考虑间隙反馈控制时滞的磁浮车辆稳定性研究

常导磁吸型(EMS)磁悬浮列车在悬浮控制中的每个环节,时滞是不可避免的,当时滞超过一定程度后,系统有可能失稳.本文针对EMS磁浮列车控制环节的临界时滞与车辆参数(如运行速度、反馈控制增益、导轨参数和悬挂参数)的关系开展研究.建立了磁浮车辆/导轨耦合动力学模型,车辆包含1节车辆和4个磁浮架,考虑车辆的10个自由度,每个磁浮架上包含4个悬浮电磁铁.导轨模拟为一系列简支Bernoulli-Euler梁,采用模态叠加法对导轨振动方程进行求解.采用传统线性电磁力模型实现车辆和轨道的耦合.采用比例-微分控制算法对电磁铁电流进行反馈控制,实现车辆稳定悬浮,并假设时滞均发生在控制环节,且只考虑间隙反馈控制环节的时滞.采用四阶龙格库塔法对耦合系统动力学方程进行求解,编写了数值仿真程序,计算得到车辆导轨耦合系统在考虑间隙反馈控制时滞时的响应.将系统运动发散时的时滞大小视为临界时滞,开展了参数规律影响分析.通过分析,给出了提高时滞条件下车辆稳定性的方法,包括增大导轨的弯曲刚度和阻尼比,减小间隙反馈控制增益并增大速度反馈控制增益,以及增大二系悬挂阻尼.      

参数激励下非线性受控系统的动力学和稳定性

研究两自由度参数激励系统的非线性动力学与控制问题．利用Lagrange方程建立含反馈控制的参激捅及其驱动机构组成的系统动力学方程，以多尺度方法获得一阶近似控制方程．然后，对系统受一阶摸态参激主共振与一、二阶模态间3：1内共振联合作用下的幅额响应及其稳定性，以及反馈参数对系统稳态行为的影响作了详细分析．结果表明，响应的稳定域位置和大小取决于位移反馈，位移立方反馈改变了系统的非线性程度，速度反馈类似于阻尼，可使系统呈现自激振动特性．     

可控约束阻尼层板的控制实验研究

对具有可控约束阻尼层的板进行了振动控制实验研究． 以压电片作为作动器,根据测量的结构振动信号,反馈控制约束层的变形,抑制板的振动． 对试验件进行了试验模态分析,讨论了压电片的附加位置;采用比例反馈对试验件进行了控制试验;试验给出了控制效果和压电片面积的关系． 研究结果证明,这种利用粘弹性阻尼抑制结构的高频振动,利用压电材料的逆压电效应控制结构的低频振动的主被动杂交控制方式对薄壁结构的振动抑制效果显著,控制频率范围宽,可靠性高．     

考虑间隙反馈控制时滞的磁浮车辆稳定性研究

常导磁吸型(EMS)磁悬浮列车在悬浮控制中的每个环节,时滞是不可避免的,当时滞超过一定程度后,系统有可能失稳.本文针对EMS磁浮列车控制环节的临界时滞与车辆参数(如运行速度、反馈控制增益、导轨参数和悬挂参数)的关系开展研究.建立了磁浮车辆/导轨耦合动力学模型,车辆包含1节车辆和4个磁浮架,考虑车辆的10个自由度,每个磁浮架上包含4个悬浮电磁铁.导轨模拟为一系列简支Bernoulli-Euler梁,采用模态叠加法对导轨振动方程进行求解.采用传统线性电磁力模型实现车辆和轨道的耦合.采用比例–微分控制算法对电磁铁电流进行反馈控制,实现车辆稳定悬浮,并假设时滞均发生在控制环节,且只考虑间隙反馈控制环节的时滞.采用四阶龙格库塔法对耦合系统动力学方程进行求解,编写了数值仿真程序,计算得到车辆导轨耦合系统在考虑间隙反馈控制时滞时的响应.将系统运动发散时的时滞大小视为临界时滞,开展了参数规律影响分析.通过分析,给出了提高时滞条件下车辆稳定性的方法,包括增大导轨的弯曲刚度和阻尼比,减小间隙反馈控制增益并增大速度反馈控制增益,以及增大二系悬挂阻尼.     

