Study on Steering Control Strategy for High-Speed Tracked Vehicle with Hydrostatic Drive

Steering control strategy for high-speed tracked vehicle with hydrostatic drive is designed based on analyzing the fundamental steering theories of the hydrostatic drive tracked vehicle. The strategy is completed by the cooperation between integrated steering control unit and pump ＆ motor displacement controller. The steering simulation is conducted by using Simulink of Matlab. It is indicated that this steering control strategy can reduce the average vehicle speed automatically to achieve the driver＇s expected steering radius exactly in the case of en- suring not exceeding the system pressure threshold and no sideslip.

Framework for fault-tolerant speed tracking control of gasoline engines using the first principle-based engine model

Optimal engine torque management,a fundamental objective,depends predominantly on engine speed tracking performance.It ensures to attain desired speed profile in the presence of uncertainties,disturbances and malfunctions.On the other hand,certain requirements such as emissions control,fuel efficiency and drivability are degraded in case of poorspeed tracking.Furthermore,constraints on engine speed tracking performance are even more stringent for hybrid power-train architecture as crankshaft speed and engine torque are the basic variables for coordinated control.Speed tracking is also considered essential for gearshift control ofthe automatic transmission.In this research work,a framework for fault-tolerant speed tracking of the gasoline engine is proposed using the First Principle-based Engine Model(FPEM).A high-fidelity direct relationship between fuel injection input and engine speed is derived by the transformation of FPEM.Fault is induced in the fuel injection subsystem to generate the torque imbalance.Using the proposed framework,a second-order sliding mode-based control technique is applied to track desired speed profile by mitigating the faultsin the fuel injection subsystem.Reference data acquired from the engine test rig is used to demonstrate the offline validity and fault tolerance capabilities of the proposed framework in MATLAB/Simulink.

Advances in design theories of high-speed railway ballastless tracks

The design theories of the ballastless track in the world are reviewed in comparison with the innovative research achievements of high-speed railway ballastless track in China.The calculation methods and parameters concerning train load,thermal effect,and foundation deformation of high-speed railway ballastless track,together with the structural design methods are summarized.Finally,some suggestions on the future work are provided.

Experimental study on dynamic load magnification factor for ballastless track-subgrade of high-speed railway

The magnitude of dynamic load produced by high-speed trains depends on many factors,of which train speed is the most critical one.However,it is quite difficult to determine the effect of train speed on dynamic load using the theoretical methods due to the complexity of the interaction between vehicle and track-subgrade.Thus large-scale model test has gradually become an important approach for studying dynamic responses of ballastless track-subgrade of high-speed railway.In this study,a full-scale model of ballastless track-subgrade was constructed in accordance with the design and construction standards for Shanghai-Nanjing intercity high-speed railway line firstly.Then,the dynamic strain of slab and the dynamic earth pressure of subgrade were measured by conducting single wheel axle excitation test.In addition,the relationship between the dynamic load magnification factor（DLF） and the train speed was obtained.Finally,the DLF of track-subgrade under different train speeds was proposed,similar to that given by German Railway Standard.

Speed Testing of the Graviton and the Movement Track of Graviton in the Spiral Galaxy

According to a series of hypothesis, for the spiral galaxy, a mathematical equation of the graviton movement track is built, it is also the central curve of the nebulae density distribution, which offers the method to measure the moving speed of the graviton. Using the observed images of the M51 galaxy, it confirms that the graviton movement curve in the spiral galaxy conforms to the image, QUOTE QUOTEis a constant. It points out that by measuring the rate of angular motion of the equivalent center in the galaxy, the real speed of the graviton can be estimated. Under the measuring condition of the M51,. The theory presented in this article also helps to calculate the rotation speed of a galaxy, provided the graviton speed is known for certain. With the model in this article and fitting data from the observation images of M51 galaxy, the guess which says “the moving speed of graviton is a constant” is supported unprecedentedly by observation data. It is for the first time that the upper limit of graviton speed, i.e. no more than times of light speed, is obtained from observation data. At the same time, the paper puts forward one possible way that the lower limit of graviton speed may be measured. And a new idea also brought forward in the paper is that the rotational angular velocity w of the equivalent center which plays an important role in a spiral galaxy may be measured according to the observed data of the thickness of galactic center of the spiral galaxy.

