Estimation of Vehicle Speed Based on Wheel Speeds from ASR System in Four-Wheel Drive Vehicles

Three major methods currently in the use of determining vehicle speed based on wheel speeds, the minimum wheel speed, minimum wheel speed corrected by slope method and the Kalman filter method, are analyzed, with merits and defects of each approach stated. Through simulations, the Kalman filter method based on minimum wheel speed shows improved accuracy, in addition to better adaptivity to vehicle reference speed. It also can be used to acceleration ship regulation （ASR） in part-time four-wheel drive vehicles.

Characteristics of wheel-rail vibration of the vertical section in high-speed railways

In order to analyze the characteristics of wheel-rail vibration of the vertical section in a high-speed railway, a vehicle-line dynamics model is established using the dynamics software SIMPACK. Through this model, the paper analyzes the influence of vertical section parameters, including vertical section slope and vertical curve radius, on wheel-rail dynamics interaction and the acting region of wheel-rail vibration. In addition, the characteristics of wheel- rail vibration of the vertical section under different velocities are investigated. The results show that the variation of wheel load is not sensitive to the vertical section slope but is greatly affected by the vertical curve radius. It was also observed that the smaller the vertical curve radius is, the more severe the interaction between the wheel and rail be- comes. Furthermore, the acting region of wheel-rail vibration expands with the vertical curve radius increasing. On another note, it is necessary to match the slope and vertical curve radius reasonably, on account of the influence of operation speed on the characteristics of wheel-rail vibration. This is especially important at the design stage of vertical sec- tions for lines of different grades.

Wear characteristics and prediction of wheel profiles in high-speed trains

Wheel/rail relationship is a fundamental problem of railway system. Wear of wheel profiles has great effect on vehicle performance. Thus, it is important not just for the analysis of wear characteristics but for its prediction. Actual wheel profiles of the high-speed trains on service were measured in the high-speed line and the wear characteristics were analyzed which came to the following results. The wear location was centralized from-15 mm to 25 mm. The maximum wear value appeared at the area of 5 mm from tread center far from wheel flange and it was less than 1.5 mm. Then, wheel wear was fitted to get the polynomial functions on different locations and operation mileages. A binary numerical prediction model was raised to predict wheel wear. The prediction model was proved by vehicle system dynamics and wheel/rail contact geometry. The results show that the prediction model can reflect wear characteristics of measured profiles and vehicle performances.

Minimum Curve Radii for High-Speed Trains, Including the Gyroscopic Moments of the Wheels

This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental principles of dynamics. The result is a design formula for the minimum curve radius needed to prevent derailment. Aside from the rail car geometric and physical properties, the minimum curve radius depends upon the square the train speed. An illustrative example shows that the wheel gyroscopic effect is destabilizing and additive to the centrifugal force derailment tendency. From a track design perspective, however, the gyroscopic effect is relatively small compared with the centrifugal force effect.

Investigation into rail corrugation in high-speed railway tracks from the viewpoint of the frictional self-excited vibration of a wheel–rail system

A finite element vibration model of a multiple wheel-rail system which consists of four wheels, one rail, and a series of sleepers is established to address the problem of rail corrugation in high-speed tracks. In the model, the creep forces between the wheels and rail are considered to be saturated and equal to the normal contact forces times the friction coefficient. The oscillation of the rail is coupled with that of wheels in the action of the saturated creep forces. When the coupling is strong, self- excited oscillation of the wheel-rail system occurs. The self-excited vibration propensity of the model is analyzed using the complex eigenvalue method. Results show that there are strong propensities of unstable self-excited vibrations whose frequencies are less than 1,200 Hz under some conditions. Preventing wheels from slipping on rails is an effective method for suppressing rail corrugation in high-speed tracks.

Analysis of torque transmitting behavior and wheel slip prevention control during regenerative braking for high speed EMU trains

The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability,improving the adhesion utilization,and achieving deep energy recovery.There remain technical challenges mainly because of the nonlinear,uncertain,and varying features of wheel-rail contact conditions.This research analyzes the torque transmitting behavior during regenerative braking,and proposes a novel methodology to detect the wheel-rail adhesion stability.Then,applications to the wheel slip prevention during braking are investigated,and the optimal slip ratio control scheme is proposed,which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control.The proposed methodology achieves the optimal braking performancewithoutthewheel-railcontactinformation.Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.

