Predictive Control Algorithm for Urban Rail Train Brake Control System Based on T-S Fuzzy Model

Urban rail transit has the advantages of large traffic capacity, high punctuality and zero congestion, and it plays an increasingly important role in modern urban life. Braking system is an important system of urban rail train, which directly affects the performance and safety of train operation and impacts passenger comfort. The braking performance of urban rail trains is directly related to the improvement of train speed and transportation capacity. Also, urban rail transit has the characteristics of high speed, short station distance, frequent starting, and frequent braking. This makes the braking control system constitute a time-varying, time-delaying and nonlinear control system, especially the braking force changes directly disturb the parking accuracy and comfort. To solve these issues, a predictive control algorithm based on T-S fuzzy model was proposed and applied to the train braking control system. Compared with the traditional PID control algorithm and self-adaptive fuzzy PID control algorithm, the braking capacity of urban rail train was improved by 8%. The algorithm can achieve fast and accurate synchronous braking, thereby overcoming the dynamic influence of the uncertainty, hysteresis and time-varying factors of the controlled object. Finally, the desired control objectives can be achieved, the system will have superior robustness, stability and comfort.     

Characterization and experiments on the friction catastrophe behaviors of brake material during emergency braking

Based on previous researches on the phenomena and mechanisms of Friction catastrophe (FC), the characterizing methods of the FC were established and the influences of braking conditions on the FC were investigated by experiments. It is found that the FC intensity, duration and starting time can be used for characterizing the FC, which reflects respectively the decreasing degree, velocity and critical time of the friction coefficient in FC. For short duration, the starting time is more practically valuable. With the increasing of initial braking velocity or braking pressure, the FC starting time becomes shorter while the FC intensity grows bigger. By comparison, the influence of initial braking velocity on the FC starting time is more obvious while the braking pressure affects the FC intensity more intensely. It is believed that the results must be valuable for further studies on the FC and can also provide a theoretical basis for reducing the occurrence of frictional failure of friction brakes.     

Thermomechanical Behavior of Brake Drums Under Extreme Braking Conditions

Braking efficiency is characterized by reduced braking time and distance, and therefore passenger safety depends on the design of the braking system. During the braking of a vehicle, the braking system must dissipate the kinetic energy by transforming it into heat energy. A too high temperature can lead to an almost total loss of braking efficiency. An excessive rise in brake temperature can also cause surface cracks extending to the outside edge of the drum friction surface. Heat transfer and temperature gradient, not to forget the vehicle's travel environment (high speed, heavy load, and steeply sloping road conditions), must thus be the essential criteria for any brake system design. The aim of the present investigation is to analyze the thermal behavior of different brake drum designs during the single emergency braking of a heavy-duty vehicle on a steeply sloping road. The calculation of the temperature field is performed in transient mode using a three-dimensional finite element model assuming a constant coefficient of friction. In this study, the influence of geometrical brake drum configurations on the thermal behavior of brake drums with two different materials in grey cast iron FG200 and aluminum alloy 356.0 reinforced with silicon carbide (SiC) particles is analyzed under extreme vehicle braking conditions. The numerical simulation results obtained using FE software ANSYS are qualitatively compared with the results already published in the literature.     

湿喷机液压制动系统制动阀性能研究

为了研究串联式双回路液压制动阀对湿喷机制动性能的影响,根据制动阀结构及工作原理,考虑稳态液动力等非线性因素,采用键合图理论建立了液压制动系统的动力学模型,基于MATLAB平台仿真分析了制动阀的静、动态特性,并在湿喷机上搭建实验平台进行其制动性能测试。结果表明：制动阀输出压力具有比例特性,后桥制动响应快于前桥,且后桥制动压力约大于前桥制动压力0.2 MPa;制动阀双段制动压力梯度的设计可以满足湿喷机在高低速行驶时动能差别较大的制动需求;制动阀阶跃响应迅速,系统能在0.3 s内趋于稳定,且无明显压力超调,制动性能稳定;在制动阀复位阶段,制动油缸将工作腔油液迅速排入油箱,解除制动。制动压力的测试值与仿真值基本吻合,验证了所建模型的准确性。研究结果可以为制动系统的参数匹配和制动阀结构优化提供参考。     

