汽车设计参数与使用参数对其转向制动稳定性影响的仿真研究

建立了汽车转向制动响应的12自由度动态数学模型，通过对CA141整车进行的实际路面转向制动稳定性试验，验证了该模型的正确性，利用上述数学模型，仿真计算了CA141汽车有关设计参数与使用参数对其转向制动稳定性的影响，并进行了分析。     

汽车制动性能比较分析

汽车的制动性能关系剑汽车安全行驶性能。ABS防抱死系统的应用是汽车安全性方面最重要的技术进展。通过对装备ABS汽车与普通汽车制动距离的计算比较分析发现,在湿滑的道路上突然制动,ABS系统可以使驾驶员能够保持车辆行驶平稳,在较短的距离内将汽车刹住。但在不湿滑的路面上,缩短刹车距离的范同值比较小。而在冰雪路面上行驶的车辆,没有装备ABS的汽车在湿路面或冻路面上制动时,制动距离会过长且不能猛烈转向。而装备ABS系统的汽车也是如此,因为尽管ABS能提供附加的制动控制和转向控制,但它不能解决这样一个客观的物理事实：那就是在较滑的路面上,可利用的牵引力很小。     

汽车在对开路面制动偏驶后的车道恢复控制研究

针对汽车在两侧路面附着系数相差较大的对开路面制动时汽车偏离正确行驶车道的状况,提出了利用主动转向方法控制汽车恢复正确行驶车道的控制策略和控制模式,并据此进行了仿真分析。仿真结果表明所提出的控制策略能控制汽车在对开路面制动偏驶后的失稳状况,并使汽车在偏驶后能快速恢复到正确行驶车道,对于提高汽车的安全行驶具有一定的意义。     

汽车控制装置发展动态

汽车各种控制装置的道路环境适应能力明显提高，制动防抱装置能够分别控制各轮的制动力，驱动防滑装置能够在各种路面条件下使用，自动变速器使用模糊逻辑方法换档，四换转向装置通过对的轮转向角实现反馈控制进一步提高了汽车操纵稳定性。     

基于LQR的汽车横摆力矩控制研究

针对汽车极限工况稳定性控制问题,论文基于最优控制理论LQR进行了汽车横摆力矩控制研究.建立了整车七自由度动力学模型,设计了LQR附加横摆力矩控制算法.为了提高制动稳定性,相对于传统单轮制动研究了单侧两轮附加横摆力矩分配方法.最后选择增幅正弦转向低附着路面行驶工况对控制算法进行了验证.仿真结果表明所研究的控制算法能够有效提高汽车极限工况行驶稳定性.     

变路面车辆稳定性控制策略研究

建立了某四轮汽车9自由度车辆模型和轮胎动力模型,并提出了一种基于侧向力利用系数的差动制动、主动转向切换控制策略。模拟了汽车以车速24.5m/s行驶时的一个紧急避让情况,研究了无控制模式、差动制动控制模式、联合控制模式下的车辆横摆角速度、质心侧偏角、质心侧向位移的变化。结果表明,所提出的差动制动联合主动转向技术的控制策略可以满足变路面下车辆稳定性控制要求。     

汽车ABS弯道制动的阶梯控制

提出了汽车ABS弯道制动的阶梯控制模型,在不同附着性能的路面上对该控制模型进行分析验证并与其它滑移率控制方法进行比较,分析表明该控制模型显著改善了汽车ABS弯道制动的制动性能,提高了汽车弯道制动的稳定性和保证了制动效能。     

混合动力汽车制动稳定性分层协调控制策略

提出了混合动力汽车制动稳定性分层协调控制策略。制动过程中横摆力矩的补偿由再生制动力矩和目标滑移率的调整来完成,而通过对目标滑移率的实时确定,实现上层横摆力矩控制与下层滑移率及再生制动力矩控制的统一调节,保证车轮不出现抱死。在Matlab/Simulink平台上建立了7自由度整车模型,分别进行了低附着路面制动转弯和对开路面制动的仿真分析,结果表明,该制动稳定性分层协调控制策略,在保持制动效能的基础上,比单独滑移率控制能更好地保证混合动力汽车的制动稳定性。     

防抱死制动系统的控制通道数对其控制效果的影响

讨论了防抱死制动系统可能的控制通道及基对汽车的制动方向稳定性，转向操纵能力和制动距离的影响，分析了控制通道与汽车制动系统和传动系统的适应性。     

柴油汽车气压式感载阀浅析

气压感载阀的应用柴油汽车在制动时．轮胎完全抱死而拖印，不仅制动效果差，轮胎使用寿命短，而且前轮抱死使柴油汽车失去操纵性，即转向失灵：后轮抱死时柴油汽车将失去稳定性而侧滑．特别是在光滑平坦的路面上极易酿成交通事故。     

Active front wheel steering model and controller for integrated dynamics control systems

We report a model and controller for an active front-wheel steering (AFS) system. Two integrated dynamics control (IDC) systems are designed to investigate the performance of the AFS system when integrated with braking and steering systems. An 8-degrees-of-freedom vehicle model was employed to test the controllers. The controllers were inspected and compared under different driving and road conditions, with and without braking input, and with and without steering input. The results show that the AFS system performs kinematic steering assistance function and kinematic stabilisation function very well. Three controllers allowed the yaw rate to accurately follow a reference yaw rate, improving the lateral stability. The two IDC systems improved the lateral stability and vehicle control and were effective in reducing the sideslip angle.     

