铁路车轮导纳分析

为控制铁路车轮的振动和噪声辐射,采用模态叠加法分析车轮频率响应,利用ANSYS建立车轮结构有限元模型,根据0～10 000 Hz的模态计算0～5 000 Hz内的频率响应,用Block Lanzos法计算50～5 000 Hz内车轮的固有频率和振型,分析车轮的固有模态和导纳特性.研究结果表明：车轮在名义接触点处受到不同方向激励时所得的导纳特性与车轮相应的模态有关;对于车轮不同接触点处的激励,在1 000 Hz以下频段,轮缘轴向激励引起的径向导纳大于踏面径向激励引起的径向导纳,在其他频段,踏面径向激励引起的径向导纳都比轮缘激励引起的径向导纳大.铁路车轮导纳分析有助于探明车轮噪声产生的机理,是轮轨噪声分析的基础.     

Adaptive neuro-fuzzy wheel slip control

Due to complex and nonlinear dynamics of a braking process and complexity in the tire–road interaction, the control of automotive braking systems performance simultaneously with the wheel slip represents a challenging problem. The non-optimal wheel slip level during braking, causing inability to achieve the desired tire–road friction force strongly influences the braking distance. In addition, steerability and maneuverability of the vehicle could be disturbed. In this paper, an active neuro-fuzzy approach has been developed for improving the wheel slip control in the longitudinal direction of the commercial vehicle. The dynamic neural network has been used for prediction and an adaptive control of the brake actuation pressure, during each braking cycle, according to the identified maximum adhesion coefficient between the wheel and road surface. The brake actuation pressure was dynamically adjusted on the level that provides the optimal level of the longitudinal wheel slip vs. the brake pressure selected by driver, the current vehicle speed, the brake interface temperature, vehicle load conditions, and the current value of longitudinal wheel slip. Thus the dynamic neural network model operates (learn, generalize and predict) on-line during each braking cycle, fuzzy logic has been integrated with the neural model as a support to the neural controller control actions in the case when prediction error of the dynamic neural model reached the predefined value. The hybrid control approach presented here provided intelligent dynamic model – based control of the brake actuation pressure in order to keep the longitudinal wheel slip on the optimum level during a braking cycle.     

考虑高速公路横向坡道转向行驶操纵稳定性的汽车轴距和轮距分析

为分析汽车轴距和轮距设计对操纵稳定性的影响,建立高速公路横向坡道转向行驶的汽车转向动力学模型,并在MATLAB/Simulink软件中建立相应的仿真模型.采用某型汽车设计轴距和轮距进行仿真,得到以不同速度在不同横向坡度道路上转向行驶时的横摆角速度、侧向加速度和质心侧偏角.根据该型汽车的转向特性和侧翻阈值评价其在高速公路...     

区域生长的轮对图像分割

轮对作为列车的重要组成部分,其踏面磨耗参数的在线检测对保障轨道交通安全具有重要意义。在基于光截图像测量技术的轮对外形尺寸动态检测中,能否获取完整的轮对轮廓图像至关重要。针对轮对图像特点,提出一种基于区域生长的轮对图像分割新算法。该算法根据不同情况下轮对图像特点,通过基点位置选取恰当的种子点,并确定合适的生长准则。经过区域生长,有效地提取轮对轮廓图像。通过大量图像验证,该算法分割结果图的交迭面积比大于80%,误分面积比小于0.02%。可以在多种情况下有效地提取轮对轮廓曲线,具有良好的抗噪能力。     

An inverse shape design method for railway wheel profiles

Optimisation of a railway vehicle–track system is a complex process. The paper presents a procedure for optimal design of a wheel profile based on geometrical wheel/rail contact characteristics such as the rolling radii difference (RRD). The procedure uses optimality criteria based on an RRD function. The criteria account for stability of wheelset, cost efficiency, minimum wear of wheels and rails as well as safety requirements. The shape of the wheel profile approximated by a piecewise cubic Hermite interpolating polynomial is varied during the optimisation process to satisfy the optimality criteria. A numerical technique called multipoint approximations based on response surface fitting (MARS) has been chosen as an optimisation method. The proposed optimum design procedure has been applied to improve the performance of metro trains in Rotterdam (RET), The Netherlands. The trains were suffering from severe wheel tread wear and as a result of that from lateral vibrations (hunting). Using the proposed procedure, a new wheel profile has been obtained and applied to the RET metro trains. The results of the optimisation have shown that the performance of a railway vehicle can be improved by improving the contact properties of the wheel and rail. After the application of the optimised wheel profile, the instability of the metro trains has been eliminated and the lifetime of the wheels has been increased from 15,000 to 120,000 km.     

