高速列车车体疲劳试验压力加载控制仿真研究

高速列车在隧道通过或明线交会时,列车表面会产生较大的气压波动,此压力波动通过车体传递到车内也会影响车内压力波动,加之运行速度的不断提高,可引起车体表面材料疲劳甚至断裂。为研究高速列车在复杂工况下车内、外压力波动对车体材料疲劳性能的影响,设计了一种能同时对车内及车外进行压力加载的试验系统。利用AMESIM与SIMULINK接口技术进行联合仿真平台的构建,并进行车内、外压力控制仿真。针对系统数学模型难以建立,且存在大容量、大时滞、非线性及多扰动等特点,采用基于前馈补偿的高阶非因果型迭代PI型控制算法实现车内及车外压力的精确控制。仿真结果表明该算法控制误差较PI型控制算法小,控制效果更理想。     

一种改进的天棚半主动控制算法

针对传统天棚阻尼控制对参数可变的磁流变半主动悬挂系统不能进行有效控制的问题,设计了一种最小控制综合与天棚混合的控制算法;首先建立了理想天棚阻尼控制算法的模型,依据最小控制综合算法模型结构特点将理想天棚阻尼控制作为参考模型;然后依据磁流变阻尼器控制力特点,改进了最小控制综合算法的反馈控制方程,得到混合控制算法的控制律;最后对改进的算法进行了仿真分析;仿真结果表明,混合控制算法在悬挂系统参数发生变化的情况下能够有效降低车体加速度和车轮动载荷,具有较好的控制效果;所设计的改进的天棚半主动控制可以提高车辆的行驶平顺性,对被控系统参数的变化具有良好的适应性,具有较高的实用价值。     

基于EEMD和球SVM的高速列车转向架故障估计 

基于监测数据评估高速列车空气弹簧、抗蛇行减振器和横向减振器关键部件的运行状态,针对故障状态下车体构架横向加速度的非平稳信号,提出IMF能量矩与改进的多类超球支持向量机相结合对车体运行状态估计,改进的的超球支持向量机对球外与球内重叠区域的样本用不同的决策,具有更好的分类效果;实验数据仿真分析表明,在速度变化下列车故障识别率稳定在87%以上,证明所用方法能够提取到故障状态下的典型特征,改进的支持向量分类器并能很好的估计出高速列车的故障状态。     

空间桁架结构的优化配置及振动控制研究

为抑制空间柔性桁架结构的低频振动,采用压电杆件进行优化配置实现桁架结构的振动主动控制。建立了空间桁架结构主动压电杆件的机电耦合模型,利用ANSYS前处理功能编制了压电桁架的机电耦合有限元程序。将可控性度量指标与逐步消减法相结合,实现了空间桁架结构主动杆件的优化配置。对结构进行初始位移扰动、正弦激励以及随机激励,并采用最优模态控制算法进行振动抑制仿真分析,对上述方法进行验证且建立振动控制评价指标进行评价。结果表明将可控性度量指标与逐步消减法相结合的方法可有效抑制空间柔性桁架结构的振动。     

高架桥声屏障高度对列车气动特性影响的数值模拟

采用计算流体力学方法对高架桥声屏障高度影响高速列车空气动力特性进行数值研究.通过网格划分、湍流模型选取、边界条件设置等来提高数值计算精度.结果表明,当高速列车运行在下风向时,头车、中间车上的侧向力随着声屏障高度增加而逐渐下降.头车所受的侧翻力矩在整车中最大,且随着声屏障高度的增加而逐渐减小.随着声屏障高度的增加,上风向工况下中间车受到的侧翻力矩要大于下风向工况.上、下风向工况下高速列车气动特性差异主要是由于流动空腔中列车所处的相对位置不同,改变了车体表面的压力分布,从而改变了车体所受到的气动力、力矩.     

