电动汽车动力学控制研究进展

近年来随着全球资源、环境问题日益严峻,节能、环保的电动汽车得到快速发展。电动汽车采用电机驱动系统,具有转矩快速响应、易于精确测量、可实现动力分散控制、可实现制动能量回收等优点。充分挖掘并利用这些优点可显著提升车辆动力学控制性能。文中从电动汽车动力学控制运行参数的识别、动力学控制结构与方法两个角度综述了十多年来的研究成果,重点介绍了轮胎-路面接触条件识别方法、驱动防滑控制方法等。对车辆横向动力学控制,包括电子差速控制、直接横摆控制、底盘集成控制等研究现状也做了总结。最后对未来电动车辆动力学控制的发展方向作了几点展望。     

一系定位刚度对转向架群配置高速货运动车组车辆动力学性能影响研究

为了提高我国铁路对大型、重型、贵重货物的快捷高效运输能力,中车唐山机车车辆有限公司研发了转向架群配置的高速货运动车组.基于多体系统动力学理论,建立了转向架群配置的高速货运动车组车辆系统动力学模型,确定了转向架群配置高速货运动车组车辆的非线性临界速度,研究了一系定位刚度对车辆运行非线性临界速度的影响;同时,利用建立的模型研究了一系定位刚度对车辆运行安全性指标以及平稳性指标的影响.研究结果表明,非线性临界速度随着一系纵向定位刚度的增加先增大后减小,而随着一系横向定位刚度的增加整体呈现减小趋势;车辆横向运行平稳性指标随着一系纵向定位刚度的增加有所增加,而垂向平稳性指标基本保持不变;一系横向定位刚度对车辆运行平稳性指标影响不明显.     

齿轮箱吊杆节点刚度对轴箱内置式高速列车驱动系统动态特性影响研究

为探明齿轮箱吊杆节点刚度对驱动系统悬挂节点力和驱动系统振动加速度的影响规律,以某型轴箱内置式高速动车为研究对象,基于多体动力学理论,建立了考虑驱动系统和齿轮啮合的车辆系统动力学模型,研究了齿轮箱吊杆节点刚度对齿轮箱吊杆节点力、电机吊点力、齿轮箱车轴铰接力、车辆平稳性和驱动系统振动加速度的影响.研究结果表明：由于1、2位驱动系统的齿轮啮合力方向不同,1位驱动系统悬挂节点的垂向力比2位驱动系统悬挂节点的垂向力大.齿轮箱吊杆节点刚度在1~30 MN/m增大时,1位齿轮箱吊杆节点力增大,1位电机吊点力减小,1位齿轮箱车轴铰接纵向力增大、横向力减小;2位齿轮箱吊杆节点力增大,2位电机吊点垂向力增大,纵向力和横向力减小,2位齿轮箱车轴铰接纵向力减小,横向力增大.齿轮箱吊杆节点刚度在30~100MN/m增大时,各悬挂节点力变化不明显.此外,车体的平稳性指标、电机和齿轮箱的振动加速度受齿轮箱吊杆节点刚度变化的影响较小.     

轴箱内置与外置直线电机地铁车辆曲线通过性能对比

为比较轴箱内置与外置直线电机地铁车辆的曲线通过性能,建立直线电机地铁车辆-无砟轨道耦合动力学模型.模型将直线电机定子和转子考虑为Euler梁,将定子与转子之间的垂向电磁力作为气隙的函数,将轨道系统简化为梁-三维实体有限元模型.详细比较轴箱内置与外置直线电机车辆曲线通过时的轮对冲角、轮轨横向力、脱轨因数、运行平稳性和车轮磨耗指数.结果表明:在不同的曲线半径和行车速度以及车轮踏面周向存在非均匀磨耗的状态下,轴箱内置直线电机车辆的曲线通过性能均优于轴箱外置车辆;随着曲线半径增加,轴箱外置直线电机车辆动力学性能迅速减小,而轴箱内置式车辆缓慢减小.     