基于缓冲阻尼的空间大惯量负载驱动系统的研究

为了实现某空间飞行器在空间低功耗平稳转动,从提高其动态性能和稳态性能的角度,提出了基于缓冲阻尼的空间大惯量负载驱动系统的设计方法.通过系统阻尼参数匹配设计,并利用弹簧阻尼技术,实现了驱动系统大惯量转动过程的快速启动和平稳制动,解决了其转角行程过冲较大的问题,满足了运动精度要求.采用SimulationX软件对该驱动系统...     

Transient Response of the Starting Rotor System with the Fault of Pedestal Looseness

The dynamic model of a pedestal looseness rotor system is built and the dynamics of the system near the resonance region is analyzed using the KBM method. Then the asymptotic method to study a dynamic system with slow-changing parameters is used to study the starting and braking course of the system. Finally, the analytical results are proved by experiment. The results can be used in the inspecting and fault diagnosis of a rotor system of this type.     

A wet‐road braking distance estimate utilizing the hydroplaning analysis of patterned tire

A wet‐road braking distance estimate for the vehicles equipped with ABS (anti‐lock brake system) is presented in this paper. The entire speed interval at braking is divided into several uniform sub‐intervals, and the energy conservation law is applied to individual sub‐intervals to predict the intervalwise braking times and the resulting velocity profile at braking and the total braking distance. The proposed method is based on a numerical‐analytical approach such that the frictional energy loss of the patterned tire is computed by 3‐D hydroplaning analysis while the other at the disc pad is analytically derived. The operation of ABS is numerically implemented by controlling the tire angular velocity such that the preset tire slip ratio on the wet road is maintained. The tire hydroplaning is analysed by generally coupling an Eulerian finite volume method and an explicit Lagrangian finite element method. Illustrative numerical experiment is presented to support the validity of the proposed estimate. Copyright © 2006 John Wiley & Sons, Ltd.     

三峡升船机系统动态响应分析

根据三峡升船机最新设计报告,采用有限元软件ANSYS构建了升船机系统有限元模型,包括承船厢、提升钢索、滑轮组、平衡重、厢内水体、驱动机构和刹车机构;通过数值模拟,对升船机系统进行了模态分析及动态响应研究,内容包括升船机系统的流固耦合模态及其在各种工况(起动、刹车、事故)下的动态响应和影响因素分析,如弹簧刚度、误载水深、阻尼、承船厢的位置等。计算结果表明:对于升船机这样一个复杂系统,该文所建立的有限元模型及数值算法是合理的,其结果可为升船机系统整体设计提供必要的参考。     

The effect of braking energy on the fatigue crack propagation in railway brake discs

Thermal fatigue cracks can often be found on the friction surface of brake discs used in railway vehicles after a period of usage and include crackle, radial and circumferential patterns. These cracks typically exhibit different initiation and propagation behavior under different braking conditions. In this paper, the effect of braking energy on fatigue crack evolution is analyzed by using experimental testing and numerical simulations. Macro observations show that a significant number of radial cracks appear on the surface of brake discs which operate at 300 km/h, while crackles typically appear after repeated emergency braking (EB) at 200 km/h. No crack growth was observed on disc surfaces after routine braking. The cyclic load that leads to the fatigue crack propagation consists of compressive stress during braking and residual tensile stress after cooling. Simulation results show that the depth of cracks correlates well with the residual tensile stress distribution in brake discs. Breaking tests exposed that the fracture surface of fatigue cracks which were covered by oxides shows nearly elliptic-type. Higher braking energy leads to a hardened layer on the friction surface and oxide generation near the crack edges, which are also important factors that contribute to accelerating crack propagation.     

