Near-field communication in vehicle ad hoc networks can effectively reduce communication overhead compared to peer-to-peer communication. However, there is still plenty of room for improvements to be made to ensure identity authentication privacy protection and to enhance the security and efficiency of key distributions during transmissions. Therefore, this article proposes an anonymous identity authentication and group key distribution scheme based on quantum random numbers. In the proposed scheme: 1) anonymous credentials for vehicles are generated by a combination of random numbers on the vehicle side and random numbers in the trusted authority (TA), and mutual recognition of vehicles and roadside identity is achieved through the TA in the form of zero-knowledge proof, which achieves privacy protection for the vehicle during authentication and 2) a combined key generation method was devised. The roadside and the TA in this case jointly generate the group key. The TA uses a previously filled quantum key to encrypt the group session key parameter GSP(c) generated by its quantum random number generator to ensure security, and the roadside obtains the group session key parameter GSP(r) by calculating the anonymous credentials of all legitimate vehicles to achieve fast updates of the group session key. This scheme achieves forward and backward security while guaranteeing one-at-a-time encryption. The signaling and computation overheads were calculated, and the signaling overhead was reduced by nearly half. In addition, the group key issuance time was significantly reduced compared with other schemes. Through formal security analysis and experimental verification, the security and feasibility of this protocol were proved.
In addressing the trade-off between prediction model accuracy and computational cost in the context of path tracking control, this paper proposes a learning-based model predictive control (LB-MPC) strategy for autonomous buses. A three-degree-of-freedom (DOF) single-track vehicle dynamic model is established, and an in-depth analysis is conducted on its step response error with respect to variations in vehicle speed, pedal position, and front wheel steering angle compared to the IPG TruckMaker model. Methods for constructing error datasets and receding horizon updates are designed, and a Gaussian process regression (GPR) is employed to establish an error fitting model for real-time error compensation and correction of the nominal single-track model. The error correction model is utilized as the prediction model, and a path tracking cost function is designed to formulate a quadratic programming (QP) optimization problem, proposing an LB-MPC path tracking control architecture. Through joint simulations using the IPG TruckMaker & Simulink platform and real bus experiment, the real-time performance and effectiveness of the proposed GPR error correction model and LB-MPC path tracking control strategy are verified. Results demonstrate that compared to traditional MPC path tracking control strategy, the proposed LB-MPC strategy reduces the average path tracking error by 79.00%.
For the problem of high temperature and uneven distribution affecting the power and safety of the electric vehicle during the battery management systems slave control board's service,a commercial BMS slave control board thermal analysis model is built and verified using the CFD theory and Icepak software.For the first time under vehicle service conditions,temperature field analysis and thermal uniformity optimization research are carried out based on the thermal analysis model.The BMS slave control board thermal simulation analysis shows that the balancing and power supply modules exceed the BMS's design temperature limit of 60 ℃ due to local heat accu-mulation,with the maximum temperature difference of the entire BMS slave control board being 21.0 ℃.A heat dis-sipation path analysis of the BMS slave control board is further carried out,and heat dissipation optimization design is realized by altering the distance,layout of the balancing resistor,PCB substrate and adding thermal pads.By in-creasing the heat dissipation capacity of the BMS slave control board,the highest temperature of the BMS slave con-trol board can be controlled below the design limit of 60 ℃,and the temperature difference of the entire circuit board can be reduced to 6.9 ℃,which enhances the safety and reliability of the BMS slave control board under actu-al vehicle service conditions,providing theoretical methods for the thermal design and optimization of the BMS slave control board.
During the pure electric vehicle high speed cruise driving condition, the unsteady air flow in the chassis cavity is susceptible to self-sustaining oscillations phenomenon. And the aerodynamic oscillation excitation could be coupled with the cabin interior acoustic mode through the body pressure relief vent, the low frequency booming noise may occur and seriously reduces the driving comfort. This paper systematically introduces the characteristics identification and the troubleshooting process of the low frequency aerodynamic noise case. Firstly, combined with the characteristics of the subjective jury evaluation and objective measurement, the acoustic wind tunnel test restores the cabin booming phenomenon. The specific test procedure is proposed to separate the noise excitation source. Secondly, according to the road test results, it is inferenced that the formation mechanism of low frequency noise is the self- sustaining oscillation with the underbody shedding vortex feedback enhancement mechanism at the bottom of the rear chassis. The low frequency exterior airflow oscillation is coupled with the interior cabin acoustic modality by the two air relief vents located at the vehicle rear body parts. Furtherly, the modal coupling mechanism is verified by the volumetric acoustic source excitation test in the semi-anechoic chamber. Considering the engineering feasibility and cost, some improvement schemes are proposed and verified by comparison. Finally, the cover of the vehicle body pressure relief vent is determined to the actual application, the cabin noise level in the specific low frequency band is reduced by 10 dB(A). This paper provides a guiding reference for solving the similar low frequency noise problem of electric vehicles at the high-speed cruise condition.
