Multi-objective Stability Control Algorithm of Heavy Tractor Semi-trailer Based on Differential Braking

Rollover and jack-knifing of tractor semi-trailer are serious threats for vehicle safety, and accordingly active safety technologies have been widely used to reduce or prevent the occurrence of such accidents. However, currently tractor semi-trailer stability control is generally only a single hazardous condition (rollover or jack-knifing) control, it is difficult to ensure the vehicle comprehensive stability of various dangerous conditions. The main objective of this study is to introduce a multi-objective stability control algorithm which can improve the vehicle stability of a tractor semi-trailer by using differential braking. A vehicle controller is designed to minimize the likelihood of rollover and jack-knifing. First a linear vehicle model of tractor semi-trailer is constructed. Then an optimal yaw control for tractor using differential braking is applied to minimize the yaw rate and lateral acceleration deviation of tractor, as well as the hitch articulation angle of tractor semi-trailer, so as to improve the vehicle stability. Second a braking scheme and variable structure control with sliding mode control are introduced in order to achieve the best braking effect. Last Fishhook maneuver is introduced to the active safety simulation and the active control system effect verification. The simulation results show that multi-objective stability control algorithm of semi-trailer could improve the vehicle stability significantly during the transient maneuvers. The proposed multi-objective stability control algorithm is effective to prevent the vehicle rollover and jackknifing.

Optimization for vehicle scheduling in iron and steel works based on semi-trailer swap transport

In order to solve internal logistics problems of iron and steel works,such as low transportation efficiency of vehicles and high transportation cost,the production process and traditional transportation style of iron and steel works were introduced.The internal transport tasks of iron and steel works were grouped based on cluster analysis according to demand time of the transportation.An improved vehicle scheduling model of semi-trailer swap transport among loading nodes and unloading nodes in one task group was set up.The algorithm was designed to solve the vehicle routing problem with simultaneous pick-up and delivery(VRPSPD) problem based on semi-trailer swap transport.A solving program was written by MATLAB software and the method to figure out the optimal path of each grouping was obtained.The dropping and pulling transportation plan of the tractor was designed.And an example of semi-trailer swap transport in iron and steel works was given.The results indicate that semi-trailer swap transport can decrease the numbers of vehicles and drivers by 54.5% and 88.6% respectively compared with decentralized scheduling in iron and steel works,and the total distance traveled reduces by 43.5%.The semi-trailer swap transport can help the iron and steel works develop the production in intension.

Modal Correlation Based Analysis on Dynamic Characters of a Commercial Semi-Trailer's Chassis Frames

In order to evaluate two different schemes＇ structural dynamic characters, dynamic response analysis of a commercial truck＇s main chassis frames is carried out. On the basis of correlation study between the tested and calculated modal results, the assembled frames＇ finite element analysis （FEA） models with sufficient precision are built up. Random response analysis in frequency domain is carried out with these FEA models, RMS values of yon Mises and main principle stresses of these two frames are obtained. It shows that the analysis resuits of the distributing tendency and concrete value ranges are coincident very well with test results. And from the results, it could be concluded that frames of scheme A endures relative better loading conditions and should be adopted as the final scheme.

The Roll Stability Analysis of Semi-Trailer Based on the Wheel Force

It is different for the liquid tank semi-trailer to keep roll stability during turning or emergency voidance,and that may cause serious accidents.Although the scholars did lots of research about the roll stability of liquid tank semi-trailer in theory by calculating and simulation,how to make an effective early warning of rollover is still unsolved in practice.The reasons include the complex driving condition and the difficulty of the vehicle parameter obtaining.The feasible method used currently is evaluating the roll stability of a liquid tank semi-trailer by the lateral acceleration or the attitude of the vehicle.Unfortunately,the lateral acceleration is more useful for sideslip rather than rollover,and the attitude is a kind of posterior way,which means it is hard to take measures to cope with the rollover accident when the attitude exceeds the safety threshold.Considering the movement of the vehicle is totally caused by the wheel force,the rollover could also be predicted by the changing of the wheel force.Therefore,in this paper,we developed a method to analyze the roll stability by the vertical wheel force.A thorough experiment environment is established,and the effectiveness of the proposed method is verified in real driving conditions.