Longitudinal-bending mode micromotor using multilayer piezoelectric actuator

Longitudinal-bending mode ultrasonic motors with a diameter of 3 mm were fabricated using stacked multilayer piezoelectric actuators, which were self-developed from hard lead zirconate titanate (PZT) ceramic. A bending vibration was converted from a longitudinal vibration with a longitudinal-bending coupler. The motors could be bidirectionally operated by changing driving frequency. Their starting and braking torque were analyzed based on the transient velocity response. With a load of moment of inertia 2.5 x 10(-7) kgm2, the motor showed a maximum starting torque of 127.5 microNm. The braking torque proved to be a constant independent on the motor's driving conditions and was roughly equivalent to the maximum starting torque achievable with our micromotors.     

并联混合动力汽车复合电源控制策略的研究

通过对复合电源在混合动力汽车(HEV)中应用的研究,设计了针对某款并联式混合动力汽车的复合电源结构,并对其效率特性进行了分析,提出了复合电源的功率分配控制策略以及电池给超级电容充电策略,基于MATALAB/Simulink,建立了复合能量存储系统模型,并嵌入ADVISOR软件中,在城市道路循环UDDS工况下进行了仿真研究。仿真结果表明,通过采用该复合电源控制策略,可以充分发挥超级电容和蓄电池各自的优点,改善整车储能系统的存储效率,提高制动能量的回收效率。     

基于S3C2410X的车辆制动监测装置研制

根据车辆104空气制动机的参数特征,研制了一种基于S3C2410X处理器的车辆制动系统监测装置,该装置可实现车辆制动系统常见故障的检测,并对检测结果及制动系统状态数据进行大容量存储,实现对制动机维护的计算机管理。监测装置由气体压力传感器和32位嵌入式计算机两部分组成。压力传感器检测列车制动管、制动缸和工作风缸的压力值。嵌入式计算机通过对传感器提供的信息进行分析处理,实现故障的判别、显示和报警。在单车试验台上进行了车辆制动机故障模拟试验,实验结果表明,该监测装置能够实现常见制动故障的实时检测和报警。     

针刺毡C/C复合材料磨擦制动压力和速度特性

用模拟刹车制动的摩擦试验机,研究探讨了一种针刺毡结构C/C复合材料在不同制动压力和制动速度下的摩擦磨损性能,并用扫描电子显微镜对摩擦表面进行了观察和分析。摩擦磨损机理由磨屑经挤压、剪切堆积在表面形成的磨屑层所决定。在5m/s制动速度或静态条件下,表面温度低(<150~200℃)吸附水气未脱附,其润滑作用导致了较低的摩擦系数值;当制动速度达到10m/s,摩擦使表面温度升高,达到了吸附水气脱附温度,引起摩擦系数急剧升高,达到了最大;此后,随制动速度及表面温度的继续升高,磨屑层间剪切强度降低,导致摩擦系数随之下降。在较高制动速度下,该种材料仍能保持较高的摩擦系数,显示出优良的高温高能摩擦性能。     

Optimal driving strategy for traction energy saving on DC suburban railways

Energy saving on electrified railways has been studied for many years and the technical solution is usually provided by a combination of driving strategy (e.g. coasting), regenerative braking and energy storage systems. An alternative approach is for the driver (or automatic train operation system if fitted) to manage energy consumption more efficiently. A formal method for optimising traction energy consumption during a single-train journey by trading-off reductions in energy against increases in running time has been demonstrated. The balance between saving energy and running faster has been investigated by designing a fitness function with variable weightings. Energy savings were found, both qualitatively and quantitatively, to be affected by acceleration and braking rates, and, by running a series of simulations in parallel with a genetic algorithm search method, the fitness function was used to identify optimal train trajectories. The influence of the fitness function representation on the search results was also explored.     

