DYNAMIC HUNTING EXTREMUM CONTROL METHOD BASED ON MEASURE AND ESTIMATION

Anextremumcontrolsystembasedoncommonhuntingmethods[1 ] cannotworkwellforindustrialprocesses:becauseofthesysteminertialandtimedelayinfluences,thesystemwillbecomeoscillat ing ,workinwrongstepsorwillbehuntingforalongtimefortheworking process.Thepreviousmethod[2 ] canonlyapplytothesystemthathasafastdynamicprocessoritsdynamicresponsecanbeignored .Thispaper proposedadynamichuntingmethod differencepre estimationandcomparisonmethod .Thismethodcanbeusedinsecond orderorhighordersystemswithlargetimecons…     

高速动车组低频周期性晃动问题分析与诊断

高速动车组同一车厢的两个转向架同相蛇行运动频率与车体固有上心滚摆频率接近时,车体因共振而出现低频周期性晃动,不仅影响乘坐舒适性,还会造成脱轨.本文根据低频周期性晃车成因,提出一种以车体横向加速度为研究对象的诊断方法.首先设置车体横向加速度阈值,对超阈值处延拓获得可能存在问题区段,然后利用集合经验模态分解法对这些区段车体...     

对探地雷达检测中的电磁波波速相关问题的思考

通过探地雷达检测技术在公路工程质量检测中的广泛应用,结合长期实践应用的经验性总结,概括性地介绍了在检测中探地雷达电磁波波速确定方法并对影响因素给予了思考及分析,同时有针对性地提出了可行的建议措施.     

The effect of wheel set gyroscopic action on the hunting stability of high-speed trains

This study explores the effects of wheel set gyroscopic action on hunting stability by calculating linear and nonlinear critical speeds. First, a dynamic model for a high-speed vehicle with 23 degrees of freedom is developed by considering wheel set gyroscopic action. The linear and nonlinear critical speeds are calculated by eigenvalue analysis and drawing a bifurcation map, respectively. Two computer programs for linear and nonlinear stability analysis are developed. Second, based on an actual high-speed vehicle in China, the effects of wheel set gyroscopic action on hunting stability are quantitatively investigated using computer simulation. Furthermore, the difference between the effects of gyroscopic moments about the x-axis and z-axis is discussed. The results show that the moment about the x-axis is harmful to hunting stability, but the moment about the z-axis is beneficial to hunting stability. However, the integrated effect of these two moments can enhance the critical speeds and suppress the hunting motion.     

列车蛇行运动仿真监测与虚拟试验研究

以列车横向振动MATLAB/Simulink模型作为监测对象,利用LabVIEW SIT模块将横向振动模型与虚拟仪器技术相结合,对列车运行横向振动数据实时采集、显示,并能在线进行分析处理,同时给出当前列车运行平稳性指标等。研究结果不仅有助于较好理解列车蛇形运动特征,而且所研究的相关虚拟试验具有硬件软件化、数据处理实时、稳定等优点,可为列车动力学检测技术研究提供有效手段。     

车辆系统Hopf分叉的代数求解方法

运用运动稳定性及分叉理论,研究了非线性车辆系统的蛇行运动分叉现象,提出利用Ｈｕｒｗｉｔｚ行列式,给出平衡点失稳而发生Ｈｏｐｆ分叉的代数判定准则和计算方法,这一方法将Ｈｏｐｆ分叉点的求解转化为一个非线性方程的求解问题,并用此方法进行了客车系统运动稳定性的研究。     

Carbody elastic vibrations of high-speed vehicles caused by bogie hunting instability

In particular locations of the high-speed track, the worn wheel profile matched up with the worn rail profile will lead to an extremely high-conicity wheel–rail contact. Consequently, the bogie hunting instability arises, which further results in the so-called carbody shaking phenomenon. In this paper, the carbody elastic vibrations of a high-speed vehicle in service are firstly introduced. Modal tests are conducted to identity the elastic modes of the carbody. The ride comfort and running safety indices for the tested vehicle are evaluated. The rigid–flexible coupling dynamic model for the high-speed passenger car is then developed by using the FE and MBS coupling approach. The rail profiles in those particular locations are measured and further integrated into the simulation model to reproduce the bogie hunting and carbody elastic vibrations. The effects of wheel and rail wear on the vehicle system response, e.g. wheelset bifurcation graph and carbody vibrations, are studied. Two improvement measures, including the wheel profile modification and rail grinding, are proposed to provide possible solutions. It is found that the wheel–rail contact conicity can be lowered by decreasing wheel flange thickness or grinding rail corner, which is expected to improve the bogie hunting stability under worn rail and worn wheel conditions. The carbody elastic vibrations caused by bogie hunting instability can be further restrained.     

铁道车辆蛇行稳定性主动控制综述

为了抑制蛇行运动,提高列车临界速度,针对铁道车辆特殊的轮轨自激振动系统综述了蛇行稳定性主动控制的总体结构形式、控制目标、控制算法、测量系统、作动系统、试验验证等关键环节的研究进展;概括了稳定性控制的典型结构形式及其各自的特点;根据不同运用场景,归纳了稳定性主动控制的主要目标,梳理了稳定性控制的主要算法以及优缺点;分析了不同反馈量测量方法的可行性和可靠性,研究了作动器动态特性对控制效果的影响;给出了稳定性控制的试验研究方法,展望了未来蛇行稳定性主动控制在算法设计、失效安全等方面的研究重点。研究结果表明：在蛇行稳定性主动控制研究中,控制方式和算法的选取要同时考虑控制目标的不同;除了高轮轨匹配等效锥度下的二次蛇行稳定性控制之外,控制目标应同时考虑低轮轨匹配等效锥度下的一次蛇行稳定性控制;控制方式应尽量简单、可靠、易于实施,且对测量系统的要求要小;测量系统也应尽量简单可测,以减小随机扰动和噪声对测量结果可靠性的影响;作动器响应时间及其时滞补偿方法共同决定了蛇行稳定性主动控制的实用效能;控制系统失效不能影响列车的运行安全,这是决定主动控制能否推广应用的关键。     

程潮铁矿矿石损失贫化影响因素调查及分析

通过对程湖铁矿三个分段生产情况的调查,找出影响程潮铁矿矿石损失贫化指标的因素。通过对各因素的分析,并运用计算机模拟和现场试验的方法对某些因素中的参数进行验证,提出了降低贫损指标的建议。     

Multiple USV cooperative algorithm method for hunting intelligent escaped targets北大核心CSCD

[目的]针对无人艇协同围捕过程中逃跑目标具备智能性,现有无人艇策略难以围捕成功的问题,提出一种基于双层切换策略的多无人艇协同围捕算法。[方法]第1层围捕策略采用改进势点法,以无人艇与势点的总直线距离最小为优化目标,采用匈牙利算法为无人艇动态分配势点,并采用人工势场法实现无人艇的协同避碰;第2层围捕策略利用了阿波罗尼奥斯圆的性质,在两艘无人艇前往逃跑目标的目标点进行拦截,剩余无人艇运动方向保持与逃跑目标相同,以不断缩紧包围区域;为应对逃跑目标不同的逃跑方式,第1层围捕策略和第2层围捕策略可互相转化。[结果]仿真实验表明,该算法相较于顺序分配势点算法和极角分配势点算法,围捕时间更少或持平,证明了该算法的有效性和先进性。[结论]该多无人艇协同双层围捕算法,对具备典型智能性的逃跑目标具有围捕效果。