Distributed and self-adaptive vehicle speed estimation in the composite braking case for four-wheel drive hybrid electric car

Considering the controllability and observability of the braking torques of the hub motor, Integrated Starter Generator (ISG), and hydraulic brake for four-wheel drive (4WD) hybrid electric cars, a distributed and self-adaptive vehicle speed estimation algorithm for different braking situations has been proposed by fully utilising the Electronic Stability Program (ESP) sensor signals and multiple powersource signals. Firstly, the simulation platform of a 4WD hybrid electric car was established, which integrates an electronic-hydraulic composited braking system model and its control strategy, a nonlinear seven degrees-of-freedom vehicle dynamics model, and the Burckhardt tyre model. Secondly, combining the braking torque signals with the ESP signals, self-adaptive unscented Kalman sub-filter and main-filter adaptable to the observation noise were, respectively, designed. Thirdly, the fusion rules for the sub-filters and master filter were proposed herein, and the estimation results were compared with the simulated value of a real vehicle speed. Finally, based on the hardware in-the-loop platform and by picking up the regenerative motor torque signals and wheel cylinder pressure signals, the proposed speed estimation algorithm was tested under the case of moderate braking on the highly adhesive road, and the case of Antilock Braking System (ABS) action on the slippery road, as well as the case of ABS action on the icy road. Test results show that the presented vehicle speed estimation algorithm has not only a high precision but also a strong adaptability in the composite braking case.     

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。     

BAS系统的设计和开发

为保证整车具有更好更快的制动性能,将制动系统的管路布置由三通道改为四通道,在现有制动系统DBC7.4ABS模块的基础上附带PBA功能,增加制动辅助（BAS）装置。通过对相应的零部件进行设计变更,对整车制动系统重新进行标定,并针对整车的技术条件进行了常温和冬季性能试验,确保整车制动性能满足欧盟法规要求,并顺利通过了E-mark认证。此制动系统的开发设计无须额外增加传感器,不会增加太多的生产成本,也不会增加整车的质量及安装空间。     

Development of a slip control anti-lock braking system model

This paper describes the initial phase of work carried out as part of an on going study investigating the interaction between the tyre, suspension system and an antilock braking system (ABS). The modelling, analysis simulations and integration of results have been performed using an industry standard Multibody Systems Analysis (MBS) program. A quarter vehicle model has been used together with an individual front suspension system represented by interconnected rigid bodies. The tyre model used can be integrated into vehicle handling simulations but only the theory associated with the generation of longitudinal braking forces is described here. An ABS model based on slip control has been used to formulate the braking forces described in this paper. The simulations, which have been performed braking on wet and dry road surfaces, compare the performance of two different tyres.     

汽车防抱死制动系统的自抗扰控制研究

汽车防抱死制动系统(Anti-lock Braking System,ABS)的作用是确保汽车制动时行驶方向的稳定性、可靠性,但是目前仍存在非线性、时变性以及参数不确定性等问题.为保证汽车制动行驶过程中的操纵稳定性和安全性,进一步实现各工况下防抱死制动系统的优化控制,以影响整车稳定的变量滑移率为研究对象,分析所设计策略...     

基于MATLAB的汽车ABS安全仿真研究

文章利用MATLAB软件对汽车制动防抱死系统进行安全仿真研究,选取合适的分析对象,把ABS系统拆成整车模型、轮胎模型以及制动器模型,分别对各模型进行受力以及运动分析,建立数学模型。最终在Simulink环境中建立仿真模型,结合整车数据,验证分析了汽车有无ABS系统时的制动效果。结果显示,装有ABS制动防抱死的汽车制动效果更好。     

Design of Regenerative Anti-Lock Braking System Controller for 4 In-Wheel-Motor Drive Electric Vehicle with Road Surface Estimation

This paper presents a regenerative anti-lock braking system control method with road detection capability. The aim of the proposed methodology is to improve electric vehicle safety and energy economy during braking maneuvers. Vehicle body longitudinal deceleration is used to estimate a road surface. Based on the estimation results, the controller generates an appropriate braking torque to keep an optimal for various road surfaces wheel slip and to regenerate for a given motor the maximum possible amount of energy during vehicle deceleration. A fuzzy logic controller is applied to fulfill the task. The control method is tested on a four in-wheel-motor drive sport utility electric vehicle model. The model is constructed and parametrized according to the specifications provided by the vehicle manufacturer. The simulation results conducted on different road surfaces, including dry, wet and icy, are introduced.     

电传动矿用自卸车轮边电机驱动系统动态特性研究

矿区环境复杂,电传动矿用汽车的轮边电机传动系统对整车动力性、制动性及平顺性有极大影响,为了综合路面激励和电机自身激励综合分析驱动系统动态特性,采用数值仿真软件建立轮边电机传动系统模型,分析其在启动加速、平稳运行及制动时的动态特性,为了验证模型的准确性进行了实车实验.结果表明该轮边电机传动系统的输出转矩发生考虑波动转矩后...     