基于轴箱高频振动的车轮不圆辨识方法研究

为实现对高速列车车轮高阶不圆的实时检测,研究了轴箱高频振动与车轮不圆的频谱特征和映射关系,采用频域积分方法对车轮不圆的幅值和阶次进行辨识.首先,通过静态测试和台架试验,研究我国高速铁路车轮多边形、钢轨波磨和轨道模态的表现形式;其次,通过高速列车长期服役性能跟踪试验,掌握转向架轴箱振动的时频特征和演化规律;最后,以现场出现车轮20阶多边形的车辆为研究对象,提出基于频域积分的车轮不圆阶次和幅值辨识方法.研究结果表明:CRTS-Ⅱ型轨道板钢轨三阶弯曲频率为592 Hz;列车以300 km/h运行时,20阶车轮多边形和136 mm波长钢轨波磨的响应频率分别为580 Hz和613 Hz;钢轨模态、车轮多边形以及钢轨波磨的振动主频较为集中,轴箱高频振动幅值随车速和镟后里程的增大而增大;采用加速度频域积分方法,从理论上可实现对车轮不圆幅值和阶次的辨识;基于线路实测轴箱加速度的20阶车轮多边形辨识结果与静态测试值相对误差不超过5%.

Parametric analysis of wheel wear in high-speed vehicles

In order to reduce the wheel profile wear of highspeed trains and extend the service life of wheels, a dynamic model for a high-speed vehicle was set up, in which the wheelset was regarded as flexible body, and the actual measured track irregularities and line conditions were considered. The wear depth of the wheel profile was calculated by the well-known Archard wear law. Through this model, the influence of the wheel profile, primary suspension stiffness, track gage, and rail cant on the wear of wheel profile were studied through multiple iterafive calculations. Numerical simulation results show that the type XP55 wheel profile has the smallest cumulative wear depth, and the type LM wheel profile has the largest wear depth. To reduce the wear of the wheel profile, the equivalent conicity of the wheel should not be too large or too small. On the other hand, a small primary vertical stiffness, a track gage around 1,435-1,438 mm, and a rail cant around 1：35-1：40 are beneficial for dynamic performance improvement and wheel wear alleviation.

400 km/h高速铁路轮轨噪声与二次结构噪声预测及分析

为评估400 km/h高速铁路列车通过桥梁时产生的轮轨噪声与二次结构噪声,基于统计能量分析法、有限元-边界元法,建立轮轨噪声和二次结构噪声数值预测模型。在此基础上,从轮轨粗糙度、车速和扣件刚度3个方面,分析轮轨粗糙度变化、车速变化以及扣件刚度变化对高速铁路高架段轮轨噪声和二次结构噪声的影响。研究结果表明:(1)在仅改变轮轨粗糙度情况下,综合噪声的变化趋势一致,随着轮轨粗糙度的增大,综合噪声也呈现增大趋势,并且轮轨粗糙度每增加1 dB,声压级增加1 dB(A);(2)在仅改变车速情况下,综合噪声的变化趋势一致,随着车速的增大,综合噪声也呈现增大趋势,但是噪声增大的速率变缓;(3)在仅改变扣件刚度情况下,扣件刚度变化对综合噪声的影响,主要集中在50~800 Hz频段,在其他频段范围内,综合噪声几乎不受扣件刚度变化的影响。在50~200 Hz频段,随着扣件刚度的增大,综合噪声也相应增大;而在200~800 Hz频段,随着扣件刚度的增大综合噪声数值减小。

珠光体型高铁车轮钢的研究进展

珠光体钢具有高强度和优异的耐磨性,广泛应用于铁路车轮。首先总结了目前我国高速动车组车轮的应用现状、轮辋强韧性水平及主要损伤形式;其次,结合350 km/h自主化高铁车轮钢的研发思路从珠光体组织及夹杂物改性控制方面重点介绍了轮辋材料强韧化机理及超高周疲劳性能的研究进展;最后,从冶金与材料学角度提出了未来更高时速高铁车轮用钢的发展思路。

400 km/h高速轮轨噪声特性及轮轨声源贡献量研究

为了研究400 km/h高速轮轨噪声特性,基于傅里叶级数方法和2.5维边界元方法,建立轮轨滚动噪声预测模型,分析轮对与轨道的声辐射特性。利用轮轨滚动噪声预测模型,对轮轨短波不平顺在不同波深和波长特征下的噪声响应,以及扣件参数对轮轨噪声的影响进行研究。结果表明,随着短波不平顺波深增大,轮轨横向力、垂向力分别呈非线性增大0.7、62.7 kN;短波不平顺波长在31.5~500.0 mm时,轮轨横向力、垂向力受影响较小;短波不平顺波深增大1 dB,轮对、轨道和轮轨系统总声功率级呈线性增大约1 dB(A);随着短波不平顺波长减小,轮对声功率增大,轨道声功率先增大后减小;随着扣件垂向刚度增大,轮对、轨道、轮轨系统总声功率级分别减小0.1、1.1、1.0 dB(A);随着扣件垂向损失因子增大,轮对、轨道、轮轨系统总声功率级分别减小0.7、4.4、4.1 dB(A);扣件的横向刚度和横向损失因子对轮轨系统总声功率级无显著影响。

