基于多传感器融合的移动机器人定位研究

针对室内未知环境下单一传感器定位累积误差大、受环境局限等缺点,设计一种多传感器非线性融合定位系统,以提高移动机器人自主导航的定位精度。该系统通过高斯牛顿方程对由激光雷达、惯性测量单元、轮式里程计测量得到的位姿信息进行融合优化,补偿由于在室内环境信息下单一传感器定位精度低所带来的定位误差。实验结果表明:应用多传感器融合定位系统的移动机器人在长6 m、宽3 m的室内面对曲折复杂的路径和各种噪声干扰时运行总路程12.8 m后,可以将定位误差稳定在0.106 3 m内,并将平均相对误差稳定在0.716%左右。与现有方法对比,使用该方法提高了室内移动机器人定位的精度和鲁棒性。     

基于ZigBee与加权质心法的室内定位方案研究

提出基于ZigBee无线网络技术和改进的加权质心算法的室内定位方案。这种定位方式对硬件要求不高,功耗低,可以弥补TI CC2431本身定位引擎易受环境干扰的缺陷。采用基于RSSI的测距原理,通过分析数据包信息,选取与待测节点距离较近的参考节点连成一块区域,引入加权因子,进行质心坐标计算,从而得出未知节点的位置坐标。应用改进的加权质心算法结合ZigBee网络进行室内定位仿真测试,仿真结果表明:该方案定位精度较高,系统稳定性好。     

基于GPS与地图匹配的移动机器人定位方法

高精度的定位结果是移动机器人路径规划等各项任务的前提,全球卫星定位系统(GPS)能够在空旷区域得到移动机器人的全局定位坐标,但在无卫星信号环境下存在定位精度低或难以定位的问题。提出一种GPS与地图匹配的组合定位方法解决部分无卫星信号复杂环境中的定位问题。首先建立一种修正航迹推算误差的新运动模型,降低航迹推算的累计误差。其次,相对航迹推算定位方法,基于无损卡尔曼滤波算法将GPS与航迹推算融合的定位方法使移动机器人的定位精度提高了79.7%。最后引入地图匹配定位,并组合GPS与航迹推算融合的结果实现复杂环境中的准确定位。实验证明:基于GPS与地图匹配的组合定位方法能够解决移动机器人在复杂环境中的定位问题,同时相对传统GPS定位方法移动机器人的定位精度提高了43%。     

面向模具企业自动化生产的RFID定位技术研究

针对模具企业自动化生产中的定位需求,对RFID定位技术在模具企业存在大量金属障碍物的环境下的应用进行了研究。在参考Landmarc系统的基础上,通过对现有算法和系统的理论分析,提出了2种改进定位算法布局的方案,并且通过模拟环境的试验验证,证明2种方案均切实可行,有效地提高了定位系统的定位精度,同时通过成本控制显著降低了自动定位系统的布置成本。     

基于改进SIFT的室内机器人惯性视觉定位系统北大核心

对移动机器人室内单目视觉定位存在的定位精度较低,光照鲁棒性差的问题,提出一种基于改进SIFT的实时惯性视觉定位系统。首先压缩SIFT尺度空间,降低描述子维度;再利用结合位置信息的描述子曼哈顿距离进行FLANN匹配,PROSAC迭代优化。在跟踪阶段结合IMU获取的初值约束匹配,剔除误匹配。在回环检测阶段利用惯导位姿给定位姿初值范围,局部搜索SIFT特征点匹配实现重定位。在室内天花板数据集上验证改进SIFT算法,匹配准确率平均提升12.4%。在室内多个场景验证定位精度,平均定位误差为0.076 m。实验结果表明,所设计的算法能够在算力受限平台实现较精准的实时室内定位。     

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%。     

开关电磁阀控制具有惯性负载液压执行机构的定位系统研究

针对实际开关电磁阀定位系统设计过程中,定位误差、定位冲击和震荡等定位效果难以预测的问题,基于AMESim对一个实际定位系统建立了控制模型并进行了仿真分析。研究表明：定位系统的负载速度和质量、定位开关和控制继电器的切换时间可以较好地预测和补偿,属于定位系统的“硬量”;开关电磁阀的响应时间和油液压缩性是影响定位系统动态过程的主要因素,其变化范围受多因素影响,不易控制,属于定位系统的“软量”;对于负载质量为5000 kg、运动速度为0?2 m／s、负载定位行程为1200 mm、油液弹性模量为1700 MPa的定位系统,当其他因素不变,开关电磁阀的响应时间从10 ms到100 ms变化时,定位误差从11?8 mm 上升为19?8 mm,定位冲击从2?8 mm增加到4 mm。     

基于非线性多传感器复合定位融合算法应用研究

针对移动机器人单传感器数据短时丢失、定位精度低、传感器频率异步等问题,采用激光雷达、IMU、轮式里程计获取定位信息,提出基于扩展卡尔曼滤波和互补融合的组合数据融合方法。先通过S-G滤波算法对初始定位数据进行预处理,利用扩展卡尔曼滤波融合算法实现IMU和轮式里程计传感器的定位数据融合,得到融合数据1;再利用互补融合算法将融合数据1和激光雷达进行融合得到融合定位数据2。其中融合数据1对激光雷达进行实时补正,解决频率异步的位移偏差,从而明显提高定位精度。最后采用Gazebo仿真平台,搭建移动机器人模型以及设置传感器的基本参数,验证算法的有效性和稳定性。实验结果表明：数据融合算法提高了非线性传感器的定位精度和稳定性,并且平均定位误差在8 cm内。     

基于PLC的主轴脉动定位控制电路

文章介绍了用可编程序控制器对机床主轴实现脉动定位控制.即当停机定位时对主轴电动机进行脉动自动控制,使电动机的转速稳定在一个较低的平均速度下实现主轴自动定位.脉动定位方法简单,特别适用主轴定位精度要求不高的场合.文中给出了定位系统的硬件和软件.实践证明,用可编程序实现主轴的脉动定位,大大提高了定位系统的可靠性,取得很好的定位效果.     

分水岭算法耦合感兴趣区域识别的智能机械手工件定位

为了解决基于图像处理技术的工件定位技术严重依赖机械定位与缺乏视觉功能而导致算法的自适应与定位精度不佳等不足,文章提出一种基于图像处理的智能机械手定位算法,并对其中的图像处理算法进行研究和实现。首先,根据经验值设定感兴趣区域,并实时计算像素灰度平均值,判断是否存在材料工件;然后将阈值控制嵌入分水岭算法中,避免过渡分割,凸显材料工件区域,计算出材料工件中心点坐标;并引入强度变化阈值和最小允许距离,基于Harris角点检测算法,刷选出最佳角点,定位材料工件的边角坐标,从而计算材料工件旋转角度。最后编程实现文中算法。实验测试表明:并与当前技术相比较,文中算法定位精度更高,可以应用于智能机械手的视觉定位系统。     

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.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.