基于Speedgoat的dVRK机械臂控制系统开发

为提高dVRK外科机器人控制系统的快速响应性和控制实时性,开发一种基于实时目标机Speedgoat的机器人实时控制系统。通过搭建宿主机-目标机机器人控制平台,设计UDP Real Time通信模型块,建立宿主机、目标机的运行模型,实现对机器人的实时控制。结果表明：实时控制系统可准确地完成对dVRK机器人的数据采集和相关控制算法验证;搭建的Speedgoat实时控制平台具有在线调参、实时仿真、目标代码快速原型化、仿真精度高、可靠性好等优点,大大缩短了dVRK机器人控制算法的研制周期。     

基于Simulink Real-Time的dVRK机械臂实时控制研究

为提高dVRK外科机器人控制系统的快速响应性和控制实时性,基于D-H参数模型建立dVRK 七自由度机械臂的连杆模型。计算机械臂的齐次变换矩阵,为机械臂的实时控制提供参考。基于MATLAB/Simulink建立机械臂各关节的PID位置控制半实物仿真模型,实现机械臂末端的实时定点控制。结果表明：所提系统可实时准确地完成外科机器人机械臂的数据采集和相关控制算法的验证。     

搬运工业机器人的教学仿真系统设计

利用OpenGL开发环境,与Visual C++相结合,建立搬运工业机器人的三维模型,开发的仿真系统具有可扩充性和可移植性,将FMS机器人的正逆运动学、正逆动力学、各种控制算法、轨迹规划封装成通用模块,并提供用户接口,供用户设计自己的模块和控制算法;增加多个输入输出模块。该结构可扩展实际的FMS机器人控制系统,从而更好地为搬运工业机器人在工作空间的工作姿态进行三维仿真,实现实时控制与实时仿真的一体化。     

新型三平移并联机器人机构的光滑滑模控制研究

有关并联机器人的研究多限于机构学、运动学和动力学方面的研究.针对一种新型三平移并联机器人机构,在根据动平台运动要求,基于运动学分析实时求得各支路主动副期望角位移,并基于动力学分析实时求得各支路主动副主要等效干扰作用的基础上,建立了控制系统模型,设计了一种新型光滑滑模控制算法,仿真实现了对各支路主动副期望运动轨迹的跟踪.仿真结果表明:所设计算法解决了传统滑模控制在数字实现时的震颤问题,且系统抗干扰能力强,对系统参数变化不敏感,具有良好的跟踪性能.其研究为进一步实现该并联机器人机构的高精度实时控制奠定了基础.     

气动连续型机器人设计及运动学分析

针对传统工业机器人柔性不足的情况,根据象鼻仿生学基本原理,采用气动柔性驱动器(FPA),设计了气动连续型机器人的机械结构,并基于"头部引导法"进行了运动学分析,设计了相应的测控系统。系统实现连续型机器人弧长、偏转角度、曲率实时检测,并将检测数据传输至上位机。由上位机实现机器人位姿实时计算。最后加工制作了该连续型机器人原型,并实现了抓取实验,原型机可实现200 g以内物体卷绕抓取,弯曲角度控制精度小于10°。     

喷涂机器人高精度运动控制算法研究

针对6自由度喷涂机器人的运动控制问题,进行了相关高精度控制算法的研究。首先,建立了基于D-H法的连杆坐标系,其次从正、逆运动学建模两个方面对喷涂机器人进行了运动控制描述。分别通过Manocha消元法和拟牛顿迭代法对喷涂机器人逆运动学在示教再现和连续轨迹的应用场景下的计算方法进行了系统研究。最后,利用MATLAB绘图工具箱对研究结果进行了仿真实验,验证了正、逆运动学正确性和逆运动学的快速性和高效性。该算法改进了消元法中运算时间长达秒级的问题,使逆解算法可实际运用于机器人实时控制系统中。     

基于步进电机驱动并联机器人的无震颤滑模控制研究

步进电机具有体积小、转矩大、转速范围宽等优点;并联机器人具有刚度大、承载能力强、误差小等特点。本文针对以步进电机驱动的新型三平移并联机器人机构的上述特点,设计了滑模控制算法,建立了控制系统模型,仿真实现了对各支路主动副期望运动轨迹的跟踪。仿真结果表明：该算法解决了滑模控制的震颤问题,系统的鲁棒性好,且系统抗干扰能力强,对系统参数变化不敏感,具有良好的跟踪性能．实现了对该并联机器人的高精度实时控制.     

基于雅可比的实时目标跟踪系统研究

以四自由度机器人为对象，研究并开发了基于雅可比逆阵的静态目标抓取和动态目标跟踪的控制系统。在系统中通过引入动态增量分割方法在线规划轨迹，使抓取静态目标的跟踪轨迹平直；引入比例积分控制策略实现了比较精确的运动目标的实时跟踪。系统使用时只需将传感器获得的目标位姿信息实时输入系统，无须运动学反解和运动规划，即可实时控制机器人的位置和姿态。该系统结构简单，实时性强，化姿控制精度较离。仿真实验表明了该系统的有效性。     

一种领航-跟随型多移动机器人编队控制方法

针对多移动机器人的路径规划、编队成形与编队保持问题,本文提出了一种集路径规划和轨迹跟踪于一体的领航-跟随型编队控制方法。将改进型人工势场法引入领航机器人的在线局部路径规划中,有效解决了领航-跟随型编队运动中的无碰撞路径规划问题;采用滑模运动控制方法,设计了一种自主调节移动机器人线速度和角速度的轨迹跟踪控制器,解决了跟随机器人实时追踪预定轨迹的实时控制问题。这种综合路径规划和轨迹跟踪的一体化多机编队控制方法,有助于解决多无人系统编队、多机协作搬运等复杂作业任务。     

RBF神经网络在机器人视觉伺服控制中的应用

传统的机器人视觉伺服控制是由系统雅可比矩阵的计算得到图像空间与机器人空间的非线性关系,这种方法不仅计算量大、系统结构复杂,而且对系统模型误差敏感。针对此问题,在分析视觉伺服数学模型的基础上,设计了RBF径向基函数神经网络来实现机器人视觉伺服系统手眼协调功能,从而简化控制算法。通过仿真实验证明所设计的径向基函数神经网络控制系统具有良好的目标定位效果和泛化能力,并且极大地缩短了视觉伺服所需时间,很好地保证了控制系统的实时性。     

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.