可控约束阻尼层梁的H∞控制实验研究

建立了可控约束阻尼层悬臂梁的动力学模型,分析了模型中的不确定性．针对模态溢出问题,研究了可控约束阻尼层梁结构的Ｈ∞鲁棒控制设计,并进行了数值仿真与控制实验研究．结果表明,与位移比例反馈控制相比,Ｈ∞控制能有效抑制可控约束阻尼层梁结构的模态振动,且对被截断模态不产生控制溢出,具有良好的鲁棒稳定性．     

结构-模态主动控制系统的最大允许时滞及稳定性探讨

根据Ｎｙｑｕｉｓｔ稳定性准则、特征值原理和ＬＱＲ控制原理,导出了结构－模态控制系统的位移速度反馈的时滞计算公式,进而可求得结构－模态主动控制系统的最大允许时滞。数值分析表明,用两种不同稳定判据得到的两个最大允许时滞计算公式的计算结果是接近的。研究了时滞补偿后结构－模态主动控制系统的稳定性问题。从具有时滞补偿控制系统的特征方法知,具有时滞补偿的控制系统保持理想控制系统的特征值,既时滞补偿结构－模态主     

基于速度反馈分数阶PID控制的达芬振子的主共振.

与传统整数阶比例-积分-微分(PID)控制器相比,分数阶比例-积分-微分控制器由于增加了两个控制参数,因此能够更灵活地控制受控对象.研究了基于速度反馈分数阶比例-积分-微分控制的达芬振子的主共振,利用平均法获得了系统的近似解析解.研究发现分数阶比例-积分-微分控制器的比例环节以等效线性阻尼的形式影响系统的共振振幅,积分环节以等效线性阻尼和等效线性刚度的形式影响系统的动力学特性,微分环节以等效线性阻尼和等效质量的形式影响系统的动力学特性.建立了主共振幅频响应方程的解析表达式和稳定性判断准则,并对主共振幅频响应的近似解析解和数值解进行了比较,二者吻合良好,验证了求解过程和近似解析解的正确性.分析了分数阶比例-积分-微分控制器的比例环节系数、积分环节系数、微分环节系数以及分数阶阶次变化时,对系统主共振幅频响应的影响.对分数阶比例-积分-微分控制器与传统整数阶比例-积分-微分控制器的控制效果进行了对比,发现当控制器各个环节的系数相同时,基于速度反馈的分数阶比例-积分-微分控制对达芬振子主共振的控制效果要优于传统整数阶比例-积分-微分控制.      

具有采样反馈的力控制系统稳定性

基于计算机的数字采样控制对离散信号进行运算并向作动器提供控制输入,是当前的主流控制技术.数字采样控制系统是这样一类控制系统,其控制对象由微分方程(组)描述,而控制律由离散采样信号给出.以采样PD(proportional-derivative)反馈作用下的单自由度力控制系统为例,基于离散系统的稳定性分析方法,研究采样控制律对控制系统稳定性的影响.为了突出采样反馈的作用,将系统取为无刚度、无阻尼的最简单形式.不同于已有研究假设位移采样信号与速度采样信号相互同步,本文研究当位移采样信号与速度采样信号不同步时受控系统的稳定性,发现位移采样信号与速度采样信号的采样周期不同组合对受控系统在增益平面上的稳定性区域有重要影响.结果表明,对所关心的三种数字采样反馈控制律,当位移采样信号滞后于速度采样信号一个采样周期时,受控系统具有最大的稳定性区域且对相同的增益值可以有最好的稳定效果.论文对这种现象进行分析,给出了一种力学解释.     

主动约束层阻尼结构的数值分析方法

采用板的一阶剪切理论（ＦＯＳＴ），利用Ｈａｍｉｌｔｏｎ原理推导了分布式主动约束层阻尼结构的有限元控制方程。作为算例，应用模态应变能（ＭＳＥ）方法研究了一边固支板的主动约束层阻尼振动控制，分析了控制系统中阻尼层厚度及反馈增益对振动控制效果的影响。     

关于一类非线性阻尼模型控制问题的一个注记

利用模态方法进行柔性体控制，就必须作模态截断。在线性粘性阻尼模型情形，阻尼正比于频率，高阶模态会很快衰减。但对于非线性阻尼模型，情况就复杂了。结果表明，高阶模态响应不总能很快衰减，并依赖于初始条件、因为对于非线性阻尼模型的控制，如何进行模态截断，是一个需要谨慎处理的问题。     

Self sustained oscillations and collective behaviours in a lattice of jets

Strongly interacting aligned multiple jets are produced behind a perforated plate placed in a uniform flow. The performation patterns investigated experimentally are a square and a triangular lattice of holes with diametersd ranging from 1 mm to 10 mm and of mesh sizeM ranging from 2.54 mm to 25.4 mm. At moderate Reynolds numbers (Re=ud/<3000), each laminar jet develops instabilities causing its effective diameter to increase, thus leading the parallel jets to merge at a distanceL from the plate. The merging distanceL is shown to exhibit a low frequency self sustained oscillation around its mean value with a lateral correlation length much larger than the mesh size. Both the merging distanceL and the oscillation frequency are shown to be functions ofM and of the jet velocity. At larger values ofRe, the merging distance approaches a constant mean value and the amplitude of the oscillations becomes vanishingly small.At the scale of the mesh of the lattice, the oscillating phenomena is shown to result from the local confinement of the jet by its nearby neighbours. This observation is consistent with the fact that when the effect of the nearby jets is simulated by rigid walls, the frequency of the jet's oscillations is found to be of the same order. The influence of the hydrodynamical régime of the individual jets on the oscillations and the role of the lattice pattern on the collective behaviour is discussed on hand of an original model which focuses on the role of the recirculation zone on the delayed non linear saturation of the instabilities of the jet.     

