全向四驱变电站巡检机器人运动控制系统设计

为了实现变电站室内外一体化巡检,开发全向四驱结构的变电站巡检机器人。着重阐述该机器人运动控制系统的开发过程:介绍全向四驱移动平台的机械结构及运动控制系统结构,建立移动平台的运动学模型,探讨全向四驱机器人不同的运动模式并提出了控制方法。对研制的全向四驱变电站巡检机器人进行测试,验证了运动控制系统的可靠性以及控制方法的有效性。     

RoboCup中型组足球机器人运动控制系统的设计

以RoboCup中型组足球机器人为研究时象,以提高机器人足球平台硬件系统性能为目标,设计了一种基于双DSP架构并结合Fuzzy-PID控制算法的足球机器人。实验结果表明,该控制系统对足球机器人的运动性能、控制精度、实时性都有了极大的改善,能满足全自主足球机器人的运动控制的要求。     

基于视觉的移动机器人避障控制系统设计

针对三轮全向移动机器人自主避障行进问题,提出一种以STM32F1处理器为核心的视觉避障控制系统。分析三轮全向移动机器人运动模型,设计避障机器人的硬件控制系统。利用OpenMV OV7725图像模块识别障碍物并获取障碍物位置信息。根据位置信息,采用模糊控制算法控制机器人移动方向,实现自主避障功能。结果表明:利用该系统,三轮全向移动机器人能自主识别并成功避开行进路线中的障碍物。     

基于并行RBF神经网络的机器人逆运动求解

机器人逆运动求解的传统方法因为需要大量公式推导往往繁琐复杂,新出现的基于神经网络的算法又存在一定的局限和不足,所以,文章在分析现有神经网络模型的基础上致力于找到一种简单快速的求解方法。考虑到RBF神经网络在非线性函数逼近中的优秀表现,文章将两个相同结构的RBF神经网络应用于机器人逆运动求解中。以NACHI-MZ04型机器人为例,首先建立其运动学模型并在此基础上得到用以训练和测试神经网络的数据,然后基于Matlab nntool搭建网络模型并分别对网络进行训练和测试,最后得到满足精度要求的网络模型。结果表明,该方法在逆运动求解问题中应用效果良好,具有一定的推广价值。     

基于神经网络的含间隙串联机器人误差控制仿真研究

串联机器人大规模应用于工业生产中,提高机器人精度成为一个重要课题。在串联机器人中,各构件通过刚性铰链串联,铰链间隙对机器人运动精度的影响不可忽略。由于间隙对机器人运动的影响具有较强非线性,较难利用解析方法获得其逆运动学模型。利用遗传算法改进的神经网络建立含间隙串联机器人的逆运动学模型,并利用其构成内模控制,实现对含间隙串联机器人的控制。仿真结果证明,该控制方法具有一定的控制效果。     

足球机器人视觉系统的自适应背景分离算法研究

针对足球机器人比赛中视觉系统涉及的图像背景分离难点,进行了自适应背景图像分离算法的研究,采用自组织神经网络与连续影像相减的背景分离方法,按所设计的算法进行预处理,仿真了分离过程,并应用在足球机器人视觉系统上,提高了机器人定位的可靠性和准确性。     

足球机器人同步协调控制的研究

在足球机器人比赛系统中，足球机器人是很关键的部分。本文分析了影响足球机器人运动协调差的原因，针对机器人运动的特点，提出了同步补偿算法及实施方案。应用表明，本算法具有较好动静态协调特性，满足了机器人比赛的要求。     

足球机器人运动控制研究

为了提高足球机器人的运动性能,基于足球机器人运动学模型,对足球机器人运动控制系统进行分析.介绍了足球机器人运动控制系统的关键技术.     

一种三轮结构的全方位机器人运动规划

全方位移动机器人具有在平面运动中的全向性,能够在狭小的环境中灵活运动。文章在分析了全方位机器人沿不同运动方向行驶时速度及加速度各向异性的基础上,对全方位机器人在无障碍平面中"点到点"的运动过程进行了研究,提出了两种三轮全方位机器人的运动规划方法,一种是无自转平移运动规划方法,另一种是平移与自转规划方法。通过仿真实验,对比了两种方法的运动时间以及行驶距离,仿真结果显示加速方法最多可以将行驶时间减小10. 3%。两种新型运动规划方法具有各自不同的特点,合理利用这些特点可以实现机器人的快速避让。     

基于机器学习的人机协调操作意图感知与控制方法研究

为了实现人机协作所需要的柔顺控制,需要机器人具有一定的合作经验。通过分析人进行意图识别的方法与过程,提出一种基于机器学习识别操作者意图的方法。建立了BP神经网络模型,对机器人进行意图识别离线训练,使其具有一定的合作技能,以便在合作过程中能够根据合作者的作用力和机器人的运动特征在线估计人的意图。该方法的优势在于克服了传统方法中建立人机合作模型困难,尤其复杂多变的人体运动模型,人体阻抗参数难以估计等缺点。实验结果证明:该方法减小了合作者作用力的同时,提升了人机协作的运动同步性,机器人柔顺性得以提高。     

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.