汽车助力转向技术及其控制策略的研究

汽车转向系统发展至今,已经历了机械转向、液压助力转向、电控液压转向、电动助力转向、主动转向、后轮随动转向、线控转向和操纵手柄式转向等形式。本文对各种助力转向系统技术及控制策略进行研究,为转向系统的进一步研究提供理论基础。     

汽车转向系统的发展趋势与关键技术

本文介绍了转向系统的发展趋势，并对机械转向、液压动力转向、电子控制液压动力转向和电子控制电动动力转向系统的发展动态和关键技术进行了阐述。     

途安汽车转向系统结构原理与维修

目前,汽车转向系统的种类主要有以下几种：纯机械转向系统、纯液压动力转向系统、电控式液压助力转向系统（EHPS）、电动助力转向系统（EPS）、四轮转向系统及线控转向系统。国产B级车很多都装备了电动助力转向系统,如一汽-大众的迈腾和上海大众的途安等。     

电动转向系统

电动转向系统(EPS,Electric Power Steering)是未来转向系统的发展方向.该系统由电动机直接提供转向助力,省去了液压动力转向系统所必需的动力转向油泵、软管、液压油、传送带和装于发动机上的皮带轮,既节省能量,又保护了环境.另外,还具有调整简单、装置灵活以及无论在何种工况下都能提供转向助力的特点.正是有了这些优点,电动转向系统作为一种新的转向技术,将挑战大家都非常熟知的、已具有50多年历史的液压转向系统.     

汽车电子转向技术发展与展望

汽车电子转向系统是一种全新概念的转向系统，其取消了转向盘和转向车之间的机械连接，通过软件协调它们之间的运动关系，可以实现一系列传统转向系统无法实现的特殊功能。它可以实现传动比的任意设置，并对随车速变化的参数进行补偿。并且可以和ABS、汽车动力学控制、防碰撞、单个车轮转向、轨道跟踪、自动侧向导航等功能相结合，实现对汽车的整体控制。综述了国外汽车电子转向技术的研究现状，介绍了电子转向系统的结构及性能特点，阐述了电子转向系统的关键技术、主要问题及解决方法，并展望了电子转向系统的发展趋势。     

汽车转向系统的现状及发展趋势

汽车转向系统的发展经历了纯机械式转向系统、液压助力转向系统、电动助力转向系统3个基本阶段,线控转向系统为其发展趋势。文中综述了国内外转向技术的发展历程、现状和发展趋势。着重介绍了现在广泛应用的电动助力转向系统的组成、工作原理及其优点,并阐述了转向系统的发展趋势。     

汽车转向系统低频共振研究

在汽车设计中,转向系统是底盘设计的重要部分。在整车NVH(Noise、Vibration、Harshness,噪声、振动与声振粗糙度)性能开发中,转向系统振动是一个重要的影响因素。转向系统由转向器、转向传动机构、转向操纵机构组成;转向操纵机构主要由转向盘、转向管柱、传动轴组成。转向系统的低频共振主要体现在转向盘共振,主要指车辆在怠速状态或者低速行驶时的转向盘振动。以某型轿车为例,对转向系统低频共振问题进行研究,提出相应的解决方案。     

广州本田雅阁轿车动力转向系统故障分析

广州本田雅阁轿车采用常流式流压助力转向系统，该系统主要由动力转向装置、转向操纵机构和转向传动机构3部分组成，其动力转向系统的故障有一般故障、转向噪声和油液渗漏等。一般故障主要包括转向沉重、转向冲击、转向不灵及转向回跳等。对该车动力转向系统的故障进行了分析。     

汽车助力转向系统的使用与维护

汽车动力转向系统根据外界施加在转向机构上的辅助动力来源，被分为电动助力转向系统（EPS）、机械式液压助力转向系统（HPS）和电控式液压助力转向系统（EHPS）3大类。助力转向系统已经被广泛应用在汽车转向机构中，它的应用让汽车转向操控变得非常轻盈。尽管助力转向系统已被很多驾驶者视作不可或缺的车辆装备，但对这一系统仍缺乏足够的了解，忽略了对它的正确使用和维护。     

广本雅阁车动力转向系统故障分析与诊断

广本雅阁轿车采用常流式液压动力转向系统,该系统主要由动力转向装置、转向操纵机构和转向传动机构组成。动力转向装置包括动力转向器、动力转向油泵、储油罐、油液软管和管路等。转向操纵机构包括转向盘和转向轴等;转向传动机构包括转向垂臂、转向拉杆、减振器及转向节臂等;动力转向装置的转向器为齿轮齿条式,转向油泵为转子式。     

New approaches to enhance active steering system functionalities: preliminary results

An important development of the steering systems in general is active steering systems like active front steering and steer-by-wire systems. In this paper the current functional possibilities in application of active steering systems are explored. A new approach and additional functionalities are presented that can be implemented to the active steering systems without additional hardware such as new sensors and electronic control units. Commercial active steering systems are controlling the steering angle depending on the driving situation only. This paper introduce methods for enhancing active steering system functionalities depending not only on the driving situation but also vehicle parameters like vehicle mass, tyre and road condition. In this regard, adaptation of the steering ratio as a function of above mentioned vehicle parameters is presented with examples. With some selected vehicle parameter changes, the reduction of the undesired influences on vehicle dynamics of these parameter changes has been demonstrated theoretically with simulations and with real-time driving measurements.     