基于模糊PID的客车防抱死制动系统硬件在环测试试验研究

基于硬件在环测试方法,搭建了客车防抱死制动系统制动硬件在环测试系统。该系统包括Matlab/xPC目标实时环境、气制动系统和整车动力学模型3部分,可对客车制动输出力进行实时数据采集计算。针对整车制动ABS控制策略引入了参数自整定模糊PID控制算法,并测试了客车在高、低附着系数路面的制动情况。测试结果表明:本方法能够很好地根据制动情况对PID参数进行实时整定,始终将车轮滑移率稳定在最佳滑移率0.2(高附着系数)和0.1(低附着系数)附近,具有良好的自适应性和控制精度。     

高速摩擦制动界面振动信号时频法分析技术研究

利用MM-1000型摩擦制动试验机进行了高速摩擦制动试验,使用加速度传感器采集了摩擦制动过程中界面轴向与径向振动信号。利用Morlet小波变换对不同制动压力、干湿工况下的振动信号进行分析,结合摩擦制动过程中瞬时摩擦系数变化对高速摩擦制动界面振动行为时频法分析技术进行了研究。结果表明:重采样能够大幅减小计算量且对低频段振动时频分析无明显影响;Morlet小波时频分析比短时傅里叶变换和HHT边际谱具有更好的分辨率,对制动界面振动信号处理效果更好;时频图中的斜率与制动过程中的转速变化相对应,表明高速摩擦制动过程中转速基本呈线性降低;结合时频图与瞬时摩擦系数曲线可以评估高速摩擦制动过程中界面状况变化过程;振动能量主要集中在基频、二倍频和三倍频,超过三倍频部分能量较少。     

Effect of braking pressure and braking speed on the tribological properties of C/SiC aircraft brake materials

Effects of braking pressure and braking speed on the tribological properties of C/SiC aircraft brake materials has been studied using a disk-on-disk type laboratory scale dynamometer. The braking temperature increased with increasing braking speed and was less affected by changes in braking pressure. The friction coefficient increased to the maximum value at 10 m/s and then fell with the increase of braking speed at the same braking pressure. The friction coefficient decreased with the increase of braking pressure at the same braking speed. The wear rate increased with braking speed increasing at the same braking pressure. The wear rate was little at braking speed below 20 m/s, and rapidly increased when the braking speed exceeded 20 m/s.     

炭纤维增强C/SiC双基体复合材料的制备及性能(英文)

以针刺炭纤维整体毡为预制体,联用化学气相沉积法与熔融渗硅法制得炭纤维增强C/SiC双基体(C/C-SiC)复合材料;研究了C/C-Si材料的显微结构、力学性能和不同制动速度下的摩擦磨损性能及机理。结果表明:C/C-SiC材料具有适中的纤维/基体界面结合强度,弯曲强度和压缩强度分别达240MPa和210MPa,具有摩擦系数高(0.41～0.54),磨损小(0.02cm3/MJ),摩擦性能稳定等特点.随着制动速度提高,C/C-Si材料的摩擦磨损机制也随之变化:在低速制动条件下主要表现为磨粒磨损;中速时以黏着磨损为主;高速时以疲劳磨损和氧化磨损为主。     

列车轴控防滑制动系统试验平台设计

介绍了基于压电阀的列车轴控防滑制动系统的组成及其试验平台。研究了硅压阻式压力传感器的温度 补偿技术,以满足室外长期稳定工作的需求。选择了基于霍尔效应的速度传感器并研究了传感器性能测试方法,提出了多特征参数的指纹识别方法,并应用于速度传感器的故障在线诊断。以压电阀为新型气压控制部件并实验 验证了压电阀较宽的工作环境温度范围;调速系统使试验平台可以在实验室环境中模拟列车运行状态,实现了列 车常用制动、紧急制动、防滑保护、故障诊断等试验功能。     

Characteristic features of the oscillation of shells of bodies of revolution immersed in a viscous fluid flow

The influence of the physicomechanical properties of large-scale shells on their oscillation in a fluid flow is investigated. It is shown that shells of length-variable rigidity may in principle ensure the phase velocity of a traveling wave along the meridian such as to transfer energy from the fluid to an elastic coating over the starting length and thus to preserve it in the form of the energy of elastic oscillations and to recover the fluid pulse on the back side. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 903–906, September–October, 2008.