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.     

Disturbance Observer-Based Sideslip Angle Control for Improving Cornering Characteristics of In-Wheel Motor Electric Vehicles

In this paper, a robust sideslip angle controller based on the direct yaw moment control (DYC) is proposed for in-wheel motor electric vehicles. Many studies have demonstrated that the DYC is one of the effective methods to improve vehicle maneuverability and stability. Previous approaches to achieve the DYC used differential braking and active steering system. Not only that, the conventional control systems were commonly dependent on the feedback of the yaw rate. In contrast to the traditional control schemes, however, this paper proposes a novel approach based on sideslip angle feedback without controlling the yaw rate. This is mainly because if the vehicle sideslip angle is controlled properly, the intended sideslip angle helps the vehicle to pass through the corner even at high speed. On the other hand, the vehicle may become unstable because of the too large sideslip caused by unexpected yaw disturbances and model uncertainties of time-varying parameters. From this aspect, disturbance observer (DOB) is employed to assure robust performance of the controller. The proposed controller was realized in CarSim model described actual electric vehicle and verified through computer simulations.     

Brushless PM machine drive in electric and hybrid electric vehicles based on the space vector current control

This paper presents a space vector current controller for a brushless permanent magnet motor in electric and hybrid electric vehicles. The proposed current controller selects space vectors based on the sector selection under a three-level hysteresis comparator to decrease the current ripple. The proposed approach can improve the performance of a brushless PM drive such as the average switching frequency and the total harmonic distortion (THD) compared with the conventional hysteresis current control. The experiment is performed first to verify the proposed control. Then, the method is implemented in a hybrid electric vehicle simulation model with standard driving cycles based on the control strategy to evaluate the drive performance in the vehicle system. The experimental and simulation results indicate that the presented control can improve the performance of the brushless PM machine drive.     

Integrated fuzzy/optimal vehicle dynamic control

There are basically two methods to control yaw moment which is the most efficient way to improve vehicle stability and handling. The first method is indirect yaw moment control, which works based on control of the lateral tire force through steering angle control. It is mainly known as active steering control (ASC). Nowadays, the most practical approach to steering control is active front steering (AFS). The other method is direct yaw moment control (DYC), in which an unequal distribution of longitudinal tire forces (mainly braking forces) produces a compensating external yaw moment. It is well known that the AFS performance is limited in the non-linear vehicle handling region. On the other hand, in spite of a good performance of DYC in both the linear and non-linear vehicle handling regions, continued DYC activation could lead to uncomfortable driving conditions and an increase in the stopping distance in the case of emergency braking. It is recommended that DYC be used only in high-g critical maneuvers. In this paper, an integrated fuzzy/optimal AFS/DYC controller has been designed. The control system includes five individual optimal LQR control strategies; each one, has been designed for a specific driving condition. The strategies can cover low, medium, and high lateral acceleration maneuvers on high-μ or low-μ roads. A fuzzy blending logic also has been utilized to mange each LQR control strategy contribution level in the final control action. The simulation results show the advantages of the proposed control system over the individual AFS or DYC controllers.     

基于微分几何的四轮独立驱动车辆运动解耦控制研究

针对车辆在纵向运动和横摆运动时的强耦合关系给车辆动力学控制带来的困难，以四轮独立电驱动车辆作为研究对象，基于微分几何理论设计了车辆系统运动解耦控制方法，将非线性强耦合的四轮驱动车辆动力学系统解耦为纵向和横向两个相对独立运动控制子系统，并设计了鲁棒控制器，以提高抵抗车辆行驶时不确定外力如侧风的干扰能力。基于 Trucksim 软件建立四轮驱动车辆模型，并针对车辆解耦控制策略和抗干扰策略进行了仿真测试。结果表明，相比于无解耦控制的车辆，采用微分几何解耦控制的四轮独立驱动车辆纵向速度偏差降低了 82.1%，横摆角速度偏差降低了80.7%，且微风干扰下的抗干扰能力明显改善，车辆稳定性显著提升。为验证该运动解耦控制策略在实时系统中的控制效果，还进行了硬件在环试验，结果表明，硬件在环试验的结果与仿真结果一致。     