Nonlinear PI front and rear steering control in four wheel steering vehicles

Vehicle steering dynamics show resonances, which depend on the longitudinal speed, unstable equilibrium points and limited stability regions depending on the constant steering wheel angle, longitudinal speed and car parameters.

The main contribution of this paper is to show that a combined decentralized proportional active front steering control and proportional-integral active rear steering control from the yaw rate tracking error can assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the yaw rate dynamics driven by the driver steering wheel input. By choosing a suitable nonlinear reference model it is shown that the responses to driver step inputs tend to zero (or reduced) lateral speed for any value of longitudinal speed: in this case the resulting controlled vehicle static gain from driver input to yaw rate differs from the uncontrolled one at higher speed. The closed loop system shows the advantages of both active front and rear steering control: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres, enlarged stability regions, reduced lateral speed and improved manoeuvrability; in addition comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced.

For the designed control law a robustness analysis is presented with respect to system failures, driver step inputs and critical car parameters such as mass, moment of inertia and front and rear cornering stiffness coefficients. Several simulations are carried out on a higher order experimentally validated nonlinear dynamical model to confirm the analysis and to explore the robustness with respect to unmodelled dynamics.     

Nonlinear PI front and rear steering control in four wheel steering vehicles

Vehicle steering dynamics show resonances, which depend on the longitudinal speed, unstable equilibrium points and limited stability regions depending on the constant steering wheel angle, longitudinal speed and car parameters.

The main contribution of this paper is to show that a combined decentralized proportional active front steering control and proportional-integral active rear steering control from the yaw rate tracking error can assign the eigenvalues of the linearised single track steering dynamics, without lateral speed measurements, using a standard single track car model with nonlinear tire characteristics and a non-linear first-order reference model for the yaw rate dynamics driven by the driver steering wheel input. By choosing a suitable nonlinear reference model it is shown that the responses to driver step inputs tend to zero (or reduced) lateral speed for any value of longitudinal speed: in this case the resulting controlled vehicle static gain from driver input to yaw rate differs from the uncontrolled one at higher speed. The closed loop system shows the advantages of both active front and rear steering control: higher controllability, enlarged bandwidth for the yaw rate dynamics, suppressed resonances, new stable cornering manoeuvres, enlarged stability regions, reduced lateral speed and improved manoeuvrability; in addition comfort is improved since the phase lag between lateral acceleration and yaw rate is reduced.

For the designed control law a robustness analysis is presented with respect to system failures, driver step inputs and critical car parameters such as mass, moment of inertia and front and rear cornering stiffness coefficients. Several simulations are carried out on a higher order experimentally validated nonlinear dynamical model to confirm the analysis and to explore the robustness with respect to unmodelled dynamics.     

双前桥转向系统匹配设计

本文主要介绍了牵引车双前桥转向系统的设计,转向器、动转泵的匹配设计,并应用UGNX6软件建立了转向系统的三维模型,对转向系统进行设计校核和优化,设计出性能优越的双前桥动力转向系统。     

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。     

机械式前轮主动转向系统的原理与应用

以宝马轿车上选装的主动转向系统为例,详细介绍了该系统的组成、双行星齿轮机构的结构及工作模式,以及该系统可变传动比、稳定车辆等功能的实现原理和系统安全性设计。指出通过与其他动力学控制系统一起实现底盘一体化集成控制将是主动转向技术未来的发展方向。     

Development of an active front steering (AFS) system with QFT control

This paper investigates an active front steering control strategy based on quantitative feedback theory (QFT). By incorporating feedback from a yaw rate sensor into the active steering system, the control system improves the dynamic response of the vehicle. The steering response of a vehicle generally depends upon uncertain quantities like mass, velocity, and road conditions. Thus, QFT is used to design a controller with robust performance. A multi-degree-of-freedom nonlinear model is co-simulated here by MATLAB Simulink and ADAMS/CAR. The performance of the control system is evaluated under various emergency maneuvers and road conditions. The result shows that the designed robust control system has good control performance and can efficiently improve handing qualities and stability characteristics.     

基于统一模型的转向-悬架系统最优综合控制方法

通过对车辆底盘系统中的转向和悬架系统建立统一的数学模型,利用M atlab/S imu link仿真,结合最优控制理论,分别对被动悬架兼前轮转向系统与主动悬架兼四轮转向综合控制系统进行了对比研究。理论分析与仿真试验表明,综合控制系统下车辆的操纵稳定性和平顺性都得到了很大的提高。     

实现快速调整某转向前桥转向角

转向前桥在汽车上一个非常重要的功能就是实现汽车转向,而转向角是决定转向前桥性能的一个非常重要的参数,本文解决了在桥总成装配线快速调整某转向前桥转向角问题。