高速履带车辆横摆运动响应特性分析与试验验证

为研究高速履带车辆操纵特性,奠定高速电驱动履带车辆的操纵稳定性评价及控制的基础,建立了高速履带车辆非线性转向动力学模型及2自由度线性转向动力学模型,并对模型进行试验验证。利用2自由度线性模型推导了高速履带车辆横摆运动传递函数,基于此进行了高速履带车辆横摆运动时域和频域响应特性分析,提出履带车辆稳态横摆角速度增益及临界阻尼车速的定义。研究结果表明:履带车辆稳态横摆角速度增益均小于1,履带车辆具有不足转向特性;履带车辆系统阻尼比在1左右;当车速小于临界阻尼车速时,车辆系统为过阻尼系统,横摆角速度响应的上升时间在0.2 s内;当车速等于临界阻尼车速时,车辆系统为临界阻尼系统,横摆角速度响应的上升时间大于10 s;当车速大于临界阻尼车速时,车辆系统为欠阻尼系统,横摆角速度响应的上升时间迅速减小至2~3 s。

高速铁路无砟轨道车辆荷载传递特性研究

为进一步探讨无砟轨道荷载设计参数取值,为我国时速400 km及以上高速铁路建设提供重要理论支撑,通过开展无砟轨道静力分析以及钢轨焊缝、车轮扁疤激励下车辆-轨道动力相互作用,揭示列车静、动力载荷特征及传递规律;同时根据轨道承载特点和无砟轨道设计原理,提出车辆竖向设计荷载取值建议。研究结果表明:(1)高速列车车轮扁疤和钢轨焊缝不平顺将造成显著的轮轨冲击,其轮载动载系数最大可达5.79,远高于现行规范取值;扣件系统对扁疤和焊缝不平顺引起的轮轨力高频成分衰减作用明显,扣件支反力的动载系数最大为2.64;(2)钢轨焊缝不平顺引起的轮轨冲击力随着车速提高以及焊缝不平顺幅值的增大而迅速增大,建议500 km/h及以下高速铁路的钢轨焊缝平直度标准取0.2 mm/m;(3)列车轮载通过扣件支反力作用于轨道板,从传递特性的角度来说,以扣件支反力作为轨道板竖向设计荷载更为合理,其动载系数可取3.0,且能满足400 km/h及以上高速铁路的行车需求。

多源干扰下的智能车模型预测纵向运动抗干扰控制

智能车纵向运动控制面临模型失配和外部环境变化等多源干扰,影响速度跟踪的精确性,本文针对性提出一种结合扰动观测和模型预测控制(model predict control,MPC)算法的纵向运动抗干扰控制方法。首先,根据车辆纵向动力学模型分析车辆纵向加速度与各项作用力之间的关系,然后将其简化为含多源干扰的质点运动型并设计模型预测控制器作为上层控制器。其次,针对内部未建模动态干扰及外部随机干扰,设计线性扩张状态观测器(linear extended state observe,LESO)进行实时估计,并通过前馈环节实施补偿,且分析了MPC闭环稳定性和LESO收敛性,最终形成扰动补偿和状态反馈的模型预测最优调节控制律。进一步地,为确保控制策略的高效执行,提出1阶自抗扰控制器作为下层控制器,将期望加速度转换为发动机转矩,从而实现对车速的闭环控制。最后,将算法部署在车载微控制单元(microcontroller unit,MCU)上,在多个速度和道路工况下进行实车测试。实验结果表明,所提出的策略可以快速且精确跟踪目标车速,具备良好的抗干扰能力。

Impact of train speed on the mechanical behaviours of track-bed materials

For the 30,000 km long French conventional railway lines(94% of the whole network),the train speed is currently limited to 220 km/h,whilst the speed is 320 km/h for the 1800 km long high-speed lines.Nowadays,there is a growing need to improve the services by increasing the speed limit for the conventional lines.This paper aims at studying the influence of train speed on the mechanical behaviours of track-bed materials based on field monitoring data.Emphasis is put on the behaviours of interlayer and subgrade soils.The selected experimental site is located in Vierzon,France.Several sensors including accelerometers and soil pressure gauges were installed at different depths.The vertical strains of different layers can be obtained by integrating the records of accelerometers installed at different trackbed depths.The experimentation was carried out using an intercity test train running at different speeds from 60 km/h to 200 km/h.This test train was composed of a locomotive(22.5 Mg/axle) and 7 'Corail'coaches(10.5 Mg/axle).It was observed that when the train speed was raised,the loadings transmitted to the track-bed increased.Moreover,the response of the track-bed materials was amplified by the speed rise at different depths:the vertical dynamic stress was increased by about 10% when the train speed was raised from 60 km/h to 200 km/h for the locomotive loading,and the vertical strains doubled their quasistatic values in the shallow layers.Moreover,the stressestrain paths were estimated using the vertical stress and strain for each train speed.These loading paths allowed the resilient modulus Mrto be determined.It was found that the resilient modulus(M_r) was decreased by about 10% when the train speed was increased from 100 km/h to 200 km/h.However,the damping ratio(D_r) kept stable in the range of speeds explored.

