基于NURBS算法的冗余机械臂轨迹规划

为有效抑制机械臂高速运动过程中的波动,提出一种基于NURBS(非均匀有理B样条)算法的七关节冗余机械臂轨迹规划方法。根据NURBS算法的性质,将关节运动路径点作为曲线控制点,根据绝对运动距离计算出非均匀节点矢量,把权因子作为控制变量进行速度、加速度条件约束,完成对由离散点组成的机械臂各关节特定轨迹进行逼近。通过计算机对建模和仿真,验证了该算法在冗余机械臂轨迹规划中的可行性和有效性。     

核电站蒸汽发生器维修机器人控制系统设计

针对一种用于核电站蒸汽发生器水室内辅助检修任务的6自由度作业机械臂,对其控制系统和运动轨迹规划进行设计研究.分析作业机械臂的工作环境和检修任务需求,设计了机器人的控制系统;对作业机械臂进行关节空间轨迹规划和笛卡尔坐标系轨迹规划,实现作业机械臂的点对点运动和连续路径运动,并利用深度相机和霍夫变换圆检测原理实现作业机械臂末端对管板圆孔的定位;对作业机械臂进行了轨迹规划运动实验和圆孔定位实验,结果表明,作业机械臂能够实现直线、圆弧轨迹运动和管板圆孔识别定位,满足蒸汽发生器的全方位检修要求.     

六自由度机械臂建模与MATLAB仿真

目的依据预设的机器人末端运动轨迹,研究机器人各关节的运行轨迹。方法利用仿真软件对机器人末端轨迹进行仿真实验。以六自由度机器人为研究对象,采用标准D-H参数法建立机器人各连杆坐标系及计算运动学方程,利用MATLAB/Robotic Toolbox工具箱建立机器人的运动学模型,在运动学模型的基础上对机器人工作空间以及轨迹规划进行仿真。仿真结果为连续平稳的末端轨迹曲线和关节角位移、角速度、角加速度的变化曲线。结果得到了连续平稳的末端轨迹曲线和关节角位移、角速度、角加速度的变化曲线等仿真结果,轨迹仿真结果表明机器人各关节运动平稳性较好。结论轨迹仿真可以避免试验中对机械臂所产生的损坏,为后续实验研究工作的开展提供支持。     

考虑冗余机械臂末端运动特性的规划方法

机械臂运动规划是机器人研究领域的重点,对机械臂能否顺利执行任务非常重要。目前,机械臂运动规划多使用RRT法,然而该方法是在关节空间进行规划,无法适用于机械臂末端执行器存在约束的任务。为了克服这个不足,该文提出了一种任务自由子空间RRT(rapidly-exploring random tree)法,在末端执行器任务空间的自由子空间中构建RRT,并对其每步扩张进行逆运动学轨迹优化,求解出相应的关节轨迹。此外,由于末端执行器速度对逆运动规划有重要影响,该文在逆运动轨迹优化阶段采用了最似梯度法,不仅考虑了末端执行器的运动速度,而且通过极小关节自由速度和优化目标负梯度的距离,重新确定了关节自由速度,增强了算法的优化能力。实验结果表明:该算法能有效解决机械臂末端存在约束的问题。     

网络远程控制中机械臂的连续轨迹控制

探讨了点位控制在二自由度机械臂网络远程控制中的问题,将连续轨迹控制应用到基于关节坐标空间的机器人控制系统中,分析了在远程操控环境中实现连续轨迹控制所需要满足的条件,给出了最佳合成速度的求法,并进行了实际系统的远程控制实验,在期望时间内实现了连续、平滑的运动效果,证实了在网络远程系统的控制中采用连续轨迹控制能够获得更高的精度。     

基于粒子群算法的空间机械臂关节驱动力矩优化设计

采用绝对节点坐标方法对空间柔性机械臂臂杆进行动力学建模,采用自然坐标法对机械臂关节进行建模,最终得到刚柔耦合的空间机械臂动力学模型.对冗余自由度机械臂进行逆运动学分析,由规划的末端轨迹得到了含自运动项的关节转角轨迹.利用动力学方程中Lagrange乘子的物理意义,对机械臂系统进行逆动力学分析,推导了关节轴瓦与轴颈在运动过程中受到的关节驱动力/力矩.利用粒子群算法优化机械臂的自运动项,得到了最小化的关节驱动力矩能耗,从而形成了一种冗余空间机械臂关节驱动力矩优化设计新方法.在平面三连杆柔性机械臂进行了数值仿真,仿真结果表明:所提出的方法在实现末端轨迹跟踪的同时,能有效降低关节力矩能耗;得到的关节力矩连续性好,能够满足工程实际需要.      

基于改进的自适应和声搜索算法的时间最优轨迹规划

根据机械臂运动约束,提出了关节空间基于改进的自适应和声搜索算法的三次样条插值轨迹规划。该算法采用自适应的记忆库取值概率、微调概率和调节步长产生新解。利用三次样条插值方法构造各关节位移、速度及加速度均连续的轨迹,然后由IAHS算法解算出最优时间。通过与基本和声搜索算法的对比,表明该算法有更强的寻优能力。     

多功能拆除机器人自动对接工具轨迹规划研究

为保证多功能拆除机器人机械臂在自动对接工具过程中的轨迹平稳连续和启停无冲击,提出了一种可配置速度的分段轨迹规划方法,即首先利用Bezier曲线生成其避障对接路径,然后在关节空间利用4-4-…-4-5次多项式对其对接路径进行分段插值。最后,以某型三臂式多功能拆除机器人对接工具为例,通过Matlab进行仿真,结果表明:4-4-…-4-5次多项式插值轨迹规划方法保证了多功能拆除机器人各关节角角度、角速度和角加速均连续,且启停位置具有零速度和零加速度,为实现多功能拆除机器人自动对接工具提供了基础。     

基于改进蚁群算法的六自由度机械臂路径规划

针对空间六自由度机械臂路径规划问题,提出了一种基于改进蚁群算法的路径规划方法。以ABB1410型号的六自由度工业机械臂为研究对象,建立D-H运动模型以求解正、逆运动学方程。设计了碰撞检测算法,使用改进后的蚁群算法进行路径规划,把机械臂末端的运动轨迹看作是依次经过规划路径的点的集合,求解机械臂运动的反解,得到相应的关节转角,实现了机械臂的路径规划。通过仿真实验验证了该方法实现六自由度机械臂路径规划的有效性及可行性。     

SCARA型四自由度机械臂规则曲线的轨迹规划

针对轨迹规划在SCARA型机械臂高效稳定运行中所起的重要作用,以四自由度机械臂为控制对象对轨迹规划算法研究,通过在笛卡尔坐标空间中进行直线插补和圆弧插补对机械臂进行轨迹规划,仿真结果表明,运用轨迹规划可以有效地提高机械臂的控制精度和工作效率.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that