压电智能桁架作动器的数目和位置的优化配置

由于离散型智能桁架结构的固有特性和作动器的优化配置是高度耦合的,即结构的固有特性影响着作动器的优化配置,相应地,作动器配置的数目和位置反过来影响结构的固有特性,很难预先给定一个作动器数目的确定准则.利用优化的方法来讨论压电类结构中作动器数目和位置的优化配置是一种较好的选择.基于结构耦合模态的最优控制,建立了考虑作动器数目和位置优化配置以及控制器参数的优化模型.针对设计变量,提出了一种基于遗传算法的优化策略.数值算例的结果表明,采用优化的方法来确定作动器的优化配置是可行的、有效的.     

并置压电传感／作动器的最优配置及反馈增益研究

提出了一种改进的模拟退火算法,对应用离散分布压电智能传感/作动器进行柔性结构振动控制的一体化全局最优配置问题作了研究。首先,给出了压电陶瓷作动器对结构产生激励的频响函数;其次,对并置的直接速度反馈控制方法,以主动控制后系统所贮存的总能量为目标函数,对压电陶瓷作动器的安放位置及反馈增益,以改进的模拟退火算法进行优化,可方便地获得全局最优解;最后以悬臂梁为例,分别给出了单点并置问题和多点并置问题的最优配置,验证了该方法的有效性。     

振动主动控制中传感器与作动器参数的优化设计

本文分析了文献[5]中方法的不足,提出了梁式结构振动主动控制中同时优化系统极点和传感器/作动器位置的联合优化设计法,指出传感器/作动器最优位置不仅与受控结构的模态频率和振型有关,还与系统的极点位置有关.对于最低阶模态频率较低(小于1.0 rad/s)的受控结构的主动控制系统不宜采用加速度传感器.     

柔性板压电作动器的优化位置与主动控制实验研究

对柔性悬臂板主动控制中作动器的优化位置进行研究,其中作动器采用压电形式,优化算法采用粒子群方法,指标函数采用基于能量的可控Gramian优化配置准则。仿真和实验结果显示,粒子群优化算法能够有效地对作动器的优化位置进行计算,尤其适用于多个作动器的位置优化问题,基于作动器最优位置的控制设计能够取得良好的控制效果。     

振动主动控制中传感器/作动器最优配置问题的模拟退火方法研究

本文对应用改进模拟退火算法对柔性结构振动主动控制中传感／作动元件配置问题进行了研究,它能有效地、方便地解决全局最优配置问题,从而有效地进行振动控制。并以一悬臂梁为例,通过单点并置问题和多点并置问题分别给出了最优配置,验证了该方法的有效性。     

振动控制传感器／作动器的数目和位置优化设计

提出一种确定传感器、作动器的数目和优化设计传感器、作动器位置的方法。以独立模态最优控制方法为基础,将模态控制力、作动器作动力和传感器测量的信号处理为随机变量,分别建立了模态控制力能量、作动器作动力能量的自相关矩阵的测量信号的能量自相关矩阵。进一步通过作动力能量的自相关矩阵的和测量信号的能量自相关矩阵包含的能量分别确定了作动器和传感器的数目。在此基础上,建立了基于控制系统作动力消耗能量最小和传感器测量信号能量最大,分别设计了控制系统的作动器和传感器的最优位置。通过数值算例证明了该方法的有效性。     

遗传算法在结构振动主动控制中的应用研究

基于遗传算法，对简支梁振动主动控制的传感器/作动器位置优化问题，提出了一种以结构总储能量小为优化目标的数学模型，并编制了遗传算法软件包Ga205对此模型进行优化计算，结果表明，较之穷举法，用遗传算法解决感器/作动器进行位置优化问题是高效的，同时也是全局收敛的。     

弹性连杆机构振动主动控制中作动器与传感器的位置优化

对机构振动主动控制中作动器和传感器位置的优化问题进行了研究。基于对连杆机构受控子系统能控度、能观度和剩余子系统能控度、能观度的分析,确定了能够综合反映主动控制器作动和检测能力及避免“溢出”的性能指标函数,建立了相应的优化模型,在此基础上,采用约束尺度法对该优化问题进行了求解。最后,通过算例说明了本文方法的可行性和正确性。     