CFRP砂轮高速外圆磨削稳定性分析

为分析不同影响因素对CFRP砂轮高速外圆磨削稳定性的影响,采用铁木辛柯梁理论对具有阶梯特征的工件进行动力学分析,结合锤击试验测得砂轮动态特性,对高速磨削过程中的砂轮-工件两自由度系统进行了磨削稳定性分析。在对阶梯工件进行动力学分析的过程中,发现阶梯特征对于动态特性的影响较小,误差小于2%。在稳定性分析中发现,不同的砂轮转速和不同的工件磨削位置均会影响磨削稳定性。磨削位置越靠近工件中心,工件刚度越弱,磨削稳定性降低易诱发颤振;而在靠近顶尖支撑的位置,由于工件刚度增强,该位置的磨削稳定性将同时受到工件和砂轮的动力学性能的影响。通过磨削试验验证了分析方法的有效性,试验结果表明,工件磨削位置的刚度差异将会影响加工表面质量,由磨削失稳导致的粗糙度增幅可达51.6%。

车轮多边形对高速车辆曲线轮轨动态作用及磨耗演变行为的影响研究

为研究车轮多边形磨损对高速车辆通过曲线时轮轨动态作用的影响,基于车辆—轨道耦合动力学理论,建立考虑轮对和构架柔性的刚柔耦合车辆—轨道动力学模型。以横向轮轨力响应为依据选取多边形阶次,制定考虑曲线运行工况的车轮多边形幅值限值,进一步分析曲线上的车轮多边形磨耗演变行为。结果表明:车轮多边形阶次对轮对横向振动存在一定程度的影响;过圆曲线路段时,多边形车轮的接触点横向位置会向名义滚动圆处靠近且对曲线外侧车轮的横向蠕滑力影响更为显著;过超高严重加剧了车轮多边形对曲线通过性能的影响;磨耗后期形成以初始阶次为主导的混合多边形圆周且对车辆动力学特性的影响加剧。

双雷达与轮轴传感器融合的列车高精度测速方法

为在列车运动过程非线性变化、噪声为非高斯的条件下,实现测速传感器的量测误差校准及融合后的速度高精度估计,提出列车测速系统配置双雷达与轮轴传感器,并根据联邦粒子滤波进行融合的测速方法。以CRH3型列车在两车站间从启动到停止的运行全过程为例,将不同速度估计方法在列车产生空转、打滑、振动以及测速传感器存在动态噪声情况下的测速误差进行分析并验证。仿真结果表明:双雷达与轮轴组合进行校准后粒子滤波相对未校准时在空转和打滑阶段均方根误差可分别降低31.52%、47.35%;对比双雷达分离振动速度校准法和双雷达角度偏差估计校准法,双雷达分离振动速度校准法在列车振动速度占比0~1和雷达安装角误差-1°~1°范围内,相对误差最大可降低39.66%。采用联邦粒子滤波融合后的测速结果较融合前双雷达和轮轴传感器滤波测速的结果MAE分别降低34.71%,14.03%,RMSE分别降低26.51%、10.98%。采用联邦粒子滤波融合的方式较联邦扩展卡尔曼滤波融合测速均方根误差降低26.97%,最大绝对误差可降低16.10%。

基于XGBoost算法的车载场景识别辅助组合导航研究

现有组合导航算法在卫星信号复杂的环境中存在误差随时间发散的问题。针对不同的车载场景增加不同的辅助策略,以提升导航精度,提出了一种基于XGBoost算法的车载场景识别辅助组合导航技术。首先,根据行车过程中的卫星导航数据和车辆状态数据构建特征,并通过Kruskal-Wallis检验比较不同车载场景下特征的分布差异;其次,使用XGBoost算法拟合经过预处理的数据,得到车载场景识别模型;最后,当识别到地库场景时,通过力学编排计算航向角的变化量,也使用轮速运动学模型计算航向角的变化量,然后对两种方式计算的航向角变化量求均值,重新计算当前时刻的姿态,再用新的姿态更新速度和位置。实验结果表明,在地库场景下,相较于不增加轮速运动学辅助的算法,增加辅助的组合导航算法的航向精度标准差平均提升55.27%。