基于动态门限值的分布式驱动电动汽车驱动力矩控制研究

为改善分布式驱动电动汽车高速行驶稳定性，避免频繁驱动控制操作对汽车行驶安全性的影响，提出了一种适应不同驾驶工况的参数动态门限值算法，设计了汽车附加横摆力矩滑模控制策略和驱动力矩二次规划优化分配控制策略，并进行了角阶跃输入工况和双正弦输入工况的仿真分析。结果表明，所设计的控制策略能有效控制汽车的质心侧偏角与横摆角速度，在保证汽车行驶稳定性的前提下，使质心侧偏角与理想值偏差减小了3.6%以上，轮胎附着利用率减少19.5%以上，有效地降低了轮胎附着利用率，提高了汽车的行驶安全性。     

分布式电驱动车辆力矩分配控制研究现状综述

分布式电驱动车辆具有控制灵活度高、传动链短、结构紧凑、传动效率高、空间布置利用率高等特点,独特的结构特点与驱动方式令其在充分挖掘车辆动力学控制潜力、增强车辆安全性、提升驱动效率、简化底盘结构等方面带来明显的技术革新,为高性能车辆控制技术提供硬件载体.然而,作为过驱动、多约束、车辆纵向-横向-垂向运动行为强非线性耦合系统...     

A Fuzzy Logic Direct Yaw-Moment Control System for All-Wheel-Drive Electric Vehicles

Summary In-wheel-motors are revolutionary new electric drive systems that can be housed in vehicle wheel assemblies. Such E-wheels permit packaging flexibility by eliminating the central drive motor and the associated transmission and driveline components, including the transmission, the differential, the universal joints and the drive shaft. Apart from many advantages of such a system, unequalled independent wheel control allows vehicle dynamic improvement to assist the driver in enhancing cornering and straight-line stability on slippery roads and in adverse ground conditions. In this paper a Fuzzy logic driver-assist stability system for all-wheel-drive electric vehicles based on a yaw reference DYC is introduced. The system assists the driver with path correction, thus enhancing cornering and straight-line stability and providing enhanced safety. A feed-forward neural network is employed to generate the required yaw rate reference. The neural net maps the vehicle speed and the steering angle to give the yaw rate reference. The vehicle true speed is estimated using a multi-sensor data fusion method. Data from wheel sensors and an embedded accelerometer are fed into an estimator, where a Fuzzy logic system decides which input is more reliable. The efficiency of the proposed system is approved by conducting a computer simulation. The proposed control system is an effective and easy to implement method to enhance the stability of all-wheel-drive electric vehicles.     

基于能量流方法的纯电动汽车低温续驶里程提升研究

以某带热泵系统的微小型纯电动乘用车为对象,开展低温 CLTC-P循环工况下的续驶里程测试,通过综合研究 测试数据并分解整车能量流,探讨提升续驶里程的潜在方向。基于AMESim平台建立包含热管理系统的整车动力经济性 模型,经校准后仿真对比不同优化方案,制定组合优化方案。试验验证结果显示,组合优化方案可将低温续驶里程提升 12.6%,其中热管理系统优化方案的贡献显著优于整车阻力优化方案和控制策略优化方案。为提升纯电动乘用车低温环 境下的续驶里程提供参考思路和方法。     

面向全矢量线控车辆极限运动的分层式协同控制

装配四轮分布式驱动-转向（4WID-4WIS）底盘的全矢量线控车辆具备多可控自由度、高速稳定性强的特点,是极限工况稳定裕度和安全性较高的理想车型。为了解决全矢量线控车辆在极限工况下纵横向控制冲突危害行车安全的问题,提出一种基于模型预测控制 （MPC） 的分层式车辆纵向和横向运动协同控制方法。建立基于单轨模型的期望运动状态识别方法,设计模型预测控制器转换动力学目标,采用泰勒展开和前向欧拉方法对预测模型进行线性离散化处理;设计基于负荷率的轮胎力优化分配方法,利用反正切轮胎逆模型求解控制执行量。仿真结果表明,协同控制方法能显著提高车辆在不同路面下的极限运动稳定性,更精准地跟踪期望运动状态,扩大稳定裕度,保障行车安全。     

