面向林地作业的腿履复合移动机器人构型设计与越障策略研究

针对林地地面环境复杂、台阶和倒木障碍多的问题,设计一种腿履复合移动机器人。在分析犬类腿部骨骼结构参数和运动特性的基础上,设计3关节构型与履带复合的移动机器人腿部结构,为了尽可能减轻整机质量,将履带部件和机器人腿部的大腿结构有机融合。构建机器人单腿的运动学模型,分析机器人足端工作空间,提出针对腿履复合移动机器人的林地越障策略,仿真分析越障过程中机器人关节的动态特性。仿真结果表明：利用腿部关节摆动和履带推进的组合和适时切换,该腿履复合移动机器人能实现灵活的台阶和倒木障碍的跨越;越障过程中,除与障碍接触时刻的关节力矩突变外,腿部关节力矩变化平稳,履带运动模式和足式运动模式切换平顺。研究为下一步机器人样机研制和控制系统开发提供了技术基础。     

基于复杂地形的四足机器人路径规划算法研究

针对四足机器人在复杂环境中摆动腿路径点规划不准确的问题,提出一种基于摆动腿路径规划的样条优化算法。该算法运用零力矩点（ZMP）稳定性准则,在对机器人COG轨迹进行规划的基础上,对机器人摆动腿足端轨迹路径点进行优化计算,并利用ADAMS建立其仿真模型用于计算机仿真。结果表明：该算法不仅能保证四足机器人安全避障,且能实现在复杂地形条件下平稳行走,验证了该算法的准确性和鲁棒性。     

多足步行机器人单腿柔性建模与仿真

以多柔体动力学理论为基础,运用拉格朗日方程建立了多足步行机器人单腿的多柔体动力学模型.通过Pro/E建立了单腿的三维实体模型,运用ADAMS对单腿模块进行了多柔体动力学仿真分析,仿真结果对于多足步行机器人的单腿柔性结构设计具有指导意义.     

六足步行机器人腿机构绳传动系统设计与仿真

针对典型步行机器人腿机构绳传动系统的缺点,设计了一种简单、小巧、实用的新型绳传动系统,并将其应用到六足步行机器人腿机构上,由此完成了六足绳传动步行机器人整机的设计.运用ADAMS软件建立了虚拟样机,并选择典型的三角步态进行整机运动仿真,仿真结果表明所设计的步行机器人虚拟样机可按给定步态进行直线行走和转弯.在此基础上,制作了真实样机.经测试,机器人行走时机体稳定,且速度较快.为进一步研究六足绳传动步行机器人奠定了基础.     

两栖复合腿机器人运动仿真及能耗分析

对水陆两栖复合腿机器人进行运动仿真及能耗分析。设计一种弧形腿与桨结合的两栖六足机器人,研究其地面三角步态行走机制,提取腿部转动关节运动模型。分析机器人能源消耗组成部分,简化得到其单周期能耗计算模型。构建9种不同腿长参数的机器人三维模型,在ADAMS软件中设置规划的转动关节轨迹,实现运动仿真。提取仿真后的电机力矩,计算一周期的能耗并进行分析。结果表明：适当减小机器人腿长参数可提高能源利用效率,这对提升腿式机器人整体性能具有一定的参考意义。     

仿生四足机器人运动学与动力学仿真分析

为了提高四足机器人的设计效率和设计的可靠性,缩短四足机器人研发周期,文章采用虚拟仿真技术对四足机器人进行仿真研究。文章对虚拟样机进行机构运动学与动力学分析,建立仿生四足机器人的运动学方程及拉格朗日动力学方程,利用三维建模软件pro/E建立实体模型导入到ADAMS中进行系统仿真,采用对角小跑步态,通过仿真结果验证了运动学和动力学数学建模的正确性,分析了影响机器人动态稳定性因素,为物理样机的设计提供了理论依据。     

永磁吸附履带式管外爬行机器人的力学分析及运动仿真

为提高管外机器人的负载能力与越障能力，设计一种永磁吸附履带式管外爬行机器人。建立机器人在管道上的静力学和动力学模型，得到机器人在轴向和周向稳定运动时的吸附力条件。利用Ansoft Maxwell对比分析磁性履带组中永磁铁2种不同布局方式，选定合适的布局方式并计算该布局方式下磁性履带组在轴向和周向运动时能够提供的吸附力，验证了磁性履带组设计方案的合理性。最后基于ADAMS进行了运动仿真，得到越障过程中质心变化规律，验证了机器人具有良好的越障性能。     

一种弹性足式机器人腿部结构设计与分析

针对足式机器人在实现奔跑、跳跃等极限运动时,腿部会受到地面较大反向冲击力的问题,使用仿生学方法以猫科动物腿部骨骼肌系统为仿生对象,通过引入变刚度弹性杆件对闭链连杆机构进行优化设计,设计一种结构简单、能够有效储存地面反向冲击力并将其转化为运动时动能的足式机器人腿部机构;建立数学模型,对变刚度弹性元件进行定量分析,并采用矢量回路法对连杆机构进行运动学分析;建立优化前后两种单腿机构的虚拟样机,使用MATLAB软件设计控制系统,并应用ADAMS对虚拟样机进行行走、跳跃仿真,对优化前后两种腿部机构进行对比实验;在此基础上搭建实物样机,并进行实验验证。实验结果表明:所提出的足式机器人腿部结构具备可实现性,能够将来自地面的冲击力转化为运动的动能,提升足式机器人的跳跃高度。     

仿生六足机器人的结构设计及运动分析

在分析多足昆虫结构特点和运动功能特点的基础上,完成了仿生六足机器人的结构设计和样机制作。基于ADAMS与MATLAB联合编程,设计仿生六足机器人CPG(中枢模式发生器)控制模型。基于ADAMS对六足机器人进行直行步态运动仿真分析,得出六足机器人的直线运动步态控制数据。通过对样机实验,结果表明仿生六足机器人的运动稳定,满足设计要求。     

六腿轮式快速移动机器人设计与分析

针对轮腿移动机器人结构复杂、控制难度大等问题,设计一种结构极为简单的轮腿融合的六腿轮式快速移动机器人。该机器人具有6条弹性腿,构成机器人的两个单侧腿结构,同轴交错分布在机器人的两侧,以轮式滚动的方式向前移动,可以有效缓冲移动时受到的冲击以及由此产生的振动。该机器人克服了独立轮式和腿式机器人的不足,既能很好地适应环境又具有很好的移动性能。对机器人进行运动学与动力学分析,运用SolidWorks建立机器人的三维实体模型,在ADAMS平台上进行运动仿真。理论分析和仿真结果表明:此设计方案是可行的,机器人可以实现快速稳定的运动。     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.