Optimization of suspension system of heavy off-road vehicle for stability enhancement using integrated anti-roll bar and coiling spring mechanism

Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.

General Torsional Stiffness Matching of Off-road Vehicle

Increasing frame torsional stiffness of off-road vehicle will lead to the decrease of body torsional deformation, but the increase of torsional loads of frame and suspension system and the decrease of wheel adhesive weight. In severe case, a certain wheel will be out of contact with road surface. Appropriate matching of body, frame and suspension torsional stiffnesses is a difficult problem for off-road vehicle design. In this paper, these theoretically analytic models of the entire vehicle, body, frame and suspension torsional stiffness are constructed based on the geometry and mechanism of a light off-road vehicle＇s body, frame and suspension. The body and frame torsional stiffnesses can be calculated by applying body CAE method, meanwhile the suspension＇s rolling angle stiffness can be obtained by the bench test of the suspension＇s elastic elements. Through fixing the entire vehicle, using sole timber to raise wheels to simulate the road impact on a certain wheel, the entire vehicle torsional stiffness can be calculated on the geometric relation and loads of testing. Finally some appropriate matching principles of the body, frame and suspension torsional stiffness are summarized according to the test and analysis results. The conclusion can reveal the significance of the suspension torsional stiffness on off-road vehicle＇s torsion-absorbing capability. The results could serve as a reference for the design of other off-road vehicles.

Effect of the off-road terrains on the ride comfort of construction vehicles

In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.

Correlating Connected Vehicle Estimated Deceleration Events with Crash Incidents near Interstate Interchanges

Historical roadway safety analyses have used labor and time-intensive crash data collection procedures. However, crash reporting is often delayed and crash locations are reported with varying levels of spatial accuracy and detail. Recent advances in connected vehicle (CV) data provide an opportunity for stakeholders to proactively identify areas of safety concerns in near-real time with high spatial precision. Public and private sector stakeholders including automotive original equipment manufacturers (OEM) and insurance providers may independently define acceleration thresholds for reporting unsafe driver behavior. Although some OEMs have provided fixed threshold hard-braking event data for a number of years, this varies by OEM and there is no published literature on the best thresholds to use for identifying emerging safety issues. This research proposes a methodology to estimate deceleration events from raw CV trajectory data at varying thresholds that can be scaled to any CV. The estimated deceleration events and crash incident records around 629 interstate exits in Indiana were analyzed for a three-month period from March 1-May 31, 2023. Nearly 20 million estimated deceleration events and 4800 crash records were spatially joined to a 2-mile search radius around each exit ramp. Results showed that deceleration events between -0.5 g and -0.4 g had the highest correlation with an R2 of 0.69. This study also identifies the top 20 interstate exit locations with highest deceleration events. The framework presented in this study enables agencies and transportation professionals to perform safety evaluations on raw trajectory data without the need to integrate external data sources.

Vehicle and terrain interaction based on Adams-Matlab co-simulation

A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.

Evaluation of the Impact of Queue Trucks with Navigation Alerts Using Connected Vehicle Data

Back of queue crashes on Interstates are a major concern for all state transportation departments. In 2020, Indiana DOT begin deploying queue warning trucks with message boards, flashers and digital alerts that could be transmitted to navigation systems such as Waze. This study reports on the deployment and impact evaluation of digital alerts on motorist’s assistance patrols and 19 Queue trucks in Indiana. The motorist assistance patrol evaluation is provided qualitatively. A novel analysis of queue warning trucks equipped with digital alerts was conducted during the months of May-July in 2021 using connected vehicle data. This new data set reports locations of anonymous hard-braking events from connected vehicles on the Interstate. Hard-braking events were tabulated for when queueing occurred with and without the presence of a queue warning truck. Approximately 370 hours of queueing with queue trucks present and 58 hours of queueing without queue trucks present were evaluated. Hard-braking events were found to decrease approximately 80% when queue warning trucks were used to alert motorists of impending queues.