钢轨波磨对地铁车辆动力学响应的影响

建立地铁车辆-轨道耦合动力学模型,将钢轨视为弹性离散点支撑的无限长Timoshenko梁,将实测钢轨短波波磨不平顺数据作为不平顺激励.通过数值计算得到在科隆蛋扣件线路上不平顺发展过程中车辆动力学响应的变化情况.随着短波波磨不平顺幅值的增大,轮对和转向架的横、垂向加速度以及轮轨横、垂向力均呈增大趋势,且受不平顺程度的影响较大.结果表明钢轨波磨主要影响车辆系统的垂向振动.     

基于SIMPACK研究空簧故障对列车动力学性能影响

基于SIMPACK建立我国某高速动车组动力学模型，研究空簧失效对车辆动力学性能影响。结果表明：空簧失效对车辆稳定性影响不明显，对平稳性和舒适性有显著影响。舒适性受空簧失气影响最严重，垂向平稳性受其影响比横向平稳性严重。横向平稳性指标最大增加率为35.2%,垂向平稳性指标最大增加率为48.6%,舒适性指标已达到极差等级(指标最大增加率为456%)。空簧失气对安全性指标也有所影响，对脱轨系数影响相对较小。     

刚柔耦合特种车辆越障行驶动力学分析及悬架优化

考虑炮管柔性,建立了某轮式特种车辆的刚柔耦合整车动力学模型,并与刚性车辆模型进行对比,分析了刚柔耦合建模对炮管响应的影响;然后计算了该车通过垂直凸台障碍路面的极限高度,分析了刚柔耦合特种车辆通过凸台障碍路面时的动力学特性.以车辆质心垂向加速度为优化目标,悬架刚度和阻尼为优化参数,对悬架进行优化.结果表明,炮管的弹性变形对炮口垂向和水平方向线位移、线速度和角速度的影响显著,建模中有必要考虑炮管柔性,以更准确地计算车辆响应;低速行驶、小的凸台高度,对减小车辆振动有利,在各种工况参数下炮管的垂向振动都比车体振动剧烈;单侧轮通过障碍可以减小路面对整车的冲击,双侧轮通过障碍可以提高车辆稳定性并减小炮管振动;悬架优化后整车和炮管的垂向加速度都明显降低,车辆平顺性得到有效改善.     

车辆平顺性的虚拟现实仿真技术

探讨了基于虚拟现实的车辆平顺性振动仿真原理，利用软件编程的方法实现了汽车在虚拟道路上的行驶运动。汽车行驶时，能够表现车箱(包括驾驶员)的垂向运动、横向运动和俯仰运动，驾驶员的垂向运动、横向运动和俯仰运动，汽车轮胎的旋转运动。其运动规律皆由车辆平顺性动力学分析数据来确定。从而实现了车辆平顺性振动运动在计算机屏幕上的虚拟显示，以图形图像运动来直观的表现车辆的平顺性。     

一种提高无人车在弯道时操纵稳定性的算法

针对车辆弯道的行驶控制中,由于车辆模型维数高、强耦合及非线性强等特点,常规控制算法稳定性差.在深入分析车辆动力学的基础上,简化并建立了其整车动力学及轮胎动力学模型,以行车轨迹与预瞄轨迹的偏差作为输入,提出了一种基于偏差的纵向减速与横向TS-PD相结合的控制算法,实现车辆的弯道自动变速跟随预瞄轨迹的控制目标.仿真结果表明:上述算法与常规控制算法相对比,系统跟踪误差由1m缩小至0.2m,车辆前轮输出更为平滑,具有较强的鲁棒性.     

轨道车辆动力学与控制研究进展

作为动力学与控制学科的一个分支,车辆动力学与控制方向的研究近年来一直很受重视。轮轨式轨道车辆在基础研究、技术攻关和产品研发等领域不断取得重要进展,这得益于近20年来我国轨道交通领域的快速发展和国家科技部门的大力支持。本文从我国轮轨式轨道车辆的发展趋势、特点和运营过程中遇到的主要问题等研究角度出发,重点介绍了轨道车辆的载荷分析与减振降噪方法,轨道车辆动力学建模、计算方法和新型结构的动态设计,以及轨道车辆关键旋转部件的状态识别等三个方面的研究成果。这些成果在一定程度上反映了作者们目前所关注的问题和拟解决途径,希望能给轨道车辆动力学与控制领域的其他研究者们提供一些借鉴和参考。     