At present,the unsupervised monocular infrared image depth estimation method is difficult to deal with low texture and low contrast areas,resulting in poor estimation effect,so an unsupervised monocular infra-red image depth estimation algorithm based on local plane guide layer is proposed in this paper.The algorithm con-sists of continuous video frame input,multi-scale feature extraction,ASPP and local planar guidance layer,compu-tational loss,joint training,and output image module.Firstly,by using multiple small-resolution grayscale blocks and multi-scale feature fusion,the problems of blurring edges and occluding objects in infrared images are solved.Secondly,by using the local plane guidance layer to introduce a plane constraint on the depth image,the noise and discontinuity in the depth image are reduced,and the problem of lack of clear processing of low texture areas of the traditional algorithm is solved.The experimental results show that the proposed depth estimation algorithm effective-ly improves the accuracy of monocular depth estimation and reduces the error,and the Abs Rel,Sq Rel,RMS,RMS(log)on the Iray dataset is 0.262,3.621,9.473 and 0.332,respectively,and the accuracy reaches 60.5％,85.2％ and 94.5％ when the threshold indicators are less than 1.25,1.252 and 1.253.
电动汽车能实现节能减排与蓄能调峰,其推广应用对于我国"双碳"战略目标的实现具有重要意义.针对现有电动汽车热管理系统尚存在换热流程复杂、系统能效低、难以轻量化集成等问题,本文中提出基于三介质换热器的电动汽车热管理系统,通过样机实验测试建立了三介质换热器计算模型,并结合电动汽车负荷模型与热泵模型建立了三介质换热器电动汽车热管理系统性能模型,分析该系统在不同工况下的运行特性,并与现有典型热管理系统方案进行性能对比.结果表明,在夏季36℃、60 km/h工况下,三介质换热器热管理系统相较于现有的采用风冷冷凝器、液冷冷凝器的热管理系统分别节能2.3%、15.1%;在冬季0℃、60 km/h工况下,采用舱外、舱内三介质换热器进行余热回收时,分别比不采用余热回收的系统节能5.9%、19.7%.
建立智能汽车的预期功能安全(SOTIF)评价体系,进行SOTIF设计是实现智能驾驶汽车规模应用的必由之路.为完善自动紧急制动(AEB)系统的SOTIF理论,实现AEB系统的SOTIF设计,本文采用系统理论过程分析(STPA)的方法对AEB系统控制模块进行安全分析.根据安全分析的结果提出AEB系统控制模块的SOTIF评价指标,并基于CRITIC法和优劣解距离(TOPSIS)法对提出的评价指标进行综合量化评价.进一步地,使用提出的评价方法对某型智能汽车的AEB系统控制模块进行了基于实车试验的SOTIF评价,评价结果验证了所提出的AEB系统控制模块的SOTIF评价方法的合理性和实用性.最后,对评价结果进行分析,并根据提出的SOTIF评价指标给出AEB系统的SOTIF改进建议.
针对低温环境下重型柴油机的冷起动,提出了喷雾撞击热壁面引燃、回流稳焰的进气预热方案.基于自主设计搭建的预热实验装置,研究了不同风速、喷油落点、喷油策略下的温升和燃烧特性,并开展了CFD数值模拟.实验结果表明:着火和温升对喷油落点呈较强的敏感性,加热板存在最佳位置,风速10 m/s下的平均温升速率达到4.24℃/s.为了兼顾温升速率、燃烧效率和维护成本,高风速下须采取喷射周期为20～25 ms、喷射脉宽为1～3 ms的喷油策略.高速液滴撞击加热板表面后发生回弹和破碎,属于Leidenfrost破碎模式.模拟结果显示:扰流板形成了局部风速低于5 m/s的回流区,促进了蒸发和油气混合,有利于着火和火焰稳定;针对喷射频率合理匹配喷射量,本质上是调控燃烧持续期与喷射周期相适应,使燃油充分利用,提高温升和放热速率.
质子交换膜燃料电池停机吹扫是保证电池在低温环境下安全存储与正常启动的重要方法.为实现快速停机吹扫,且满足-40℃无损存储与低温启动的要求,本文首先构建了吹扫过程水平衡模型,对吹扫过程水的产生和移除进行分析;其次,对吹扫主要参数进行敏感性分析,确定了电池温度为强敏感性参数,增湿温度为中敏感性参数,气体流量为弱敏感性参数;再次,对吹扫结果进行30次-40℃/60℃的冻结/解冻循环试验,并对试验后电池进行物理形貌和电化学分析;最后,进行了-40℃低温启动验证.结果表明,通过对吹扫参数的优化大幅缩短了低温停机吹扫时间,吹扫后的电池在-40℃低温存储后性能未见衰减,形貌无明显变化,且吹扫后的电池能够实现-40℃低温启动.
