基于图像处理的爬壁机器人焊缝识别与跟踪

基于爬壁机器人移动平台和单目相机的图像采集系统,设计了一种焊后焊缝图像处理方法,将改进的自适应中值滤波算法与灰度形态学方法结合,实现从信噪比较高的图像中提取特征。采用基于边缘检测和Hough变换的焊缝位置提取算法,经测试识别准确率达70%,且单幅图像平均处理时间为200ms,能满足管道爬壁机器人行进过程中的实时焊缝跟踪,并提供了一种引导机器人沿焊缝前进的自主定向方案。     

高职实践类课程教学改革探索与实践

数字化制造时代如何培养制造业转型所需的复合型一线人才,是高职院校亟待探索并解决的问题.以"典型零件数控铣削工艺与编程"课程为例,研究项目教学法,基于数字化制造流程"行动导向"在课程教学内容、教学模式改革中的应用,探索并实践提高学生数字化制造职业岗位能力和职业素养的新途径,为数字化制造模式下高职实践课程教学改革提供借鉴.     

一种新型半对称三平移一转动(3T1R)并联操作手的运动学研究

基于方位特征(POC)方程的并联机构拓扑结构设计理论与方法,提出了一种能实现三平移一转动(3T1R)的2RRPaR+2RSS并联操作手机构.对该机构进行了结构特性分析,计算了其自由度及POC集,并得出其耦合度为2;依据该机构的结构特性及几何约束条件,采用二维搜索法对该机构的位置正解进行了求解,推导出了其位置逆解,并验证...     

Atomic-scale anisotropy of nanoscratch behavior of single crystal iron

In this paper a parallel molecular dynamics (MD) model has been developed to investigate the nanoscratch process of single crystal iron. The simulations were performed for two cases with different crystallographic orientations and scratch directions. In Case I the scratch plane is (1 0 0) and the scratch direction is [0 0 1]. In Case II the scratch plane and the scratch direction are (1,−1,2) and [1 1 1], respectively. To validate the MD simulation the nanoscratch testing was conducted using the TriboIndenter. The simulation results reveal that the vertical force and the lateral force tend to increase with the scratch displacement for both cases. Case I has smaller forces than Case II. However, the coefficient of friction for both cases is similar, which is in good agreement with the experimental value. The crystallographic orientation also affects the scratch hardness. The scratch hardness of Case I is smaller than that of Case II.     

The development of a CAD environment to determine the preferred build-up direction for layered manufacturing

Stereolithography is a process used to produce polymer components rapidly directly from a computer representation of the part. There are several factors to be considered in order to make efficient use of the process. In particular, the build-up orientation of the part critically affects the part accuracy, the total build time and the volume of the support structures. The purpose of this study is to determine the optimal build-up part orientation for the StereoLithography Apparatus (SLA) process to improve part accuracy, and minimise the total build time and the volume of the support structure. Additionally, an algorithm is developed to calculate the staircase area, quantifying the process errors by the volume of materials supposed to be removed or added to the part, and the optimal layer thickness for the SLA system which can handle the variable layer thickness. Thus, the optimal part orientation is determined based on the user's selections of primary criteria and the optimal thickness of layers is calculated for any part orientation.     

Measurement of Particle Orientation in Tape Cast Ceramic Microstructures

Anisotropic microstructures in ceramic green bodies result in nonuniform dimensional changes during sintering. Quantitative characterization of particle orientation together with processing/orientation relationships in these ceramic components are essential to control the dimensional variations during sintering. In this report, we discuss some practical aspects of measuring edge orientation in microstructures obtained by Field Emission Scanning Electron Microcscopy. Edges in the scanning direction were found to be less sensitive to the edge detection operator. Various edge sharpening algorithms were used to improve the edge contrast and hence achieve unbiased edge detection. Edges were detected using the Laplacian of Gaussian operator. Edge orientation polargrams were obtained by computing the intensities of detected edges with a 5×5 Prewitts operator convolved with a Gaussian. The computed edge orientation polargrams from the edge sharpened images were found to be internally consistent. Quantitative measure of particle orientation in tape cast ceramic microstructures was used for the first time to explain nonuniform sintering shrinkages.     

Isotropic high-resolution three-dimensional confocal micro-rotation imaging for non-adherent living cells

Recently, micro-rotation confocal microscopy has enabled the acquisition of a sequence of micro-rotated images of nonadherent living cells obtained during a partially controlled rotation movement of the cell through the focal plane. Although we are now able to estimate the three-dimensional position of every optical section with respect to the cell frame, the reconstruction of the cell from the positioned micro-rotated images remains a last task that this paper addresses. This is not strictly an interpolation problem since a micro-rotated image is a convoluted two-dimensional map of a three-dimensional reality. It is rather a 'reconstruction from projection' problem where the term projection is associated to the PSF of the deconvolution process. Micro-rotation microscopy has a specific difficulty. It does not yield a complete coverage of the volume. In this paper, experiments illustrate the ability of the classical EM algorithm to deconvolve efficiently cell volume despite of the incomplete coverage. This cell reconstruction method is compared to a kernel-based method of interpolation, which does not take account explicitly the point-spread-function (PSF). It is also compared to the standard volume obtained from a conventional z-stack. Our results suggest that deconvolution of micro-rotation image series opens some exciting new avenues for further analysis, ultimately laying the way towards establishing an enhanced resolution 3D light microscopy.     

直线定向公差的测定

对加注符号φ的直线平行度、垂直度和倾斜度公差给出一个共同的定义,并且建立了这些直线定向公差评定的统一模型,运用最小二乘法原理导出了一个简易算式。通过对2个实测数据的处理表明,该方法有较高的计算精度,可以作为三坐标测量机上直线定向公差测定的一个实用方法。     

An orientation‐independent DIC microscope allows high resolution imaging of epithelial cell migration and wound healing in a cnidarian model

Epithelial cell dynamics can be difficult to study in intact animals or tissues. Here we use the medusa form of the hydrozoan Clytia hemisphaerica, which is covered with a monolayer of epithelial cells, to test the efficacy of an orientation‐independent differential interference contrast microscope for in vivo imaging of wound healing. Orientation‐independent differential interference contrast provides an unprecedented resolution phase image of epithelial cells closing a wound in a live, nontransgenic animal model. In particular, the orientation‐independent differential interference contrast microscope equipped with a 40x/0.75NA objective lens and using the illumination light with wavelength 546 nm demonstrated a resolution of 460 nm. The repair of individual cells, the adhesion of cells to close a gap, and the concomitant contraction of these cells during closure is clearly visualized.     

平底刀最优刀轴矢量规划算法

在进行自由曲面平底刀五轴数控加工刀轴矢量规划时,现有算法多以材料去除率最大作为优化目标,然而加工效率最高的刀轴矢量不一定是刀具最优姿态,还需要综合考虑加工质量、刀轴光顺等因素。从这几个方面建立单个刀轴矢量和相邻刀轴矢量光顺性的度量指标,并以归一化度量指标加权和最小作为优化目标建立刀轴矢量优化模型,经理论分析将多目标规划问题转化为力学平衡问题,弹簧模型中高斯球面上运动节点的平衡位置就是最优刀轴矢量。仿真结果表明SE权因子影响加工效率,DW、DM权因子影响机床运动平稳性,DF权因子影响切削条件,选择合适的权因子可以获得材料去除率大、加工效率高以及在工件坐标系、机床坐标系和进给坐标系下光顺的刀轴矢量。