基于跟驰模型的列车运行优化控制模拟研究

列车运行的优化控制是降低运输成本,提高运输服务质量以及实现轨道交通可持续发展的重要方式.本文在传统优化速度跟驰模型的基础上,以能量节约为目标提出了一种改进的模拟模型,用以模拟分析城市轨道交通系统中列车运行的优化控制.所提出的模型是通过在经典的优化速度跟驰模型(见Phys.Rev.E 51 1035 Bando等,1995)中引入新的目标优化速度函数来实现在复杂限速条件下列车运行的优化控制.数值模拟则是以北京市地铁亦庄线为例,利用亦庄线实测数据开展研究.结果表明,所提出的模型能够很好地描述复杂限速条件下列车运行的动态特性,模拟测量得到的结果和亦庄线的实测数据较为符合,由此说明所提出模型的有效性.进一步,通过分析列车运行时空图,列车运行的速度变化及运行时间等,讨论了复杂环境下列车流的时空演化特性.     

真空管道交通列车外流场仿真算法分析

列车运行阻力激增、气动噪声加剧和横向运行失稳等问题严重影响既有高速铁路的进一步提速,构建真空运营环境可以有效解决这些问题。基于有限密闭空间的真空空气动力学数学理论、仿真和试验分析,建立三维静态和动态模型,对四种算法进行系统的对比分析,得出真空管道交通列车外流场仿真算法的合理性设置。研究表明,列车和管道中间气体的三维效应、压缩效应和非定常效应对列车外流场影响显著。研究结果为真空管道交通仿真分析提供理论依据.     

低真空管道列车表面压力变化规律研究

既有高速铁路进一步提速受限,构建低真空管道运行超高速列车的发展趋势日益明显.运用滑移网格技术,建立动车组列车和低真空管道的三维耦合模型,考虑管道气体的瞬态压缩效应,分析低真空管道横截面积、动车组列车运行速度、管道环境温度和环境压力对车体表面压力的影响.研究表明,低真空管道横截面积、动车组列车运行速度、管道环境温度和环境...     

风力机风轮振动特性研究

针对风轮的轴向窜动效应和陀螺效应振动特性,采用流固耦合分析原理进行模态数值模拟及风力机实际运行状态下的试验验证.结论发现:轴向窜动效应振动的触发源于塔架弹性,气动载荷和离心力对该类振动频率的变化基本没有影响;陀螺效应振动的触发源于同一时刻不同叶片表面气动压力的不对称,气动载荷中的周向力是导致该类振动频率发生变化的主要原因,轴向力则对其振动频率的变化没有影响,离心力对该类振动频率的变化影响不大,且近似成线性.相关研究成果,可能为很多风力机在远短于设计寿命期内频繁发生叶根损伤和断裂、变速箱齿轮严重磨损、发电机主轴变形等一些困扰学界的问题提供新的分析思路和答案.     

普速列车与动车组交会过程的车窗安全性研究

随着既有线路上普通快速列车和动车组运行速度的提高,会车时两车之间的气动压力会明显增大。因此,会车压力波给交会的普通快速列车和动车组造成的舒适性和安全性等影响明显加剧。采用基于雷诺时均法(RANS)的RNG k-e二方程的湍流模型仿真计算普通快速列车时速140km与动车组时速200km时,明线和隧道两种工况下会车过程的压力波动情况,并用计算得到的车窗处压力从车窗玻璃的静强度、车窗玻璃的动态冲击强度和车窗安装强度三个方面分析了交会过程的车窗安全性。结果表明: 明线会车过程两车交会侧车窗受正压和负压的影响,隧道会车过程两车交会侧车窗主要受较大的负压的影响。受压缩波和膨胀波的叠加影响,交会压力波的头波波峰和尾波波谷的波动较小,而头波波谷和尾波波峰的波动较大。在隧道会车时,动车组车窗中心处的负压极值最大值约为明线会车的3.87倍,压力波幅值最大值和最大压力平均变化率较接近;普通快速列车车窗中心处的负压极值最大值约为明线会车的4.25倍,压力波幅值最大值和最大压力平均变化率相差较大。车窗的长宽比越大,安装结构强度越大,安装结构越宽,安装强度越大。     

Aerodynamic vibrations of a maglev vehicle running on flexible guideways under oncoming wind actions

