基于气动肌肉驱动的下肢康复机器人设计与仿真

为实现气动肌肉在多自由度康复机器人中的应用,设计一种用于步态康复训练二自由度下肢康复辅助训练机器人,驱动器由气动肌肉和拉伸弹簧并联驱动关节以实现节能辅助行走。建立人体下肢运动学和动力学模型,并以标准CGA步态曲线作为关节输入,通过SolidWorks/Motion进行运动学仿真,验证所设计的模型符合人体下肢运动规律。针对气动肌肉伸展时存在非线性使得关节控制困难,提出了模糊自适应PID控制算法。在MATLAB/Simulink中进行仿真控制实验,仿真结果表明：相比传统PID算法,模糊PID自适应控制算法使外骨骼达到更好的跟随效果。最后通过实验平台验证了模糊PID自适应控制算法能够满足患者主动康复训练的需求。     

步态康复训练机器人行走步态仿真研究

步态康复训练机器人是对下肢行走障碍患者进行步态康复训练的一种助力康复设备,其行走步态的研究对于控制方案的制定有着重要意义.本文作者提出了步态康复训练机器人总体结构设计方案,利用Matlab/Simulink仿真环境下的机构系统模块集(SimMechanics)建立了步态康复训练机器人系统的仿真模型,并将斯坦福OpenSim下肢肌肉骨骼模型得到的下肢关节运动数据作为设定输入对机器人进行了运动仿真分析和研究,为下一步机器人样机制作和实际控制奠定了理论基础.     

一种六自由度上肢康复训练机器人运动学及工作空间仿真分析

针对现有上肢康复训练机器人存在功能集成度低和结构庞杂的缺陷,设计了一种6DOF可穿戴式上肢康复训练机器人。采用SolidWorks构建机器人的三维模型,通过ADAMS/View提供的模型交换接口导入ADAMS中进行运动学仿真。基于D-H表示法建立机器人的正向运动学模型,利用MATLAB软件对机器人进行运动学仿真及工作空间仿真分析。得到机器人末端轨迹仿真曲线与理论曲线一致,检验了机器人运动学方程推理的准确性,工作空间仿真结果说明了该方案的合理性。     

步行康复训练机器人设计研究

针对中风或者不完全脊柱损伤患者术后康复需求,设计并制作了一种移动式新型步行康复训练机器人。通过四颗按钮开关,控制减重机构实现不同比例的减重;通过HJ6霍尔操纵杆,控制步行康复训练机器人的训练模式,包括前后直线运动和左右转弯运动。利用经典力学方法对步行康复训练机器人的关键零部件进行了分析,最终选择了合适的零件。最后,制作了步行康复训练机器人样机,并进行了运动功能实验。实验结果表明:步行康复训练机器人能实现所要求的功能,基本满足患者术后康复训练的需要。     

基于滑模PID控制的下肢康复外骨骼控制研究

为增强外骨骼机器人在医疗方面的康复效果,通过研究人体运动机理及人体各关节运动数据,设计了一款基于液压控制的下肢外骨骼机器人。首先,通过建立外骨骼动力学模型,基于拉格朗日法求出髋关节、膝关节处的驱动力矩,建立了髋关节、膝关节的动力学方程;针对动力学模型在实际计算过程中存在着误差及摩檫等因素影响,提出了一种PID和滑模控制相结合的控制算法;运用Matlab软件进行了模拟仿真实验,仿真结果表明,该控制系统能够使外骨骼机械腿达到良好的跟随效果;最后搭建样机实验平台,验证了控制算法的有效性,能够满足患者进行主动康复训练的需求。     

六自由度肩关节康复机器人设计与仿真

针对肩关节运动损伤康复训练问题,通过分析肩关节的运动方式,设计一种外骨骼肩关节康复机器人。对机器人的整体样机机械结构进行简单建模设计,并解决了肩关节旋转中心瞬时可变性的问题;通过D-H法推导出机器人运动学方程,并通过MATLAB验证了运动学方程的正确性。利用ADAMS软件中建立的虚拟样机模型,对机器人进行运动学和动力学的仿真,得到各关节角速度与时间的关系和各关节的驱动力矩曲线。最后通过蒙特卡洛法,计算出机器人末端运动的位置云图,得到机器人末端的运动范围。仿真分析验证了机器人结构的可行性和运动学方程的正确性,可以实现康复目的。     

基于MATLAB的手臂康复机器人仿真研究

手臂康复机器人通过牵引患肢按规定轨迹运动,以锻炼肌肉、恢复运动功能,实现手臂康复训练.该机器人采用极坐标形式,由电机驱动各关节协调控制实现手臂的平面运动,该机器人可以在水平面和垂直面进行手臂运动锻炼.建立了基于MATLAB的手臂康复机器人控制模型,基于虚拟现实技术进行了仿真,仿真结果说明系统达到了预期效果.     

基于气动软体驱动器的可穿戴手功能康复装置北大核心

针对脑外伤和中风等引起的手部运动功能缺失患者,采用自制气动软体驱动器设计一种用于手功能恢复的可穿戴康复装置。基于Yeoh本构方程建立软体驱动器形变模型,进行静力学实验验证和有限元仿真。试制样机并搭建康复装置实验平台,进行康复装置位姿和抓取实验。结果表明:该康复装置柔顺灵活,具有较好的适应性,可用于辅助患者完成人手部分功能和康复训练,实现日常物品抓取。     

沉井基础取土作业机器人设计与研究

针对传统沉井基础施工设备取土效率低、地层适应性较差、作业区域存在盲区等问题，设计一款沉井基础取土作业机器人。结合施工需求，对机器人进行结构设计，并对其伸缩臂进行有限元静力学分析，验证了伸缩臂结构设计的合理性和可靠性；基于D-H法和几何法分别建立了机器人正、逆运动学模型，基于几何法建立了机器人关节空间到驱动空间的运动学模型，将铣挖头位姿控制最终转换为各关节液压驱动器的位置控制；设计了机器人关节驱动电液比例控制系统，采用PID控制器对其进行校正，通过仿真验证了控制策略的有效性；通过现场试验对机器人整机使用性能进行分析。试验结果表明：沉井基础取土作业机器人满足沉井施工需求，达到预期目标。     

基于心肺复苏用途的上肢外骨骼助力机器人仿真研究（英文）

针对心肺复苏助力用途,设计了一种新型的上肢外骨骼助力机器人。以D-H矩阵为基础建立了上肢外骨骼助力机器人的运动学方程,得到机器人末端点的位姿矩阵并验证,利用代数解法求得逆运动学。通过Matlab编程求解出上肢外骨骼助力机器人的可达工作空间。运用ADAMS对机器人进行了运动学和动力学仿真,证明了结构的合理性以及运动学的正确性,同时动力学仿真得到的各关节最大力矩为电机选型和后续的运动控制提供依据。     

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.