基于GPS与地图匹配的移动机器人定位方法

高精度的定位结果是移动机器人路径规划等各项任务的前提,全球卫星定位系统(GPS)能够在空旷区域得到移动机器人的全局定位坐标,但在无卫星信号环境下存在定位精度低或难以定位的问题.提出一种GPS与地图匹配的组合定位方法解决部分无卫星信号复杂环境中的定位问题.首先建立一种修正航迹推算误差的新运动模型,降低航迹推算的累计误差....     

基于二维码的单目视觉测距移动机器人定位研究

为了提高移动机器人在未知环境下定位精度,使用里程计结合高清摄像机单目视觉测距对移动机器人定位技术进行了研究,针对编码器短距离定位精确,长距离定位存在积累误差的问题,提出非接触式的基于二维码单目视觉测距的方法实现移动机器人的定位。在二维码世界坐标已知的情况下,移动机器人向前运动,高清摄像机通过识别二维码,得知二维码的世界坐标,由此推导出机器人相对于二维码的世界坐标,得出的机器人坐标是基于二维码的绝对坐标值,故消除了编码器存在的累计误差,从而使移动机器人定位更加准确。与传统的里程计定位方式相比,该定位算法定位成功率提升30%~50%。     

基于改进人工蜂群算法的无人机三维航迹规划

为应对无人机遇到的复杂任务状况,提高航迹规划效率,提出一种基于改进人工蜂群算法的无人机三维航迹规划方法。为降低无人机三维航迹规划的难度,将航迹规划数学模型通过简化建模转化为函数优化问题;为提高航迹优化效率,通过改进蜜源初始化方式、引入动态评价选择策略、引入Metropolis准则等方式对传统人工蜂群算法在该问题求解中的缺陷进行改进,通过MATLAB进行20次仿真实验,验证了改进人工蜂群算法在无人机三维航迹规划中的可行性和优化效率。     

基于激光SLAM的移动机器人导航算法研究

定位技术是机器人技术中导航控制和路径规划的关键问题,传统定位方式采用全球定位系统(GPS),难以完成精准的定位导航功能,不依赖于GPS的定位导航方法是目前机器人领域的研究热点。提出一种基于激光雷达采集的点云信息帧间匹配方法,根据改进式激光点云数据的位姿估计算法,结合非线性优化进行了校正和优化,完成移动机器人对未知环境的精确定位。通过ROS机器人操作系统搭建实验平台,对改进算法进行验证,证明改进后帧间匹配算法的建图和定位效果对应的鲁棒性与定位精度效果更佳,可满足工程要求。     

基于动量观测器和双编码器的协作机器人碰撞检测

为提高协作机器人高速运行时碰撞检测灵敏性，提出一种基于动量观测器和双编码器的碰撞检测方法。基于广义动量的动力学模型构建机器人外力矩观测器；利用双编码器的实时位置偏差和机器人关节传动结构等效柔性特征估计外力矩；设计反应策略实现碰撞后机器人快速停车及能被人工推动。仿真和实验结果表明：在机器人高速运行时，相比传统的基于动量偏差观测器算法，此算法响应时间更短，最大碰撞力更小，提升了高速下碰撞的检测灵敏度，增强了安全防护效果。     

基于改进人工蜂群算法的无人机航迹规划研究

为应对无人机遇到的复杂任务状况,快速寻找一条可行较优航迹,通过改进初始化蜜源方式、引入模拟退火算法的Metropolis准则、引入复合形法等对人工蜂群算法进行改进,提出了一种基于改进人工蜂群算法的无人机航迹规划方法。针对无人机航迹规划问题建立数学模型,采用该改进人工蜂群算法进行寻优,并通过MATLAB进行仿真验证。仿真实验结果表明,该改进人工蜂群算法有效提高了无人机航迹规划的鲁棒性、收敛速度和精度。     

双电机驱动的管道检测机器人空间定位

本文目的是研究双电机驱动的机器人在管道里的空间定位。针对此，构建了双电机驱动机器人运动模型，并采用了PID算法控制机器人实现差速转向和直线运动。进而结合编码器与陀螺仪采集的数据，进行位移计算和位置坐标推导。最后，进行机器人管道定位试验，取真实轨迹位置坐标与算法计算位置坐标各30组，通过Origin软件仿真其运动轨迹，并进行误差分析。结果显示两种轨迹基本重叠，平均误差小于3.5%，表明该定位算法可应用于双驱机器人开展管道检测时的空间定位计算。     

焊接机器人上旋转编码器功能分析及故障排除

旋转编码器是焊接机器人上一个重要的传感元件 ,用来检测焊接机器人各轴运动角度、位置、速度和加速度。旋转编码器出现故障 ,便会造成焊接机器人停机影响生产 ,并且国外旋转编码器高昂的价格会加大企业的成本。通过近几年的摸索实践 ,我们积累了一些维修经验 ,现将焊接机器人上旋转编码器的功能原理及故障排除作一分析介绍。1　焊接机器人上旋转编码器的功能分析焊接机器人由其控制系统按照一定程序协调各轴运动来完成焊接过程。各轴主要有电动机、电机伺服系统、放大系统和旋转编码器等元件组成。旋转编码器与电动机通过轴杆相连 ,电动机…     

一种基于激光测距波纹板机器人自动焊接轨迹恢复方法

基于国内外波纹腹板H型钢机器人自动焊接研究情况,提出了一种机器人自动焊接波纹板的新方法. 基于工控机系统可离线编程及运行过程中实时存储数据的优点和机器人多自由度的良好可达性,通过编程使工控机与机器人之间实现交互通信,借助编码器和传感器外部设备与采集卡配合使用实现数据的采集与存储. 利用改进后的限幅滤波算法处理数据,将处理后的数据传输至机器人,机器人执行程序文件,从而实现波纹腹板H型钢的机器人自动焊接. 结果表明,该方法是可行的,且具有很高的实用性,旨在为将来波纹腹板H型钢的自动化焊接发展提供一个参考.     

基于麦克风阵列的储罐内爬壁机器人定位系统研究(英文)

为提高储油罐内爬壁机器人本体智能及作业效率,研究设计了基于被动声定位技术的机器人定位系统。该定位系统利用麦克风阵列拾取机器人发出的声信号,运用改进的时延估计定位方法处理信号,从而定位爬壁机器人。介绍了系统的总体定位算法,并通过实验表明该系统具有实时实现的有效性和应用价值。     

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.     

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.