接头作为白车身框架的关键结构,合理的接头设计对白车身承载能力的提升具有重要意义.本文以B柱下接头为研究对象,提出了基于薄板承载特性的车身接头通用结构设计方法.首先阐述了薄板结构的载荷类型、传力方式和承载特性,为后续的通用接头结构提供理论基础;其次通过灵敏度分析识别了接头载荷条件,用于分析接头的薄板承载特性;然后建立了T型接头薄板的设计规则,并归纳了接头通用结构设计.应用实例与试验表明:接头刚度和车身扭转刚度分别提升35%和8.5%,质量仅增加0.16%.该方法可以快速、有效地改进接头结构设计,提升车身刚度性能.
Under the trend of vehicle intelligence and electrification, it is an important optimization goal of the regionalized thermal environment management performance of the passenger compartment to meet the requirements of both human thermal comfort and vehicle energy saving. Especially in the narrow space environment with highly non-uniform heat flow characteristics, the thermal environment of the passenger compartment can be optimized efficiently only by correctly understanding and quantifying the differences and related effect of local human body heating, response and heat demand. Therefore, combing the physical and physiological thermal regulation characteristics of the human body and its relationship with the environmental heat transfer of the passenger compartment, a numerical analysis model of the thermal response of the human body is established to analyze the variation law of human skin temperature and thermal sensation under the effect of non-uniform local heat flow. The influence factor analysis method is applied to quantify the characteristics of the relationship between local and overall thermal sensation, and different key parts of the effect of local heat flow on the overall thermal sensation of the human body are obtained. The results show that under the same intensity of cold/heat excitation, the head and hands of the human body are the main parts that affect the overall thermal sensation of the human body, with the largest variation amplitudes of the skin temperature and thermal sensation response. In a high temperature environment, the key parts with requirement for local cooling are the head, hands, chest and back in turn while in a cold environment those with requirement for local heating are the head, hands and feet.
提出一种纯电动汽车传动系统与电机结构参数协同设计优化方法,来提高纯电动汽车动力性与经济性,同时降低永磁同步电机齿槽转矩以降低电机的振动噪声.首先,以电机结构参数为输入,额定转矩与齿槽转矩为输出,开展了基于电机多参数仿真和不同机器学习预测模型精度的研究,并建立永磁同步电机额定转矩和齿槽转矩的高精度机器学习预测模型;其次,利用电机基本设计参数(额定转矩、峰值转矩、额定转速、峰值转速)以及峰值效率构建永磁同步电机效率map图的快速预估数学模型;再次,基于电机齿槽转矩预测模型以及电机效率map图的快速预估数学模型,建立电机结构参数与效率特性的映射关系;最后,以电机结构参数和传动比为优化变量,整车动力性、经济性以及电机齿槽转矩为优化目标,运用遗传算法进行多目标优化.仿真结果表明,相较于优化前,优化后的整车性能0-100 km/h加速时间缩短了27.3%,15 km/h最大爬坡度提高了40.5%,WLTC工况能耗减少了1.6%,电机齿槽转矩降低了42.2%.
基于一台三缸1.5TGDI增压直喷发动机研究了三火花塞点火均质稀燃对发动机性能的影响.结果表明:三火花塞可有效拓展稀燃极限,压缩比15时,采用三火花塞在2 000 r/min、8 bar BMEP的特征工况点可实现lambda 1.95的稳定燃烧,最低油耗相比单火花塞降低约5 g/(kW·h),NOx原始排放可降低至约50×10-6,此时lambda受增压能力限制难以进一步增加;压缩比增加至16所能实现的最低油耗相比压缩比15改善不明显,且稀燃极限有所下降.三火花塞对爆震倾向改善作用较小,但可显著加快稀混合气的燃烧速率,相同lambda条件下其燃烧持续期相比单火花塞可缩短约3-6°CA,lambda 1.95时的燃烧持续期相比当量燃烧仅增加约2°CA.通过对潜在最高热效率的研究表明,采用三火花塞设计可在压缩比15条件下最终实现45.02%的有效热效率.
为改善高速低附着路面上的车辆动力学性能,本文针对分布式驱动电动汽车提出一种基于多参数控制的操纵稳定性控制策略,包括上层轨迹跟踪控制和下层转矩分配控制.上层控制器设计基于2自由度车辆模型和驾驶员预瞄偏差模型,提出了MPC轨迹跟踪控制策略,实现对侧向偏差、横摆角偏差、质心侧偏角、横摆角速度的多参数控制.下层控制器以轮胎负荷率最小为优化目标,获得4个车轮电机转矩的最优分配量,借助于7自由度动力学模型,在双移线、蛇行工况下完成了CarSim-Simulink联合仿真.结果表明:提出的控制策略改善了高速、低附着工况下的操纵稳定性和轨迹跟踪精度.
