Analysis of the Effect of Trailer Tire Size on the Articulated Vehicle’s Stability

This research paper aims to identify the effect of tire size on the handling characteristics of a trailer attached to a vehicle. In various stability tests, different models with different tires from the market were tested. A successful outcome of this research would generate an efficient tire selection process and improve the handling of a trailer attached to a vehicle while maximizing fuel efficiency. In this study, different accurate tire models using the magic formula were developed in vehicle dynamics modelling and simulation software. These models were then simulated on on-road conditions to predict vehicle and trailer behaviour under different conditions within the software. Two distinct tests were conducted, the J-Turn test and the Double Lane change test. The results of these tests were used to evaluate the handling characteristics and decide on a better tire size for the trailer attached to the vehicle.

Research on Risk Assessment Method of Long-Tube Trailer Road Transportation

Road transport safety has always been paid attention to by the safety production managers of enterprises. In this study, cloud model and analytic hierarchy process were applied to the safety of long-tube trailer transport. The opinions of 30 experts were analyzed, from which 29 key parameters were selected. The study addressed the relevance of the parameters and the possibility of automatic collection and transmission to obtain 12 core risk factors. The macro-safety risk indicator system for long-tube trailers was established based on the identified risk indicators. Finally, a risk assessment model for road transport of long tube trailers consisting of 3 dimensions of likelihood, severity and sensitivity was constructed. This model provides a technical method for strengthening the risk control of road transport of long-tube trailers.

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.

Attention Drawing of Movie Trailers Revealed by Electroencephography Using Sample Entropy

A movie trailer is a common advertising tool in the entertainment industry. Detection of a viewer’s brain responses to a movie trailer can help film producers to tailor a more appealing trailer of a movie. In this study, we acquired electroencephalographic (EEG) signals from subjects when they watched movie trailers (labeled as Movie session), and compared with their resting state session (labeled as Resting session) or when they watch nature scenes (labeled as Nature session). We used Sample Entropy (SampEn) to analyze the EEG signals between different sessions. Results showed that the complexity ratios at Fp1, Fp2 and Fz channels derived from Movie session were significantly lower than that in Resting state or when subjects watched Nature session (p < 0.001). Our results suggest that the brain status can affect the complexity of their EEG. Further, the attraction of attention of a movie trailer can be observed from the change of EEG.

Prediction Research on Ride Comfort of Special Full Trailer used by Precision Equipment

In order to evaluate a full trailer’s vibration performance,lumped mass model of seven degrees of freedom is set up to predict the ride comfort of whole vehicle.The acceleration history and the transfer function of each measuring point can be got from simulation.The analysis results show that the maximum acceleration RMS value of the vehicle mass center is about 0.3g,which satisfies the requirements of attenuating vibration of precision equipment being transported on particular roads and speeds.So the research provides valuable reference for the optimum selection of the suspension system’s parameters.

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.

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.

基于模糊快速滑模的农用牵引车辆直线路径跟踪控制

为解决无人驾驶牵引式农机在非结构化环境中作业时直线跟踪精度低、上线速度慢、抗干扰能力差等问题,提出了一种基于模糊快速滑模控制的农用牵引式车辆直线路径跟踪控制方法。首先利用车辆运动学模型与参考路径建立牵引车辆直线路径跟踪误差模型,并提出一种基于模糊参数整定的快速滑模直线路径跟踪方法,解决了滑模控制算法的控制器抖振与机具快速上线问题。通过Lyapunov稳定性分析可知,所设计控制方法可保证牵引机具跟踪参考路径,同时铰接角收敛至零。最后,基于Simulink仿真与实车试验对该控制方法的有效性与优越性进行测试。田间实车试验表明,使用本文控制方法时,拖车和挂车最大路径跟踪横向误差分别为0.11、0.12 m,拖车和挂车跟踪误差方差分别为0.0013、0.0015 m^(2);相较于传统基于等速趋近律设计的滑模控制器,上线时间提升约58%,最大跟踪误差减小约66%。

水稻黄矮弹状病毒的leader区和trailer区的序列分析及其体内转录物的鉴定

克隆及测定了水稻黄矮病毒基因组RNA的 3′端leader区和 5′端trailer区的序列 .结果表明 ,RYSV的 3′leader长 2 0 3个核苷酸 ,5′trailer长 191个核苷酸 .两者末端的 9个核苷酸完全互补 ,可形成弹状病毒基因组RNA的典型的锅柄结构 .与其他弹状病毒的leader和trailer相比较 ,RYSV的leader和trailer较长 ,除leader的 3′末端和trailer的 5′末端序列具有一定的保守性外 ,其余的核苷酸序列无明显的同源性 .用 3′RACE方法在感染RYSV的水稻中检测出leader的转录物 ,并证明该leaderRNA具有polyA尾巴 .这是继苦苣菜黄脉病毒的leaderRNA后第 2例弹状病毒leaderRNA带polyA尾巴的报道 .用类似的方法没有检测到带polyA尾巴的trailer的正链转录物 .

