英文翻译外文文献翻译346四轮转向汽车的转向特性及控制技术.docx

1 附 录 附录 A Steering Behavior and Control Technology 0f Four wheel Steering AutomobiIe ABSTRACT This paper analyses the characteristics of car four-wheel steering control to, summarizes the principle of construction four-wheel steering cars. Introduced the four-wheel steering system control strategy. Points out the four-wheel steering system control technology faces difficulties, and prospects the trend of its development. Keywords: four-wheel steering; Steering characteristics; Working principle; Control; Development; 1. Introduction With modern road traffic system and the development of modern automobile technology, people on the cars steering control performance and driving stability requirement is increasing day by day. As the most effective improve vehicle handling performance of a kind of active chassis control technology - four-wheel steering technology. In the 1980s began in cars get application, and as the modern automobile industry and continuous development. Car four-wheel steering means in turn, the rear car can be relative to body active steering, that the car can be up to four wheels role. To improve the car turned to maneuverability, handling stability and driving safety. 2. The cars steering four-wheel steering 2.1 4ws cars and 2ws steering process analysis Ordinary two wheel steering can not only the front car around its own wheel rotation and relative to body deflection around the precision, then wheel rotation and not only deflection. When the driver turned the steering wheel, front wheel steering, changed directions face front tyre, produced a transverse force, through the front wheel effect on body, make the body yawing and produce centrifugal force, the rear wheels cornering, 2 produced change direction, participate in the sports car to. And the rear and front car 4ws as, can rotation can also deflection. When the driver turned the steering wheel, front and rear wheels, that car almost at the same time to change direction, realize steering movement. In turn, the 2ws car before active steering wheel rotation just makes passive steering. Obviously, 2ws cars in steering process from the steering wheel rotation to rear wheel steering movement in between the existence of certain lag time. This phase lag 2ws automobile steering characteristics make the servo sex becomes poor, and that the car steering radius increased. In addition, 2ws car at a high speed, the steering wheel Angle relative to certain incremental, body yaw-rate and lateral acceleration incremental increases, made the car at a high speed handling and stability becomes poor. And in turn, the car 4ws has done before, rear wheel steering, active in the process of steering, high sensitivity, fast response, effectively overcome the shortcomings. 2.2 4ws automobile steering way According to the theory analysis and road test showed that a four-wheel steering can improve the maneuverability and steering control stability of high speed, modern 4ws car is developed according to the guiding ideology. Generally speaking, in the process of steering cars in 4ws, according to different driving conditions, front and rear wheel steering Angle should follow certain rules between. At present, the front, rear typical 4ws deflection rules generally are described below: (a) inverse phase steering As shown in figure A1 (a) shows, steering wheel Angle at low speeds or larger, front and rear inverse phase shift, realize that the rear wheels with the front deflect deflect instead, and with the steering wheel Angle deflection Angle increases and increases in a certain range. This redirection speed way can improve the manipulation of the car, reduce automobile portability turning radius, making cars maneuverability. Easy car turned turn, obstacle avoidance and driving, garage and parking. As for cars, if rear inverse phase 5 , then turned can reduce minimum steering radius was about 0.5. (b) phase with steering As shown in figure A1 (b) shows, in a high-speed or steering wheel Angle is lesser, front and