Real-Time Co-optimization of Gear Shifting and Engine Torque for Predictive Cruise Control of Heavy-Duty Trucks

Fuel consumption is one of the main concerns for heavy-duty trucks.Predictive cruise control(PCC)provides an intriguing opportunity to reduce fuel consumption by using the upcoming road information.In this study,a real-time implementable PCC,which simultaneously optimizes engine torque and gear shifting,is proposed for heavy-duty trucks.To minimize fuel consumption,the problem of the PCC is formulated as a nonlinear model predictive control(MPC),in which the upcoming road elevation information is used.Finding the solution of the nonlinear MPC is time consuming;thus,a real-time implementable solver is developed based on Pontryagin’s maximum principle and indirect shooting method.Dynamic programming(DP)algorithm,as a global optimization algorithm,is used as a performance benchmark for the proposed solver.Simulation,hardware-in-the-loop and real-truck experiments are conducted to verify the performance of the proposed controller.The results demonstrate that the MPC-based solution performs nearly as well as the DP-based solution,with less than 1%deviation for testing roads.Moreover,the proposed co-optimization controller is implementable in a real-truck,and the proposed MPC-based PCC algorithm achieves a fuel-saving rate of 7.9%without compromising the truck’s travel time.

跨临界CO2汽车空调多PID控制动态性能仿真研究

为了研究出一种高效的汽车空调控制逻辑系统,借助GT-SUITE仿真软件,建立了跨临界CO2空调动态仿真模型,以节流阀开度、压缩机转速、风机转速为被控参数,以排气压力、送风温度和车厢温度为目标参数,研究了多PID控制的启动顺序和启动延迟时长对系统动态响应性能的影响,并研究了环境温度和车速随时间变化的动态工况下系统的动态响应特性。结果表明:排气压力—送风温度—车厢温度的启动顺序可以提高动态响应性能,使排气压力和送风温度的稳定时间分别缩短75%和38.9%,节流阀开度、压缩机转速、风机转速的波动范围分别减小85%、50%和63.3%;3个PID控制器依次延时40 s启动时压缩机和风机转速的波动范围相比其他延时控制分别下降50%和63.3%,即提升了控制系统的稳定性;在环境温度和车速随时间发生变化的过程中,PID控制响应迅速,控制目标参数的实时值稳定性高。本文提出的控制方式高效稳定,可为实际空调工程的控制设计提供参考。

Vehicle Ride Comfort Based on Matching Suspension System

The existing investigations of vehicle ride comfort mainly include motion characteristics analysis based on creating a multi-body dynamic simulation model,and the parameters analysis to improve the suspension control for the target.In the study of creating multi-body dynamics simulation models,there is usually without considering calibration and test verification,which make it difficult to ensure the production of engineering.In the study of improving the suspension control parameters for the target,there is a lack of systematic match about comfortable and human characteristics,so it is difficult to implement in the field of driving and leading the vehicle design.In this paper,based on the different characteristic of suspension system that effects on the vehicle ride comfort, according to the suspension system dynamic mechanism,the research methods of vehicle road test,bench test and CAE simulation is used,at the same time,several sensitivity analysis of vehicle ride comfort related to suspension stiffness and damping and speed is made. As a result,the key suspension systematic parameters are given that have important impact on vehicle ride comfort.Through matching parameters,a calibration analysis of suspension system based on human comfort is obtained.The analysis results show that the analysis methods for the design target of making the vehicle with best comfort are effective.On the basis of the theory study,five suspension parameter matching principles are explored to promise the vehicle with perfect ride comfort,which also provide theoretical basis and design methods for the passenger car best match of suspension system stiffness and damping.The research results have the promotional value of practicability and a wide range of engineering application.