对开路面弯道制动ABS控制策略研究

在对开路面弯道制动工况下分析了轮胎受力情况,提出一种基于转角预测前馈、路径偏移量反馈的车辆最佳滑移率动态调节方法,在SIMPACK中建立汽车多体模型,在MATLAB/Simulink中搭建控制系统,并进行了虚拟在环试验。试验结果显示,与传统ABS相比,所提出的控制方法可以显著改善车辆的侧偏位移、横摆角速度以及制动时方向的稳定性,保证了制动效能,使车辆侧向稳定性得到显著提高。     

汽车全工况操纵和制动动力学17自由度的建模与仿真

本文描述了１７自由度汽车全工况操纵与制动过程动力学模型的建模，仿真与验证。该模型考虑了侧风，有无防抱系统，高速，变车速，双移线转变制动等各种极端工况，仿真结果与美国密执安大学的仿真结果十分吻合，证实了该算法与模型具有很好的精度。     

Trends in vehicle motion control for automated driving on public roads

ABSTRACT

In this paper, we describe how vehicle systems and the vehicle motion control are affected by automated driving on public roads. We describe the redundancy needed for a road vehicle to meet certain safety goals. The concept of system safety as well as system solutions to fault tolerant actuation of steering and braking and the associated fault tolerant power supply is described. Notably restriction of the operational domain in case of reduced capability of the driving automation system is discussed. Further we consider path tracking, state estimation of vehicle motion control required for automated driving as well as an example of a minimum risk manoeuver and redundant steering by means of differential braking. The steering by differential braking could offer heterogeneous or dissimilar redundancy that complements the redundancy of described fault tolerant steering systems for driving automation equipped vehicles. Finally, the important topic of verification of driving automation systems is addressed.     

制动与转向协调动作的车辆避撞控制研究（双语出版）

为了弥补现有汽车避撞控制策略以及碰撞风险评价指标单一的不足，提出转向和制动协调的主动避撞控制系统。首先规划了五次多项式换道路径，在对其理论分析的基础上得到转向临界避撞距离和与目标车道车辆的安全距离约束。其次，考虑道路附着系数和系统延迟的影响，基于制动过程给出制动临界避撞距离，并以纵向行驶安全系数ξ和碰撞时间倒数T^-1_TC划分安全行驶区域，利用驾驶人实车跟车数据标定稳态跟随/定速巡航区域的阈值。随后，通过转向/制动临界避撞距离的对比给出2种避撞方式的安全收益范围。最后搭建Simulink/CarSim联合仿真模型，并对其进行不同初始条件下的避撞仿真试验。研究结果表明：转向操作在制动距离不足时仍是有效的；当主车高速近距离接近静止前车时，主车可以顺利采取转向换道动作，而常规ACC系统在2.5 s处的车间相对距离为-0.76 m，事实上已经发生了碰撞；当相邻车道前车与主车纵向间距不满足换道安全距离约束时，避撞控制系统进入紧急制动模式，最大制动减速度达到-0.8g（g为重力加速度），实际最小车间距为5.1 m；通过转向和制动的协调动作，充分发挥了车辆的避撞潜力；ξ和T^-1_TC指标的融合，可以更好地评估碰撞风险并实现不同控制模式的转换，在保证行车安全的同时可避免过分制动给乘客造成的紧张感。     

智能分布式驱动汽车路径跟踪/制动能量回收协同控制策略研究

为了解决智能分布式驱动汽车路径跟踪与制动能量回收系统间的协同控制难题,充分考虑分布式驱动汽车四轮扭矩独立可控在智能驾驶系统中的优势,设计适应不同路面附着条件的智能分布式驱动汽车转向、制动分层协同控制策略。上层控制器依据不同的路面类型设计差异化的多目标代价函数,以综合优化各工况下的控制目标。高附路面下,制定满足最大能量回收值的全局参考车速,在线优化路径跟踪指令,实现最优能量回收的同时减小系统运算负荷;低附路面下,优先考虑车辆的路径跟踪性能和行驶稳定性,在多目标代价函数中取消对全局参考车速的跟随要求,增设终端速度约束与能量回收项性能指标并减小能量回收项性能指标的权重系数。上层控制器基于模型预测控制方法对多目标代价函数进行滚动优化与预测求解,得到期望的前轮转角及4个车轮的总制动扭矩需求。下层控制器根据制动扭矩需求对四轮的液压制动扭矩和电机制动扭矩进行分配,最终完成整个复合制动过程。基于MATLAB/Simulink和CarSim软件,搭建控制器在环仿真平台,并在高附和低附路面条件下对所提出的策略进行试验验证。研究结果表明：高附路面下,所提出的控制策略在准确跟踪期望路径的同时相较固定比例制动力分配方法可提升2.7%的能量回收值并减少约0.02 s的单次计算时间;低附路面下,与使用高附控制策略相比,能够保证车辆的路径跟踪准确性与行驶稳定性,同时可提升7.8%的能量回收值;控制器在环试验结果证明了该协同控制策略对车辆性能提升的有效性。     

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.     

An adaptive integrated algorithm for active front steering and direct yaw moment control based on direct Lyapunov method

In this article, an adaptive integrated control algorithm based on active front steering and direct yaw moment control using direct Lyapunov method is proposed. Variation of cornering stiffness is considered through adaptation laws in the algorithm to ensure robustness of the integrated controller. A simple two degrees of freedom (DOF) vehicle model is used to develop the control algorithm. To evaluate the control algorithm developed here, a nonlinear eight-DOF vehicle model along with a combined-slip tyre model and a single-point preview driver model are used. Control commands are executed through correction steering angle on front wheels and braking torque applied on one of the four wheels. Simulation of a double lane change manoeuvre using Matlab^®/Simulink is used for evaluation of the control algorithm. Simulation results show that the integrated control algorithm can significantly enhance vehicle stability during emergency evasive manoeuvres on various road conditions ranging from dry asphalt to very slippery packed snow road surfaces.