一种基于视觉补偿的移动机器人地图匹配室外定位算法（英文）

在室外环境中,由于车轮打滑、里程计存在严重的累积误差,同时由于二维激光测距仪扫描到环境信息量少,在进行地图匹配时,机器人常常陷入相似或对称环境,导致定位失败。针对以上问题,在二维激光地图匹配的基础上,提出了利用单目视觉信息补偿激光信息与里程计信息的定位方法。该方法利用单目摄像机获取环境中的色块信息补偿二维激光信息;摄像机同时作为视觉里程计实时辨识车轮打滑,校正里程计的误差;最后利用粒子滤波算法融合多传感器信息。该实验利用Pioneer3-AT机器人平台在大学校园进行,实验证明该方法具有较高的定位精度。     

基于视觉激光惯性相结合的机器人SLAM算法

针对弱纹理环境下SLAM系统只依靠单一传感器鲁棒性较差的问题,提出一种视觉、单线激光雷达与惯性相结合的机器人SLAM算法。在视觉与雷达预处理阶段,视觉提取点线特征,同时雷达帧间匹配过程采用激光点到其最近两个点连线的距离构建误差方程,实现更高精度匹配效果。采用惯性传感器与轮速里程计进行雷达运动畸变校正,同时雷达估计信息为单目点线特征三角化提供良好深度值,再利用点线视觉信息、雷达点云信息与惯性测量单元紧耦合优化机制提高机器人SLAM的精确度。最后,将该方法在仿真环境和真实弱纹理环境进行实验。结果表明：该方法定位准确率达到98.6%,在弱纹理环境中定位效果具有较强的鲁棒性和准确性,满足实际需求。     

基于二维码的单目视觉测距移动机器人定位研究

为了提高移动机器人在未知环境下定位精度,使用里程计结合高清摄像机单目视觉测距对移动机器人定位技术进行了研究,针对编码器短距离定位精确,长距离定位存在积累误差的问题,提出非接触式的基于二维码单目视觉测距的方法实现移动机器人的定位。在二维码世界坐标已知的情况下,移动机器人向前运动,高清摄像机通过识别二维码,得知二维码的世界坐标,由此推导出机器人相对于二维码的世界坐标,得出的机器人坐标是基于二维码的绝对坐标值,故消除了编码器存在的累计误差,从而使移动机器人定位更加准确。与传统的里程计定位方式相比,该定位算法定位成功率提升30%~50%。     

基于单目稀疏法多传感器融合移动机器人定位

针对移动机器人室内定位过程中,单目视觉难适应光照变化、里程计累计误差导致定位误差较大问题,提出边缘侧多传感器融合的定位方法.以稀疏直接法(半直接法)作为单目视觉的前端,实时单目相机估计位姿,通过惯性传感器恢复尺度输出位置信息,并且获取IMU的加速度以及偏航角、里程计当前速度,通过扩展卡尔曼滤波算法融合3种传感器信息,实现更加精确的定位.在移动机器人侧处理传感器读取的信息,从而减小机器人体积.边缘侧混合式多传感器信息融合使移动机器人在单个传感器失效以及无法人为干预时,也能够精确实时地在多种复杂环境中完成自主定位.     

基于ORB特征和里程计信息的机器人视觉导航

提出一种基于ORB(oriented FAST and rotated BRIEF)特征和里程计信息的移动机器人视觉导航方法。该方法提取输入场景的ORB特征作为显著路标,同时提取机器人里程计信息计算行为模式,将显著路标和行为模式作为状态节点进行机器人环境拓扑地图的构建。基于特征匹配技术进行机器人的状态定位,并选择状态中对应的行为模式实现机器人的路径跟踪导航,且在导航过程中有防止偏移既定路线的调整机制。实验表明:文中的方法能够较好的完成机器人的导航任务,并且对环境中的动态信息具有一定的鲁棒性。     

基于ROS的惯性和视觉里程计的机器人室内定位

高精度定位是室内移动机器人的基础,针对视觉里程计在室内定位中存在的精度与累计误差的问题,提出基于ORB-SLAM2与IMU的VIORB-SLAM2视觉惯性组合定位方法,首先建立视觉里程计与机器人的坐标系联系。然后利用惯性传感器构建机器人运动预测模型,基于Kinect使用ORB-SLAM2输出视觉里程计作为机器人位姿更新,通过扩展卡尔曼滤波器对视觉里程计与IMU输出的位姿进行最优估计。设计了硬件和软件平台对提出的方法进行实验。实验表明该方法优于单独使用传统的轮式里程计与视觉里程计,有效提高了机器人移动过程中的定位精度,减少误差累积。     

基于语义ORB-SLAM2算法的移动机器人自主导航方法研究

提出了一种基于单目视觉和激光雷达的同步定位与制图融合语义信息的新方法,该方法利用从单目视觉中提取的特征和在激光雷达深度地图中的对应关系来获得相对于关键帧的姿态数据,同时对图像进行语义分割;通过从深度卷积神经网络CNN获得的语义特征来细化语义信息,地图中的每个点都与一个语义特征相关联,以执行语义引导的本地和全局姿态优化。提出的语义标记和SLAM的耦合具有更好的鲁棒性和准确性。在室内环境中对装备单目视觉和激光雷达的移动机器人进行验证实验,实验结果表明:该方法可以提高机器人导航精度,实现机器人智能自主导航,同时也可以提供语义信息的图像数据。     

基于特定平面的单目视觉焊缝起始点导引

为了解决传统采用立体视觉和模板匹配方法实现焊缝起始点自动化导引过程中存在的算法复杂、运算速度慢以及导引精度不高等问题,提出了一种基于特定平面的单目视觉焊缝起始点导引方法。首先,采用"单目双位"和随机一致性算法对放置待焊工件的工作平面进行标定,将导引范围限制在该特定平面上;然后以手持点激光作为主动光源照射到该平面上,在保持摄像机坐标系姿态不变的情况下,导引摄像机至焊缝起始点,进而计算该点在机器人基坐标系下的三维坐标指导机器人运动使焊枪到达焊缝起始点。     

基于单目视觉的工业机器人拆垛系统设计与实验

基于单目视觉提出了工业机器人拆垛系统构想。为实现工业机器人视觉拆垛系统中机器人精确运动控制与工件位姿识别,运用D-H位移矩阵法建立了机器人运动学模型,得到机器人末端相对机器人坐标系的位姿信息。基于形状模板匹配法提出目标图像识别算法,得到各个目标图像在相机坐标系下的位姿信息;将三维视觉模型与机器人运动学模型进行信息融合,建立机器人视觉拆垛控制系统数学模型。基于CCD工业相机、4-DOF工业机器人搭建视觉定位抓取实验系统。通过对空间目标进行抓取的实验,验证基于单目视觉的工业机器人拆垛系统的正确性、精确性、鲁棒性。     

基于单目视觉的Z轴位置自适应识别定位系统研究

针对工业上单目视觉系统难以适应工件Z轴位置变化的问题,开发基于单目视觉的Z轴位置自适应识别定位方法与系统。采用激光三角测距原理检测工件坐标系平面与相机坐标系平面的距离,配合下位机微机控制系统实现工件平台Z轴位置自适应,进一步融合HSV颜色空间模型,通过改进模板匹配算法完成工件识别定位。联合Halcon与Visual Studio进行单目视觉Z轴位置自适应识别定位系统软件开发以及实验验证。结果表明:该系统在工作范围内平均定位误差小于1 mm,具有较好的Z轴位置自适应调节能力和较高的定位精度。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.