Effect of annealing cooling rate on microstructure and mechanical property of 100Cr6 steel ring manufactured by cold ring rolling process

Pre-heat treatment is a vital step before cold ring rolling and it has significant effect on the microstructure and mechanical properties of rolled rings.The 100Cr6 steel rings were subjected to pre-heat treatment and subsequent cold rolling process.Scanning electron microscopy and tensile tests were applied to investigate microstructure characteristic and mechanical property variations of 100Cr6 steel rings undergoing different pre-heat treatings.The results indicate that the average diameter of carbide particles,the tensile strength and hardness increase,while the elongation decreases with the decrease of cooling rate.The cooling rate has minor effect on the yield strength of sample.After cold ring rolling,the ferrite matrix shows a clear direction along the rolling direction.The distribution of cementite is more homogeneous and the cementite particles are finer.Meanwhile,the hardness of the rolled ring is higher than that before rolling.

Kinetic equation based on non-steady-state diffusion of oxygen in solid copper

The kinetics of internal oxidation of dilute Cu-Al alloys, containing 0.4475%-2.214%Al (mole fraction) was investigated over the temperature range of 1023-1273K and the depth of internal oxidation was measured by microscopy. Based on non-steady-state diffusion, a rate equation is derived to describe the kinetics of internal oxidation of plate: X=k-t-, where X is the oxidation depth, t is the oxidation time. For the internal oxidation of Cu-Al alloys employed in the synthesis of alumina dispersion strengthened copper, the permeability of oxygen in solid copper is obtained from the internal oxidation measurements. Investigation shows that the depth of the internal oxidation is a parabolic function of time, the typical shape of the front of internal oxidation is of planar morphology, and there is no evidence for preferential diffusion along grain boundaries.

送风温度对车用跨临界CO_(2)制冷系统影响的仿真研究

为研究送风温度对实际车用跨临界CO_(2)制冷系统综合性能的影响,借助GT-Suite仿真软件,建立了单级跨临界CO_(2)制冷系统的仿真模型。基于设计的三种工况,在风量设置上限的情况下对比了不同送风温度下系统的性能,提出了有效COP_(eff)的概念并对此进行研究。结果表明:在其他工况相同的条件下,提高送风温度可以提高系统的COP、有效COP_(eff)以及带风机功耗的有效COP_(eff,b);在低冷负荷工况下,考虑系统风机功耗后的综合性能COP_(b)存在最优值为3.819,即系统存在对应的最优送风温度,但当负荷增大至一定水平时,最优送风温度不再存在。

Lightweight Design of Commercial Vehicle Cab Based on Fatigue Durability

To better improve the lightweight and fatigue durability performance of the tractor cab,a multi-objective lightweight design of the cab was carried out in this study.First,the finite element model of the cab with counterweight loading was established and then confirmed by the physical testing,and use the inertial reliefmethod to obtain stress distribution under unit load.The cab-frame rigid-flexible couplingmulti-body dynamicsmodelwas built by Adams/car software.Taking the cab airbag mount displacement and acceleration signals acquired on the proving ground as the desired signals and obtaining the fatigue analysis load spectrum through Femfat-Lab virtual iteration.The fatigue simulation analysis is performed in nCode based on the Miner linear fatigue cumulative damage theory.Then,with themass and fatigue damage values as the optimization objectives,the bending-torsional stiffness and first-order bending-torsional mode as constraints,the thickness variables are screed based on the sensitivity analysis.The experimental design was carried out using the Optimal Latin hypercube method,and the multi-objective optimal design of the cab was carried out using theKriging approximationmodel fitting and particle swarmalgorithm.The weight of the optimized cab is reduced by 7.8%on the basis of meeting the fatigue durability performance.Finally,a seven-axis road simulation test rig was designed to verify its fatigue durability.The results show the optimized cab can consider both lightweight and durability.

Optimization of Engine Control Strategies for Low Fuel Consumption in Heavy-Duty Commercial Vehicles

The reduction of fuel consumption in engines is always considered of vital importance.Along these lines,in this work,this goal was attained by optimizing the heavy-duty commercial vehicle engine control strategy.More specifically,at first,a general first principles model for heavy-duty commercial vehicles and a transient fuel consumptionmodel for heavy-duty commercial vehicles were developed and the parameters were adjusted to fit the empirical data.The accuracy of the proposed modelwas demonstrated fromthe stage and the final results.Next,the control optimization problem resulting in low fuel consumption in heavy commercial vehicles was described,with minimal fuel usage as the optimization goal and throttle opening as the control variable.Then,a time-continuous engine management approach was assessed.Next,the factors that influence low fuel consumption in heavy-duty commercial vehicles were systematically examined.To reduce the computing complexity,the control strategies related to the time constraints of the engine were parametrized using three different methods.The most effective solution was obtained by applying a global optimization strategy because the constrained optimization problem was nonlinear.Finally,the effectiveness of the low-fuel consumption engine control strategy was demonstrated by comparing the simulated and field test results.