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern China.Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the past.There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles.Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop.NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer.It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission greatly.THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH4 may be an important reason for this phenomenon.Further on-road emission tests, especially CH4 emission test should be carried out in subsequent research.In addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.

特种公路运输半挂车转向液压系统优化设计

针对某特种公路运输半挂车转向液压系统进行了优化,优化后的液压系统降低了车辆受环境温度变化的影响、消除了行车摆尾现象,改善了整车的转向性能。

基于点云技术的汽车外廓尺寸测量方法研究

针对《机动车安全技术检验项目和方法》(GB 38900—2020)中对于汽车外廓尺寸测量的新要求,采用整车点云数据技术,对牵引车与各类挂车连接后外形上的共性和外廓分割的关键位置进行了研究。通过改进三维点云分割算法,提出一种一并式测量汽车列车和挂车外廓尺寸的测量新方法。该方法可在不改变硬件的前提下,仅通过软件和算法升级,实现一次测量即可测得汽车列车(牵引车、半挂车组合)外廓尺寸参数。以多种结构挂车为试验案例验证了所提方法的可行性,并通过适应性试验分析了所提方法的有效性。研究结果表明,该方法完全能够满足GB 38900—2020中的新增要求,具有广泛的适用性与较高的测量精确度。该方法可将传统方法测量耗时从“小时级”提升为“秒级”,显著提高相关机构的工作效率。

半挂液罐车弯道安全车速优化控制

为降低半挂液罐车驶过弯道路段过程中的侧翻事故风险,提出了基于最优控制的半挂液罐车弯道安全车速优化控制方法。该控制方法以侧翻事故防控为优先目标,以高效通行为辅助目标,帮助半挂液罐车在驶向弯道时提前获得无横向失稳隐患的最优车速控制方案,实现“预防式”的车辆主动安全控制。同时为提高控制方案有效性,利用正弦波动方程拟合罐内液体纵向转移过程,结合基于改进准静态法的罐内液体横向偏移规律,构建了具有纵横双维度描述能力的罐内液体晃动模型,提高了最优控制问题成本函数中半挂液罐车横向稳态表征指标的准确性。仿真结果表明:受控半挂液罐车驶过弯道过程中的瞬时横向载荷转移率始终处于[-0.7,0.7]的安全范围内;不同弯道半径下车辆瞬时横向载荷转移率均有下降,且在弯道半径61 m时降幅最大;受控半挂液罐车最大瞬时横向载荷转移率最大降幅达到0.07;车速控制对道路通行效率的负面影响较小。该控制方法帮助半挂液罐车避免侧翻事故,适用于多种不同半径的弯道路段。

基于稀疏化数据的重载半挂牵引车工况构建

针对北方环境下重载半挂牵引车跨区域典型行驶工况的缺位现象,以及工况构建对优质数据的高度依赖问题,应用道格拉斯-普克(Douglas-Peucker,DP)算法将采集数据处理为稀疏节点数据与驾驶行为特征数据,基于稀疏节点数据划分行驶片段,经主成分分析和k-means聚类构建初始工况,初始工况与驾驶行为特征数据匹配和叠加形成典型行驶工况。结果表明,该工况构建方法的平均相对误差相比传统方法降低了约19.63%,其仿真油耗与原始数据仿真油耗的相对误差也在5%以内。同时,该方法可以实现低频数据向高频数据的映射,有助于解决工况构建对采集数据颗粒度的高度敏感性问题。

重型半挂车主动防侧翻控制策略研究

以重型半挂车为研究对象,提出一种基于差速制动的重型半挂车主动防侧翻控制策略,采用线性二次型最优控制理论并结合差速制动原理设计了防侧翻控制器,融合了基于逻辑门限值的滑移率控制,防止制动时车轮发生抱死。联合仿真试验结果证实:所提出的防侧翻控制方法能够阻止重型半挂车发生侧翻,明显提高了车辆的抗侧翻性能,其中挂车的横向载荷转移率、侧倾角、质心侧偏角、横摆角速度、侧向加速度改善率分别为13.25%、36.71%、31.51%、21.63%、22.39%,改善了车辆转弯时的侧向稳定性。