rear wheels with phase shift, realize that the rear wheels deflect the deflection direction with front wheel. Make the car body yaw-rate greatly reduce automobile body, can reduce the tendency of cornering undergo dynamic, guarantee the overtaking the highway, elevated highway, in and out, in the approach and flyovers insufficient steering state. Now, there are many 4ws cars take improving vehicle handling performance focuses on making cars on high-speed steering stability, without excessive demands in low-speed driving car course-altering maneuvers flexibility. The features is low by front wheel steering car only when only in car speeds, after up to a certain value, rear, only participate in steering phase 3 with four-wheel steering. （ a） Reverse a steering （ b） Coincidental a steering Figure A1 four-wheel steering the front of the car, rear deflection rule 3. Four-wheel steering car components and working characteristics 4ws car is in front wheel steering system, and on the basis of suspension in cars on install a set of rear wheel steering system, both through certain questions of contact, making cars in front wheel steering also participate in the meanwhile, rear wheel steering. After decades of research and development, have molding 4ws car type has a variety of, composition, structure is different, working principle and control methods vary. The typical electric 4ws system mainly by the front wheel steering system, sensors, ECU, rear wheel steering actuators and rear wheel steering transmission mechanism etc. the sensor will front wheel steering motor sports the signal and the signal into ECU were analyzed and calculated, will process after the drive signal to rear wheel steering actuators, rear wheel steering actuators action, through the rear wheel steering transmission mechanism, rear wheel deflection. Meanwhile, ECU when carried out monitoring car operation condition, calculate target steering Angle and rear real-time steering Angle, the difference in value between real-time adjustment to rear wheels corner. Such, can according to the actual sports car, to realize the state car four-wheel steering. General 4ws cars equipped with two turning mode, can enter 4ws state, also can keep the traditional 2ws state, drivers can pass the driving indoor steering mode switch selection. When 4ws car in the course of driving the electronic control system malfunction, rear wheel automatic back into the middle, the automatic into the front wheel steering state, ensure like ordinary front wheel steering car driving safely as automobiles. Meanwhile, dashboard 4ws indicator, warning drivers, stored on ECU fault condition of warranty, so that by yards. 4. Four-wheel steering control of the car 4ws system not only to realize the need for automotive steering movement, and guarantee the vehicle steering traveling stability. At present, in the research and development of automobile 4ws centered on improving car, the transient manipulation stability as a starting point, explore due to rear brought car in response to changes, and 4 adopts various rear wheel control strategy and produce different effect. Auto four-wheel steering control depends on tires were lateral force, four-wheel steering can make cars in turn, the rear directly involved in for car yawing movement and lateralizing control. Through timely, accurate control of the rear wheel steering Angle, not only can shorten the process of steering the transient response, and can actively control cars the trajectory and attitude. In turn, that the car during its longitudinal direction centerline of the direction, even with the direction of the car horn decreases overlap, attitude Angle of steering bodywork cornering, improves the lateral stability car. 4.1 control goals That car in turn to basic keep PianJiao zero gravity side car. So can greatly improve the car to the steering wheel input dynamic response characteristics, largely improved yaw-rate and lateral acceleration of transient performance indicators, lower the body posture change. From the PianJiao zero target start. According to certain control program is to realize the rear wheels to function is derived based four-wheel steering. Of course, the modern 4ws cars also have some other control goal request. 