Directional dynamics along arbitrary curves in cellular automata

This paper studies directional dynamics on one-dimensional cellular automata, a formalism previously introduced by the third author. The central idea is to study the dynamical behavior of a cellular automaton through the conjoint action of its global rule (temporal action) and the shift map (spacial action): qualitative behaviors inherited from topological dynamics (equicontinuity, sensitivity, expansivity) are thus considered along arbitrary curves in space-time. The main contributions of the paper concern equicontinuous dynamics which can be connected to the notion of consequences of a word. We show that there is a cellular automaton with an equicontinuous dynamics along a parabola, but which is sensitive along any linear direction. We also show that real numbers that occur as the slope of a limit linear direction with equicontinuous dynamics in some cellular automaton are exactly the computably enumerable numbers.     

基于多体动力学的车辆道岔通过性能研究

道岔复杂的轮轨关系及其变截面特性是车辆通过道岔时引起振动甚至脱轨的关键因素.根据60kg/m钢轨18号可动心轨道岔设计布置图,在多体动力学软件中建立车辆—道岔耦合系统模型,在此基础上对车辆—道岔系统模型进行验证,仿真计算车辆侧向和直向通过道岔的动力学响应.结果表明转辙器区、辙叉区轨道截面变化和轮轨型面匹配是影响车辆动力学性能的主要因素.最后,对车辆侧向通过离散轨道模型工况下的动力学响应进行仿真计算,讨论道岔轨下整体刚度和阻尼对模型动力学性能的影响,为改善车辆通过道岔时的动力学性能、道岔轨下刚度与阻尼参数匹配提供理论基础.     

生产厂商逆向供应链演化稳定策略分析

生产型企业通过实施逆向供应链策略取代传统供应链的单向运作模式,可以减少对环境的负面影响和对资源的过度依赖,对本企业生产的废旧产品回收再利用成为当前发展新趋势。将逆向供应链作为一类复杂适应系统,基于复制动态方程和演化稳定策略,构建了逆向供应链演化博弈模型,分析和讨论了逆向供应链中每一个供应商决策如何影响供应链绩效。在市场机制下,供应商的额外收益超出实施逆向供应链的成本,供应商才会采取实施逆向供应链策略,而在政府管制下,相应规制可以有效促进逆向供应链策略的实施。     

机器人逆动力学简化实时快速算法

本文基于机器人动力学模型，通过引入相对误差准则，提出了一种计算机人逆动力学的简化实时快速算法；该算法，根据动力学模型中各元素在期望工作轨迹上的变化速率不同，运用相对误差准则确定出它们的实时计算周期，达到碱少单位控制周期内计算动力学模型的操作数，文中给出了计算实例。     

Multi-machine operations modelled and controlled as switched linear repetitive processes

Many industrial processes involve the processing of a single workpiece by successively passing it through a sequence of machines. The most common example is metal rolling where the metal strip of finite length is shaped by passing it through different sets of rolls and the output from one forms the input to the next and so on. In this paper, we develop a new approach to the analysis and overall control of such systems by first modelling them as a linear repetitive process with switched dynamics. The end result is control law design algorithms which can be implemented using LMI based computations.     

A network dynamics approach to chemical reaction networks

A treatment of a chemical reaction network theory is given from the perspective of nonlinear network dynamics, in particular of consensus dynamics. By starting from the complex-balanced assumption, the reaction dynamics governed by mass action kinetics can be rewritten into a form which allows for a very simple derivation of a number of key results in the chemical reaction network theory, and which directly relates to the thermodynamics and port-Hamiltonian formulation of the system. Central in this formulation is the definition of a balanced Laplacian matrix on the graph of chemical complexes together with a resulting fundamental inequality. This immediately leads to the characterisation of the set of equilibria and their stability. Furthermore, the assumption of complex balancedness is revisited from the point of view of Kirchhoff's matrix tree theorem. Both the form of the dynamics and the deduced behaviour are very similar to consensus dynamics, and provide additional perspectives to the latter. Finally, using the classical idea of extending the graph of chemical complexes by a ‘zero’ complex, a complete steady-state stability analysis of mass action kinetics reaction networks with constant inflows and mass action kinetics outflows is given, and a unified framework is provided for structure-preserving model reduction of this important class of open reaction networks.     