基于数字孪生技术的智能网联半挂汽车装调与测试平台构建

半挂汽车在高速发展的现代物流行业起着关键作用,随着半挂汽车制造业向智能化和网络化转型,行业面临测试成本高昂、测试环境复杂和效率低下等挑战。本研究通过半挂汽车动力学模型、控制模型和三维模型,创建了数字孪生对象,并构建了智能网联半挂汽车的数字孪生装调测试平台。该平台实现了对装调和测试过程的实时监控、预测和优化,有效提升了测试效率和质量,为半挂汽车的数字化和智能制造提供了创新的解决方案。

考虑测量零偏的半挂车辆侧向速度校正估算方法

为准确估算自动驾驶半挂车辆的牵引车侧向速度,提出了一种考虑传感器测量零偏的校正估算方法。在三自由度车辆动力学模型的基础上,将前轮转角、横摆角速度零偏和侧向加速度零偏等扩围到状态变量中,建立了测量零偏估计模型,考虑到动力学模型失配的影响,设计了基于运动学模型的反馈校正机制,对侧向速度和横摆角速度的估计结果进行反馈调节,利用平方根容积卡尔曼滤波算法实现该方法,并分析了估计器的可观性,最后,基于TruckSim与MATLAB/Simulink联合仿真平台进行了验证,结果表明:该方法不仅可以消除测量零偏的影响,还具有良好的收敛速度,性能明显优于未考虑测量零偏和仅考虑测量零偏的估算方法。

汽车列车在对开路面上的制动失稳机理研究

为研究半挂汽车列车在彩色沥青对开路面上的制动失稳机理,提高半挂汽车列车行车安全性。文章测试分析了对开路面附着系数特性,建立了5自由度半挂汽车列车模型,仿真分析了半挂汽车列车在对开路面上的制动稳定性及其影响因素。附着系数测试结果显示,干燥条件下,沥青路面比彩色路面和对开路面分别高19%和9%;潮湿条件下,彩色路面比沥青路面和对开路面高1.4%。仿真结果显示,半挂汽车列车最大铰接角ψm和最大横摆角速度差ωm与制动力和车速成正相关,其峰值与载荷成负相关;ψm和ωm对制动力的敏感性高于车速;对开路面会导致车辆横摆角速度差和折叠角提前发生“突变”,进而增加车辆横向失稳的风险。文章对探究分离路面附着系数特性及提高半挂汽车列车行车安全具有积极意义。

自动驾驶半挂车辆转向齿隙补偿控制研究

为了保障自动驾驶半挂车辆轨迹跟踪控制的有效性,提出一种考虑转向系统齿隙补偿的控制方法。建立基于三自由度车辆动力学模型的轨迹跟踪模型,在此基础上设计基于线性二次型调节器(LQR)的轨迹跟踪控制器。建立考虑左右两侧差异的转向系统齿隙模型,并设计基于递推最小二乘法的齿隙模型参数辨识方法。利用辨识得到的参数建立转向齿隙逆模型,补偿轨迹跟踪控制器的输出。采用实车数据和仿真数据分别验证了齿隙模型参数辨识方法,基于TruckSim-Simulink联合仿真平台验证了齿隙补偿控制。结果表明,所设计的辨识方法可以快速识别出转向系统模型左右两侧的转向传动比和齿隙,考虑齿隙补偿的轨迹跟踪控制精度和稳定性明显提升。

半挂车工字形纵梁埋弧自动焊焊接工艺改进分析

在如今的时代背景下,半挂车工字形纵梁作为半挂车的主要承载结构,必须配合高质量焊接工艺来确保整体质量能够满足车辆性能需求。文章对半挂车工字形纵梁进行分析,并对半挂车工字形纵梁中的埋弧自动焊焊接工艺提出个人看法,希望为关注半挂车工字形纵梁埋弧自动焊的人群带来参考。

