一种采用自夹紧模糊控制的缆索检测机器人设计

针对斜缆索检测机器人爬升所需夹紧力的特点,设计一种带气动夹紧装置的缆索机器人,能根据缆索机器人自身重力与所攀爬的缆索状态进行夹紧力的自适应模糊控制.气动夹紧机械臂能实时提供合适的夹紧力,在保证检测机器人获得足够摩擦力的同时避免由于夹紧力过大而对缆索造成二次损伤;同时,采用自夹紧技术的机器人,可以调节夹紧机构的气缸行程,实现同一个检测机器人检测各种不同直径和倾斜度的斜拉桥缆索.自夹紧功能的实现对于缆索机器人的结构改进和保护缆索避免二次损伤,具有积极意义.     

铁路货车摘钩机器人的动力学分析与仿真

针对编组站驼峰摘钩问题,设计一种三自由度行走式摘钩机器人.在上关节处建立各连杆的坐标系,用D-H参数法推导出机器人的运动学方程,同时用拉格朗日法建立机器人的动力学方程.在Pro/E软件中建立摘钩机器人的三维模型,并将其导入ADAMS软件进行动力学仿真,得到摘钩机器人各关节的力/力矩-时间曲线.与理论计算结果进行对比,表明所建立的摘钩机器人的动力学方程是正确的,进而说明该摘钩机器人的结构可行.     

关节一体化机器人动力学与阻抗控制算法研究

文章针对关节一体化机器人在高速复杂运动下能保持手臂平滑运动同时具有拖曳式示教的功能问题。首先文章利用DH法建立了转换坐标系,得到了各关节连杆的相对关系,运用弦位迭代的算法解决了手臂运动解耦问题。其次,针对关节一体化机器人空机械手的结构特点,建立了用牛顿—欧拉法的动力学方程。再次,在分析阻抗控制原理的基础上,设计了笛卡尔空间基于力的阻抗控制结构,并在关节空间实现笛卡尔空间经典阻抗控制问题。最后在机器人实验平台,基于关节转矩反馈设计阻抗控制器,并进行阻抗控制实验,实现机器人拖曳式示教功能,验证了所设计算法的有效性。     

基于逆动力学分析的上下料机器人关键零部件选型

以SCARA型四自由度物料搬运机器人为研究载体,提出一种基于逆动力学分析的机器人关键零部件选型方法.该方法是使用Denavit-Hartenberg参数法建立机器人运动学模型,使用Newton-Euler迭代动力学方程建立机器人的动力学模型,利用数学软件Mathematica建立机器人逆动力学仿真系统,并在关节空间下进行仿真分析,最后获得机器人在运动过程中各关节的功率、扭矩、转速及相邻连杆间的相互作用力等参数的一套机器人关键零部件选型方法.该方法为机器人结构设计以及电机、减速机等关键零部件的选型提供理论依据,同时也适用于其他类型的机器人关键零部件选型.     

基于MATLAB的MH24机器人3D建模仿真研究

在机器人的建模仿真研究中,多关节机器人因其结构复杂易导致建模不准确,机器人在仿真运动过程中难以体现实际的运动情况。为提高多关节机器人仿真运动时的模型逼真效果,提出了一种结合机器人工具箱和三维绘图软件构建机器人3D仿真模型的方法。以安川的MH24通用机器人作为研究对象,对各关节结构和连杆参数进行建模分析,求解该机器人的正逆运动学方程。使用Solid Works绘图软件建立机器人各关节的3D模型,通过机器人工具箱对各关节3D模型和D-H参数模型进行整合,构建了逼真的MH24机器人3D仿真模型,完成了机器人各连杆的动态仿真驱动和末端执行器的轨迹规划仿真分析。通过正运动学方程和求解的机器人末端执行器的位姿矩阵值验证了3D建模的精确性。     

基于时间最短的冲压机器人轨迹规划

针对一种4自由度串联冲压机器人的自动上下料过程,在机器人的初始位姿与目标位姿已知,而运动时间和路径不确定的前提下,以最大限度提高机器人工作效率为目标,以工程实际中关节驱动力、驱动速度和工艺过程为约束条件,进行了单工作周期时间最短优化研究。首先采用D-H参数法建立机器人的连杆坐标系,列出关节变换矩阵和运动学方程,通过微分变换法求出机器人的雅克比矩阵,采用牛顿-欧拉法得出各关节力矩的表达式;然后以时间为参数,运用5次多项式拟合关节位移变化轨迹;最后采用二分法求解满足各关节速度约束和力(矩)约束的最优运动时间,从而生成各关节运动轨迹,并且进行了对比实验。结果表明,该轨迹规划方法能有效地缩短冲压机器人的工作周期。     

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。     

基于粒子群算法的拆装机器人逆解研究

为了使连续生产线工件拆装实现自动化,设计了一种满足工业需求的关节型拆装机器人,并对其样机加工装配。采用D-H法将机器人的三维模型转化为连杆坐标系,通过坐标变换求出机器人的运动学正解。由于机器人结构中连杆关联的原因,采用常规的逆变换法和几何法不能求出逆解,因此提出以"目标点位姿误差最小"为目标函数,各关节转角极限为约束条件,利用粒子群优化算法,对机器人的逆解求最优解。最后,通过对机器人位姿点和连续运动轨迹进行逆解求解验证并对其运动过程仿真分析。实验结果表明该方法求逆解速度快、精度高,能够满足规划的路径,克服了传统方法仅适应于特殊构型机器人的逆解的不足,解决了该机器人的逆解求解。     

具有惯性补偿的机器人变刚度碰撞传感器研究

针对现有机器人手部碰撞检测装置灵敏度低和适应性差的问题，基于电磁力伺服的可变刚度手部惯性力补偿机制，设计一种具有惯性自适应功能的变刚度机器人碰撞传感器。该传感器的碰撞触发力阈值随机器人手部惯性力而自适应改变，以消除惯性力对碰撞检测的影响并实时提高碰撞检测的灵敏度。碰撞实验结果显示：该电磁变刚度方法可显著降低传感器预紧弹簧的压缩力，提高机器人末端执行器碰撞过程的动态检测灵敏度，进而提升机器人在人机协作中的碰撞检测和安全防护的智能化水平。     

桥梁检测机器人运动分析与运动规划研究

针对桥梁检测机器人对于高墩、高厚度桥梁不同部位的便捷检测需求,开展五自由度桥检机器人运动分析与运动规划研究。采用改进型D-H方法进行正向运动学建模,通过解析方法求解两种形式的运动学逆解,推导雅可比矩阵,分析机器人的奇异位型;通过蒙特卡洛方法得到机器人工作空间,确定工作空间可覆盖待检测区域;由连杆力与力矩平衡方程推导各关节受力关系,基于关节负载能力开展运动规划研究。仿真分析结果证明了方法的可行性,说明机器人能够完成预定的工作任务需求。     

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.     

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.     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。