Exploring Crowdsourced Hard—Acceleration and Braking Event Data for Evaluating Safety Performance of Low-Volume Rural Highways in Iowa

There are over four million miles of two-lane roadways across the United States, of which a substantial portion is low-volume roads (LVR). Traditionally, most traffic safety efforts and countermeasures focus on high-volume high-crash urban locations. This is because LVRs cover an extensive area, and the rarity of crashes makes it challenging to use crash data to monitor the safety performance of LVRs regularly. In addition, obtaining up-to-date roadway information, such as pavement or shoulder conditions of an extensive LVR network, can be exceptionally difficult. In recent times, crowdsourced hard-acceleration and braking event data have become commercially available, which can provide precise geolocation information and can be readily acquired from different vendors. The present paper examines the potential use of this data to identify opportunities to monitor the safety of LVRs. This research examined approximately 12 million hard-acceleration and hard-braking events over a 3-months period and 26,743 crashes, including 9373 fatal injuries over the past 5-year period. The study found a moderate correlation between hard acceleration/hard-braking events with historical crash events. This study conducted a hot spot analysis using hard-acceleration/hard-braking and crash datasets. Hotspot analysis detected spatial clusters of high-risk crash locations and detected 848 common high-risk sites. Finally, this paper proposes a combined ranking scheme that simultaneously considers historical crash events and hard-acceleration/hard-braking events. The research concludes by suggesting that agencies can potentially use the hard-acceleration and hard-braking event dataset along with the historical crash dataset to effectively supervise the safety performance of the vast network of LVRs more frequently.

摩托车多连杆后悬架硬点的多目标优化

针对摩托车在行驶过程中的俯仰振动和垂向振动问题,提出了一种基于多连杆后悬架系统硬点坐标的优化方案,通过优化原型车上后悬架系统的关键硬点,提高摩托车的行驶平顺性;建立摩托车整车模型,通过路试试验验证了仿真模型的准确性;以车身质心俯仰振动角加速度均方根值和垂向振动加权加速度均方根值最小化为优化目标,以多连杆悬架系统硬点的坐标为设计变量,采用NSGA-Ⅱ遗传算法完成多连杆后悬架系统的多目标优化。结果表明,优化后整车俯仰振动角加速度均方根值降低了24.0%,垂向振动加权加速度均方根值降低了39.2%,提高了摩托车的行驶平顺性,具有重要的工程应用价值。

基于人工智能技术的低空飞行器管控关键技术研究

以人工智能技术在低空飞行领域的应用为切入点,分析了人工智能技术驱动下低空飞行器向平台无人化、控制智能化、任务多元化发展带来管控对象多元复杂、管控难度不断提升、管控时空深度拓展的现实挑战。提出了以预实践决策提升飞行审批效率、以自主式决策实时监控飞行状态、以数据驱动式决策精准处置违规行为的主要决策方法和发展途径,剖析了人工智能技术、软杀伤技术、硬毁伤技术在管控建设及应急处置中的运用要点和优缺点。

A survey on multi-sensor fusion based obstacle detection for intelligent ground vehicles in off-road environments

With the development of sensor fusion technologies, there has been a lot of research on intelligent ground vehicles, where obstacle detection is one of the key aspects of vehicle driving. Obstacle detection is a complicated task, which involves the diversity of obstacles, sensor characteristics, and environmental conditions. While the on-road driver assistance system or autonomous driving system has been well researched, the methods developed for the structured road of city scenes may fail in an off-road environment because of its uncertainty and diversity.A single type of sensor finds it hard to satisfy the needs of obstacle detection because of the sensing limitations in range, signal features, and working conditions of detection, and this motivates researchers and engineers to develop multi-sensor fusion and system integration methodology. This survey aims at summarizing the main considerations for the onboard multi-sensor configuration of intelligent ground vehicles in the off-road environments and providing users with a guideline for selecting sensors based on their performance requirements and application environments.State-of-the-art multi-sensor fusion methods and system prototypes are reviewed and associated to the corresponding heterogeneous sensor configurations. Finally, emerging technologies and challenges are discussed for future study.

