晶圆片盒传输机械手设计与运动仿真

为满足立式扩散炉设备中晶圆片盒传输效率及定位精度高的要求,设计了一种五自由度混合型机械手,主体结构由Y、Z轴方向模组及SCARA机械手组成。利用改进型D-H法建立各连杆间的运动学模型,并进行运动学正逆求解;针对无穷逆解的问题,通过构造目标优化函数结合粒子群优化(PSO)算法进行求解。最终基于MATLAB完成仿真分析,结果表明所建立的运动学方程正确,机械手的工作空间满足使用要求,所得最优逆解可使机械手末端达到设定的定位精度。     

基于MATLAB的码垛机械手运动学分析与仿真

对一种五自由度码垛机械手建模,采用改进版D-H法建立起机械手的7个连杆坐标系,通过坐标变换推导出机械手末端工具坐标系相对基座的位姿,由关节变量分离法求得逆运动学问题中5个关节角的解析式,最后使用Robotics Toolbox提供的函数在MATLAB环境下建立起机械手运动学仿真模型并进行实例仿真,指出常规的逆解验证过程存在的不足进而提出采用相应的补充验证手段的观点,验证了正、逆运动学求解的正确性,为后续分析、控制与优化提供运动学参考。     

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。     

连杆式串联机械手结构及运动学研究

文章基于通用机械手在简单工况中使用的问题提出了一种连杆式串联机械手结构并进行了研究分析。首先对研究对象的结构进行了参数设计,然后详细分析了该机械手的运动学问题,基于D-H参数建模法确定了各关节坐标系及参数表,对其正、逆解进行了求解运算,最后使用Robotics Toolbox建立了相应的运动学模型,对其正、逆解和运动轨迹进行了验证和仿真。研究结果表明了该机械手的运行表现平滑稳定,且结构简单,成本较低,非常适合应用于简单自动化工况。     

基于小脑神经网络解决机械手逆运动学控制问题

由于机械手逆运动学问题的求解存在多解且非常复杂,以往解决机械手的逆运动学求解问题主要是通过神经网络逆模型来建立机械手的逆运动学模型然后通过遗传或改进的BP算法来训练神经网络的权(阀)值矩阵从而达到问题的求解,然而这种方法在建立神经网络的逆模型时要对训练数据进行限制或筛选使其成为单解问题(即满足逆映射关系存在的要求),这对于那些对数据事先进行处理很困难或根本无法进行的复杂系统是不可行,为此提出了一种采用小脑神经网络和约束条件相结合的方法来解决逆运动学问题.研究结果表明此方法可以很好的解决机械手的逆运动学控制问题,同时该方法可以推广应用到那些通过数学模型求解困难或者数学模型不确知的复杂系统反求问题.     

冗余度机械手逆运动学果蝇优化算法的改进

逆运动学问题是冗余度机器人运动控制、轨迹规划和动力学分析的基础,也是机器人学中最重要的问题之一。以末端执行器位姿的误差最小为优化目标,建立适应度函数,将求解冗余度机械手的逆运动学问题转化为一个等价的优化问题,在优化算法的基础上通过杂交变异果蝇优化算法(HMFOA)进行冗余度机械手逆运动学问题的求解。采用嗅觉搜索杂交突变机制和视觉搜索的动态实时更新机制,有效解决果蝇优化算法(FOA)的收敛问题,并提高算法的收敛速度。为进一步验证HMFOA的有效性,在七自由度机械手上对HMFOA进行了测试,将其结果与FOA、LGMS-FOA和AE-LGMS-FOA等算法进行了比较,证明HMFOA能有效地解决冗余机械手的逆运动学问题。     

火车煤采样机双动采样的运动分析与仿真

为了解决火车煤采样机和火车同时运动（即双动）的情况下如何完成全断面采样的问题,采用D H法建立了采样机的空间坐标系,进行了运动学分析,得出了其运动学方程;提出了一种利用Matlab解非线性方程组法求解逆运动学问题的方法,并通过仿真得到了采样机的运动轨迹、各液压缸位移、马达角位移曲线以及液压缸速度和马达角速度曲线,为利用控制器控制采样机按照预定轨迹采样提供了必要的数据。该方法可以广泛应用于多自由度关节型机械手的智能运动控制,具有较大的推广价值。     

火车煤采样机双动采样的运动分析与仿真（英文）

为了解决火车煤采样机和火车同时运动(即双动)的情况下如何完成全断面采样的问题,采用D-H法建立了采样机的空间坐标系,进行了运动学分析,得出了其运动学方程;提出了一种利用Matlab解非线性方程组法求解逆运动学问题的方法,并通过仿真得到了采样机的运动轨迹、各液压缸位移、马达角位移曲线以及液压缸速度和马达角速度曲线,为利用控制器控制采样机按照预定轨迹采样提供了必要的数据。该方法可以广泛应用于多自由度关节型机械手的智能运动控制,具有较大的推广价值。     

人形跑步机器人的逆运动学分析

提出一种人形跑步机器人逆运动学的分析方法。由于机器人在跑步时存在一个双脚离地的腾空阶段,因此建立了惯性坐标系、参考坐标系和物体坐标系,用来确定机器人身体各个部分的相对位置。采用齐次坐标转换矩阵分析机器人质心和双脚轨迹与机器人各个关节角度、角速度、角加速度等的关系,并用Newton-Raphson方法根据机器人质心轨迹和双脚轨迹计算出各个关节的运动参数,完成逆运动学分析。并通过算例验证这种方法的有效性。     

医用服务机器人机械手的运动学建模及控制

结合TVT-99D型机械手的结构特点,基于D-H法则建立了机械手的运动学模型,给出了机械手运动学正解和逆解的求解过程.在此基础上,对其控制系统进行了设计,并在"远程脑控制的医用服务机器人"上进行了机械手运动控制实验研究.实验结果表明,该控制系统控制精度高、运行稳定、实时性强,能完成药瓶的快速、准确、可靠抓取.     

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.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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。     

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).     

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.