大长宽比AGV循迹导航控制方法研究

为解决现有的大长宽比AGV远距离横向移动存在的累积姿态偏差问题，提供可配合控制方案的机械结构，设计用于大长宽比AGV横向移动的控制方法，给出横向行驶的姿态调整算法。该方法利用车首和车尾安装的视觉相机识别循迹导航条，反馈至控制系统，调整AGV行进姿态。结合车身偏移类型，控制系统形成控制策略，实现大长宽比AGV循迹行走。并用一个应用实例验证了该方法可有效识别出大长宽比AGV的偏移并进行调整矫正。     

基于倍福CX控制器的AGV控制系统设计

对传统的人工叉车进行自动化改造可以大幅度提高车间物流自动化水平。以倍福控制器CX5130作为AGV控制核心,倍福控制器分别与激光导航传感器和无线终端通过TCP/IP协议通信,实现与AGV本体和调度系统的数据交换。激光导航传感器通过反光柱返回激光导航仪发射的激光束实现AGV的定位。倍福HMI界面作为人机界面方便操作和监控。实现AGV的自动运行之后,通过PID算法提高了AGV的定位精度。实验结果表明:所设计的控制系统能满足AGV系统使用要求,成本低,验证了其有效性和可行性。     

全方位行走AGV及其控制系统

全方位行走AGV是由全方位轮(Maknam轮)移动机构和其控制系统构成。本文结合AGV的特点,着重分析全方位轮的结构、运动规律、工作原理、系统特点和制导方式,以及采用三环数字伺服系统对AGV的自动与手动控制。     

基于S7-1200 PLC的AGV控制系统的设计与实现

以西门子公司S7-1200 PLC作为AGV运动控制器,利用磁导航传感器对地面铺设磁条路径寻迹,通过RFID对站点位置进行读取,同时以触摸屏作为人机交互界面,开发建立了AGV控制系统。实现了AGV的直行、转向、自动运行、调速及站点停车等功能。通过实验表明,使用该控制系统的AGV在运行过程中稳定可靠,操作便捷,很好地实现了功能需求。     

基于电子地图辅助视觉导航的AGV设计

文章介绍了一种基于电子地图辅助视觉导航的自动导向车(AGV)的结构、功能及工作原理,并详细介绍了电子地图的表示、电子地图辅助方法及该AGv的优点.在电子地图中采用虚拟标志符区分柔性生产线中的分支路径,来引导AGV在正确的分支路径上行走.     

基于混合禁忌蝙蝠算法的AGV物料配送调度研究

针对作业车间的物料配送调度问题,考虑到AGV在加工过程中只参与物料运输的特性,把整个生产车间的物料调度视为一个小型的车间物流系统,在此基础上提出一种实现AGV行走路径、运输时间和配送成本等多目标最优化的多AGV作业调度模型。采用单层整数分段编码和ROV编码转换方案,通过在基本蝙蝠算法中引入禁忌表、藐视准则和局部搜索寻优等策略,构建了一种混合禁忌蝙蝠算法来求解该调度模型。仿真结果表明该算法具有一定的可行性,可以获得比较好的效果,为多AGV在一定约束条件下的车间物料调度提供了一种切实有效的实践方案。     

基于改进遗传算法的自动导航小车路径规划调度

为解决智能车间物料运输AGV小车调度问题,以AGV补料任务行走总距离最短为目标,结合路径选择及任务排序双重标准,提出双层编码方式;同时为避免染色体上的基因聚集到小的邻域内,提出一种改进的遗传算法,算法增加了多种变异过程,相较于传统遗传算法扩大了解的空间,防止局部最优解的产生。最后通过MATLAB对环境进行建模、仿真,并与基本遗传算法进行对比。实验结果表明：所提出的改进算法能高效且可靠地解决AGV在多任务目标情况下的路径规划问题。     

基于无传感器矢量控制的PMSM在AGV中的应用

对于PMSM而言,编码器反馈信号的精确性十分重要。但是在一些恶劣环境下,编码器的精确性受到了极大的影响甚至于可能出现编码器损坏,所以出现了伺服电机的无传感器控制。通过在AGV上使用无传感器控制,使AGV在一些恶劣环境下仍然能够正常且精确地工作。通过滑模观测器和滤波器达到对PMSM运行的估算,从而取代了正常工作中的PMSM编码器反馈,以达到对PMSM无传感器控制。同时提出在PMSM低速运转情况下通过改变PMSM的运动控制方式,以避免电机在低速运动时因为受到齿槽效应等因素的影响而出现速度波动较大的现象,并且通过实验证明了该方案的可靠性。     

基于到达时间差异的超声波AGV定位

为满足移动的AGV对大范围、近距离定位的要求，设计了一种新的主动信标式AGV超声导航系统。该系统采用信号到达时间差异来确定AGV位置，降低了对时间的同步要求。实验表明：在2m^2范围内，平均误差为2、15mm，这说明该系统的定位精度达到和优于现有的超声波定位系统，该导航方案可满足AGV的要求。     

基于机床方向和位置矩阵的AGV路径规划

针对目前AGV路径规划时存在的缺陷，提出了一种基于机床位姿矩阵的AGV的路径规划方法。该方法通过建立车间环境信息库，即机床的相对位置关系矩阵、相邻机床距离矩阵及机床的姿态矩阵，对AGV的运动速度加以有效控制，使AGV能准确地按预定路径由起始位置到达目标位置，保证在制品准确及时地传输。仿真结果表明，该方法计算判断简单、省时，实时性好。     

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.     

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.