of the hydraulically interconnected suspension is developed and integrated with the full vehicle model to investigate the anti-roll and anti-pitch characteristics. Time domain analysis of the vehicle model with the proposed suspension is conducted under different road excitations and steering/braking manoeuvres. The dynamic responses are compared with conventional suspensions to demonstrate the potential of enhanced ride and handling performance. The results illustrate the model-decoupling property of the hydraulically interconnected system. The anti-roll and anti-pitch performance could be tuned independently by the interconnected systems. With the improved anti-roll and anti-pitch characteristics, the bounce stiffness and ride damping can be optimised for better ride comfort and tyre grip.     

Vehicle modeling with nonlinear tires for vehicle stability analysis

The dynamic stability of a vehicle depends on various maneuvering features, such as traction, braking, and cornering. This study presents nonlinear vehicle models for estimating the stability region and simulating the dynamic behavior of a vehicle. Two types of vehicle models were found by considering the degrees of freedom and linearity. A simple model with nonlinear tire dynamics is useful for determining the stability region, while a complex model (a multi-body dynamic model in MSC.ADAMS) is appropriate for carrying out accurate simulations. Actual data for a mid-sized passenger car were used, and the models were validated by comparison with test results.     

An Extended Adaptive Kalman Filter for Real-time State Estimation of Vehicle Handling Dynamics

This paper considers a method for estimating vehicle handling dynamic states in real-time, using a reduced sensor set; the information is essential for vehicle handling stability control and is also valuable in chassis design evaluation. An extended (nonlinear) Kalman filter is designed to estimate the rapidly varying handling state vector. This employs a low order (4 DOF) handling model which is augmented to include adaptive states (cornering stiffnesses) to compensate for tyre force nonlinearities. The adaptation is driven by steer-induced variations in the longitudinal vehicle acceleration. The observer is compared with an equivalent linear, model-invariant Kalman filter. Both filters are designed and tested against data from a high order source model which simulates six degrees of freedom for the vehicle body, and employs a combined-slip Pacejka tyre model. A performance comparison is presented, which shows promising results for the extended filter, given a sensor set comprising three accelerometers only. The study also presents an insight into the effect of correlated error sources in this application, and it concludes with a discussion of the new observer's practical viability.     

汽车操纵性和稳定性的联合优化

在二自由度汽车操纵动力学模型和汽车开环系统操纵性、稳定性评价指标的基础上，提出了同时考虑汽车操纵性和稳定性的加权操纵稳定性评价指标，以及考虑各种车速重要性的加权均匀操纵稳定性评价指标。应用复合形法，对汽车操纵性和稳定性进行的联合优化实例表明，利用所提出的加权均匀操纵稳定性评价指标，可以有效地实现汽车操纵性和稳定性在所有车速范围内的优化。     

Lateral handling improvement with dynamic curvature control for an independent rear wheel drive EV

The integrated longitudinal and lateral dynamic motion control is important for four wheel independent drive (4WID) electric vehicles. Under critical driving conditions, direct yaw moment control (DYC) has been proved as effective for vehicle handling stability and maneuverability by implementing optimized torque distribution of each wheel, especially with independent wheel drive electric vehicles. The intended vehicle path upon driver steering input is heavily depending on the instantaneous vehicle speed, body side slip and yaw rate of a vehicle, which can directly affect the steering effort of driver. In this paper, we propose a dynamic curvature controller (DCC) by applying a the dynamic curvature of the path, derived from vehicle dynamic state variables; yaw rate, side slip angle, and speed of a vehicle. The proposed controller, combined with DYC and wheel longitudinal slip control, is to utilize the dynamic curvature as a target control parameter for a feedback, avoiding estimating the vehicle side-slip angle. The effectiveness of the proposed controller, in view of stability and improved handling, has been validated with numerical simulations and a series of experiments during cornering engaging a disturbance torque driven by two rear independent in-wheel motors of a 4WD micro electric vehicle.