随机荷载作用下结构主动控制的作动器优化配置

针对实际工程结构在持续的环境干扰下的控制问题,提出一种同时选择其作动器数目、位置和控制增益的次优化配置方法。该方法通过不断地从作动器的可选位置中删除对二次型性能泛函最优值贡献最小的可选位置,并同时调节性能泛函中的控制参数,使结构的响应和控制力同时达到其最大值为止。该方法简单易行,计算效率高,避免了复杂的梯度和成本函数计算,适合于实际工程应用。通过对一个多层剪切型框架进行仿真计算,验证了该方法的有效性。     

作动器／传感器配置优化的遗传算法应用

针对空间柔性结构,研究了振动主动控制中作动器/传感器的配置和控制器增益的全局优化问题。首先采用空间柔性结构的状态空间模型建立了以最大耗能准则为基础的目标函数,将优化问题归结为一个有约束的非线性优化问题,然后根据其特点,采用了一种十进制浮点数编码的遗传算法,并融合、设计了一些简单且优良的遗传操作,使得优化过程不依赖于初值,而且可以快速可靠地求得全局最优解。通过一个悬臂梁单点同位配置算例,证明了该算法的可行性和优越性。     

A risk-based sensor placement methodology

A risk-based sensor placement methodology is proposed to solve the problem of optimal location of sensors to protect population against the exposure to, and effects of, known and/or postulated chemical, biological, and/or radiological threats. Risk is calculated as a quantitative value representing population at risk from exposure at standard exposure levels. Historical meteorological data are used to characterize weather conditions as the frequency of wind speed and direction pairs. The meteorological data drive atmospheric transport and dispersion modeling of the threats, the results of which are used to calculate risk values. Sensor locations are determined via an iterative dynamic programming algorithm whereby threats detected by sensors placed in prior iterations are removed from consideration in subsequent iterations. In addition to the risk-based placement algorithm, the proposed methodology provides a quantification of the marginal utility of each additional sensor. This is the fraction of the total risk accounted for by placement of the sensor. Thus, the criteria for halting the iterative process can be the number of sensors available, a threshold marginal utility value, and/or a minimum cumulative utility achieved with all sensors.     

沉管隧道健康监测试验中传感器位置的优选

基于单节沉管隧道缩比模型在地震激励作用下的健康监测试验,借助商业有限元软件ANSYS对单节隧道缩比模型进行等代地震荷载下的平面应变分析和整体模态分析,得到传感器优化布置初选点.再利用遗传算法对初选点进行优化排序,得到传感器优化布置的最终方案.该方法与EFI法传感器优化布置结果吻合较好.该方法对于大型结构的传感器优化布局有一定的借鉴作用.     

Enhanced damping of lightweight structures by semi-active joints

Summary Lightweight structures typically have low inherent structural damping. Effective vibration suppression is required, for example, in certain applications involving precision positioning. The present approach is based on friction damping in semi-active joints which allow relative sliding between the connected parts. The energy dissipation due to interfacial slip in the friction joints can be controlled by varying the normal pressure in the contact area using a piezo-stack actuator. This paper focuses on the optimal placement of semi-active joints for vibration suppression. The proposed method uses optimality criteria for actuator and sensor locations based on eigenvalues of the controllability and observability gramians. Optimal sensor/actuator placement is stated as a nonlinear multicriteria optimization problem with discrete variables and is solved by a stochastic search algorithm. At optimal locations, conventional rigid connections of a large truss structure are replaced by semi-active friction joints. Two different concepts for the control of the normal forces in the friction interfaces are implemented. In the first approach, each semi-active joint has its own local feedback controller, whereas the second concept uses a global, clipped-optimal controller. Simulation results for a 10-bay truss structure show the potential of the proposed semi-active concept. Dedicated to Professor Franz Ziegler on the occasion of his 70th birthday     

Multi-objective optimization of a triple layer piezoelectric bender with a flexible extension using genetic algorithm

This article presents an electromechanical analysis for a piezoelectric bimorph actuator with a flexible extension, which is used to increase the tip deflection. The performance measuring attributes of such an actuator are derived, and a genetic algorithm is used for multi-objective optimization. The analysis reveals that for a thick flexible extension, the length of the extension provides Pareto optimal solutions for multi-objective optimization. The analysis also shows that as the thickness of the flexible extension decreases, the Pareto optimal solutions converge to a single solution for multi-objective optimization. We have considered nonlinear deflection behavior of piezoelectric materials at high electric fields, and series and parallel electrical connections in the analysis.     