A Fuzzy Logic Direct Yaw-Moment Control System for All-Wheel-Drive Electric Vehicles

Summary In-wheel-motors are revolutionary new electric drive systems that can be housed in vehicle wheel assemblies. Such E-wheels permit packaging flexibility by eliminating the central drive motor and the associated transmission and driveline components, including the transmission, the differential, the universal joints and the drive shaft. Apart from many advantages of such a system, unequalled independent wheel control allows vehicle dynamic improvement to assist the driver in enhancing cornering and straight-line stability on slippery roads and in adverse ground conditions. In this paper a Fuzzy logic driver-assist stability system for all-wheel-drive electric vehicles based on a yaw reference DYC is introduced. The system assists the driver with path correction, thus enhancing cornering and straight-line stability and providing enhanced safety. A feed-forward neural network is employed to generate the required yaw rate reference. The neural net maps the vehicle speed and the steering angle to give the yaw rate reference. The vehicle true speed is estimated using a multi-sensor data fusion method. Data from wheel sensors and an embedded accelerometer are fed into an estimator, where a Fuzzy logic system decides which input is more reliable. The efficiency of the proposed system is approved by conducting a computer simulation. The proposed control system is an effective and easy to implement method to enhance the stability of all-wheel-drive electric vehicles.     

一种新型电动汽车整车控制器快速检测方案

电动汽车整车控制器VCU是电动汽车(混合动力汽车、纯电动汽车)的中央控制单元,是整个控制系统的核心,负责车辆的驱动力矩的控制、制动能量回馈控制、整车能量管理、CAN网络维护与管理、故障诊断与处理、车辆状态监测等,保证整车在较好的动力性、较高经济性及可靠性的状态下正常稳定地工作。整车控制器的品质稳定性对整车运行和安全起到重大作用。为了满足生产节奏,整车控制器快速检验设备成为了品质检验的必备工具。本文介绍对整车控制器快速检验设备的开发及应用。     

智能网联环境下基于安全势场理论的车辆换道模型

为有效刻画未来智能网联环境下车辆在换道过程中面临的驾驶风险,保证车辆执行更加安全的换道决策,建立基于安全势场理论的车辆换道模型.首先针对车辆换道过程中所遇到的驾驶风险进行评估,利用势场理论给出车辆行驶过程中不同运动状态下安全势场的空间分布.其次根据换道过程中相关车辆不同安全势场分布情况计算出换道结束时的车间临界距离,相...     

A Comparison between Four Computing Models of Different Complexity Describing the Steering Behavior of Two-axled Automobiles

SUMMARY

In this paper chassis controls for vehicle handling and active safety have been reviewed. In particular, we have observed the effectiveness and limit of 4WS and DYC. It is pointed out that DYC is more effective in vehicle motion with larger side-slip and/or higher lateral acceleration and taking the nonlinearity of tire and vehicle dynamics into consideration is essential for introducing the control law for the chassis controls and their integration/coordination. We wish to emphasize that there is a need to further propose control laws based on deeper observation and understanding on the tire and vehicle dynamics.     

