基于摆缸关节的液压机械臂运动学及工作空间分析

针对传统机械臂输出转矩较小的问题,设计了基于叶片式液压摆动油缸(摆缸)作为关节的6自由度液压机械臂,该液压机械臂具有诸多优势,其最大的优点是具有很高的负重比。运用改进的D-H法建立了该液压机械臂的运动学模型,得出其正运动学方程。在MATLAB中进行了液压机械臂的轨迹规划仿真,得到了各关节转角的特性曲线,验证了液压机械臂结构设计的合理性。利用蒙特卡洛法分析计算了其工作空间,借助MATLAB绘制了其末端执行器的工作空间云图,为今后液压机械臂的深入研究提供了重要依据。     

QY 7t型重箱转载机械臂的运动学求解与分析

以QY-7t型重箱转载机械臂为研究对象,绘制了其三维结构图,阐释了各关节的运动特点,基于标准的D-H参数建模法确定了各关节坐标系及参数表,推导了机械臂的正、逆运动学方程,列示了逆解唯一性的程序求解原理图,并结合所建立的运动学方程,验证了机械臂末端位置能够满足其作业要求。     

混凝土液压拆除机械臂运动学分析与研究

混凝土液压拆除机械臂运动学分析是混凝土液压拆除机器人运动及控制器设计的重要组成部分。将混凝土液压拆除机械臂作为研究对象,通过D-H法则建立机械臂连接杆坐标系,并完成机械臂的运动学分析。运用ADAMS对模型进行运动学仿真分析,获得了机械臂的运动包络图,测量了机械臂喷枪末端的位移、速度及加速度曲线,验证了理论分析的正确性。结合理论分析与仿真,分析实际使用中机械臂喷枪末端的姿态和运动情况,为末端机械臂的轨迹规划和控制提供了理论依据。     

偏置式空间机械臂关节角参数化逆运动学求解

针对偏置式空间7自由度(DOF)冗余机械臂,提出了一种基于关节角参数化的运动学求解方法。根据空间机械臂的结构特点对其臂型进行了分析,采用D-H(Denavit-Hartenberg)法建立空间机械臂坐标系。采用D-H法对空间机械臂操作空间进行了描述,在考虑运动学约束的基础上,得到了以关节角为变量的正运动学模型。通过分析逆运动学模型的可解性,采用矩阵逆乘的解析法求解了该类机械臂逆运动学的完整解析解。在Matlab环境下,使用Matlab Robotic Tools对机械臂的初始姿态进行了仿真。通过给定的机械臂末端位姿,根据推导的逆运动学算法对空间机械臂各个关节的角度进行了求解。机器臂的运动学逆解算将作为机器臂运动规划和轨迹控制的基础。     

基于蒙特卡洛法的七自由度拟人机械臂工作空间分析

应用D-H法对七自由度拟人机械臂建立关节坐标系并确定杆系参数,建立机械臂运动学模型,应用齐次变换法推导出机械臂末端执行器的位姿。根据机械臂关节空间到工作空间的映射关系,提出采用蒙特卡洛法分析该机械臂的工作空间,得出机械臂工作空间的云图。为后续的机械人轨迹规划、动力学分析、运动控制和参数优化提供了参考依据。     

七自由度仿人机械臂正逆运动学及工作空间分析

针对传统协作机械臂关节惯量大、所需驱动功率大的问题,设计了基于套索传动的七自由度机械臂。该机械臂具有诸多优势,其最大的优点就是驱动电机后置使得关节惯量小、结构紧凑。根据D-H法建立正运动学方程,在分析了机械臂结构特性的基础上,定义了机械臂运动的臂平面、参考平面以及臂型角ψ,通过给定末端位姿~0T_7和臂型角ψ求解运动学逆解。在MATLAB环境中对机械臂正、逆运动学方程进行可视化验证,验证了正、逆运动学方程的正确性。最后利用蒙特卡洛法分析了机械臂的工作空间,求得机械臂工作空间云图。     

6R工业机器人几何求逆优化算法及仿真分析

为提高机器人工作性能,满足实际复杂工况需求,研究了SNR3-C30型6 R工业机器人的运动状态和轨迹规划.首先,根据D-H法建立机械臂连杆坐标系以及运动学方程;其次,基于其末端执行器的位姿矩阵特性,提出一种结合位姿分离思想的几何求逆优化算法,该算法利用机器人各关节相对腕部的几何位置关系来求解前三个关节角θ1,θ2,θ3...     

六自由度串联机械臂运动学及其工作空间研究

根据实际生产需要设计和建立了一种用于焊接车间上下料的六自由度串联机械臂及专用末端执行器模型,针对机械臂的正运动学以及其末端执行器的可达空间进行了研究。基于D-H法对机械臂运动学数学模型进行建立并求得其正运动学方程。提出在Matlab环境下利用Robotics toolbox10.2通过代入各个关节随机参数的方法与机械臂正向运动学分析结果进行对比验证。基于机械臂末端执行器的可达空间与各个关节之间的对应关系,在Matlab中通过采用蒙特卡洛法对机械臂末端执行器的工作区域进行了分析,用描点的方式对机械臂末端执行器工作区域的点云图进行了描绘,通过对点云图的研究得出所设计机械臂结构较为合理的结论。     

液压支架油缸内壁缺陷修复机械臂的运动学分析与仿真

针对矿用液压支架油缸内壁局部缺陷修复,设计一种能深入液压支架油缸筒内进行内壁修复的焊接机械臂。基于改进D-H参数建模方法,对设计的内表面修复焊接机械臂进行运动学建模,并求解了内表面修复焊接机械臂的正、逆运动学。借助MATLAB软件,采用蒙特卡洛法,对该焊接机械臂的有效工作空间进行了仿真分析,利用Robotics Toolbox工具箱对油缸内壁缺陷修复机械臂进行关节轨迹规划,通过仿真得到各关节的角位移、角速度、角加速度曲线。仿真结果表明：该机械臂运行平稳,轨迹连续,满足运动学要求。     

混凝土水力破拆机械臂运动学分析及仿真

以混凝土水力破拆机械臂为研究目标,运用D-H法建立机械臂各连杆坐标系模型,并进行对机械臂运动学分析,验证了运动学模型的正确性;在ADAMS中,按顺序控制对机械臂模型进行运动学仿真分析,得到了机械臂最大破拆高度、最大横向破拆宽度、最大破拆深度、运动包络图和喷枪末端的位移曲线,为机械臂的轨迹规划和控制提供了理论依据。     

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).     

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.     

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.     

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。