本文采用湍流火焰传播速度模型描述火花点燃(SI)燃烧,针对单个自燃点仍采用湍流火焰传播速度模型,将所有自燃点的当量湍流火焰速度集合作为总当量湍流火焰速度用来描述压燃燃烧,进而建立了火花辅助压燃(SACI)准维燃烧模型.基于该模型研究了空气、外部废气再循环(EGR)稀释对SACI的影响,仿真和实验匹配良好.计算表明:SACI的火焰传播速度高于SI,随点火提前而增大,外部EGR稀释的火焰传播速度低于空气稀释;点火推迟或者增加外部EGR都会导致火焰前锋面面积峰值升高,衰减速度减慢,燃烧等容度减弱;稀释率相当时,空气稀释的热效率更高,但外部EGR稀释的尾气后处理更容易.
制动器的散热能力与乘用车的行车制动性能关联紧密,其中高性能车型在激烈驾驶过程中对制动器的散热能力有更高的需求.本文针对某型碳陶通风盘式制动器总成开展台架实验,并通过对制动盘降温工况中冷却系数的计算,提出了一种表示对流及辐射综合换热的通用拟合关系式,对定量描述制动器的散热性能具有重要参考价值.随后,对该制动器模型进行计算流体力学(computational fluid dynamics,CFD)仿真,探讨了不同变量对该型制动器散热特性的影响,揭示了防尘罩对制动器散热的影响机制.结果表明:对于制动盘初始表面平均温度500℃且无防尘罩遮挡的降温工况,对流换热占总换热量的75%以上,其中制动盘外表面的对流换热起主导作用;此外,当制动盘受防尘罩遮挡时,贴近防尘罩一侧制动盘表面空气温度升高以及制动盘通风道内质量流率的下降使其散热能力显著降低.本文分析结果对制动器散热导流通道的优化设计具有重要指导意义.
为满足100 kW大功率氢燃料电池发动机工作时气体供应需求,开发进气系统控制策略.首先对燃料电池电堆及进气系统进行建模,依托被控对象模型设计开发了"MAP前馈+PID反馈"的阴、阳极进气控制策略,采用单片电压状态与系统效率加权求和的方式标定阳极吹扫时间,并通过台架测试验证了该策略部署到实际控制器中的控制效果.结果显示,在稳态和瞬态工况中均实现了对压力和流量的快速响应,使得电流拉载速率提高到120和-170 A/s,阳极压力稳态和瞬态控制精度分别为98.93%和95.10%,全功率单片电压平均值为15 mV,一致性较好.基于测试数据标定搭建了阴极进气系统状态方程,开发了集成非线性扰动观测器和基于Lyapunov直接法的非线性控制器的进气方案,经MIL仿真测试显示了对空气进气控制目标的准确控制,为进一步提高控制系统响应精度提供了理论基础.
现有的跨域自适应目标检测器主要通过特征分布匹配学习域不变特征来减小域偏移.然而,它们忽略了现实世界中因目标检测对象组合不同和类不平衡等引起的标签分布偏移问题,导致这些方法泛化性较差.为解决这一问题,本文提出一种基于特征和标签联合分布匹配的域自适应目标检测算法,以同时在特征和标签级别上显式对齐域分布.首先,提出一个图像级分类嵌入模块,通过对比学习增强全局特征可迁移性和可判别性.然后,提出类级分布对齐模块,通过多级特征对齐实现域间多模态结构对齐.最后,提出增强一致性正则化模块,通过区域一致性正则化实现跨域标签分布对齐.在多个数据集上的实验表明,所提出的域对齐算法能有效地促进跨域数据迁移前后语义一致性,为智能汽车跨视觉域应用提供了一种有效的解决方案.
本文构造副车架静刚度与K&C性能的并行仿真流程,提出考虑多学科性能耦合的副车架静刚度目标修正方法,并系统地建立一体式空心铸铝副车架分层级设计优化方法.首先,建立副车架计算模型并改进加载方法,提出局部坐标系下的静刚度计算方法,并集成副车架静刚度分析、模型缩减分析、K&C性能分析3种工况,执行多样本分析并通过实验设计矩阵转换,构建K&C性能与静刚度性能的组合代理模型,基于组合代理模型利用K&C性能修正静刚度目标;其次,开展多性能约束的副车架多层级拓扑优化,通过第1层级拓扑优化完成等壁厚主体结构设计,通过第2层级拓扑优化完成变壁厚结构设计.结果表明:经过多层级拓扑优化的副车架1阶、2阶扭转模态分别提升39.3%、14.9%,静刚度及K&C性能满足目标要求,其他各项性能指标均得到显著提升且实现轻量化.本文可为副车架静刚度性能目标制定、K&C性能提升及副车架结构优化提供参考.
