火龙果采摘用轮式AGV行走系统导航避障策略研究

以某火龙果种植园区为作业背景,针对前轮导向、后轮差速驱动型AGV研究其在无障碍直线循迹和局域轨迹主动防碰避障2种模式下的导航避障策略。对于前一种避障模式,采用模糊控制算法以AGV沿直线垄道中心行驶的横向位置偏差和航向偏角为输入、前轮期望导向角为输出,结合AGV运动学模型控制前后轮协同作用;对于后一种避障模式,基于滚动优化原理,设计了AGV在局域轨迹下主动避让静/动态障碍物的避障算法。最后,在Matlab中仿真验证表明:该导航避障策略具有一定的有效性和可靠性,为轮式AGV实际应用于果园导航避障提供了理论参考。     

两轮移动机器人控制系统研究

研究一种两轮同轴、差速驱动的新型的两轮移动机构的控制系统软硬件设计。为了实现对该机构行走过程的平衡控制，其控制系统采用C8051单片机作为核心控制器，用倾角传感器、陀螺仪和脉冲编码器测量车体的姿态，通过模糊自适应控制器分别控制车体左轮和右轮，实现了平衡行走。     

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。     

四轮轮毂电机电动汽车电子差速控制研究

针对四轮轮毂电机电动汽车转向时四轮差速问题，进行了电子差速控制研究。设计了电子差速控制策略，建立差速运动参考模型，根据四轮轮毂电机电动汽车四轮驱动力矩独立可控的优势，通过驱动力矩分配器对四轮驱动力矩进行合理分配，实现了实际轮速跟踪参考轮速，并在Matlab/Simulink里搭建了四轮轮毂电机电动汽车电子差速系统模型，通过CarSim与Matlab/Simulink联合仿真进行了验证。结果表明：电子差速差速控制策略能够有效实现转向时四轮差速控制，提高电动汽车的操纵稳定性。     

双轮差速移动机器人轨迹跟踪混合控制算法研究

针对双轮差速移动机器人轨迹跟踪问题,提出一种基于前馈运动学和带有干扰观测器的解耦动力学的混合控制算法。首先,对双轮差速移动机器人的运动学、动力学以及位姿误差进行数学建模。其次,为保证移动机器人轨迹跟踪的快速收敛,采用前馈控制并结合位姿误差设计出运动学控制器;为保证移动机器人在速度上的跟踪性能,采用前馈解耦补偿器,加入干扰观测器,运用具有积分链式结构的微分器,设计出动力学控制器;将动力学控制器加入到运动学控制器中,设计了前馈运动学和带有干扰观测器的解耦动力学的混合控制器,并用Lyapunov函数直接法证明了系统的收敛性和稳定性。最后,通过仿真和样机验证,机器人稳定运行时左右摆差可达±9mm,证明了该混合控制算法的有效性和可行性。     

基于Koopman算子的差速驱动AGV数据驱动控制

针对差速驱动AGV(automated guided vehicle)动力学的非线性、强耦合性、以及未建模问题导致无法建立精确模型进行轨迹跟踪控制任务，为此提出一种基于Koopman算子的数据驱动控制策略(koopman data-driven control, KDC)。首先，基于Koopman算子理论，利用扩展动态模态分解(EDMD)方法，得到了该AGV系统的近似高维线性动态显式表达式，即Koopman算子的近似表达。然后，基于导出的该高维线性Koopman动态表达式，设计线性模型预测控制器(MPC)实现AGV轨迹跟踪控制。最后，通过仿真测试对Koopman模型进行了对比验证，同时仿真实验验证轨迹跟踪效果，结果表明从数据中获取的模型信息精确，能高度拟合AGV的动力学模型，所设计的控制策略计算耗时少，在轨迹跟踪控制的精度和稳定性方面具有一定的有效性和先进性。     

磁导航AGV路径跟踪控制系统设计

针对磁导航自动导引车(Automated Guided Vehicle, AGV)的路径跟踪问题,以前轮舵机转向、后轮电机差速驱动型AGV为研究对象,首先对AGV进行运动分析,建立了前轮转角与后轮转速之间的关系,提出了一种改进的模糊PID控制算法分别设计了转向模糊控制器与转速模糊控制器,实时根据路况合理调整舵机转角和电机转速,使前轮配合后轮转向运动,提高路径跟踪精度。在MATLAB中对算法进行验证,结果表明该方法有效减小了系统的超调,缩短了系统达到稳态的时间,AGV车沿设定路径行驶时,控制精度在±5 mm以内,实现AGV车的稳定运行。     

基于麦克纳姆轮的磁导航AGV纠偏控制研究

采用麦克纳姆轮的移动平台是通过4个轮子转速的相互配合来实现全向移动,因此,每一个轮子的运动都会影响整体的运动方向和速度,若一个轮子出现与地面脱离接触以及打滑等情况,则整个移动平台的移动方向会发生很大的偏离。针对磁导航麦克纳姆轮全向移动AGV沿预定路线行进过程中产生偏离的问题,设计了一种基于姿态角度传感器的路径纠偏控制方法,以采集到的偏差数据作为输入,对AGV的行驶路径进行纠偏。通过试验验证了该方法的有效性。     

Robocup F-180全方位小型足球机器人运动学分析

在小型足球机器人两个前轮之间安装踢球器、控球器等装置不仅会对车体各部分的布局造成一定的影响，也会使小车的运动性能发生变化。本文建立了三轮和四轮全方位小型足球机器人的运动学模型，分析了主动轮速度和从动滚子速度随两前轮夹角不同而产生的变化，讨论了车体沿任意方向直线运动时夹角的变化对车体运动性能的影响，对车体机构的设计具有指导意义。     

基于模糊PID控制的差动AGV稳定性控制研究

随着物流行业的快速发展，企业与工厂运输货物的效率亟待提高，传统生产运输方式逐步将被淘汰，在仓储和物流中主要用AGV运输货物，因此保持AGV稳定运行极为重要。提高AGV的稳定性可以提高物流的作业效率与稳定性，AGV的转向稳定性控制就是AGV控制系统中的核心因素之一，因此关于AGV稳定性控制的研究与应用得到了越来越多的重视。建立AGV模型，对AGV转向不稳定性进行分析。采用动态仿真方法分析AGV定点转向参数的稳定性规律，验证理论推导方程的正确性。根据分析结果，确定AGV定点转向运动学影响因素。经过参数优化后，研究其定点转向控制方法，选择模糊PID控制算法设计相应的转向控制策略。优化后，所研究的AGV在实际运行中转向更稳定，满足工作要求。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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