考虑滚动半径差异的适时四驱汽车限滑控制策略

结合小备胎识别和轮速补偿技术,设计了基于前、后轴附着率相等的限滑前馈控制和基于轴速差的限滑反馈控制,搭建了适时四驱汽车动力学仿真平台,对小备胎识别、轮速补偿、限滑控制的有效性进行了验证。实现了适时四驱汽车中央差速及差速限滑功能,提高了车辆的动力性和行驶稳定性,避免了因滚动半径差异导致的限滑控制功能误触发,解决了因备胎滚动半径小而导致的电控多片离合器异常磨损、烧蚀等问题。

升力翼高速列车曲线通过时的轮轨黏着性能研究

建立考虑轮轨关系、升力翼及流场耦合特性等因素的车辆系统动力学模型,分析升力翼高速列车曲线通过时的运动姿态和轮轨接触特性响应,研究列车在曲线轨道运行的轮轨黏着性能,探讨轨道不平顺、曲线半径、运行速度及轮轨接触条件对轮轨黏着性能的影响。研究结果表明:气动升力通过改变列车运行动态响应和轮轨接触特性导致内、外侧轮轨垂向力和纵向蠕滑力重新分配,促使内侧轮更易失去黏着;气动升力和运行速度的增大均会劣化轮轨黏着性能,但曲线半径的增大将显著提升轮轨黏着水平;轨道不平顺削弱了轮轨黏着性能,干态、湿态、油态条件下的轮轨黏着性能依次恶化。列车牵引运行时,干态、湿态、油态条件下的轮轨均能满足牵引力安全限值要求,但制动运行时,湿态和油态条件下的轮轨均不能满足制动力安全限值要求。研究结果可为超高速列车的安全运行与节能设计提供技术支持。

复杂多变工况下高铁轮对轴承故障识别研究

为提升复杂多变工况下轴承故障识别精度,研究了高铁轮对轴承故障识别方法。复杂多变工况下的轮对轴承振动信号经集合经验模态分解后,获得多个IMF分量及剩余分量,计算各分量的排列熵,以此为初始特征集,将朴素贝叶斯算法和最大均值差异(FSBD)方法相结合筛选有效特征,进行源域深度迁移自编码器训练,将输出参数作为目标域深度迁移自编码器的初始参数,检测目标域特征子集,输出故障识别结果。实验结果表明:该方法可实现轮对轴承振动信号的分解,完成初始特征FSI值的计算,选取特征数为150时,轮对轴承故障识别效果最突出,识别精度达到98.5%。

高速动车组变轨距转向架轮轴结构及联接设计

为实现高速动车组跨国互联互通要求,结合变轨距转向架总体设计方案,提出了高速动车组变轨距转向架关键技术之一的轮轴结构及其联接结构的设计方案。对能够实现车轮轴向滑动且传递扭矩的轮轴及联接结构组成进行了总体介绍,突破传统轮轴配合设计理念,采用在车轮与车轴之间增加滑动轴承和衬套、轮轴分别压装内外齿套结构实现车轮滑动及扭矩传递功能。对车轮、车轴的材料选型和结构设计进行了论述,选取成熟应用的轮轴材质,并设计出全新阶梯状轮毂结构。按照EN和UIC标准,对车轮和车轴进行了强度计算及分析,其静强度和疲劳强度均满足要求。同时为验证轮轴联接可靠性,按照GB/T17855—2017标准,对花键进行齿面接触强度、齿根弯曲强度、齿根剪切强度、齿面耐磨损能力及外花键扭转与弯曲强度计算,计算结果满足运用要求。

基于线控底盘的无人驾驶轨迹跟踪控制研究

为提高结构化工况下无人驾驶汽车轨迹跟踪的精确性,提出一种融合纵向车速跟踪控制器的预瞄轨迹跟踪控制算法。针对四轮转向的特性,基于传统纯跟踪算法设计了四轮转向纯跟踪控制模型;针对纯跟踪算法跟踪效果受车速影响较大的缺陷,设计了纵向车速跟踪控制器并采用n维插值表方式在不同曲率处设置不同车速;将四轮转向纯跟踪算法融合纵向车速跟踪控制器,以达到更好的跟踪效果。仿真与实车试验表明,试验平台可较精确地跟踪规划轨迹并平稳抵达目标终点,实车轨迹跟踪过程中最大横向误差控制在0.497m。