智能材料系统和结构及其控制与优化

本文介绍与分析智能材料系统和结构及其应用研究情况,讨论其中的主动元件:形状记忆合金、压电材料、ER流体.着重讨论神经网络等控制与优化方法在智能材料系统和结构研究中的应用.最后提出了智能材料系统和结构研究中需要自动控制、计算机等信息科学协同解决的问题.     

智能结构损伤自诊断的PSO-LSWSVM方法

损伤检测方法是关联智能结构实现损伤自诊断功能的一个重要研究内容。针对支持向量机研究的关键与难点——核函数的构造及核参数的优化问题,基于小波核函数的近似正交性,研究基于小波核的最小二乘支持向量机（LSWSVM）方法,并采用粒子群优化算法（PSO）对LSWSVM参数进行优化,从而构造PSO-LSWSVM方法。基于压电元件的正逆压电效应,搭建损伤自诊断压电智能结构试验系统,对各压电传感器的响应信号进行功率谱密度最大值（PSM）特征提取。基于各压电传感器的响应信号特征,将该PSO-LSWSVM方法应用于智能结构损伤自诊断,并对该方法进行性能评价。结果表明,在同等条件下,LSWSVM有比基于高斯核函数的最小二乘支持向量机（LSSVM）更高的损伤检测精度及更强的推广能力,相比于传统遗传算法（TGA）,该方法中粒子群优化算法（PSO）具有较好的寻优能力和收敛速度。     

基于FX-LMS算法的微振动主动隔振控制系统开发

控制系统是基于压电智能结构的各类微振动主动隔振系统的核心部分,而控制性能好、运算快速、实现方便的控制算法则是控制系统开发的关键.基于FIR数字滤波器,并应用FX-LMS自适应算法,对基于压电智能结构的各类微振动主动隔振系统的控制算法进行推导,并对其实现过程进行分析,以便于控制系统开发.在此基础上,利用该FX-LMS算法开发了某一维微振动主动隔振平台的自动控制系统,用于对该算法的控制效果进行实验测试和验证.实验结果表明,所推导的FX-LMS算法具有良好的控制效果,应用领域广阔.     

智能材料和智能结构——形状记忆材料

研究了形状记忆材料,如形状记忆合金、陶瓷和聚合物的结构、生产方法、特性和应用。形状记忆材料具有许多优秀的智能特性,例如传感（热、应力和场）、大行程执行器、高阻尼、自适应响应、形状记忆、超弹性等,可用于各种智能系统。形状记忆材料中的激励感应相变导致了材料的许多独特的性能,支配着材料性质的显著变化。讨论了改进目前材料系统和研发新的形状记忆材料所面临的技术障碍和挑战。     

减振降噪智能结构的研究

智能材料结构是飞机中的一项重要技术，而减振降噪自适应智能结构是其中的一个重要分支。本针对飞机，直升机和空间结构的一些典型结构的减振降噪方法进行了研究，对以上结构分别制作了实验模型，在其上布置压电传感器和驱动器，借助测控系统平台，通过一定的自适应控制算法对振动进行隔离和抑制，取得良好效果。     

基于压电阻抗技术的螺栓松动检测试验研究

针对工程结构中螺栓松动问题,采用万能试验机对螺栓联接结构进行加载模拟螺栓预紧力的变化,在不同螺栓预紧力作用下,测量螺栓联接结构上所安装的压电材料的阻抗变化,利用压电导纳实部均方根偏差(RMSD)对螺栓的松紧程度进行识别;分析损伤指标(RMSD)随预紧力变化的规律和压电材料安装位置及联接结构接触面粗糙度对损伤指标的影响。试验结果表明:在不同频率段和不同预紧力的作用下,随着预紧力的增大,损伤指标呈减小的趋势;压电材料的安装位置和接触面粗糙度对损伤指标测量结果均有一定的影响;损伤指标可以较准确地识别螺栓预紧力的变化。     

基于增量PID的压电微位移器驱动控制系统开发

对基于数字增量PID算法的压电微位移器驱动控制系统进行了理论分析和开发研究,提出了基于数字增量PID算法的压电微位移器控制系统的设计方案,并利用通用计算机及数据采集板对其进行了开发,最后将该微位移控制系统用于基于压电堆驱动器的机械手手指张合运动控制系统中,取得了良好的控制效果.该微位移器控制系统具有实现简便、控制效果好...     

基于蚁群算法的车身振动主动控制研究

针对乘用车车身结构振动抑制问题,采用基于蚁群算法的参数自适应PID控制器,以压电元件为测量和控制元件,进行了振动主动控制仿真和实验研究;首先对白车身结构进行实验模态分析,确定了压电元件的布片位置并确定压电控制的传递关系,然后设计基于蚁群算法的PID参数自适应控制器,制定了控制方案,进行了模拟仿真分析,最后搭建试验平台,以某国产乘用车白车身为被控结构,进行了车身振动主动控制实验;系统仿真和实验结果表明,施加控制时车身的振动幅值较未施加控制时大幅减小,在振动幅值较大的低频区域,其振动幅值明显降低;从而验证了应用基于蚁群算法的参数自适应PID控制技术,不仅可以有效降低车身的振动幅度,而且对传统控制方法控制效果不佳的振动低频区域,控制效果明显。     