低计算量的窄带ANC算法优化及实车DSP系统试验分析

车内主动噪声控制中常使用的传统滤波-x最小均方(Filtered-x Least Mean Square,FxLMS)算法由于计算复杂度高,往往导致系统硬件算力不足,降噪效果不理想。文章提出一种基于改进局部次级通路建模方法的自适应陷波(Local-secondary-path Filtered-x Least Mean Square,LFxLMS)算法及其相应的窄带主动噪声控制(LFxLMS-based Narrowband Active Noise Control,LFx-NANC)系统。所提出的改进局部次级通路建模方法具有更高的建模精度,且该系统相较于传统系统大大降低了计算复杂度。通过基于Matlab软件的仿真分析,验证了该系统对稳态及非稳态多谐波噪声的降噪性能。基于ADSP-21489控制器搭建车内双通道LFx-NANC系统,实现了在稳态工况下主驾位置处二、四、六阶降噪量分别达到34.67、21.41、10.29 dB(A);在加速工况下主驾位置处总声压级和二阶降噪量分别达到6.01 dB(A)和20.40 dB(A),同时在其他位置均有较好的降噪效果。文中提出的方法为主动噪声控制的工程应用提供了参考。

基于SSD与FaceNet的人脸识别系统设计

人脸识别技术广泛应用于考勤管理、移动支付等智慧建设中。伴随着常态化的口罩干扰,传统人脸识别算法已无法满足实际应用需求,为此,本文利用深度学习模型SSD以及FaceNet模型对人脸识别系统展开设计。首先,为消除现有数据集中亚洲人脸占比小造成的类内间距变化差距不明显的问题,在CAS-IA Web Face公开数据集的基础上对亚洲人脸数据进行扩充;其次,为解决不同口罩样式对特征提取的干扰,使用SSD人脸检测模型与DLIB人脸关键点检测模型提取人脸关键点,并利用人脸关键点与口罩的空间位置关系,额外随机生成不同的口罩人脸,组成混合数据集;最后,在混合数据集上进行模型训练并将训练好的模型移植到人脸识别系统中,进行检测速度与识别精度验证。实验结果表明,系统的实时识别速度达20 fps以上,人脸识别模型准确率在构建的混合数据集中达到97.1%,在随机抽取的部分LFW数据集验证的准确率达99.7%,故而该系统可满足实际应用需求,在一定程度上提高人脸识别的鲁棒性与准确性。

柴油含硫量对国六重型柴油机排放的影响

基于某款国六重型柴油机,搭载全流发动机台架,分别采用3种不同典型硫含量的柴油,对比世界统一瞬态循环(WHTC)下NO_(x)、HC和CO排放的差异。结果表明:随着柴油含硫量的升高,NO_(x)排放量也会显著升高,但HC、CO的排放量一直维持在较低水平,无明显变化。

基于DBO-MPC的混合动力汽车能量管理策略

混合动力汽车(hybrid electrical vehicle,HEV)的能量管理策略直接决定了车辆的燃油经济性、驾驶性能和寿命,为解决HEV能量管理策略的最优性与实时行驶工况不确定性之间的矛盾,以混联式HEV为研究对象,提出一种基于模型预测控制(model predictive control,MPC)与蜣螂优化算法(dung beetle optimizer,DBO)的HEV能量管理策略。首先,该策略采用基于堆叠式长短时记忆神经网络(stacked long-short term memory neural network,Stacked LSTM-NN)的车速预测模型预测未来行驶车速。其次,根据预测车速将混合动力汽车的功率分配问题描述为MPC预测范围内的滚动优化问题,提出考虑燃料消耗和电池保护的成本函数,利用DBO算法对预测时域内发动机功率进行优化求解。最后,在城市道路循环(urban dynamometer driving schedule,UDDS)工况下分别对所提策略的车速预测精度和经济性与其他策略进行仿真对比验证。结果表明:与传统LSTM速度预测模型相比,Stacked LSTM速度预测模型的RMSE降低了13.9%,每步平均预测时间减少1 ms;与基于规则的策略相比,基于DBO-MPC的策略模型节油率达到25.3%,同时SOC状态波动更为平稳,对电池的保护效果更好。