基于动力学仿真的半挂车支承装置设计

针对重型设备装卸时易对半挂车产生冲击力,造成运输车辆损伤的情况,对半挂车设计进行优化。首先,设计半挂车支承装置,通过模型简化分析构建运动方程;其次,分别建立半挂车运输的实体模型与运动仿真模型,进行运动仿真分析;最后,对比安装支承装置前后,重型设备上下运输时的运动仿真情况,对支承装置进行优化设计,制作样机,进行现场试验。结果表明:设计方案在运输车进行重型设备装载运输时,给车辆提供额外支撑,能有效防止重物过重而导致的车辆倾翻现象,提高了半挂车系统的稳定性与安全性。

基于青藏线实测载荷的半挂车疲劳寿命预测

为研究某款主流半挂车型的耐久性能,在青藏线上实测关键加速度、位移、应变信号,分析得到该线路中对车辆疲劳寿命影响较大的路段。建立半挂车整车虚拟试验台架,用青藏线实测轴头及鞍座处加速度信号进行虚拟迭代,得到台架驱动信号,导出车身外载荷激励。使用激励信号计算车身及关键位置焊缝的疲劳寿命。结果表明:用实测道路载荷与虚拟试验相结合来分析车辆疲劳寿命的技术路线可行。基于该方案计算得到的半挂车疲劳寿命满足设计需求。

基于自适应响应面法的长规格铝合金厢式半挂车轻量化研究

为了解决厢式半挂车结构性能和轻量化之间的矛盾以降低能源消耗,运用结构优化方法对铝合金厢式半挂车进行轻量化设计。以规格为12 m长的铝合金厢式半挂车为研究对象,采用高强度铝合金替代传统钢材作为厢式半挂车的主要材料,并对车厢底板截面进行设计。通过HyperWorks软件对已应用了铝合金轻质材料的厢式半挂车进行刚度、强度分析,用部分因子设计法筛选设计变量后通过可拓展的格栅序列法进行采样,在此基础上用最小二乘法构建近似模型,最后利用自适应响应面法完成优化设计。结果表明:该方法能够在满足刚/强度要求的前提下,进一步实现车身总体减重6.8%,完成厢式半挂车结构轻量化设计。

基于实测载荷谱的半挂车虚拟台架试验研究

路试实测了某轻量化半挂车在109国道格尔木至拉萨区段的轴头加速度、悬架压缩量等关键信号,搭建了半挂车整车虚拟刚性台架模型。通过计算附加散体载荷模型的车身、车轴带接附点约束的Craig-Bampton模态得到柔性化整车虚拟试验台架;基于实测轴头加速度进行虚拟迭代,得到用于驱动台架模型的轴头位移信号,证明了虚拟台架模型与实车动力学响应的一致性。该虚拟台架可进一步为疲劳寿命预测提供载荷谱数据。

基于聚类的半挂牵引车行驶工况构建改进方法

针对传统K-均值聚类算法易陷入局部最优以及最佳聚类数难以确定的问题,提出一种基于高斯混合模型聚类的改进方法。选定淄博市博山-沂源路段作为测试道路,以半挂牵引车为试验车辆,利用车载终端设备采集车辆行车数据。在对原始数据预处理的基础上,以速度为运动学片段划分标准,采用主成分分析和聚类分析对特征参数进行降维分类处理,依据距离聚类中心越近越能代表该类特征的原则选取运动学片段,构建丘陵山区半挂牵引车代表性行驶工况。与传统的K-均值聚类相比,采用高斯混合模型聚类构建的丘陵山区车辆行驶工况特征值误差仅为2.05%,精度更高,更能反映丘陵山区道路线形复杂的特点。与国内采用的半挂牵引车测试工况(CHTC-TT工况)相比,所构工况与之差异明显,表明了开发反映丘陵山区行驶特征的半挂牵引车代表性行驶工况的必要性。