智能结构自适应消振控制系统开发与实现

从振动主动控制设计思想出发，基于自适应控制策略，对实现结构振动响应主动控制的自适应控制系统进行了研究与开发；在此基础上，应用自适应滤波前馈控制方法对一压电机敏刚架结构进行了振动主动控制实验，取得了良好的抵消振动效果，从而表明了这一系统的有效性与可靠性。     

基于PZT的法珀滤光器平板平行度控制系统的设计与实现

主要介绍以HPV系列压电陶瓷驱动电源为核心的法珀滤光器平板平行度控制系统。该系统包括电容式边缘传感器支持电路、压电陶瓷、压电陶瓷控制电源、计算机及其接口电路。该控制系统可以实现伺服控制,其软件可扩展,可移植性比较强。通过对软件扩展和硬件调整,该控制系统可以直接应用于大型拼接望远镜面型控制。     

基于PCL的一维形状记忆合金系统的开发与应用

智能材料的发展给结构设计带来新的方向,同时也给商用有限元软件的应用迎来新的挑战.由于MSC Nastran的局限性,尚不能很好地模拟一些智能材料.结合实际工程需要,利用Patran完善的前、后处理功能及二次开发语言,将一维形状记忆合金(Shape Memory Alloys,SMA)材料系统集成到Patran中,能方便地实现在Patran中定义其材料属性和对布置有SMA的驱动结构以及复合材料结构的快速建模分析,最后利用本文系统建立SMA复合梁以及SMA丝驱动的机翼后缘模型,并进行验证,证明此模块功能的正确性和有效性.     

VIBRATION CONTROL OF A SMART STRUCTURE USING PERIODIC OUTPUT FEEDBACK TECHNIQUE

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self‐controlling. The objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a Periodic Output Feedback (POF) control technique for the vibration control of a smart flexible cantilever beam system for a Single Input Single Output case. A POF controller is designed for the beam by bonding patches of piezoelectric layer as sensor/actuator to the master structure at different locations along the length of the beam. The entire structure is modeled in state space form using the Finite Element Method by dividing the structure into 3, 4, 5 elements, thus giving rise to three types of systems, viz., system 1 (beam divided into 3 finite elements), system 2 (4 finite elements), system 3 (5 finite elements). POF controllers are designed for the above three types of systems for different sensor/actuator locations along the length of the beam by retaining the first two vibratory modes. The smart cantilever beam model is developed using the concept of piezoelectric bonding and Euler‐Bernouli theory principles. The effect of placing the sensor/actuator at various locations along the length of the beam for all the three types of systems considered is observed and the conclusions are drawn for the best performance and for the smallest magnitude of the control input required to control the vibrations of the beam. The tip displacements with the controller is obtained. Performance of the system is also observed by retaining the first 3 vibratory modes and the conclusions are drawn.     

Integration of design and manufacturing for structural shape optimization

This paper presents an integrated design and manufacturing approach that supports shape optimization of structural components. The approach starts from a primitive concept stage, where boundary and loading conditions of the structural component are given to the designer. Topology optimization is conducted for an initial structural layout. The discretized structural layout is smoothed using parametric B-Spline surfaces. The B-Spline surfaces are imported into a CAD system to construct parametric solid models for shape optimization. Virtual manufacturing (VM) techniques are employed to ensure that the optimized shape can be manufactured at a reasonable cost. The solid freeform fabrication (SFF) system fabricates physical prototypes of the structure for design verification. Finally, a computer numerical control (CNC) machine is employed to fabricate functional parts as well as mold or die for mass production of the structural component. The main contribution of the paper is incorporating manufacturing into the design process, where manufacturing cost is considered for design. In addition, the overall design process starts from a primitive stage and ends with functional parts. A 3D tracked vehicle roadarm is employed throughout this paper to illustrate the overall design process and various techniques involved.     

基于CMOS传感器的智能循迹小车 图像识别技术研究

介绍了一种以Freescale公司HCS12单片机为核心控制单元的智能自循迹小车系统.为了使小车能沿既定轨迹快速行进,需要有灵敏的转向和快速的加减速响应,这取决于快速有效的图像提取和处理技术.该系统利用CMOS黑白摄像头获取图像对跑道路径进行识别,获得合适的轨迹参数,并通过图像滤波整形、轨迹提取、模糊控制、道路记忆等优化算法实现对舵机和驱动电机的精确控制,从而使得行进中的小车具有良好的转向调节能力和加减速响应.实验结果表明,该套设计方案简单可靠,具有较好的动态性能和鲁棒性,能使小车在风云变幻的大赛中跑出令人满意的成绩.     