This paper intends to present a computational framework of aerodynamic analysis for a maglev (magnetically levitated) vehicle traveling over flexible guideways under oncoming wind loads. The guideway unit is simulated as a series of simple beams with identical span and the maglev vehicle as a rigid car body supported by levitation forces. To carry out the interaction dynamics of maglev vehicle/guideway system, this study adopts an onboard PID (proportional-integral-derivative) controller based on Ziegler-Nicholas (Z-N) method to control the levitation forces. Interaction of wind with high-speed train is a complicated situation arising from unsteady airflow around the train. In this study, the oncoming wind loads acting on the running maglev vehicle are generated in temporal/spatial domain using digital simulation techniques that can account for the moving effect of vehicle's speed and the spatial correlation of stochastic airflow velocity field. Considering the motion-dependent nature of levitation forces and the non-conservative characteristics of turbulent airflows, an iterative approach is used to compute the interaction response of the maglev vehicle/guideway coupling system under wind actions. For the purpose of numerical simulation, this paper employs Galerkin's method to convert the governing equations containing a maglev vehicle into a set of differential equations in generalized systems, and then solve the two sets of differential equations using an iterative approach with the Newmark method. From the present investigation, the aerodynamic forces may result in a significant amplification on acceleration amplitude of the running maglev vehicle at higher speeds. For this problem, a PID+LQR (linear quadratic regulator) controller is proposed to reduce the vehicle's acceleration response for the ride comfort of passengers.     

A multi-input multi-output adaptive feed-forward controller for vibration alleviation on a large blended wing body airliner

Turbulent atmosphere, gusts, and manoeuvres significantly excite aircraft rigid body motions and structural vibrations, which leads to reduced ride comfort and increased structural loads. In particular BWB (Blended Wing Body) aircraft configurations, while promising a significant fuel efficiency improvement compared to wing-tube configurations, exhibit severe sensitivity to gusts. In general, a flexible aircraft represents a lightly damped structure involving a large variety of uncertainties due to fuel mass variations during flight, control system nonlinearities, aerodynamic nonlinearities, and structural nonlinearities, to name just a few. Especially at the beginning of flight testing of a newly developed aircraft type, plant models generally require a lot of verification and adjustment based on obtained flight test data, before they can be used reliably for control law design. Adaptive control already is a well-established method for many active noise and vibration control problems, and thus is proposed here for application to the problem of gust load alleviation. However, safety requirements are significantly higher for gust load alleviation systems than for most noise and vibration control systems. This paper proposes a MIMO (Multi-Input Multi-Output) adaptive feed-forward controller for the alleviation of turbulence-induced rigid body motions and structural vibrations on aircraft. The major contribution to the research field of active noise and vibration control is the presentation of a detailed stability analysis of the MIMO adaptive algorithm in order to support potential certification of this method for a safety-critical application. Finally, the proposed MIMO adaptive feed-forward vibration controller is applied to a longitudinal flight dynamics model of a large flexible BWB airliner in order to verify the derived vibration controller on a challenging control problem.     

Robust H∞ control of active vehicle suspension under non-stationary running

Due to complexity of the controlled objects, the selection of control strategies and algorithms in vehicle control system designs is an important task. Moreover, the control problem of automobile active suspensions has been become one of the important relevant investigations due to the constrained peculiarity and parameter uncertainty of mathematical models. In this study, after establishing the non-stationary road surface excitation model, a study on the active suspension control for non-stationary running condition was conducted using robust H_∞ control and linear matrix inequality optimization. The dynamic equation of a two-degree-of-freedom quarter car model with parameter uncertainty was derived. The H_∞ state feedback control strategy with time-domain hard constraints was proposed, and then was used to design the active suspension control system of the quarter car model. Time-domain analysis and parameter robustness analysis were carried out to evaluate the proposed controller stability. Simulation results show that the proposed control strategy has high systemic stability on the condition of non-stationary running and parameter uncertainty (including suspension mass, suspension stiffness and tire stiffness). The proposed control strategy can achieve a promising improvement on ride comfort and satisfy the requirements of dynamic suspension deflection, dynamic tire loads and required control forces within given constraints, as well as non-stationary running condition.     

On the efficacy of an inertial active device with internal time-delayed feedback for controlling self-excited oscillations

An inertial, active device running on its internal feedback is proposed for controlling the self-excited vibration of a single degree-of-freedom Rayleigh oscillator. The control strategy utilizes the time-delayed feedback of the acceleration of the sprung mass of the device. The feedback law is recursive in nature and based on large amount of weighted information regarding the past history of the dynamics. The proposed device, when properly tuned, either completely quenches or reduces the amplitude of vibration. A comparison with a passive absorber reveals that the proposed active absorber can achieve better stability conditions. However like a passive absorber, the device has finite robustness, i.e., it can control only a certain level of instability inherent in the primary self-excited system.     