小型集材挂车满载工况下的有限元建模与分析

小型集材挂车于林间作业存在多种工况,包括满载弯曲、满载扭转、紧急制动和急速转弯。为解决挂车在满载工况下车载系统的可靠性与安全性较差的问题,建立小型集材挂车的三维装配模型,进行静态分析。通过有限元分析,研究挂车在4种典型工况下的结构变形和应力分布。研究表明,满载弯曲工况下,最大位移为4.5177 mm,最大应力为115.19 MPa,安全系数为3.08;满载扭转工况下,最大位移为0.98448 mm,最大应力为71.929 MPa,安全系数为4.935;满载制动工况下,最大位移为4.9946 mm,最大应力为120.05 MPa,安全系数为2.957;紧急转弯工况下,最大位移为4.3658 mm,最大应力为104.64 MPa,安全系数为3.39。结果显示研究设计的小型集材挂车在林间作业时满载工况下稳定性较强,确保木材的可靠采集和运输。基于该结果可进一步优化挂车设计和性能,以适应不断变化的需求和环境要求。

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。

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.

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。

拖拉机挂车气制动系统设计

介绍了拖拉机挂车气制动系统的通用要求,阐述了储气筒、空气压缩机和卸荷阀的设计要点。分别从储气筒、刹车阀、卸荷阀、空气压缩机出气管和气制动管路等方面介绍挂车气制动系统的布置原则。介绍了管路直径、材料选取规范,对管路固定和连接、软管布置、零部件通用化进行说明。

Sequence analysis of leader and trailer regions of rice yellow stunt rhabdovirus and characterization of their in vivo transcripts

The 3’ leader and the 5’ trailer of the rice yellow stunt rhabdovirus (RYSV) genomic RNA have been cloned and sequenced. Sequence data indicate that the RYSV leader region is composed of 203 nucleotides (nt) and the trailer region 191 nt. The terminal 9 nt of the two regions are complementary and capable of forming a putative panhandle structure common to rhabdovirus genomes. In comparison with the leader or trailer sequences of other rhab-doviruses reported so far, both the leader and trailer of RYSV are the longest and there is no obvious sequence homolo-gy between the counterparts except for a few terminal nt and the UGUU motif in the leader sequences. Polyadenylated plus-strand leader RNA has been detected in RYSV-infected rice plants by 3’ RACE. This is the second example in rhabdoviruses following the report for sonchus yellow net virus (SYNV) for existence of a polyadenylated leader RNA. No polyadenylated plus-strand transcripts of the RYSV trailer have been found using the similar method.

基于TRIZ理论医药配送机器人的设计

为解决现有医药配送机器人空间容量小、智能化程度低、配送过程药品防护不到位等问题,基于医院实际工况提出合理性解决方案。以TRIZ理论为基础,运用创新工具对配送机器人各部分进行创新设计,完成拖车式医药配送机器人结构设计和控制系统设计,并通过样机验证了方案的可行性。所设计的医药配送机器人在拖车式结构和立式循环车厢配合下极大地提高了容积,采用机械臂实现药品的取放,大大提高了智能化程度,自适应底盘的设计增加了对药品的防护性。该机器人运行过程不需要人为介入即可稳定、可靠地完成整个药品配送过程,有效解决了现有药品的配送难题,具有广阔的推广运用价值。

基于流固耦合的厢式中置轴挂车联合仿真

厢式货车的迎风面积较大,在强风天气高速行驶有很大安全隐患,结构参数是影响车辆空气动力学的因素之一。基于Fluent和TruckSim单向耦合的方法,建立厢式中置轴挂车的空气动力学和多体动力学流固耦合联合仿真模型。通过计算流体动力学(Computational fluid dynamics,CFD)对厢式中置轴挂车进行气动特性分析,运用多体动力学模型进行侧风稳定性验证。利用可实现k—ε湍流模型进行数值模拟,得到厢式中置轴挂车双力矩中心处的气动系数曲线。建立气动系数的数学模型作为联合仿真的接口,仿真结果表明挂车与牵引车车厢之间的间隙对挂车气动特性有一定影响。以横摆角速度和侧向加速度作为评价指标,发现当车速为80 km/h时,间隙越大车辆越不稳定;当车速为40 km/h时,间隙越大可有效提高车辆的行驶稳定性。因此,提出用可伸缩牵引杆来解决中置轴挂车行驶稳定性的方法。研究结果可为考虑空气动力学设计的多节车厢类挂车提供参考。

拖挂式移动机器人的多约束避障轨迹规划

基于七次多项式曲线研究了拖挂式移动机器人多约束避障轨迹规划问题,建立了具有非完整约束特性拖挂式移动机器人的前向和后向运动学模型。在速度、加速度、急动度、曲率和曲率导数等多约束条件下,提出基于七次多项式曲线的避障轨迹规划方法。考虑平稳性、舒适性和交通效率等设计了优化目标函数,对七次多项式曲线参数进行优化。仿真结果表明,所提出的基于七次多项式曲线的避障轨迹规划方法,能够得到多约束条件下满足最优避障时间和最优避障距离的避障轨迹规划结果。

离轴拖挂轮式移动机器人跟踪控制研究

针对离轴拖挂轮式移动机器人挂车的轨迹跟踪控制问题,基于拖车和挂车运动轨迹的相对曲率关系提出了一种动态跟踪方法。建立离轴拖挂轮式移动机器人的运动学模型和动力学模型。通过拖车和挂车位置几何关系给出了两车的速度关系,进而得到两车运动轨迹相对曲率之间的关系。基于曲率关系将挂车的运动任务转化为拖车的运动任务,并结合动态跟踪方法设计比例积分反馈控制器完成拖车的运动任务。最后通过模拟仿真实现了挂车精确的轨迹跟踪控制,仿真结果表明在所提控制器的作用下,挂车在拖车的拉拽下可精确地跟踪目标轨迹曲线。由于所使用的动态跟踪方法引入了目标轨迹曲线的相对曲率,极大地提高了跟踪的精确性。