A molecular dynamical study of granular fluids I: The unforced granular gas in two dimensions

Results of a numerical study of the dynamics of a collection of disks colliding inelastically in a periodic two-dimensional enclosure are presented. The properties of this system, which is perhaps the simplest model for rapidly flowing granular materials, are markedly different from those known for atomic or moleclar gases, in which collisions are of elastic nature. The most prominent feature characterizing granular systems, even in the idealized situation in which no external forcing exists and the initial condition is statistically homogeneous, is their inherent instability to inhomogeneous fluctuations. Granular gases are thus generically nonuniform, a fact that suggests extreme caution in pursuing direct analogies with molecular gases. We find that once an inhomogeneous state sets in, the velocity distribution functions differ from the classical Maxwell-Boltzmann distribution. Other characteristics of the system are different from their counterparts in molecular systems as well. For a given value of the coefficient of restitution,e, a granular system forms clusters of typical separationL ₀l/(1-e ²)^1/2, wherel is the mean free path in the corresponding homogeneous system. Most of the fluctuating kinetic energy then resides in the relatively dilute regions that surround the clusters. Systems whose linear dimensions are less thenL ⁰ do not give rise to clusters; still they are inhomogeneous, the scale of the corresponding inhomogeneity being the longest wavelength allowed by the system's size. The present article is devoted to a detailed numerical study of the above-mentioned clustering phenomenon in two dimensions and in the absence of external forcing. A theoretical framework explaining this phenomenon is outlined. Some general implications as well as practical ramifications are discussed.     

探空火箭全弹道仿真分析

探空火箭广泛应用于近地空间环境探测和空间技术试验,为此研究了探空火箭从发射到落地过程中各阶段的动力学特性.将探空火箭整个工作过程分为发射离轨、自由飞行、探空仪分离以及稳定落地四个阶段,建立了离轨下沉、火箭分离、降落伞拉直-充气等较精细的动力学模型,仿真分析了关键设计参数对探空火箭发射、分离以及落地的影响.研究结果可为探空火箭分析设计提供理论参考.     

Molecular dynamics simulations of mutated Mycobacterium tuberculosis l-alanine dehydrogenase to illuminate the role of key residues

l-Alanine dehydrogenase from Mycobacterium tuberculosis (l-MtAlaDH) catalyzes the NADH-dependent interconversion of l-alanine and pyruvate, and it is considered to be a potential target for the treatment of tuberculosis. The experiment has verified that amino acid replacement of the conserved active-site residues which have strong stability and no great changes in biological evolutionary process, such as His96 and Asp270, could lead to inactive mutants [Ågren et al., J. Mol. Biol. 377 (2008) 1161–1173]. However, the role of these conserved residues in catalytic reaction still remains unclear. Based on the crystal structures, a series of mutant structures were constructed to investigate the role of the conserved residues in enzymatic reaction by using molecular dynamics simulations. The results show that whatever the conserved residues were mutated, the protein can still convert its conformation from open state to closed state as long as NADH is present in active site. Asp270 maintains the stability of nicotinamide ring and ribose of NADH through hydrogen bond interactions, and His96 is helpful to convert the protein conformation by interactions with Gln271, whereas, they would lead to the structural rearrangement in active site and lose the catalytic activity when they were mutated. Additionally, we deduce that Met301 plays a major role in catalytic reaction due to fixing the nicotinamide ring of NADH to prevent its rotation, and we propose that Met301 would be mutated to the hydrophobic residue with large steric hindrance in side chain to test the activity of the protein in future experiment.     

基于Intel MIC平台大规模耗散粒子动力学模拟的设计与优化

耗散粒子动力学(DPD)模拟是一种重要的研究流体动力学特性的计算模拟方法,基于Intel MIC平台设计实现了面向大规模耗散粒子动力学模拟,充分结合了DPD模拟本身的特性和MIC平台的特征。对DPD模拟中的近邻列表构建和短程作用力关键代码实现了向量化优化,在CPU和MIC协处理器之间采用任务计算负载平衡机制,支持MPI进程内线程数量负载平衡控制。分别在原型程序上和LAMMPS集成中做了性能对比分析,实验结果显示了引入相关优化技术的有效性,为进一步研究面向MIC众核平台的分子动力学相关工作奠定了基础。