基于KANN-DBSCAN带宽优化的核密度估计载荷谱外推

针对核密度估计载荷外推全局固定带宽的局限性,提出一种基于KANN-DBSCAN(K-average nearest neighbor density-based spatial clustering of applications with noise)改进带宽取值的核密度估计(kernel density estimation, KDE)载荷外推方法。通过KANN-DBSCAN聚类算法对载荷数据进行分组聚类,采用拇指法求得不同簇间的最优带宽,然后进行核密度估计,再采用蒙特卡洛模拟进行外推。以某电动汽车在用户道路的实测载荷数据为应用对象,对外推方法的合理性进行检验。从统计参数检验量、拟合度检验和伪损伤检验3个指标对外推效果进行评估。结果表明:相比固定带宽的核密度估计外推方法,基于KANN-DBSCSN核密度估计的外推方法获得的外推载荷在统计参数上与实测载荷更为接近,均值、标准差和最大值的误差分别仅为1.9%、 4.3%和1.9%;幅值累计频次曲线拟合度R2均大于0.99,伪损伤均接近1。结果验证了该聚类方法在核密度估计载荷外推的有效性,有助于编制汽车在用户道路上的载荷谱,为具有相似载荷分布特点的机械零部件载荷外推提供了参考。

基于MSIGJO的网联商用车换道轨迹规划方法

针对网联商用车换道安全性、平顺性较低的问题,提出一种基于多策略改进金豺优化算法(multi-strategy improved golden jackal optimization,MSIGJO)的网联商用车换道轨迹规划方法。首先,基于V2X(vehicle to everything)技术获取智能网联商用车周围状态信息,建立商用车换道安全距离模型;其次,引入商用车换道平顺性、经济性和换道效率作为指标,构建多目标协同优化函数;最后,引入动态权重位置更新策略和翻转策略改进金豺优化算法(golden jackal optimization,GJO),进而提出MSIGJO算法,利用MSIGJO算法求解函数得到最优换道轨迹。研究结果表明:该方法在商用车换道过程中横向跟踪精度提升了12.67%,侧向加速度变化率和质心侧偏角变化率分别降低了11.94%和12.65%,有效提升智能网联商用车换道安全性和平顺性,为智能网联商用车换道轨迹规划研究提供参考。

某商用车驾驶室结构碰撞仿真与优化研究

为全面提升商用车碰撞安全性能,保障驾驶室乘员的人身安全,在新旧标准更替之际,以国产某型通过GB 26512—2011标准的某型载货车为研究对象,引入GB 26512—2021标准新增的正面A柱摆锤撞击试验和顶部强度试验。在Hypermesh中建立驾驶室碰撞仿真模型,并通过实车正面碰撞试验从而验证有限元模型的精确性。针对在顶部强度试验中出现车身门窗上边缘侵入假人头部现象,将结构灵敏度分析与传力路径相结合进行优化,提出驾驶室结构的改进优化方案,并通过实车碰撞验证仿真结果。结果表明,优化后的驾驶室结构,具有足够的生存空间,符合新国家标准的碰撞要求。

