模糊辩识器的参数辨识

本文针对基于ＢＰ网络进行参数辨识的模糊辨识器,采用更为合理的学习步长－变步长,从而在线辨识更加快速,为实时控制节约了宝贵的时间。     

一种改进变步长LMS算法及其在系统辨识中的应用

在分析传统LMS算法及变步长LMS的基础上，本文提出了一种改进的变步长LMS算法并应用于系统辨识。新算法利用瞬时误差的四次方和遗忘因子共同来调整步长，进一步解决了收敛时间和稳态误差的矛盾。将新算法应用到系统辨识中时，与传统LMS算法和变步长LMS算法相比，仿真表明新算法有更快的收敛速率。     

基于三阶非线性Volterra模型的自适应快速辨识算法

摘要：目的：在RFID倒扣封装设备研制中,高速倒扣机械手具有很强的非线性和时变特性,线性控制方法难以满足要求,因此采用非线性自适应逆控制方法进行控制。此方法的关键是采用三阶非线性Volterra模型对机械手进行在线实时辨识,并满足建模精度和速度的要求。但采用常规方法因其计算时间长不能满足辨识速度要求。文章提出了一种快速辨识算法,可使系统辨识满足以上要求。方法：首先,利用不同阶输入向量的结构关系,由低阶输入向量直接构建高阶输入向量。接着,根据不同阶核的相关性从低阶核加速估计高阶核。最后,把线性变步长LMS方法引入到非线性自适应算法中,并用Lyapunov全局稳定理论进行证明。结果：通过对实际系统的辨识实验表明：与常规方法比较,辨识时间从100毫秒缩短为30毫秒,提高辨识速度3.3倍,降低辨识失调93.3%,同时还具有更高的辨识精度。结论：满足了对非线性系统辨识的精度要求和实时性要求。     

超磁致伸缩执行器位移模型的参数辨识

准确辨识模型参数是提高超磁致伸缩执行器位移控制精度的关键,针对单一算法难以实现对超磁致伸缩磁滞非线性模型参数准确识别的问题,将遗传算法与模拟退火算法融合,首先利用遗传算法的快速搜索能力得到一个较优群体,再利用模拟退火算法的突跳能力对整个群体进行优化调整,并在算法中引入最优保留策略和动态步长搜索方法,提出一种改进的遗传模拟退火算法,并将其应用于对超磁致伸缩执行器位移磁滞非线性模型参数辨识。该算法兼具遗传算法和模拟退火算法的优点,既有较快的收敛速度,又提高了辨识精度和最优解质量。通过试验验证,超磁致伸缩棒伸长量的模型计算结果与测量值符合程度较好,平均相对误差为3.85%,该方法能方便有效地辨识模型参数。     

ITD法辨识模态参数的有效性研究

实践表明，时域法在辨识参数过程中有时会出现数值不收敛现象，甚至无法辨识出所需要的参数，使得时域辨识方法失效。本文研究了ＩＴＤ法辨识模态参数的有效性问题，给出了提高ＩＴＤ法有效性的方法。     

Matlab在系统辨识中的应用

首先介绍了系统辨识的基本原理.简要介绍了Matlab中系统辨识的实现方法.并结合具体的例子.显示Matlab系统辨识工具箱在系统辨识中的强大功能和辨识快速准确等优点。     

基于 RP-EKF 的无人机动力系统参数辨识

针对无人机动力系统电池电压波动导致系统噪声大、辨识结果精度低的问题,本研究提出了一种基于反向预测-增广卡尔曼滤波(RP-EKF)的无人机动力系统参数辨识方法。首先构建增广参数矩阵,将压降噪声模型考虑入辨识环节,其次提出反向预测卡尔曼滤波算法,设定新息平方比阈值,计算原始预测新息平方与反向预测新息平方的比值,通过对比预测新息比与阈值完成过程噪声调整并实现估计模型修正。实验结果表明,本文提出的基于RP-EKF的参数辨识方法,平均误差为39.22 rpm,均方根误差为55.85 rpm,平均相对偏差为0.85%,相比于最小二乘算法与卡尔曼滤波算法,本文方法辨识结果平均误差分别提高41.51%和22.26%,均方根误差提高49.63%和13.0%,平均相对偏差提高41.7%和22.7%。本文提出的算法拥有更高的辨识精度。     