基于车辆悬架的载荷设计方法

汽车的轻量化设计一直是各大主机厂追求的设计方向,尤其是近几年电动车的发展,市场对续航能力的要求越来越高,而整车重量与续航强相关,因此,轻量化的设计显得尤为重要,而轻量化设计的源头就是悬架的载荷设计。论文基于某多连杆后悬架结构,提出一种载荷设计的方法,综合考虑悬架的载荷分配及运动学特性和动力学特性(KC),通过试验设计(DOE)及最优化设计手段寻求硬点最佳分布,达到降低悬架载荷目的,从而为结构轻量化设计提供良好基础。

轨道车辆车轮表面金属陶瓷涂层的制备与性能研究

为提高轨道车辆车轮材料Q235表面的耐磨性,利用YAG固体激光器在车轮表面激光熔覆制备了Al_(2)O_(3)-Ni金属陶瓷复合涂层。利用扫描电镜(SEM)、硬度计、摩擦磨损试验仪,分析了基体和涂层的微观组织和耐磨损性能。结果显示,复合涂层主要由胞状晶、定向生长的柱状晶和等轴晶组成,复合涂层的厚度随着Al_(2)O_(3)含量的增加而变小,过多的Al_(2)O_(3)会造成颗粒团聚。当Al_(2)O_(3)含量为20%时,复合涂层的整体硬度最高,耐磨性能最好,磨损量和摩擦系数最小,磨损表面为较浅的犁沟,出现少量磨屑。磨损机制表现为粘着磨损和磨粒磨损。

Off-road testing scenario design and library generation for intelligent vehicles

To realize the widespread application and continuous functional development of intelligent vehicles,test and evaluation of vehicle's functionality and Safety Performance in complex off-road scenarios are fundamental.Since traditional distance-based road tests cannot meet the evolving test requirements,a method to design the function-based off-road testing scenario library for intelligent vehicles(IV)is proposed in this paper.The testing scenario library is defined as a critical set of scenarios that can be used for IV tests.First,for the complex and diverse off-road scenarios,a hierarchical,structural model of the test scenario is built.Then,the critical test scenarios are selected adaptively according to the vehicle model to be tested.Next,those parameters representing the challenging test scenarios are selected.The selected parameters need to fit the natural distribution probability of scenarios.The critical test-scenario library is built combing these parameters with the structural model.Finally,the test scenarios that are most approximate to the natural driving scenario are determined with importance sampling theory.The test-scenario library built with this method can provide more critical test scenarios,and is widely applicable despite different vehicle models.Verified by simulation in the off-road interaction scenarios,test would be accelerated significantly with this method,about 800 times faster than testing in the natural road environment.

副车架软硬连接对整车舒适性的影响分析

论文通过副车架衬套软连接和机加工铁块代替副车架衬套硬连接两种方案,基于某试验场路面对副车架软硬连接进行平顺性和路噪试验。以随机路面加权加速度均方根和脉冲路面四轮冲击振动有效值为评价指标,分析副车架软硬连接对整车舒适性的影响。结果表明,副车架软硬连接对车辆整体平顺性影响不大,但软连接车内噪声明显优于硬连接。

井下防爆无轨胶轮车悬架系统的仿真及优化

为提高车辆的稳定性和平顺性,通过ADAMS/CAR模块建立矿用防爆无轨胶轮车前钢板弹簧悬架模型,分析车轮跳动对前轮外倾角、前轮前束角、主销内倾角、主销后倾角等四个车轮定位参数的影响。通过研究分析,确定了影响前钢板弹簧悬架模型的优化目标为前悬主销后倾角和前束角。采用灵敏度分析法对影响前悬主销后倾角和前束角的主要硬点参数变量进行分析,确定需要优化的关键硬点坐标作为设计变量并对硬点坐标进行优化。优化结果表明,关键硬点位置对车辆钢板弹簧悬架的跳动有很大影响,对关键硬点位置进行优化可以显著减小车辆的跳动,为矿用防爆无轨胶轮车的悬架设计提供了重要依据。