Theoretical modeling and characteristic analysis of moving-train induced ground vibrations

An integrated train-track-subsoil dynamic interaction model of moving-train induced ground vibration is developed on the basis of vehicle dynamics, track dynamics and the Green's functions of subsoil. The model takes account of the vibrations of vehicle components, the quasi-static axle loads and the dynamic excitations between the wheels and track. The analyzed results from an example show that the ground vibration characteristics have a close relationship with train speed and soil properties; the dynamic responses excited by wheel-track irregularity have big influence on the high frequency components of ground vibration; with the increase of distance to the track, the ground acceleration has the tendency of decrease, and the relevance of acceleration curves and train excitation becomes less obvious; the intersections of moving load speed-lines and subsoil dispersion curves are some resonance frequencies that cause the amplification of ground vibrations; there exists a critical speed for moving train that is close to the minimum velocity of the Rayleigh's wave in the subsoil.     

无尾升力式飞行器Weissman判据图仿真

针对无尾升力式飞行器横航向气动耦合严重的问题,开展了Weissman判据在此类飞行器稳定性设计中的应用研究.采用调整布局的方法获得飞行器布局集,采用基于Newton理论的工程方法获得对应的气动数据集.运用飞行动力学仿真手段分析了飞行器在无控和副翼控制时的横航向飞行稳定性.结合仿真结果和Weissman判据分区规则获得飞行器Weissman判据图.研究表明,无尾升力式飞行器的关键设计点气动稳定性位于Weissman判据图的B区.文章的方法可用于再入机动飞行器的耦合稳定性设计.      

基于补偿控制的无人地面车辆轨迹跟踪方法

针对无人地面车辆轨迹跟踪精度不高,鲁棒性差的问题,提出了一种基于补偿控制的算法。该算法分为运动学和动力学两部分：基于方向角调整策略的运动学控制律能确保无人地面车辆有效跟踪参考轨迹;基于PD与模型参考模糊滑模自适应控制相结合控制的动力学控制律能有效补偿建模不精确和外界扰动带来的影响。仿真结果表明：该算法能够有效跟踪参考轨迹,控制量分配合理且鲁棒性较好。     

升力体外形布局参数对横侧向耦合稳定性的影响分析

针对高速飞行器存在横侧向耦合易失控问题,建立了基于部件组合思想的CST几何外形参数化建模方法,以升力体外形为例,采用拉丁超立方试验设计方法和高速气动特性快速分析方法,分析了升力体主要布局参数对横侧向耦合稳定性参数开环动态偏离稳定判据（C_nβ,dyn）和闭环横向控制偏离判据（LCDP）的影响规律.升力体外形主导布局参数对横向操纵滚转反逆参数LCDP是二次非线性影响,横侧向稳定性的主导布局参数随着攻角变化有明显变化.文章为耦合稳定性影响规律研究建立了有效的分析方法,研究结论可为高超声速升力体式飞行器总体抗失控设计提供规律建议.      

轮式机器人轨迹跟踪控制系统的设计

针对轮式机器人轨迹跟踪控制系统误差收敛速率低、精度和实时性差的问题,采用反演控制算法并结合李雅普诺夫稳定性分析方法对轮式机器人的轨迹跟踪系统进行了优化设计。建立了轮式机器人轨迹跟踪控制系统的运动学模型,并对该模型进行位置偏差分析;在反演控制算法中引入了分部虚拟控制量,并分析和设计了其他间接受控量,提高了算法运行的效率;采用李雅普诺夫收敛定理对系统的收敛性进行分析,根据分析的结果提出了算法更加简单的控制律。利用Matlab软件的Simulink库对设计的轨迹跟踪控制系统试验研究。结果表明,与基于李雅普诺夫直接法或者迭代学习算法设计的轮式机器人轨迹跟踪控制系统相比较,设计的控制系统具有跟踪精度高、收敛速度快、实时性好的优点。