基于螺旋理论的6R串联工业机器人奇异位形分析

针对6自由度串联工业机器人,对其工作空间中的奇异位形进行了分析。基于旋量理论,运用旋量指数积(POE)方法对机器人进行运动学建模,得到正运动学方程,并基于旋量指数积法对速度雅克比矩阵进行了推导。根据机器人处于奇异位形时的条件,对雅克比矩阵的行列式进行求解,从而得到机器人处于奇异位形时的所有情况,并给出了发生奇异时的机器人的构型。在此基础上,基于可操作度、雅克比条件数及最小奇异值等灵巧度指标使用MATLAB对机器人的奇异位形进行了仿真,仿真结果表明该机器人在3种情况下处于奇异位形,与分析结果一致,验证了文中方法的正确性。     

基于旋量理论的STANFORD机器人的逆运动学分析

针对Stanford机器人关节的结构特点,基于旋量理论,采用Paden-Kahan子问题的方法求解Stanford机器人的运动反解。研究表明:该方法可消除多关节耦合变量,大大简化计算量,计算精度高,为求解Stanford机器人的运动学逆解提供了一种新方法。     

基于MEA-BP神经网络的6DOF工业机器人逆运动学研究

针对6DOF工业机器人逆运动学求解存在计算量大、通用性差、有奇异性等问题,提出一种基于思维进化算法(MEA)优化BP神经网络的工业机器人逆运动学求解方法。在机器人工作范围内,随机生成若干组关节角度值,通过正运动学方程获得机器人末端连杆位置和姿态,以末端连杆位置和姿态作为模型输入,关节角度作为模型输出,通过对样本数据的训练确定模型参数。使用该模型进行机器人逆运动学求解,并与传统的基于BP和RBF神经网络的求解方法进行比较,结果表明:该求解方法精度高、泛化能力强。     

基于旋量理论的4-R(SS)2并联机器人正运动学分析

研究机器人运动学较为传统的方法为D-H参数法,以4-R(SS)2并联机器人为研究对象,基于旋量理论,根据指数积公式对该机器人进行正运动学分析,得到机器人的位姿变换矩阵。旋量法只需要建立惯性坐标系S和工具坐标系T,经过每一个关节变量之间的变换,最终可得到其运动学方程。与D-H参数法相比,此方法使运动学模型变得更为简单,并且具有更明确的几何意义。最后对并联机器人进行运动仿真,构建其仿真模型,确定机器人各结构的参数,输入随机关节变量,得到的结果与文中计算的结果进行对比,验证本文方法的准确性。     

7自由度串联机器人运动学分析

为了保证机器人运动角度精确,以此研究7自由度串联机器人的运动学特性,对其进行正向运动学和逆向运动学的分析。首先,通过旋量理论方法建立该7自由度串联机器人的正向运动学方程。其次,在应用旋量理论得到正向运动学方程的基础上,通过将几何法和位姿分离法两种方法结合用来求解机器人的逆解。最后,将结果在Adams/MATLAB联合仿真进行验证,求解逆解方法的正确性,经过仿真得到运动学角度函数变化曲线以及关节角度变化值,与理论所得到的角度值进行比较分析,结果验证了该方法的有效性和正确性,表明该方法具有精度高、运算量小的特点。     

IRB4400喷涂机器人运动学分析研究

喷涂机器人的运动学分析是动力学控制和轨迹规划的理论基础,为提高运动学求解效率,以ABB IRB4400喷涂机器人为研究对象,在Robotics Toolbox中对其建立了D-H模型,进行了正运动学分析。并针对机器人一般逆运动学求解方法复杂低效的问题,研究了BP神经网络智能算法在该型机器人逆运动学求解中的应用。运用正运动学分析结果,在Matlab中利用蒙特卡洛法编程实现了机器人的工作空间仿真,利用神经网络算法求解得到的逆解进行了轨迹规划仿真,得到了机器人工作空间仿真图,连续光滑的关节角、角速度和角加速度曲线图。从而验证了机器人建模的正确性、正运动学分析的合理性和逆运动学算法的有效性,为实际编程作业效率的提高提供了参考。     

基于雷塞控制系统的五轴焊接机器人的轨迹规划

运用Denavit-Hartenberg方法建立了以旋转关节关节角和移动关节移动分量为变量的基于雷塞系统的五轴焊接机器人运动学模型,对五轴焊接机器人正运动学和逆运动学问题进行了求解分析;采用抛物线过渡的线性插值法对焊接机器人进行了轨迹规划,通过MATLAB Robotics Toolbox工具箱对五轴焊接机器人进行了运动学仿真,得到了焊枪末端轨迹图以及关节角、角速度、角加速度与时间的变化曲线,验证了所设计参数的合理性,达到了良好的效果。     

6自由度3P3R温室服务机械臂运动学分析

应用Lie群知识和旋量理论等现代数学工具,描述了机械臂的刚体运动及传递关系。通过指数积公式与关节旋量建立了串联构型机械臂的运动学模型,分析了运动学正解与逆解,并以某型6自由度3P3R温室服务机械臂为例,对运动学算法进行了验证。基于旋量与指数积的运动学算法与D-H参数法等效,但相比之下,几何与物理意义明确,计算过程更简单且无奇异性,更适合机械臂运动控制系统设计需要。     

基于旋量法的飞机表面清洗机器人运动学分析

针对5自由度飞机表面清洗机器人,通过旋量和指数积公式求解了运动学正解,得出末端执行器相对惯性坐标系的位形。采用运动螺旋求解了运动学正解的雅可比矩阵,为机构的奇异性、实时控制、可操作性的研究提供了理论基础。     

马鞍形焊缝焊接机器人运动学分析及MATLAB仿真

运用Denavit-Hartenberg方法建立了以关节角为变量的马鞍形焊缝焊接机器人运动学模型,对马鞍形焊缝焊接机器人正运动学和逆运动学问题进行了求解分析;采用三次多项式插值的方法对焊接机器人进行了轨迹规划,通过MATLAB Robotics Toolbox工具箱对马鞍形焊缝焊接机器人进行了运动学仿真,得到了焊枪末端轨迹图以及关节角、角速度、角加速度与时间的变化曲线,验证了所设计参数的合理性,达到了良好的效果。     

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.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

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.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

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.