基于LabVIEW的飞机机轮转速模拟装置

针对飞机的地面模拟试验,基于LabVIEW和数据采集卡,开发了飞机机轮转速模拟装置。该装置可同时输出4路正弦信号,模拟飞机机轮转速传感器信号。利用图形界面可以方便地设置信号的幅值和输出方式,输出信号的频率与转速成正比,转速通过读取已知转速-时间曲线或根据当前刹车压力积分计算得到。通过网络可与其它计算机传递数据和指令,实现远程控制。实际应用表明,该装置操作简便,很好地满足了试验需求。     

Online prediction model for wheel wear considering track flexibility

The objective of this study is to develop a new online model for wheel wear that takes into account the track flexibility. The proposed model consists of two parts that interact with each other, namely, (a) a locomotive/track coupled dynamics model considering the track flexibility, which is validated by field measurement results, and (b) a model for the wear estimation. The wheel wear prediction model can be employed in online solutions rather than in post-processing. The effect of including the track flexibility on the wear estimation is investigated by comparing the results with those obtained for a rigid track. Moreover, the effect of the wheel profile updating strategy on the wheel wear is also examined. The simulation results indicate that the track flexibility cannot be neglected for the wheel wear prediction. The wear predicted with the rigid track model is generally larger than that predicted with the flexible track model. The strategy of maintaining unchanged wheel profiles during the dynamic simulation coincides with the online updating strategy in terms of the predicted wear.     

轻轨线路曲线半径对车轮磨耗的影响

为分析线路曲线半径对轻轨列车车轮磨耗的影响,以长春市轻轨3号线70％低地板轻轨列车车轮为研究对象,建立独立旋转轮对的轻轨车辆-轨道耦合动力学计算模型、轮轨接触模型和Archard材料磨耗模型,对轻轨列车车轮磨耗进行仿真分析.计算结果表明:轻轨列车通过半径为50 m的曲线时,圆曲线上的车轮磨耗比缓和曲线更严重,整体轮对比独立轮对磨耗更严重;曲线半径大于150 m时,内、外侧车轮磨耗随着曲线半径增大而减小,并且在曲线半径相同的条件下,独立轮对各车轮磨耗量均比整体轮对各车轮磨耗量约大2 ～3 mm;随着列车行驶里程的增加,车轮磨耗率有先增大后减小的变化趋势,即可以将车轮磨耗分为快速磨耗和稳定磨耗2个阶段.轻轨车辆外侧车轮的磨耗率大于内侧车轮,说明车轮磨耗主要发生在外侧车轮.     

霍尔车轮传感器的研制

铁路车轮传感器是铁路监测及控制的重要基础设备。近年,徐州电务段完成了铁路霍尔车轮传感器的研制和试验。该研制和试验基于霍尔效应原理,研制出的产品比采用LC谐振原理的车轮传感器灵敏度高、抗干扰能力强、抗振动性能强、体积小;与国外同类产品相比,功耗在无车占用的情况下低75%,在有车占用情况下低50%,输出电压的稳定度提高了10%,电源电压范围扩展了3倍,在钢轨出现"肥边"的情况下,灵敏度显著提高,满足了铁路编组场计算机系统对车列的定位和速度检测的要求。     