4.2 control strategy model based The general situation of the studies are 4ws system based on a simple dof vehicle model of linear. This is just a kind of utopian mathematical model, when modeling overlooked in some of the dynamic parameters of the car without considering changes, automobile driving produces in the process of many of the random uncertainties and not very accurate. Early 4ws controller design are based on linear dynamic equation with the hypothesis, but due to the above reasons, make the design of control system doesnt meet practical needs, there is no guarantee that the vehicle steering control stability. 4.3 control method Different cars driving performance requirements of steering and different models of the car wheels deflection 4ws law is not the same. Thus, different 4ws vehicle USES control method is endless and same, various control method has its emphases respectively. At present, in some molding 4ws with car on the control method basically has: (a). The set than simply steering system 4ws. (b). Than before, rear wheel steering front-wheel corner function 4ws system. (c).Than before, rear wheel steering j speed function 4ws system is. (d). The 4ws with first-order lagging system. (e).With reversed-phase characteristics 4ws system (f). With optimal control characteristics of 4ws system. (g). Has since learning, white the ability to adjust the 4ws system. Former five kinds of control system belong to classical control theory category, only to satisfy car under certain conditions, but also cant adapt to the need of motor sports of 5 random changes, along with the computer technology and some advanced control theory of development, 4ws system will towards adaptive, intelligent direction. 4.4 4ws system control technology development At present, for research and development of car 4ws remains constant developing and perfecting stage. Although researchers from structure to control principle of four-wheel steering on have done a lot of research, 4ws technology have made many progress. But, in the use of modern control theory of automotive steering control strategy choice of methods of determination and control, mainly depend on experience, the corresponding theoretical basis is still very lack, 4ws technology not really into wide use in commercial car on stage, no widely used. In the technology in relatively mature 4ws cars, most use electric hydraulic power 4ws system. With the rapid development of electronic technology, computer technology in cars, the wide application of electronic electric 4ws system will be the trend of the development of automobile 4ws. Although in 4ws system research and development has made great development, however, as the core technical problems 4ws system - 4ws system controller design, what on earth as the best control objectives? Adopt what kind of control method? Still no in this field is the same view. Already, early before of the 4ws and the system based on a simple dof vehicle model, linear controller design are based on 4ws with linear dynamic equation hypothesis, PID control strategy. We know, 4ws system control mainly dependent on tires were transverse force. Early studies is the automobile tires as linear model, general 4ws control is based on the transverse force by tire wheel in proportion to the side PianJiao assumptions, this assumption just in the lateral acceleration smaller range effective. When in the lateral acceleration larger range, tire cornering characteristics of nonlinear area, will go to one side of the PianJiao tyres by transverse force in the response of the relationship of scale, and no longer the longitudinal force by tire vertical load, etc, have relations. In fact, car in turning down the street, tire basically all work in nonlinear area. At this time, garnish with linear control theory for