A Geometric Representation Scheme Suitable for Shape Optimization

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具有路径记忆功能的智能车控制系统

研究一种具有路径记忆功能的智能车控制系统。该智能车使用红外光电传感器实现路径识别,依靠电机驱动前进,使用舵机帮助智能车转向。该系统采用路径记忆算法对智能车进行控制,将记忆下的赛道信息作为主要控制信息,通过提前判断弯道的曲率大小,从而得到一个最佳过弯速度,使其运行更平稳、快速。     

Pre-programmable polymer transformers as on-chip microfluidic vacuum generators

This paper develops novel polymer transformers using thermally actuated shape memory polymer (SMP) materials. This paper applies SMPs with thermally induced shape memory effect to the proposed novel polymer transformers as on-chip microfluidic vacuum generators. In this type of SMPs, the morphology of the materials changes when the temperature of materials reaches its glass transition temperature (T _g). The structure of the polymer transformer can be pre-programmed to define its functions, which the structure is reset to the temporary shape, using shape memory effects. When subjected to heat, the polymer transformer returns to its pre-memory morphology. The morphological change can produce a vacuum generation function in microfluidic channels. Vacuum pressure is generated to suck liquids into the microfluidic chip from fluidic inlets and drive liquids in the microchannel due to the morphological change of the polymer transformer. This study adopts a new smart polymer with high shape memory effects to achieve fluid movement using an on-chip vacuum generation source. Experimental measurements show that the polymer transformer, which uses SMP with a T _g of 40°C, can deform 310 μm (recover to the permanent shape from the temporary shape) within 40 s at 65°C. The polymer transformer with an effective cavity volume of 155 μl achieved negative pressures of −0.98 psi. The maximum negative up to −1.8 psi can be achieved with an effective cavity volume of 268 μl. A maximum flow rate of 24 μl/min was produced in the microfluidic chip with a 180 mm long channel using this technique. The response times of the polymer transformers presented here are within 36 s for driving liquids to the end of the detection chamber. The proposed design has the advantages of compact size, ease of fabrication and integration, ease of actuation, and on-demand negative pressure generation. Thus, this design is suitable for disposable biochips that need two liquid samples control. The polymer transformer presented in this study is applicable to numerous disposable microfluidic biochips.     

FAULT TOLERANT CONTROL OF FLEXIBLE SMART STRUCTURES USING ROBUST DECENTRALIZED FAST OUTPUT SAMPLING FEEDBACK TECHNIQUE

This paper presents the modeling, design and simulation of a Robust Decentralized Fast Output Sampling (RDFOS) feedback controller for the vibration control of a smart structure (flexible cantilever beam) when there is actuator failure. The beam is divided into 8 finite elements and the sensors / actuators are placed at finite element positions 2, 4, 6, and 8 as collocated pairs. The smart structure is modeled using the concepts of piezoelectric theory, Euler‐Bernoulli beam theory, Finite Element Method (FEM) techniques and the state space techniques. Four multi‐variable state‐space models of the smart structure plant are obtained when there is a failure of one of the four actuators to function. The effect of failure of one of the piezo actuators to function during the vibration of the beam is observed. The tip displacements, open and closed loop responses with and without the controller are observed. For all of these models, a common stabilizing state feedback gain F is obtained. A robust decentralized fast output sampling feedback gain L which realizes this state feedback gain is obtained using the LMI approach. In this designed control law, the control inputs to each actuator of the multi‐model representation of the smart structure is a function of the output of that corresponding sensor only and the gain matrix has got all off‐diagonal terms zero and this makes the control design a robust decentralized one. Then, the performance of the designed smart system is evaluated for Active Vibration Control (AVC). The robust decentralized FOS controller obtained by the designed method requires only constant gains and hence may be easier to implement in real time.     

智慧矿山信息可视化研究

目前智慧矿山信息可视化研究主要围绕三维虚拟场景搭建和真实场景监控展开,忽视了从管理人员关注点的角度进行有选择性的可视化展示。针对该问题,基于“四横三纵”的智慧矿山总体架构,采用ISVE(信息-认知主体-可视化展示-效果)可视化方式选择模型构建了智慧矿山可视化信息框架,将智慧矿山信息系统划分为工程数字化系统、综合自动化系统及管理信息化系统,基于面向服务对象的思想对各系统中的信息进行分类,并研究了各类信息的属性;提出以认知主体为中心选择信息可视化方式,根据煤矿企业各层级管理人员的信息关注点来选择合适的信息可视化方式,从而提高管理人员认知效率,促进煤矿企业信息化和智慧化发展。     

A new method for actuating parallel manipulators

This paper presents a new technique of actuating a parallel platform manipulator using shape memory alloy (SMA). This is a type of smart materials that can attain a high strength-to-weight ratio, which makes them ideal for miniature application. The work is mainly to develop a new SMA actuator and then incorporating the actuator in building the parallel manipulator prototype. The SMA used in this study is a commercial NiTi wire. The SMA wire provides an actuating force that produces a large bending and end displacement. A 3-UPU (universal–prismatic–universal) parallel manipulator using linear SMA actuators was developed. The manipulator consists of a fixed platform, a moving platform and three SMA actuators. The manipulator workspace was specified based on the restrictions due to actuator strokes and joint angle limits. System identification techniques were used to model both heating and cooling processes. An ON/OFF control was performed and the results showed closeness in simulation and experimental results. This study showed that shape memory alloy actuated beam can successfully be used to provide linear displacement. The built prototype indicates the feasibility of using SMA actuators in parallel manipulators.