迟滞非线性系统辨识与补偿控制研究

针对智能材料中存在的迟滞问题,对其开展了迟滞非线性特性分析,建立了迟滞系统。该迟滞系统由两个部分串联构成:一部分是滤去传递函数影响的Preisach模型;另一部分是不考虑迟滞影响的系统传递函数。将离线和在线辨识方法应用到辨识迟滞系统中,应用最小二乘法离线辨识得到了辨识传递函数参数,再用此辨识传递函数参数作为神经网络辨识的初始权值,得到了神经网络在线辨识的辨识模型;建立了辨识传递函数的逆模型控制系统和前馈逆模型PID控制系统,并对辨识系统进行了迟滞非线性补偿。研究结果表明,模型辨识方法的可行性和补偿控制的有效性在仿真中得到了验证。     

基于DSP处理器的振动特征参数辨识研究

本文主要介绍了数字信号处理器在振动特征参数辨识中的应用,简要阐述了神经网络辨识振动参数方法和基于数字信号处理器的辨识系统,并设计悬臂梁试验系统进行验证。     

电动负载模拟器摩擦模型参数辨识方法

为实现电动负载模拟器的高精度控制，针对负载模拟器运行中受到的摩擦力影响问题，提出基于改进布谷鸟算法（improved cuckoo search algorithm，简称ICSA）的摩擦模型参数辨识方法。首先，搭建了电动负载模拟器试验样机，建立了动力学数学模型,并引入一种连续摩擦模型代替传统不连续摩擦模型；其次，将布谷鸟算法（cuckoo search algorithm，简称CSA）进行改进，在辨识中自动调整判定概率和步长的数值，提高了收敛速度和收敛精度；然后，通过逐点试验的方法得到了负载模拟器角速度范围为［-1,1］rad/s的摩擦力数据，并利用ICSA算法对摩擦力模型进行辨识；最后，进行了验证试验。试验结果表明： ICSA算法能准确快速地辨识出连续摩擦模型的6个参数，且收敛速度快、准确性高；当迭代达到最大迭代次数时，ICSA算法的目标函数值较CSA算法减小了45.2%。     

Wear of single crystal silicon as a function of surface roughness

With increasing activities on micro electro-mechanical systems (MEMS) type microactuators, there is a growing need in understanding the tribological properties of silicon, the most commonly used wafer material for those devices. In particular, it is of interest if single crystal silicon used in microactuators exposed to rather low vertical loads is subject to wear. Therefore, wear tests using monocrystalline silicon on both sides of the tribological interface were conducted.A classic way to measure wear on sliders in contact with a tape or a rotating disk is to create an imprint using a Berkovich diamond tip mounted on a picoindenter. However, in our case we used a different approach. We created three studs on a slider’s surface by recessing the material outside the studs through an ion milling process. During the wear tests, the studs wore off. By measuring the remaining stud height, the wear volume could be determined at any point in time. The tests were performed on a pin on disk tester with a gimbaled slider to realize a flat on flat contact and a rather low normal force of 30 mN.     

5kW扭振模拟机组轴系扭振试验研究

本文在介绍TVAP—M扭振测试分析软件包的基础上,着重介绍了应用TVAP—M在5kW汽轮发电机组轴系扭振模拟机组上进行的一系列机电互作用扭振试验.通过试验确定了该模拟机轴系的扭转固有特性.试验表明:在低频情况下,变频励磁激振是一种行之有效的激振方式.最后利用串补电容方式对机电互作用下的次同步谐振进行了探讨.     

