二自由度云台的机器视觉控制

本文建立了基于机器视觉反馈的云台控制模型,并通过相邻帧间的目标位置预测来简化搜索算法,实现快速高效的视觉云台对运动目标的连续跟踪.在制定系统空间转角输入量的控制策略中,简化了控制模型并对产生的偏差量进行了分析.结果表明,简化后的控制算法能够实现快速反馈和像面调整,在25帧/秒时实现对运动目标稳健跟踪,且跟踪精度高于传统算法;在目标速度2 m/s、相机60帧/秒时,改进算法实现了对运动目标的连续跟踪.同时提出了立体视觉系统模型及其在云台控制中的应用,通过像面坐标获取空间位置信息以规避目标跟丢现象.     

基于立体视觉的机器人焊接遥操作研究

研究了在立体视觉辅助下的机器人焊接遥操作技术.将立体视觉显示技术和机器人遥操作技术相结合,显著提高了焊接遥操作系统的操作性能.自主开发了基于PC的页面交互显示的立体视觉系统,以空间鼠标作为输入机器人控制命令的手控器,精确地控制远端焊接机器人的定位和跟踪焊缝.深入研究了手动跟踪焊缝的控制算法和遥控示教技术,以提高焊接遥操作的灵活性.焊接遥操作在立体视觉辅助下比二维视频监控辅助下跟踪焊缝的精度有大幅度提高,能够遥控示教空间曲线焊缝,系统操作简单,灵活.     

双目立体视觉动态角度测量方法

为实现对大幅度动态摆角及运动过程中物体空间姿态角的在线测量,提出一种基于双目立体视觉技术的动态角度测量方法。通过标定好的双目系统实时跟踪采集被测物体的特征点图像,重建特征点的空间三维坐标,进而计算出待测物的动态摆角或空间姿态角。实验结果表明:该系统在测量摆角时示值误差为±0.02°,测量空间姿态角时示值误差为±0.12°,同时具有非接触的优点,适用于动态摆角的在线测量及运动物体的空间姿态跟踪。     

基于计算机视觉的虚拟手的实现

随着虚拟现实技术的不断发展和成熟,人们已经不满足于简单的鼠标键盘交互.利用人手与虚拟环境进行交互,可以提高计算机的可操作性.但是对手的跟踪比较复杂,因为手是一个高自由度的关节结构.在分析手的运动学模型以及总结手运动约束关系的基础上,利用双目立体视觉系统,即用两台摄像头同时采集手的图像,通过识别在手上设置的关键点位置,结合设计的简化计算模型,推算出手指的运动位置,从而在虚拟环境中再现手的姿态.该方法降低了对硬件的要求,没有数据手套运动不灵活、沉重等缺点,计算模型的简化能够提高识别的速度,在与虚拟现实环境的交互中得到了较好的应用.     

一种小型激光跟踪测量系统的研制

为实现大尺寸范围内的坐标跟踪测量,研制了一种小型激光跟踪测量系统。设计了光机电一体化的机械结构,实现减小系统体积与提高抗干扰能力。设计了系统的光学模块,通过优化基于位置敏感探测器的目标偏差量采集部分的光路,实现目标允许最大偏差量的增大。通过开展位置敏感探测器的标定实验,完成位置敏感探测器的线性区间与偏差比例系数的测量,为跟踪控制算法开发提供了关键参数。进行了跟踪控制模块的设计,并完成跟踪控制算法的开发,实现系统的快速跟踪测量。开发了系统三维可视化测量软件,实现用户对系统与目标的空间位置及运动状态的实时掌控。实验结果表明,系统的跟踪稳定性与位移分辨力分别为20μm和40μm,系统的跟踪速度最高可达480 mm/s,加速度最高可达506 mm/s²,跟踪距离范围不小于70 m,具有三维坐标测量与三维可视化功能,与现有跟踪仪相比具有体积、重量以及测角范围上的优势,具有良好的跟踪性能与应用前景。     

基于视差空间运动估计的高精度立体视觉定位

立体视觉定位算法的运动估计通常在3D欧式空间中进行,但由于特征点3D坐标的噪声各向异性且分布不均匀,3D重建在深度方向上比另两个方向上的准确性差,从而导致3D欧式空间运动估计精确不高.本文提出了一种新的基于视差空间运动估计的高精度立体视觉定位算法.算法首先采用视差空间4点闭环线性解法和RANSAC算法得到初始鲁棒运动估计和匹配内点.接着,利用新的视差空间再投影误差函数提出了基于LM算法的视差空间运动参数非线性优化方法,对初始运动参数进一步优化.视差空间噪声分布均匀且各向同性,本文的初始运动参数线性估计和非线性优化都在视差空间中进行且能达到全局最小.仿真实验和真实实验结果表明,本文算法能得到高精度的立体视觉定位结果,优于传统的3D欧式空间运动估计方法.     

立体视觉曲面重建与系统误差分析

采用立体视觉空间曲面重建技术对三维曲面表面成像进行边缘提取、图像匹配、匹配点空间位置计算等步骤,得到三维曲面表面点的空间位置,利用空间点信息对三维曲面形状进行重建,恢复曲面三维形状;并讨论了立体视觉系统的摄像机分辨率、测量范围和摄像机间距等参数之间的关系.利用该方法对堆积物表面形状及体积进行测量实验结果表明,该方法能准确、快速、方便地给出三维曲面的形状.     

基于立体视觉的钢卷检测技术

本文提出了基于立体视觉的钢卷检测技术,利用双目立体视觉系统得到钢卷图像对,进行立体矫正和立体匹配获取视差图,利用视差图的深度信息,提出基于深度直方图的方法分割出目标钢卷。再根据三角测量原理计算出钢卷视差图中每个像素点的深度,从而获取钢卷的点云数据。对钢卷点云数据进行高斯滤波,圆柱特征拟合后,获得钢卷的空间几何信息和位置信息。实验结果表明,检测的钢卷坐标和钢卷真实坐标之间的误差在允许的范围(100mm)以内,并且检测效率大大提高。     

立体视觉测量系统的空间分辨力和结构参数设置

立体视觉测量系统的空间分辨力随着物体的空间位置和移动方向的变化而变化,系统的空间分辨力高低在很大程度上会影响整个系统的测量精度。本文根据立体视觉测量系统的成像公式,对整个系统观察范围内的所有空间点的空间分辨力进行了详细分析与计算。结果表明,两个 CCD夹角在 80°~100°时系统的空间分辨力最高,并且 X方向的空间分辨力整体上高于 Y方向, Z方向的空间分辨力变化相对较小,最终的实验结果和仿真结果相吻合,根据系统空间分辨力的分布规律,本文制定出了制出了空间分辨力最优的立体视觉系统的参数设置方案。     

一种改进的运动目标跟踪方法

为解决障碍物在三维目标跟踪中产生的遮挡问题,使用基于光流法和立体视觉的目标跟踪系统,同时结合自适应滤波方法来预测跟踪目标三维速度的期望值。采用模糊控制系统解决不同速度的耦合问题,通过计算跟踪算法与预测算法的速度差值来判断运动目标是否受到遮挡。实验结果表明:在确保91.2%识别率的前提下,该算法识别运动目标平均每帧耗时15 ms。该跟踪算法具有较好的鲁棒性和实时性。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...