research, appear reluctant to. 4ws vehicle handling dynamics problems is very complicated nonlinear multibody dynamics problems of the control system for 4ws research should be taken into account in the sports car, in-depth study of affecting its state response, establish simulation kinetic parameters of actual sports car mathematical model, adopt more effective control strategy. With the continuous development of control technology, some advanced modern control method has been applied in 4ws system control study, as optimal control and adaptive control, sliding mode control, robust control etc, in recent years, appeared again fuzzy control, based on artificial neural network theory, control method, etc. The study of 4ws control system from linear field gradually transition to nonlinear fields, some multi-degree-of-freedom car dynamics models have proposed 4ws, but mostly in infancy, is not mature. The future of the 6 development of the system is studied 4ws trend for mainly concentrated : (a). Further research and development of new rear wheel steering actuators and rear wheel steering transmission mechanism, improve the manipulation of steering portability, flexibility and steering Angle of accuracy. (b). For 4ws system, further development, design high performance, high precision, high sensitivity sensor, in order to correctly detection car sports signal. (c). Deep study turning the tyre during transient characteristics as the main factors, to join in the mathematic model of the system 4ws. (d). The control theory and control into method is applied to the 4ws controller study. 7 附录 B 四轮转向汽车的转向特性及控制技术 摘要 本文分析比较了四轮转向汽车的转向特点，概述了电控四轮转向汽车的结构原理。介绍了四轮转向系统的控制策略。指出了四轮转向系统控制技术所面临的困难，并展望其发展趋势。 关键词：四轮转向；转向特点；工作原理；控制；发展； 1.引言 随着现代道路交通系统和现代汽车技术的发展，人们对汽车的转向操纵性能和行驶稳定性的要求日益提高。作为改善汽车操纵性能最有效的一种主动底盘控制技术 四轮转向技术。于二十世纪 80年代中期开始在汽车上得到应用，并伴随着现代汽车工业的发展而不断发展。汽车的四轮转向是指汽车在转向时，后轮可相对于车 身主动转向，使汽车的四个车轮都能起转向作用。以改善汽车的转向机动性、操纵稳定性和行驶安全性 。 2.四轮转向汽车的转向特性 2.1 4ws汽车与 2ws汽车转向过程分析 普通两轮转向汽车的前轮既可绕自身的轮轴自转又可绕主销相对于车身偏转，而后轮只能自转而不偏转。当驾驶员转动方向盘后，前轮转向，改变了行驶方向，地面对前轮胎产生一个横向力，通过前轮作用于车身，使车身横摆，产生离心力，使后轮产生侧偏，改变前进方向，参与汽车的转向运动。而 4ws汽车的后轮与前轮一样，既可自转也能偏转。当驾驶员转动方向盘后，前、后轮几乎同时转向，使汽车改变前进方向，实现转向运动。 2ws 汽车在转向时，前轮作主动转向 ， 后轮只是作被动转向。显然， 2ws 汽车在转向过程中，从方向盘转动到后轮参与转向运动之 间 存在一定的滞后时间。 2ws 汽车的这种相位滞后特性使汽车转向的随动性变差，并使汽车的转向半径增大。另外， 2ws汽车在高速行驶时 ， 相对于一定的方向盘转角增量、车身的横摆角速度和横向加速度的增量增大，使汽车在高速行驶时的操纵性和稳定性变差。而 4ws汽车在转向时，前、后轮都作主动 转向，在转向过程中，灵敏度高，响应快，有效地克服了上述缺点。 8 2.2 4ws汽车的转向方式 根据理论分析研究和大量路试表明，四轮转向能够提高汽车转向的机动灵活性和高速行驶时的操纵稳定性，现代 4ws 汽车就是根据这一指导思想研制的。一般来说，4ws 汽车在转向过程中，根据不同的行驶条件，前、后轮转向角之间应遵循一定的规律。目前，典型 4ws汽车前、后轮的偏转规律一般如下所述。 (a)逆相位转向 如 图 B1 (a)所示，在低速行驶或者方向盘转角较大时，前、后轮实现逆相位转向，即后轮的偏转方向与前轮的偏转方向相反，且偏转角度随方向盘转角增大而在一定范围内增大。这种转向方式可改善汽车低速时的操纵轻便性，减小汽车的转弯半径，提高汽车的机动灵活性。便于汽车掉头转弯、避障行驶、进出车库和停车场。对轿车而言，若后轮逆相位转向 5， 则可减少最小转向半径约 0 5m。 (b)同相位转向 如 图 B1(b)所示，在中、高速行驶或方向盘转角较小时，前、后轮实现同相位转向，即后轮的偏转方向与前轮的偏转方向相同。使汽车车身的横摆角速度大大减小，可 减小汽车车身发生动态侧偏的倾向，保证汽车在高速超车、进出高速公路、高架引桥及立交桥时，处于不足转向状态。现在，有许多 4ws汽车把改善汽车操纵性能的重点放在提高汽车高速行驶的操纵稳定性上，而不过分要求汽车在低速行驶的转向机动灵活性。其工作特点是低速时汽车只采用前轮转向，只在汽车行驶速度达到一定数值后，后轮才参与转向，进行同相位四轮转向。 （ a）逆向位转向 （ b）同向位转向 图 B1 四轮转向汽车的前、后轮偏转规律 3. 四轮转向汽车的组成及工作特性 4ws汽车是在前轮转向系统的基础上，在汽车的后悬架上安装一套后轮转向系统，两者之问通过一定的方式联系，使得汽车在前轮转向的同时，后轮也参与转向。经过几十年的研究与开发，已经成型的 4ws汽车类型有多种，组成、结构不同，控制方式及工作原理也各 异 。典型的电控 4ws 系统主要由前轮转向系统、传感器、 ECU、 后 轮转向执行机构和后轮转向传动机构等组成。如 图 B2 所示，转向时，传感器将前轮转向 9 的信号和汽车运动的信号送 入 ECU进行分析计算，将处理后的驱动信号传给后轮转向执行机构，后轮转向执行机构动作，通过后轮转向传动机构 , 后轮偏转 。同时， ECU进行 时监控汽车运行状况，计算目标转向角与后轮实时转向角之间的差值，来实时调整后轮的转角。这样，可以根据汽车的实际运动状态，实现汽车的四轮转向。一般的4ws 汽车设有两种转向模式，既可进入 4ws 状态 ， 也可保持传统的 2ws 状态，驾驶员可通过驾驶室内的转向模式开关进行选择。当 4ws汽车在行驶过程中电子控制系统出现故障时，后轮自动回到中间位置，汽车自动进入前轮转向状态 ， 保证汽车像普通前轮转向汽车一样安全地行驶。同时，仪表板上的“ 4ws”指示灯亮，警告驾驶员，故障情况被存储在 ECU中，以 便于维修时检码。 图 B2 4ws控制工作原理图 4 四轮 转向汽车的控制 4ws 系统既要实现汽车转向时所需的运动，又要保证汽车转向时的行驶稳定性。目前，在 4ws汽车的研究和开发方面，主要是以改善汽车的瞬态操纵稳定性为出发点，探索由于后轮参与转向而带来的汽车响应变化，以及采用各种后轮控制策略而产生的不同效果。汽车四轮转向的控制依赖于轮胎所受的侧向力，四轮转向能使汽车在转向时，后轮直接参与对汽车横摆运动和侧向运动的控制。通过适时、精确地控制后轮的转向角度，不仅可缩短转向过程的瞬态响应，而且能主动地控制汽车的运动轨迹和姿态。在转向过程中，使汽车的前进方向与其纵向中心线的方向一致，即使得汽车的方向角与姿态角重合，减小转向时车体的侧偏，提高了汽车的侧向稳定性。 4.1控 制目 标 使汽车在转向时能够基本保持汽车重心侧偏角为零。这样能够大幅度提高汽车对方向盘输人的动态响应特性，很大程度上改善了横摆角速度和侧向加速度的瞬态性能指标，降低车身姿态的变化。从侧偏角为零的目标出发。按照一定的控制程序导出