金刚石飞切加工微结构表面的表面粗糙度研究

为了获得具有纳米级表面质量的微结构表面,利用‘Nanosys-300’超精密复合加工系统实现了微结构表面的三维金刚石飞切加工,研究了主轴转速、进给量以及背吃刀量对微结构表面粗糙度的影响。通过对理论表面粗糙度分析可知：金刚石飞切加工微结构时理论表面粗糙度沿法线方向并没有变化,而沿进给方向存在着周期变化。减小进给量f和金刚石飞刀前端角ε或增大切削半径可以降低理论粗糙度值。实验分析结果表明：表面粗糙度值Ra随进给量的增加而增加,主轴转速对Ra影响不大。切削PC时,在5μm-40μm范围内,Ra随背吃刀量的增加而增加;而切削LY12时,在2μm-10μm范围内,Ra随背吃刀量的增加而减小。实验中Ra最好可达38nm（LY12）和43nm（PC）。最后利用优化工艺参数加工出了微沟槽阵列和微金字塔矩阵微结构。     

Effect of lubrication on impact drive mechanism

The impact drive mechanism (IDM) device moves utilizing impulsive force caused by rapid deformations of piezoelectric elements and friction. Most of the devices utilizing impulsive force and frictional force are used on only a dry base. In this paper, the movement performance of the IDM on fluid lubricated surfaces is investigated. The movement on fluid lubricated surfaces and that in oil are as minute as that on a dry base. In experiments, the movement of the device of the IDM on a fluid lubricated surface is the same as the calculated movement by assuming a dry surface. The standard deviation of movement on a fluid lubricated surface is smaller than that on a dry surface. Considering the small distribution of the movement and the antirust of the devices, the devices utilizing impulsive force should be driven under the boundary lubrication.     

平面机构运动分析的有限元件法

要使用一种特殊有限元的方法进行平面机构的运动分析,需首先对组成平面机构的常用单元进行分析,并给出了描述单元的变形模态参数与单元节点坐标之间的函数关系,进而用传递函数的概念对机构的位置,速度和加速度进行分析,在此基础上,编制了计算机程序,对ＺＬ５０装载机的工作装置的运动进行了计算给出了数值模拟结果。     

Distribution patterns and morphology of sensilla on the apical segment of the antennae and palpi of Hydradephaga (Coleoptera: adephaga).

The sensilla on the terminal antennomere of selected Hydradephagans (Coleoptera) are modified in several distinct ways as compared to the sensilla on the terminal antennomere of Geadephagans (Coleoptera). There are no long sensilla of any type on antennae of Hydradephagans, the sensilla are either short, peg-like sensilla that may be recessed in the antennal surface or they are multiporous plate-like sensilla. Multiporous plate-like sensilla have not been found on the antennae of Geadephagans. A pit sensillum occurs on the antennae of one family, Gyrinidae, in the Hydradephaga whereas it is found on the antennae of several species from the families of Geadephaga. The sensilla on the terminal antennomere of Hydradephaga are often grouped into sensory fields that could be located on a particular area of the antennomere. Sensory fields are also located on the apices of the maxillary and labial palps and the most unique sensory fields occur in the Noteridae. The maxillary palpal apex of Hydrocanthus oblongus (Noteridae) is bifurcate and a sensory field with several types of sensilla is at the apex of each branch. The terminal labial palpomere is greatly enlarged and has a long, slender sensory field at the apex and a secondary sensory field on a thumb-like projection. The sensilla on the palpal apices are more diverse and complex in form as compared to the sensilla on the palps of Geadephaga. The most complex sensillum has a cuticular collar and a dome that is divided into six or seven triangular sections. The dome may be opened or closed and a peg-like sensillum with a very wide apical pore is situated beneath the dome.     