一种方向盘上操作手数目检测算法

提出一种基于机器视觉检测方向盘上操作手数目的方法。首先确定图像中方向盘的位置,计算方向盘在椭圆区域的尺寸参数,进而获得方向盘椭圆形中心线上点的坐标,以此坐标点为中心截取30×60大小的窗口为感兴趣区域,并将截取的感兴趣区域倾斜角度作归一化处理。归一化之后的感兴趣区域经直方图均衡化和二值化等预处理操作后,利用双阈值判定法判断单一感兴趣区域中是否有类似手形存在,再以特定步长沿椭圆中心线按逆时针方向搜索全方向盘区域,根据方向盘的V-φ图形判断方向盘上的操作手数目。     

连续纤维增强复合材料商用车车轮的抗冲击性能仿真

为实现车轮的轻量化,采用碳纤维增强树脂基复合材料、基于国标要求的轮辋与轮辐截面尺寸设计一款商用车车轮,并根据层合板设计原则设计其铺层结构。为验证车轮的抗冲击性能,基于车轮30°冲击试验标准,在Abaqus软件中建立车轮冲击试验的有限元仿真模型,分别基于蔡 吴准则和Hashin准则对车轮冲击过程的受力状态进行模拟,根据仿真结果改进车轮的铺层方式,从而提高车轮的抗冲击性能,使其满足冲击试验要求。与同等规格的铝合金车轮相比,复合材料车轮取得约25.3%的轻量化效果。     

Control of wheel system under uncertainty

Consideration was given to the nonholonomic mechanical systems with rolling or the wheel systems such as mobile robot, car, or wheeled tractor. Analysis was confined to the kinematic models with regard for the dynamics of the controlling drives. Control of system motion along a given trajectory (planar smooth curve) was studied. The designed control law stabilizes this motion in large in the basic variables. The main result lies in solution of the problem of control under uncertainty when only sufficiently general dynamic characteristics of the wheel system drive are known.     

Worm wheel mechanism with passive rollers

In this study, we developed new worm wheel mechanisms with passive rollers as their teeth and confirmed useful functions of these worm wheels with passive rollers to transmit power from worm gears with higher energy efficiency than ordinary worm wheels. By using passive rollers as their teeth, the developed worm wheels could realize high-power transmission efficiency with rolling frictional resistance instead of sliding frictional resistance. A worm wheel with conical passive rollers and one with disk-shaped passive rollers was fabricated as prototypes and examined in experiments. Smooth back-drivability of the worm wheels with passive rollers, which is difficult to realize with conventional worm wheels, was also demonstrated in the experiments. These serial experiments revealed that the developed worm wheel mechanism with passive rollers can replace conventional worm wheels with the same number of teeth and module in ordinary power transmission mechanisms with worm gearing and realize higher energy efficiency and smooth back-drivability. These features can be very useful to realize safe and soft actuators for automation systems in a human environment.     

轮轴压装过程的有限元分析

由于轮轴压装质量直接影响轨道列车的安全运行,针对轮轴压装不当产生轮轴内表面严重机械损伤的问题,应用有限元法对其进行研究.用Abaqus建立过盈配合下轮轴的有限元模型,仿真分析压装过程中压装力和等效应力的变化及分布规律,发现应力集中位置位于车轴轮座与轮毂孔的结合处及注油孔的外沿,因此应对应力集中位置做重点探伤;压装过程中压装力和最大等效接触应力都不断变化,其中压装力随着压装位移的增大而逐渐增大,而最大等效接触应力随着压装位移的增大呈先增大后减小的趋势;通过对比不同压入位移时轮轴的等效应力发现,压入位移超过190 mm时,车轴左端卸荷槽处开始发生形变,出现应力集中现象,因此压入位移应控制在190 mm以内.     

惯性轮倒立摆的鲁棒镇定

用一个时滞状态反馈控制律镇定惯性轮倒立摆,不仅保证闭环系统全局渐近稳定,还允许闭环系统承受一定的时滞.将惯性轮倒立摆转化为存在高阶非线性的4维积分器链,然后设计一个明确规定了饱和度和时滞参数的饱和控制律.用简单方式证明了闭环的全局渐近稳定性.仿真表明设计是有效的.     