基于车辆运行数据的纯电动汽车用户驾驶风格识别与驾驶能耗分析

驾驶风格是用来体现驾驶员在车辆运行状态下对车辆操作的行为特征,对用户驾驶风格进行识别与分析,有利于推进智能驾驶的发展。根据基于116 辆纯电动汽车的车辆运行数据,通过主成分分析方法与K-means 聚类算法,对用户驾驶行为进行分类分析,对驾驶风格进行了分类识别。利用XGBoost 算法构建纯电动汽车驾驶行为与能耗输入模型,利用SHAP 对模型进行解释。结果表明,将驾驶风格聚为3 类具有较好的分类效果,可分别对应冷静型、普通型与激进型;当驾驶员的驾驶风格趋向于激进型时时,车辆的驾驶能耗越高,驾驶风格激进一个层级,车辆百公里电耗增加3~4倍。当驾驶员行车时,其车速越高,油门踏板踩得越深,车辆加速度的绝对值越大,车辆的驾驶能耗越高。驾驶员的驾驶风格越激进,车辆的驾驶能耗越高。     

电动汽车多自由度整车建模与仿真分析

多自由整车动力学模型是开发电动汽车虚拟样机的核心技术。为研究不同自由度整车动力学模型的适用工况,文章根据经典的汽车动力学思想,利用Matlab/Simulink分别建立了整车动力学模型DOF_2、DOF_7和DOF_10,并进行了单移线工况的仿真实验。实验结果表明,2自由度和7自由度整车模型可适用于模拟低速转弯的行驶工况,10自由度整车模型可适用于模拟低速转弯和高速转弯等多种工况。综上,文章所建模型可为不同工况下整车控制和自适应巡航等项目提供研发平台。     

Advanced Chassis Control Systems for Vehicle Handling and Active Safety

In this paper chassis controls for vehicle handling and active safety have been reviewed. In particular, we have observed the effectiveness and limit of 4WS and DYC. It is pointed out that DYC is more effective in vehicle motion with larger side-slip and/or higher lateral acceleration and taking the nonlinearity of tire and vehicle dynamics into consideration is essential for introducing the control law for the chassis controls and their integration/coordination. We wish to emphasize that there is a need to further propose control laws based on deeper observation and understanding on the tire and vehicle dynamics.     

纯电动汽车自动驾驶功能设计

针对纯电动车自动驾驶功能,设计一种利用PID算法对车辆的驱动扭矩进行控制的系统,使得车辆的实际速度与驾驶员的期望速度一致,实现车辆自动驾驶的功能。通过实车验证和调试,该控制系统具有良好的响应精度。相较于传统汽车通过控制喷油量的多少来控制车速,具有更好的鲁棒性和实时性。     

基于功能安全的分布式驱动电动汽车前轮失效补偿控制

分布式驱动电动汽车可以实现四轮转矩分配和差动转向,提升整车的动力学控制性能和经济性,但是四轮转矩独立可控的特点也对功能安全提出挑战.当前轮单侧电机出现执行器故障失效情况时,不仅会产生附加横摆力矩降低车辆安全性,差动转向功能的存在还会使车辆严重偏航.基于此,在设计分布式驱动-线控转向一体化底盘的基础上,基于功能安全提出一...     

Lateral Collision Avoidance Robust Control of Electric Vehicles Combining a Lane-Changing Model Based on Vehicle Edge Turning Trajectory and a Vehicle Semi-Uncertainty Dynamic Model

This paper presents a new control scheme for lateral collision avoidance (CA) systems to improve the safety of four-in-wheel-motor-driven electric vehicles (FIWMD-EVs). There are two major contributions in the design of lateral CA systems. The first contribution is a new lane-changing model based on vehicle edge turning trajectory (VETT) to make vehicle adapt to different driving roads and conform to drivers’ characteristic, in addition to ensure vehicle steering safety. The second contribution is vehicle semi-uncertainty dynamic model (SUDM), which is SISO model. The problem of stability performance without the information on sideslip angle is solved by the proposed SUDM. Based on the proposed VETT and SUDM, the lateral CA system can be designed with H_∞ robust controller to restrain the effect of uncertainties resulting from parameter perturbation and lateral wind disturbance. Single and mixed driving cycles simulation experiments are carried out with CarSim to demonstrate the effectiveness in control scheme, simplicity in structure for lateral CA system based on the proposed VETT and SUDM.