汽车车内噪声主动控制系统扬声器与麦克风布放优化方法

利用声固耦合边界元仿真方法与多目标遗传算法,实现了面向对象的车内噪声主动控制(ANC)系统扬声器麦克风布放方案的优化。首先基于自适应算法,推导了车内噪声主动控制系统降噪性能预测方法,并利用声固耦合边界元仿真方法,实现了面向对象的ANC系统降噪性能预测;在该仿真模型的基础上,建立对应的代理模型,以实现对系统降噪性能的快速预测;最后利用多目标遗传算法,获得系统关于扬声器麦克风数量与多个频率下降噪量的Pareto最优解集。该最优解集能定量描述ANC系统扬声器麦克风数量与降噪性能之间的关系,并为该系统与车辆的匹配提供依据。     

Active vibration control of composite plate with optimal placement of piezoelectric patches

The active vibration control of a composite plate using discrete piezoelectric patches has been investigated. Based on first order shear deformation theory, a finite element model with the contributions of piezoelectric sensor and actuator patches to the mass and stiffness of the plate was used to derive the state space equation. A global optimization based on LQR performance is developed to find the optimal location of the piezoelectric patches. Genetic algorithm is adopted and implemented to evaluate the optimal configuration. The piezoelectric actuator provides a damping effect on the composite plate by means of LQR control algorithm. A correlation between the patches number and the closed loop damping coefficient is established.     

环境振动试验传感器布置优化方法研究

为了快速获得最优的加速度传感器布置位置,依据电动振动台多点控制原理和夹具传递函数特性,建立了传感器布置优化计算模型。以一夹具为实例建立有限元模型,利用nastran软件求出传递函数,然后,根据所建优化模型获得传感器最优布置位置,最后,通过夹具振动试验测试夹具与试品连接部位处的响应。测试结果表明优化方法所得的响应加速度均方偏离度明显小于传统方法,证明了该优化方法是实用和可行的,并能为环境振动试验中的传感器布置和夹具设计提供实践与理论指导。     

斜拉桥传感器优化布点的研究

在振动模态试验中,传感器位置和数目的选择对试验结果的质量有很大的影响。首先回顾了近年来关于传感器最优布点方法的研究。然后以一座三跨预应力混凝土斜拉桥为研究对象,采用有效独立法和基于模态保证标准的算法这两种最优布点算法,对斜拉桥主梁上加速度传感器的最优布点进行了初步的探讨。结果表明:有限元模型和所监控模态振形的阶数对最优传感器布点的选取有较大的影响;用有效独立法对类似的斜拉桥进行优化布点计算时,能得到较为理想的布点方案。     

Optimal coordinate sensor placements for estimating mean and variance components of variation sources

In-process optical coordinate measuring machines offer the potential to diagnose the sources of the variations that are responsible for product quality defects. Such a sensor system can thus help manufacturers to improve product quality and reduce process downtime. The effective use of sensor data in the diagnosis of the sources of variations depends on the optimal design of the sensor system, which is often also called the problem of sensor placement. This paper addresses coordinate sensor placement for the diagnosis of dimensional variation sources in assembly processes. Sensitivity indices for the detection of the process mean and variance components are defined as the design criteria and are derived in terms of process layout and sensor deployment information. Exchange algorithms, originally developed for optimal experimental design, are revised and then used to maximize the detection sensitivity. A sort-and-cut procedure is proposed, which is able to significantly improve the algorithm efficiency of the current exchange routine. The resulting optimal sensor layout and its implications are illustrated in the specific context of a panel assembly process.     

Optimal placement of actuators and sensors in control-augmented structural optimization

A control-augmented structural synthesis methodology is presented in which actuator and sensor placement is treated in terms of (0, 1) variables. Structural member sizes and control variables are treated simultaneously as design variables. A multiobjective utopian approach is used to obtain a compromise solution for inherently conflicting objective functions such as structural mass, control effort and number of actuators. Constraints are imposed on natural frequencies, peak transient displacements and accelerations, peak actuator forces and dynamic stability as well as controllability and observability of the system. The combinatorial aspects of the mixed (0, 1)-continuous variable design optimization problem are made tractable by combining approximation concepts with branch and bound techniques. Some numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.