上海地铁车辆统型车轮疲劳强度分析

为分析上海地铁车辆统型车轮的疲劳强度,建立上海地铁车辆统型车轮和上海地铁11号线车轮的有限元模型,依据国际铁路联盟的UIC标准以及欧洲的EN标准模拟车轮在直线、曲线和道岔等工况下的应力;分析车轮疲劳强度的计算方法,并依据Haigh图评估分析这2种车轮的疲劳强度.结果表明,2种车轮均具有良好的静强度和疲劳强度性能,都能满...     

Development of a transformable wheel actuated by soft pneumatic actuators

Small mobile robots with transformable wheels have recently emerged thanks to their increased mobility and maneuverability. When a high payload is applied to these robots, however, wheel transformation becomes difficult because they must directly overcome the payload’s weight. In this paper, we propose a wheel that can be transformed from its starting circular shape (radius, 56 mm) to a wheel with three legs (radius, 99 mm) under a high payload with low operating force. The key design principle of this wheel is to kinematically decoupled legs and passive locking. Its legs are kinematically decoupled but operated by a single air pump using a pneumatic channel connected to soft pneumatic actuators installed at each leg. Application of pressure causes the legs to behave like a coupled system through the pneumatic channel. With pressurization, the two legs that are not in contact with the ground easily emerge from body, and the leg in contact with the ground emerges once the wheel rotates. Once emerged, each leg is supported by a rigid pawl instead of by the soft pneumatic actuators. This setup enables the legs to be transformed independently with low air pressure, even under high payloads. It reduces system weight and the energy required to maintain the transformed shape. This legged wheel can overcome obstacles up to 2.9 times the radius of the wheel in its circular form, and wheel transformation can be accomplished with 85 kPa air pressure for payloads up to 1115 g.     

Effect of gravity in wheel/terrain interaction models

Predicting the motion of wheeled robots in unstructured environments is an important and challenging problem. The study of planetary exploration rovers on soft terrain introduces the additional need to consider the effect of nonterrestrial gravitational fields on the forces and torques developed at the wheel/terrain interface. Simply reducing the wheel load under Earth's gravity overestimates the traveled distance and predicts better performance than is actually observed in reduced‐gravity measurements. In this paper, we study the effect of gravity on wheel/terrain interaction. Experiments were conducted to assess the effect of reduced gravity on the velocity profile of the soil under the wheel, as well as on the traction force and sinkage developed by the wheel. It was shown that in the velocity field of the soil, the decay of the tangential velocity component becomes gradual with reducing gravity, and the decay of the normal to rim velocity is slower in Lunar gravity. It was also found that wheel flexibility can have an important effect on the dynamics as the contact patch and effective radius vary periodically. These results were then used together with traditional semiempirical terramechanics models to determine and validate the simulated drawbar pull values. The developed simulation model includes the effect of wheel flexibility, dynamic sinkage, and gravity.     

静止和旋转孤立车轮局部流场的评价

为研究车轮周围流场特征,分别对某孤立车轮静止和旋转工况下周围流场进行数值研究,并给予试验验证.计算采用定常雷诺时均纳维斯托克斯方程.在1∶15的模型风洞中进行试验.数值模拟结果与试验数据吻合.针对数值模拟结果,详细分析静止和旋转孤立车轮周围流场的流动情况、表面压力因数、气动阻力因数和气动升力因数等,得到孤立车轮旋转对车轮附近局部流场的影响以及形成机理.车轮的转动使总体压差减小,降低气动阻力和升力,改善气动性能。     

Design and experimental validation of a nonlinear wheel slip control algorithm

We present a new wheel slip controller and validate it both experimentally and in simulation. The control strategy is based on both wheel slip and wheel acceleration regulation, and ensures global asymptotic stability in closed loop. The stability analysis is established using tools for cascaded systems. This approach has the advantage of setting conditions on the control gains that are considerably milder, if compared with those obtained from Lyapunov’s direct method. Simulations are provided to illustrate the robustness against vertical load variations and uncertainties in tyre–road friction. Furthermore, tests on a tyre-in-the-loop facility show that with our control law the wheel slip converges precisely to the assigned reference.