智慧高速铁路运行控制系统发展趋势综述

在保障安全的前提下,高速铁路运行控制系统进一步结合现代感知、控制、通信以及人工智能技术实现智慧化,是未来高速铁路发展的前沿方向。分析目前高速铁路运营中仍存在异物侵限造成安全事故、突发事件导致列车延误、运力与运量不匹配等问题,提出高速铁路运行控制系统的智能化、智慧化是解决上述问题的重要手段,是保持和提升我国高速铁路技术整体竞争力的核心组成部分。新时期的智慧高速铁路运行控制系统以实现列车(群)全天候全无人自主追踪运行控制为目标,主要包括移动闭塞、列车运行净空感知、列车状态智能监测、列车自主追踪、智能调度指挥、车-地动态自组网通信等关键技术。结合新一代使能技术,研究高速铁路运行控制智能技术的应用及其发展趋势,对我国智慧高速铁路的发展具有参考价值。

基于轨迹预测增强的复杂场景多目标跟踪方法

以冬奥会的短道速滑比赛场景为例,针对短道速滑中运动员的目标外观差异性小、运动变化快、目标间遮挡频繁等运动特点,设计一个应用于短道速滑场景的多目标跟踪数据集,并提出一种基于轨迹预测增强的多目标跟踪方法.首先计算包围框交并比距离与外观特征余弦距离,联合判断检测响应与跟踪轨迹的相似性解决目标外观相似问题;然后通过跟踪轨迹的全局特征和运动线索恢复被遮挡目标丢失的信息,提高中断轨迹的重关联能力;最后根据检测先验控制新轨迹的初始化,减少噪声检测对轨迹跟踪中身份交换的影响.实验结果表明,与DeepSORT方法相比,所提方法在短道速滑场景中能够稳定地跟踪轨迹,有效地减少了轨迹中断,其中,IDF1提升21个百分点,MOT准确度提高14.3个百分点;该方法在目标差异性小、运动变化快的短道速滑场景中保证长期稳定跟踪,对多目标跟踪在复杂场景中的应用具有启发意义.

2022年北京冬奥会雪车项目推橇启动速度与比赛成绩的关系分析

目的:分析2022年北京冬奥会上雪车项目优秀运动员的推橇启动速度、赛道适应性及比赛成绩的变化规律,探索国外优秀运动员的程序化参赛模式,以期为中国雪车运动员的训练提供理论支持。方法:采用文献资料法、观察法、专家访谈法和数理统计法等研究方法,收集国际训练周内国外优秀男子和女子雪车运动员的滑行数据,包括出发时间、推橇启动速度和区间速度等,运用SPSS 22.0进行数据分析,并通过专家访谈进一步探讨影响比赛成绩的关键因素。结果:雪车比赛成绩受推橇启动速度、赛道选择和滑行技术的多重影响;优秀运动员通常采用“先快后慢再快”的推橇启动策略,结合赛道特性逐步优化滑行路线;不同运动员在适应赛道时的速度控制节奏与其最终成绩有显著相关性;男子和女子运动员的启动速度和区间速度均表现出阶段性的波动和稳定性,尤其在比赛节奏的掌控上体现出明显优势。结论:推橇启动速度与比赛成绩密切相关,但启动速度过快未必带来最佳成绩。运动员需要通过赛道试滑调整启动速度和滑行路线,合理平衡速度与技术,以达到最优成绩。国外运动员的程序化参赛模式对赛道适应性有较大帮助。建议:中国雪车运动员应借鉴国外优秀运动员的程序化训练模式,重点关注启动速度与滑行路线的匹配,提升赛道适应性和滑行技术,以备战未来国际赛事。

基于多策略改进的SMC-GTO电机速度跟踪控制

针对传统控制算法在农业机器人驱动电机速度控制方面存在的响应时间长、跟踪效果差以及参数整定难度大,导致驱动电机转速难以在短时间内收敛至预期值的问题,提出一种基于多策略改进的SMC-GTO电机速度跟踪控制算法。首先,为了缩短驱动电机速度响应时间,提高速度跟踪效果,设计了一种新型趋近率的改进滑模控制器(I-SMC);其次,为了快速整定滑模控制器参数,引入了多策略改进的大猩猩部队优化算法(MIGTO)。仿真结果表明:I-SMC能够将电机运行过程中的动态误差累计与过冲控制在0 rad/s内,并且可以在0.4 s内响应至预定速度。MIGTO算法在开发和探索阶段均展现出卓越的性能,尤其在整定基于新型趋近率的改进滑模控制器参数工作中表现突出。该研究通过引入I-SMC和MIGTO算法,成功改进了驱动电机速度控制方式,有效缩短了响应时间,提升了速度跟踪效果。