基于滑模自抗扰的电制动系统动态负载模拟

为精准模拟传动系弹性及齿隙作用下电制动系统非线性机械负载,提出了自适应模糊滑模自抗扰的测功机控制算法。首先,针对一款前驱电动汽车,建立融合感应电机模型的车辆及台架机电一体化模型,引入典型正常制动和防抱死制动控制作为测试对象。其次,构建扩张状态观测器估计台架系统未建模动态,以自适应模糊滑模控制测功机实时模拟高度非线性机械负载。最后,开展了制动控制策略台架测试的仿真研究。结果表明:提出的方法可精确模拟电制动系统动态负载,有效提高制动控制算法台架测试精度。     

基于模糊解耦控制的车辆转向制动系统研究

车辆转向系统和制动系统之间存在着很强的速度耦合关系,造成两个系统之间的性能相互影响,使得车辆在转向制动这一工况成了汽车最危险的工况之一。本文结合实际车辆参数建立转向系统的二自由度模型和制动系统的单车轮模型,针对车辆转向制动工况设计了模糊解耦控制器,实现了车辆的转向与制动同时控制。经验证含有模糊解耦控制的车辆转向制动系统具有很好的动态控制效果,并且有很强的鲁棒性和自适应性。     

重型载货汽车气压制动系统危险状态识别

针对重型载货汽车因气压制动系统发生管路破裂、机械故障或热衰退导致制动效能下降且不易察觉从而引发严重交通事故的问题，提出基于主成分分析降维（PCA降维）和马尔可夫模型的气压制动系统危险状态识别方法。考虑到三轴载货汽车双回路制动系统的结构复杂性以及制动过程制动踏板动作、系统压力建立和实现车辆减速具有明显的时序性特点，首先采用PCA降维的方法对系统状态进行辨识；然后运用驾驶人制动意图与制动系统响应的双层隐形马尔可夫模型对系统状态进行识别。受驾驶人习惯影响制动踏板作用瞬间辨识度低，采用混合高斯聚类法提取不同制动意图时制动保持阶段数据建立制动意图识别模型和系统响应识别模型，通过二者匹配程度判定系统状态。最后，分别依据实车试验数据对模型进行离线训练和在线辨识验证。试验结果表明：系统正常状态下，基于PCA降维和马尔可夫模型相结合的识别方法能够准确、有效地识别制动系统状态；制动管路断开压力降低状态下，PCA降维方法能够及时有效识别其危险状态。     

Advanced emergency braking under split friction conditions and the influence of a destabilising steering wheel torque

The steering system in most heavy trucks is such that it causes a destabilising steering wheel torque when braking on split friction, that is, different friction levels on the two sides of the vehicle. Moreover, advanced emergency braking systems are now mandatory in most heavy trucks, making vehicle-induced split friction braking possible. This imposes higher demands on understanding how the destabilising steering wheel torque affects the driver, which is the focus here. Firstly, an experiment has been carried out involving 24 subjects all driving a truck where automatic split friction braking was emulated. Secondly, an existing driver–vehicle model has been adapted and implemented to improve understanding of the observed outcome. A common conclusion drawn, after analysing results, is that the destabilising steering wheel torque only has a small effect on the motion of the vehicle. The underlying reason is a relatively slow ramp up of the disturbance in comparison to the observed cognitive delay amongst subjects; also the magnitude is low and initially suppressed by passive driver properties.     

分布式驱动电动汽车回馈制动失效的液压补偿控制

分布式驱动电动汽车各驱动轮转速和转矩可以单独精确控制,便于实现整车动力学控制和制动能量回馈,从而提升车辆的主动安全性和行驶经济性。但车辆在回馈制动过程中,一旦1台电机突发故障,其他电机产生的制动力矩将对整车形成附加横摆力矩,从而造成车辆失稳,此时虽可通过截断异侧对应电机制动力矩输出来保证行驶方向,但会使车辆制动力大幅衰减或丧失,同样不利于行车安全。为了解决此问题,提出并验证一种基于电动助力液压制动系统的制动压力补偿控制方法,力图有效保证整车制动安全性。以轮毂电机驱动汽车为例,首先建立了整车动力学模型以及轮毂电机模型,通过仿真验证了回馈制动失效的整车失稳特性以及电机转矩截断控制的不足;然后,建立了电动助力液压制动系统模型,并通过原理样机的台架试验验证了模型的准确性;接着,基于滑模控制算法设计了制动压力补偿控制器,并在单侧电机再生制动失效后的转矩截断控制基础上完成了液压制动补偿控制效果仿真验证;最后,通过实车试验证明了所提控制方法的有效性和实用性。研究结果表明：在分布式驱动电动汽车单侧电机再生制动失效工况下,通过异侧电机转矩截断控制和制动系统的液压主动补偿,能够使车辆快速恢复稳定行驶并满足制动强度需求。     

Automotive Steering Control in a Split-µ Manoeuvre Using an Observer-Based Sliding Mode Controller

Summary In this paper a sliding mode integral action controller and sliding mode observer are used to enhance vehicle stability in a split- µ manoeuvre. Anti-lock braking systems (ABS) have become an integral part of modern cars, and they have dramatically improved vehicle handling in braking manoeuvres. However, when a vehicle attempts to brake on a surface with uneven friction coefficient such as on wet or icy roads, a so-called split- µ scenario, the yaw moment generated by the asymmetric braking can prove demanding for an inexperienced driver. The controller presented hereworks in conjunction with a conventional ABS system to provide safe and effective braking through steer-by-wire. This paper extends previous state-feedback work by only using certain measurable quantities in the controller, estimating further signals by employing an observer.     