基于城轨新材质车轮性能的分析研究

为提高城轨车辆车轮的硬度和强度,大幅提升车轮材料的力学性能与服役表现,文章对车轮的化学成分、拉伸性能、硬度均匀性、显微硬度、踏面变形层EBSD组织、磨损性能均匀性进行分析研究。结果表明:高Cr高V的车轮比低Cr低V的车轮强度和韧性高;两种车轮的表面变形层显微硬度分布均表现出较大的波动性,低Cr低V车轮表层硬化程度较高Cr高V车轮显著;低Cr低V车轮局部表层晶粒变形和细化程度以及塑性变形和位错密度高于高Cr高V车轮,随着距离踏面深度的增加,两种车轮表面变形层微观组织结构差异逐渐减小。材料抗磨损性能随深度增加而缓慢下降;高Cr高V车轮强度和韧性指标高于低Cr低V车轮。

基于电动汽车轮胎异常磨损的悬架硬点优化分析

对电动汽车车身质量增大带来的轮胎异常磨损进行了悬架硬点分析及优化设计。运用Adams/Car建立双叉臂前悬架刚柔耦合虚拟样机模型,验证了车身质量增大会对外倾角与前束角的匹配关系产生影响,也会增大轮胎侧滑。在优化设计中提出选取更多硬点但仅优化其Z坐标的方案,二次优化与初次优化的结果对比表明,方案可行且可大幅降低优化计算量和缩减研发周期,同时优化后的电动车型双叉臂悬架的车轮外倾角与前束角的匹配关系得到了优化、轮胎侧滑量大大减小,有效减轻了轮胎的异常磨损。

A Hard Reform New official vehicle management system is in the works

Guangzhou, capital of south China’s Guangdong Province, will further reform the use of official cars as part of its efforts to alleviate traffic jams, said the city’s traffic authorities on January 23.

佛山某贴临车辆段超高层住宅结构设计

佛山某超高层住宅项目,建筑高度为147.71 m,存在扭转不规则、凹凸不规则、局部不规则(底部穿层剪力墙)。采用Stawe和Midas Building进行小震、中震及大震等分析,查找结构薄弱部位并予以加强;对穿层剪力墙进行屈曲稳定分析,根据分析的结果确定计算长度;基础埋深无法满足要求时,保证大震下结构不发生整体倾覆破坏,可采取筏板外围设置抗拔桩来增强抗倾覆力矩;针对有硬质夹层场地,结合超前钻的结果,根据夹层厚度确定持力层,且通过侧阻换算进行桩长优化,达到安全性和经济性兼顾的目的,可为类似场地上工程项目的设计提供有价值的参考。

基于RRT与MPC的智能车辆路径规划与跟踪控制研究

为分析智能车辆实时规划和跟踪控制的相互影响关系,基于改进的快速随机搜索树规划算法(improved-RRT)与线性时变的模型预测控制算法,提出了一种智能车路径规划与跟踪控制系统的构架。首先,采用目标导向、节点修剪、曲线拟合和最优路径选择等方法对基础RRT规划算法进行改进,保证规划路径满足车辆运动学约束并趋近最优解。然后,基于线性时变模型预测控制算法,实现智能车对期望路径的稳定控制。硬件在环仿真结果表明,车速为36 km/h,规划步长为2 m,规划周期为0.1 s时,侧向加速度小于0.2g,满足安全性和实时性要求。最后,分析了车速、规划步长和规划周期等因素对实时规划和稳定跟踪的影响。