双回路控制下拖拉机发动机管理系统的设计

随着拖拉机发动机控制系统的复杂性在不断增加,拖拉机发动机扭矩管理系统需要满足多种工况需求,配备多种传感器和执行器,同时具备高效能和燃油经济性。为此,设计了基于双回路速度跟踪控制的拖拉机发动机扭矩管理系统,通过两个回路实现对发动机扭矩的精确控制,其中一个回路用于速度跟踪,另一个回路用于调节发动机扭矩。通过精确的速度控制和扭矩管理,系统可以在不同工况下实现高效的能量利用和优化的运行性能。试验结果表明:系统能够有效地实现发动机扭矩的准确控制,提高了拖拉机的整体性能和燃油经济性。研究结果旨在改进拖拉机发动机控制系统的性能,提高其适应多种工况的能力,并实现更高的燃油经济性。

Methodology to Evaluate Fatigue Damage of High-Speed Train Welded Bogie Frames Based on On-Track Dynamic Stress Test Data

The current method of estimating the fatigue life of railway structures is to calculating the equivalent stress amplitude based on the measured stress data. However, the random of the measured data is not considered. In this paper, a new method was established to compute the equivalent stress amplitude to evaluate the fatigue damage based on the measurable randomness, since the equivalent stress is the key parameter for assessment of structure fatigue life and load derivation. The equivalent stress amplitude of a high-speed train welded bogie frame was found to obey normal distribution under uniform operation route that verified by on-track dynamic stress data, and the proposed model is, in effect, an improved version of the mathematical model used to calculate the equivalent stress amplitude. The data of a long-term, on-track dynamic stress test program was analyzed to find that the normal distribution parameters of equivalent stress amplitude values differ across different operation route. Thus, the fatigue damage of the high-speed train welded bogie frame can be evaluated by the proposed method if the running schedule of the train is known a priori. The results also showed that the equivalent stress amplitude of the region connected to the power system is more random than in other regions of the bogie frame.

基于MPC的智能网联卡车队列最优能耗控制

针对高速公路智能网联卡车队列的能耗优化问题,提出了一种基于模型预测控制的双层控制算法。算法由速度规划层和跟踪控制层两部分构成,其中速度规划层结合道路坡度及车辆状态,通过线性能量守恒模型来消除动力学模型中的非线性项,并以发动机输出功率作为油耗优化指标,采用线性模型预测控制方法获得车队的规划速度;为减少简化车队模型引起的不确定性,跟踪控制层采用基于线性矩阵不等式的分布式鲁棒模型预测控制算法,设计状态反馈控制器对上层规划的最优速度进行跟踪。仿真结果验证了上述双层控制算法的可行性和有效性,可以在保证最优能耗控制的前提下实现车队安全稳定行驶。

高速磁浮列车-轨道梁耦合系统轨道不平顺敏感波长研究

轨道不平顺是诱发车-桥系统耦合振动的主要激励源之一,探明系统耦合振动不平顺敏感波长,对线路管理具有重要参考价值。首先,建立了高速磁浮列车-轨道梁耦合系统空间模型,其中磁浮列车被模拟为具有537个自由度的多体动力学模型,轨道梁被模拟为空间有限元模型,两者之间通过基于比例-微分(proportional-differentiation, PD)控制理论的磁轨关系耦合。其次,以上海高速磁浮为研究背景,选用5车编组列车驶过20跨简支梁桥为计算条件,通过与实测结果对比,验证了模型的正确性。最后,考虑轨道谐波不平顺激励,探讨了不同方向的轨道不平顺组合、不同轨道不平顺幅值和不同车速对列车和桥梁动力响应敏感波长及列车运行平稳性的影响。结果表明:磁浮列车-桥系统横向振动和竖向振动耦合性很弱;在设计车速430 km/h下,车体竖向、侧滚和点头加速度敏感波长分别为140~180 m、60~100 m和120~160 m,车体横向和摇头加速度敏感波长大于200 m;当波长为80、105、115、140和160 m时,会分别引发车体侧滚、摇头、横向、点头和竖向方向的共振;车体和主梁的响应幅值与轨道不平顺幅值基本呈线性关系;当轨道不平顺幅值为1 mm时,在计算车速200、250、300、350、390和430 km/h工况下,车体侧滚加速度峰值随车速变化不大,其他4个自由度方向的加速度峰值随着车速的增大而减小,主梁竖向加速度幅值随车速的增大呈线性增大;从车体的横向和竖向Sperling指标可以看出,车体的Sperling指标均小于2.5,磁浮列车的运行平稳性良好。