Footholds optimization for legged robots walking on complex terrain

This paper proposes a novel continuous footholds optimization method for legged robots to expand their walking ability on complex terrains. The algorithm can efficiently run onboard and online by using terrain perception information to protect the robot against slipping or tripping on the edge of obstacles, and to improve its stability and safety when walking on complex terrain. By relying on the depth camera installed on the robot and obtaining the terrain heightmap, the algorithm converts the discrete grid heightmap into a continuous costmap. Then, it constructs an optimization function combined with the robot’s state information to select the next footholds and generate the motion trajectory to control the robot’s locomotion. Compared with most existing footholds selection algorithms that rely on discrete enumeration search, as far as we know, the proposed algorithm is the first to use a continuous optimization method. We successfully implemented the algorithm on a hexapod robot, and verified its feasibility in a walking experiment on a complex terrain.     

Sensilla on the antennae,legs and ovipositor of Spathius agrili Yang (Hymenoptera: Braconidae), a parasitoid of the emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

To investigate the host‐finding mechanisms of Spathius agrili Yang, a parasitoid of the emerald ash borer, Agrilus planipennis Fairmaire, a highly concealed insect pest of Fraxinus spp. The morphology and ultrastructure of sensilla on the antennae and legs of both sexes and on the ovipositors and ovipositor sheaths of females were observed using SEM. Results showed that abundant sensilla trichodea (ST) are distributed on the antennae of both females and males, with the sharp trichoid with a socket at the base being the most numerous sensillum. There are 6–7 sensilla placodea on each segment of the flagellum, arranged lengthways in parallel rows. There are very few sensilla styloconica on the female antennae. The tibiae have mostly sensilla chaetica, whereas three types of ST and the relatively plentiful sensilla chaetica are present on the tarsi. Besides ST, a mass of sensilla squamiformia and small short spines are distributed on the pulvilli. Basically there are no sensilla on the female ovipositor, only steering mechanisms for drilling bark and a variety of v‐shaped grooves. However, a large numbers of short sensilla chaetica and microtrichia are found on the internal surface of ovipositor sheath. The outer surface of the ovipositor sheath also has ST. In addition, a clear spring‐like extension structure can be observed on the fore parts of ovipositor sheath. These findings suggest that the main function of sensilla on the antennae is olfaction, while the sensilla on legs and ovipositor sheaths are mechanoreceptors and tactile sensors. Microsc. Res. Tech. 2010. © 2009 Wiley‐Liss, Inc.     

基于Ansys对提升机卷筒集中应力的分析

针对提升机卷筒在人孔周边及筋板处因应力集中而容易产生裂纹的情况,以降低卷筒上人孔的应力集中为目的,重点运用ANSYS软件对直径2．0mJK型提升机卷筒的人孔的不同形状进行有限元分析,对不同人孔形状做出对比,并对腰形孔的不同位置进行了分析。     

Topographic effects on adhesive force mapping of stretched DNA molecules by pulsed-force-mode atomic force microscopy

Adhesive interaction between a tip and a sample surface was examined on a microscopic scale by pulsed-force-mode atomic force microscopy (PFM-AFM). The signal measured by monitoring pull-off force is influenced by various factors such as topography, elasticity, electrostatic charges, and adsorbed water on surfaces. Here, we focus on the topographic effects on the adhesive interaction. To clarify the topographic influence, the adhesive force measurement of a stretched DNA molecule with a smaller radius of curvature than that of a tip was carried out at low relative humidity (RH) with an alkanethiol-modified tip. The experimental conditions such as low RH and the use of the alkanethiol-modified tip were required to minimise the influence of water capillary force on hydrated DNA strands. The hydrophobic modification of a substrate surface was also important to minimise the adsorbed water effect. The DNA molecules were stretched on the substrate surfaces by an immobilisation process called a dynamic molecular combing method. The two-component vapour-phase surface modification with an alkylsilane mixed with a silane derivative containing an amino end group enhanced the DNA adsorption due to the electrostatic interaction. The experimental results for the topographic effects on the adhesive force mapping were reproducible.