六自由度机械手的运动轨迹规划与仿真

轨迹规划是影响六自由度机械手运动学性能,保证其平稳快速完成指定任务的重要内容。文中基于D-H坐标系,建立机械手运动学模型,求解正、逆运动学方程。采用4-3-4多项式关节插值算法,对六自由度机械手进行轨迹规划。利用MATLAB对机械手进行运动学仿真,输出各关节位置、速度及加速度曲线。基于仿真结果,将4-3-4轨迹规划方法与三次多项式轨迹规划进行比较,结果表明:4-3-4多项式插值轨迹规划方法可以保证机械手平稳快速地到达期望位姿,完成指定任务。     

一种三自由度Stewart并联平台重心稳定分析及Simulink仿真

以三自由度Stewart并联平台为研究对象,提出了一种Stewart并联平台重心稳定的分析方法,并对其进行Simulink仿真。利用三维建模软件Creo建立三自由度Stewart平台的三维模型。通过Creo里的接口,将Stewart平台三维模型导入Simulink中生成对应的Simmechanics模块,包括3条运动支链,每条支链由铰链、电动缸、驱动杆、动、定平台等组成。在Simulink的仿真环境中,对3条支链的电动缸添加驱动模块,再使用Fcn函数编程,使驱动模块对电机施加驱动,从而产生驱动杆不同的伸长量,达到动平台的预定运动轨迹。在Simulink环境下,通过编程实现三自由度Stewart并联平台动平台的一种特殊运动,即动平台与水平面成一定的二面角旋转一周,而动平台自身的重心保持稳定。     

高速并联机械手轨迹规划及数值仿真

在运动学分析和动力学分析的基础上,针对抓放操作的需要,在操作空间研究diamond高速并联机械手的两种轨迹规划方式：正弦运动规律和34-5次多项式运动规律,借助数学工具MATLAB,计算出速度、加速度、力矩、电机功率等运动学参数值和动力学参数值,并进行计算机数值仿真,比较两种运动规律的优缺点,可作为控制机械手运动的优选依据。     

逆向驱动焊接机器人NURBS轨迹规划

针对焊接机器人逆向运动学不易求解且多解或无解的缺点,提出一种基于ADAMS和MATLAB的逆向驱动轨迹规划方法,并采用非均匀有理B样条(non-uniform rational B-splines,NURBS)进行关节曲线拟合,并进行焊接机器人的运动学仿真.结果表明,与正弦曲线和五次多项式等传统规划算法相比,逆向驱动NURBS轨迹规划算法,获得的各关节角位移曲线光顺性较好,机械手各方向的位移误差均较小,误差小于1 mm,从而快速准确实现焊接机器人的预期轨迹,为焊接机器人轨迹规划提供了一种新思路.     

六自由度机器人运动学仿真及轨迹规划

为减小机器人运动过程中的振动和冲击,延长机器人使用寿命,提高轨迹规划的精度,以六自由度工业机器人为研究对象,针对采用五次多项式样条规划的轨迹因加加速度有突变而导致的轨迹精度不高的问题,采用五次和七次非均匀B样条对机器人轨迹进行规划。机器人的运动学建模和轨迹规划的仿真通过MATLAB平台实现。仿真结果表明,采用五次和七次非均匀B样条规划的运动轨迹速度、加速度光滑,加加速度连续没有突变,机器人轨迹精度较好,运动性能优于五次多项式样条。     

基于MATLAB的仿人焊接机械手运动学分析和仿真

针对在狭小空间或密闭容器内以及危险作业环境中焊接的特殊要求,以UG软件为基础设计了一种仿人焊接机械手。采用D-H方法建立了焊接机械手的运动学方程,并讨论了该机械手的运动学问题。然后运用MATLAB软件对机械手的运动学进行了仿真,通过仿真观察到机械手各个关节的运动,并得到所需的数据,说明了所设计参数的合理性和运动算法的正确性,为焊接机械手的动力学、控制及轨迹规划的研究提供了可靠的依据。     

基于凸轮设计理论的多关节机械手轨迹规划

当机械手进行快速运动且运动时间确定时,为实现机械手作业轨迹平滑,关节轨迹的速度、加速度、脉动曲线保持连续且减少轨迹最大加速度峰值,结合凸轮从动件运动轨迹设计方法,提出改进梯形加速度函数曲线机械手关节空间的轨迹规划方法。文章以3R机械手为载体进行仿真,仿真结果表明,同样工作任务下,该方法使机械手关节运动平稳,关节最大加速度明显小于传统的5次多项式插值的机械手关节轨迹规划。     

齿轮精整机械手轨迹规划与运动仿真研究

齿轮精整机械手主要用于粉末冶金齿轮自动化生产线,将冶金成型的齿轮毛坯从传送带上抓起放到冲压设备上,对齿面进行精整和硬化处理,避免人工操作引起意外事故.根据机器人的工作任务,在MATLAB中建立数学模型,进行轨迹规划,解算出各关节运动参数.在ADAMS中建立机械手仿真模型,利用解算得到的数据,用Controls Toolkits建立控制系统,通过PID环节控制关节力矩,进行运动仿真研究,通过仿真观察各关节的运动并获得驱动力矩、角速度和角加速度等参数,为齿轮精整机械手控制系统的设计、模拟运动作业提供了理论依据和主要参数,为动态特性优化设计提供理论指导.     

采用混合算法优化的3?P RRR并联冗余机械手驱动力矩研究

为了降低平面3-PRRR并联冗余机械手驱动力矩,提高机械手运动平台运动的稳定性,采用混合算法优化机械手运动参数,并对驱动力矩进行仿真验证。针对传统非冗余机械手驱动系统进行改进,给出了平面3-PRRR并联冗余机械手简图,设计了冗余机械手驱动系统,采用雅克比矩阵对冗余机械手运动平台运动轨迹进行转换,推导出冗余机械手3个分支闭环运动轨迹方程式。引用粒子群算法并进行改进,添加了遗传算法中交叉和变异操作,设计出了混合粒子群算法。采用混合算法优化冗余机械手运动参数,通过MATLAB软件对冗余机械手3个分支驱动力矩变化进行仿真,与优化前进行对比。结果显示:优化前,平面3-PRRR并联冗余机械手驱动力矩较大,整体波动幅度较大;优化后,平面3-PRRR并联冗余机械手驱动力矩较小,整体波动幅度较小。采用混合算法优化平面3-PRRR并联冗余机械手运动参数,可以降低机械手驱动力矩,减少冗余机械手运动系统能量消耗。     

基于虚拟样机的DELTA并联机械手动力学仿真和伺服选型

通过编程逆解DELTA机械手最大运动空间轨迹;采用虚拟样机技术,利用ProE/Mechanism和ADAMS软件对DELTA并联机械手进行动力学仿真,对比验证机构仿真结果,得出驱动轴运动参数;在此基础上,提出一种伺服电机精确选型的新方法。所建立的虚拟样机模型也为DELTA机械手的研究提供了一个运动学分析和控制的平台。     

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.