中低速磁悬浮铁路路基轨道梁计算方法

研究目的:中低速磁悬浮铁路是一种新型交通运输系统,其路基-轨道梁结构对系统的安全性、运行稳定性和乘坐舒适性有重要影响。为简单合理确定车辆荷载作用下路基-轨道梁结构的挠度和内力以便为实际工程设计提供理论依据,基于Winkler弹性地基上的Timoshenko梁模型,建立中低速磁悬浮铁路路基轨道梁计算方法。研究结论:(1)通过拟静力法将车辆动力荷载转换为等效惯性力,结合梁体边界条件,采用Laplace变换方法,推导出了竖向集中荷载作用下轨道基础梁的挠度和内力的计算公式,并通过室内模型试验和现场测试进行了验证;(2)轨道基础梁的挠度和弯矩沿梁体长度均呈中间大、两端小的抛物线型分布模式,二者理论值与试验值的最大误差分别约为10%、5.6%;(3)梁体剪力沿长度呈跨中为零的线性分布,理论值与试验值最大误差约为5%;(4)本文所建立的计算方法可为中低速磁悬浮铁路路基轨道梁的实际工程设计提供参考。

考虑路基剪切效应的高速铁路有砟轨道-车辆系统移动元分析

为在现有三层离散支撑梁有砟轨道模型中考虑路基土体间的剪切效应,在Pasternak双参数地基模型基础上对剪切层进行离散处理,采用移动单元法建立了考虑路基土体剪切效应的有砟轨道-车辆耦合动力学模型,将移动单元法与MATLAB相结合,编制计算程序,通过MATLAB数值计算,研究路基剪切效应对车-轨耦合系统的影响,以及轨道不平顺和轨枕空吊对系统动力特性的影响规律。研究结果表明,考虑路基剪切效应时,钢轨、轨枕、道砟的位移响应均有不同程度的减小,并且抑制情况从钢轨到道砟相差逐渐增大,三者的加速度响应也均有较为明显的下降,其对加速度响应的抑制效果从道砟到轨枕依次减小,但钢轨的加速度减幅大于道砟,对轮轨接触力有一定影响,但影响不明显,减幅仅为0.85%;不平顺幅值和波长特性对系统的动力响应会产生显著影响,随着幅值增大和短波成分增加,系统动力响应加剧,其中2 m左右短波不平顺和90%百分位数谱对轮轨动力特性影响显著;列车经过空吊区域时,空吊及周围区域轨道结构动力响应会发生突变,导致系统动力响应超过限值。建立的基于移动单元法的有砟轨道-车辆耦合模型及相关分析可为高速铁路的振动分析提供参考依据。

中低速磁浮梁轨一体轨道梁钢混接头试验研究

针对中低速磁浮分离式轨道梁建筑高度较大、无法考虑F轨刚度贡献等问题,提出了一种开孔钢板式梁轨一体轨道梁结构,并针对其钢-混结合部的静力性能开展足尺模型试验和有限元仿真计算分析.首先,介绍了梁轨一体轨道梁工程背景以及钢-混结合部的结构特征;其次,设计了钢-混结合部静载模型试验,测试F轨、钢连接件和混凝土等构件在各级荷载下的应力和位移;最后,建立了钢-混结合部实体有限元模型,并结合试验数据分析了钢-混结合部的受力性能、传力机理以及设计参数影响.研究结果表明:1)在1.50倍设计荷载内,钢-混结合部基本处于弹性状态,连接件承载力满足设计要求;荷载继续增大时,F轨的荷载-应力曲线表现出一定的非线性;5.47倍设计荷载下,混凝土梁体发生开裂破坏.2)F轨内外磁极位移均较小,钢-混结合部刚度较大;F轨内外磁极位移差在设计荷载下满足设计限值;1.58倍设计荷载下内外磁极位移差达到0.54 mm,开始超过位移差限值;表明钢混结合部刚度的富裕量小于强度,钢连接件应以刚度控制设计.3)在正常运营状态,磁浮列车荷载主要由钢连件的钢板承压传递,焊钉与开孔钢板传力比例较小;钢连接件中开孔直径、贯穿钢筋直径对传力影响较小,钢连接件腹板厚度增加使得钢混结合部处传力更加平顺.