基于XGBoost算法的商用车驾驶风险辨识模型

驾驶员作为交通事故的重要诱因,其一系列风险驾驶行为对道路交通安全具有重要影响。针对当前驾驶风险等级分类不合理、辨识精度低等问题,提出一种商用车驾驶风险辨识模型。即首先从车辆状态、驾驶状态、驾驶员操作三个方面,共建立18个能够表征商用车驾驶风险的特征参数;采用因子分析法(FA)对特征参数降维优化,并生成蕴含更为明确风险驾驶行为信息的综合变量;接着应用K-means聚类算法分别将风险驾驶行为特征聚为2、3和4类并对比分析,结合肘部法则和轮廓系数综合确定最佳的聚类数目k,消除人为经验确定k值主观性强的缺陷;最后,利用极端梯度提升(XGBoost)算法对商用车驾驶风险进行识别,并与决策树、随机森林、K近邻等算法在精度上进行比较。研究结果表明:在上述研究条件下XGBoost算法对商用车驾驶风险的理论识别率最高可达98%,该结果对于自动驾驶辅助系统的设计、道路交通安全性的提升具有重要意义。

基于接头灵敏度分析的驾驶室刚度模态优化

针对商用车驾驶室接头结构设计不合理的问题,文中提出一种基于接头灵敏度分析的驾驶室刚度模态优化方法。首先,从驾驶室有限元模型中截取所需接头,并采用有限元分析技术对其进行力学特性分析,找出接头结构的关键控制因素;其次,以弹性模量为设计变量进行接头灵敏度分析,找出对驾驶室刚度模态影响较大的接头结构;然后,选用第3代遗传算法对该优化问题进行多目标优化;最后,采用TOPSIS算法从帕累托前沿解中选取更符合用户偏好的驾驶室刚度模态优化方案。优化结果表明:在驾驶室质量基本不变的情况下,驾驶室刚度模态均有较大提升。

基于CFD的某商用车扬尘污染仿真优化分析

针对某新型商用车在泥土路面低速行驶工况中,易扬起地面尘土造成局部空气污染问题。建立商用车CFD仿真分析模型,进行实验对标以验证仿真模型的精确性。将DPM离散相模型分析方法与离散动力学相结合,对商用车外流场中多相流进行数值仿真,揭示了扬尘污染的产生机理。由此制定不同的扬尘治理方案,结合HyperStudy软件进行优化分析,寻求最佳扬尘治理方案,并开展实验验证。研究结果表明:通过优化风扇位置,更换“U型”护风罩并优化导风板尺寸的改进方案,扬尘颗粒数相较原车减少了44.67%,在保证散热性能的前提下,明显改善了扬尘污染现象。

基于虚拟迭代的某牵引车车架疲劳耐久性分析

为高效评估用户里程内车辆疲劳耐久表现,以某6×4牵引车车架为研究对象,通过襄阳试验场强化道路采集车辆轮心六分力。在HyperMesh中建立包含主副油箱附件的车架有限元模型并校核其静强度,应用惯性释放理论获取其单位载荷下应力场分布结果。建立整车刚柔耦合多体动力学模型并开展K&C试验进行模型校核,基于试验场六分力数据,利用Adams/car与Femfat-Lab联合仿真虚拟迭代得到悬架系统与车架连接处载荷谱。结合车架单位载荷应力场结果、车架疲劳载荷谱及车架材料ε-N疲劳曲线,根据Miner线性累积损伤理论,采用nCode软件对车架进行疲劳仿真分析。结果表明:该牵引车车架结构可以满足用户周期里程内的疲劳寿命要求,与试验场实车耐久试验结果一致。

基于FEM与MBD的商用车驾驶室疲劳耐久性分析

为提高商用车驾驶室疲劳仿真与强化路耐久试验的关联性,以某(6×4)牵引车驾驶室为研究对象,提出一种将实测路谱与虚拟仿真相结合的疲劳耐久分析方法。在Hypermesh中建立含配重加载的驾驶室有限元模型,并应用惯性释放法获得其单位载荷下应力分布结果。采用Adams/car软件搭建驾驶室-车架刚柔耦合多体动力学模型,以试验场实车采集的驾驶室气囊悬置位移、加速度信号作为期望信号,通过Femfat-Lab虚拟迭代获取其疲劳分析载荷谱。基于Miner线性疲劳累积损伤理论在nCode中进行疲劳仿真分析,结果表明:导流罩支架等疲劳破坏部位与试验场路试结果基本一致,所提出的疲劳分析方法对研究汽车系统级疲劳耐久性具有重要的参考价值。