反馈控制感应同步器双相激磁电源研究

本文对转台测角系统感应同步器双相激磁电源进行分析，用反馈方式抑制漂移误差，提高测角系统的精度和稳定性。经实验验证，这个方案是成功的。     

Effect of delay combinations on stability and Hopf bifurcation of an oscillator with acceleration-derivative feedback

This paper presents new observations of delayed AD (acceleration-derivative) controller in active vibration control and in bifurcation control of a Duffing oscillator. Based on the stability analysis of the linear delayed oscillator, it is found that combination of the two delays in acceleration feedback and velocity feedback has a significant influence on the stable region in the parameter plane of the gains. By calculating the real part of the rightmost characteristic roots of the controlled oscillator with fixed delays, it is shown that a delayed acceleration feedback with positive gain can work much better than the corresponding delayed negative acceleration feedback, which is used in classic control theory. For given feedback gains, by calculating the critical delay values, it is shown that a delayed positive acceleration feedback can result in a much larger stable delay interval than the corresponding delayed negative acceleration feedback does. As an application of these results to a delayed Duffing oscillator with acceleration-derivative feedback, a delayed positive acceleration feedback can be well used to postpone the occurrence of Hopf bifurcation in the delayed nonlinear oscillators.     

Torsional Vibration Control and Cosserat Dynamics of a Drill-Rig Assembly

Aspects of drill-string vibrations in the context of a recently developed integrated model of a drill-rig assembly based on the Cosserat theory of rods are discussed. Computer simulations are used to compare existing rotary feedback strategies currently in use to optimise drilling performance where torsional slip-stick vibrations are a hazard. Guided by the wave nature of axial and torsional vibrations in axially symmetric drill-string configurations, we present a new control mechanism, torsional rectification, and compare its performance with existing controllers within the context of the model. The practical guidelines for the improvement of drilling rates in a wide variety of circumstances are discussed.     

单面薄膜反馈止推轴承的参数设计

—本文阐述了单面薄膜反馈止推轴承的参数设计与容差设计，以及正交法参数设计与容差设计的有关知识；介绍了一种设计程序的功能及使用方法。为研制大负荷、小摩擦力矩、高稳定性的精密轴系提供了一种快速、可靠的设计、计算工具，也为应用正交法解决其它设计问题提供了一个参考实例     

Parametrization of sets of stabilizing controllers in mechanical systems

Procedures to parametrize a set of stabilizing controllers are reviewed. These procedures are the key ones in the frequency-domain synthesis of the optimal (minimum H ₂-and H _∞-norms) controller or filter for a linear stationary system. A relationship between the parametrization procedures proposed by different authors is shown. Examples of parametrization procedures in synthesis problems (delay problems, multichannel filtering problems, etc.) are given __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 6, pp. 3–27, June 2008.     

Exact Finite Dimensional Feedback Control via Inertial Manifold Theory with Application to the Chafee–Infante Equation

A class of nonlinear parabolic partial differential equations is considered, and an exact finite dimensional feedback control law is designed in order to force the systems to behave in a prescribed way. The feedback law is obtained via inertial manifold theory by reducing the system to finite dimensions. The control achieved is exact, as opposed to approximate, as obtained in a previous work. The result is applied to the Chafee–Infante equation, a one-dimensional scalar reaction-diffusion equation, with distributed control.     

A result on a feedback system of ordinary differential equations

A monotone system of ordinary differential equations is considered. It is shown that the omega limit set of a bounded trajectory of this system contains an equilibrium point or a nonconstant periodic orbit. As an application, a four-dimensional system of ordinary differential equations of Lotka-Volterra type is presented. It is shown that if the interior equilibrium point of this system is unstable, then a periodic orbit is contained in the omega limit set of its bounded trajectories.     

国外动调陀螺仪再平衡技术的发展

本文在综合大量文献的基础上，详细介绍了国外模拟、数字再平衡技术的发展过程以及现阶段研究状况。同时，对动力调谐陀螺仪模拟、数字再平衡回路进行了分析比较，归纳了两者的主要优缺点。另外，还简略介绍了直接数字控制技术。