考虑预碰撞时间的自动紧急制动系统分层控制策略研究

为提升汽车的主动安全,对车辆自动紧急制动系统控制策略进行研究。利用分层控制的思想对控制策略进行建模,上层控制器为对车辆制动减速度进行决策的预碰撞时间模型,根据汽车追尾事故深度调查的驾驶员紧急制动数据分析制动系统的制动减速度,在考虑舒适性的条件下确定预碰撞时间阈值。下层控制器按照上层控制器输出的制动减速度,分析车辆轮胎模型和制动系统的关系,通过PID控制调节制动压力对车辆进行控制。在安全评价规程标准工况下验证控制策略的可靠性,通过追尾事故场景的重建来验证控制策略的有效性。仿真结果表明:设计的控制策略在相对车速65km/h以内时能有效避撞,而高于65km/h时能最大程度地降低碰撞车速,减小伤害。     

Automotive Steering Control in a Split-µ Manoeuvre Using an Observer-Based Sliding Mode Controller

Summary In this paper a sliding mode integral action controller and sliding mode observer are used to enhance vehicle stability in a split- µ manoeuvre. Anti-lock braking systems (ABS) have become an integral part of modern cars, and they have dramatically improved vehicle handling in braking manoeuvres. However, when a vehicle attempts to brake on a surface with uneven friction coefficient such as on wet or icy roads, a so-called split- µ scenario, the yaw moment generated by the asymmetric braking can prove demanding for an inexperienced driver. The controller presented hereworks in conjunction with a conventional ABS system to provide safe and effective braking through steer-by-wire. This paper extends previous state-feedback work by only using certain measurable quantities in the controller, estimating further signals by employing an observer.     

A practical identifier design of road variations for anti-lock brake system

Emergency brake technologies have always been a major interest of vehicle active safety-related studies. On homogeneous surfaces, traditional anti-lock brake system (ABS) can achieve efficient braking performance and maintain the handling capability as well. However, when road conditions are time variant during the braking process, or different at the bilateral wheels, braking stability performance is likely to be degraded. To address this problem and enhance ABS performances, a practical identifier of road variations is developed in this study. The proposed identifier adopts a statechart-based approach and is hierarchically constructed with a wheel layer and a full vehicle layer identifier. Based on the identification results, modifications are made to a four-phase wheel-behaviour-based ABS controller to enhance its performance. The feasibility and effectiveness of the proposed identifier in collaborating with the modified ABS controller are examined via simulations and further validated by track tests under various practical braking scenarios.     

基于AMESim与Simulink/Stateflow的汽车ABS联合建模与仿真研究

通过建立AMESim与Simulink/Stateflow的汽车ABS联合仿真模型,模仿了4独立通道制动系统的整车模型在低附着制动工况下的制动过程.AMESim与Simulink/Stateflow联合建模构成的4轮整车制动模型可以考虑更多因素对汽车实际运行工况的影响.仿真结果显示,该模型能很好的模拟真实的制动工况,缩短制动距离与节约制动时间,且易于变更参数以缩短设计周期.     

基于Simulink和VR工具箱的车辆制动稳定性计算机仿真

基于Matlab／Simulink建立了用于研究车辆制动稳定性的7自由度仿真模型；使用V—Realm Bulider2．0建立了相关的虚拟场景，并通过VR工具箱提供的接口实现了Simulink模型与虚拟世界的关联，从而可以利用Simulink模型产生的信号数据控制和操纵虚拟世界中车辆的运动状态。通过仿真结果及其虚拟演示，证实此模型能够很好的体现车辆在制动时的运动特征。     

Level and attitude control of the active suspension system with integral and derivative action

A 7-DOF full-car model with optimal active control suspension is utilized to evaluate the vehicle dynamic performances which are achieved through proposed controllers. The optimal controller, which includes the integral action for the suspension deflection, considerably improves the attitude control of a vehicle because the rolling and pitching motion in cornering and braking maneuvers are reduced, respectively. In the viewpoint of level control, the integral control acting on the suspension deflection results in the zero steady-state deflection in response to static body forces and ramp road input. The dynamic characteristics of the suspension control system are evaluated in terms of time domain and frequency domain. The simulations in the time domain demonstrate the advantages of the active suspension system obtained by penalizing the integral and derivative of suspension deflections and the derivative of roll and pitch angles in the performance index. The frequency characteristic curves obtained by simulations regarding integral action or derivative action show the increase of both ride comfort and road-holding performances by maximizing the use of suspension deflections. The potential of derivative control is shown by the performances of the car traveling over a bump and braking.