机械臂逆运动学避障最优求解算法

针对多自由度机械臂在障碍物环境下逆运动学求解存在多解性和碰撞问题，研究了一种将碰撞检测算法、最短行程方法与差分进化算法相结合的具有避障能力的机械臂逆运动学最优求解算法。首先，以六自由度机械臂为研究对象，对机械臂和障碍物进行建模，并建立求逆运动学解的目标函数，目标函数由末端执行器位姿误差函数、目标角度与初始角度之间的变化量函数、碰撞检测函数加权求和组成；其次，利用差分进化算法对目标函数进行最优求解，为了减小函数权重对求解速度和精度的影响，设计了一种自适应权重优化算法，使得求解关节角度在优化求解初期快速达到最短行程位姿角度附近，而在优化求解后期具有更高的的求解精度，即可求得具有避障能力、行程最短且高精度的最优逆运动学解；最后，以UR5机械臂为例，通过MATLAB软件中的Robotics Toolbox工具箱对算法进行仿真验证,验证了算法的有效性。     

一种6自由度关节机器人逆运动学共形几何代数法

为获得一种6R(R为转动副)焊接机器人运动学逆解,使用共形几何代数(CGA)对焊接机器人运动学进行研究.利用共形几何代数中基本几何元素的表达以及几何形体的内积和外积运算,获得了焊接机器人各关节点的位置;通过构造经过关节点的直线与直线以及平面与平面的内积,得出机器人所有关节转角余弦表达,从而获得了焊接机器人位置逆解所有解析解.最后,以一种空间6自由度关节机器人为例求解运动学逆解,结果表明,新方法正确有效,几何直观性好.     

利用共形几何代数的串联机器人位置逆解求解方法

为获得串联机器人位置逆解的解析解,使用共形几何代数对串联机器人位置逆解进行了研究。利用共形几何代数中基本几何元素的内积和外积运算,获得串联机器人各关节点的位置,然后通过构造经过关节点的直线与直线以及平面与平面的内积,求解出机器人所有关节转角,从而直接获得了串联机器人位置逆解的解析解。该方法求解简捷,几何直观性好,避免了经典机器人运动学理论中欧拉角、矩阵的运算以及复杂的多元高次非线性方程组求解,求解过程和结果可以明显地反映机器人几何结构与机器人运动之间的几何关系。以一种空间6R串联机器人位置逆解为例进行了求解,算例计算表明该方法正确、有效,计算效率提高了近44倍。     

基于MATLAB的6R机器人逆运动学求解分析

本文通过D-H方法建立6R机器人坐标模型,将机器人末端执行器位姿~0T_h逆解问题转化为末端腕部点位姿~0T_6的逆解问题,排除~0T_h中含常量d_6的多项式,大大简化了求运动学逆解的复杂度。通过反变换法求得6R机器人逆解,提出以"最短行程+关节运动同向"为原则确定机器人最优逆解的方法,可以降低机器人运动能量消耗,同时减少关节运动换向,提高机器人运行稳定性和可靠性。利用MATLAB进行编程,设置6R机器人"关节加权系数"及"关节运动同向加权系数",对上述运动学逆解求解及优化方法进行了验证,说明该分析方法是有效性的。     

机器人运动学逆的并行算法

对普通的运动学求逆方法进行了改进,使求逆运动学不必调用正弦和余弦超越函数;提出了一种查表法代替反正切运算,从而使求每个关节角的时间减少 895 μs,因而使整个求逆过程减少运算时间 5.37 ms。为了进一步减少运算时间,本文采用 4 CPU分二级并行求逆运算,并采用任务分配式方法,最后将求 CinCinnati 机器人运动学逆时间由普通方法的 20.272 ms 降至 4.907 ms。4CPU 二级并行运算还能使求机器人关节角速度和角加速度的运算时间降至单 CPU的 1/3。     

一种焊接机器人运动学分析新方法

提出了一种焊接机器人的运动学新方法.基于共形几何代数框架内的刚体运动表达,求解了焊接机器人的运动学正解.采用几何体外积运算获得了各关节点位置;通过几何体的内积运算以及简单的代数计算,获得了各关节角符号形式的余弦表达,从而获得该机器人运动学逆解的所有解析解.最后,以一种焊接机器人运动学为数字实例对新算法进行验证.结果表明,方法几何直观性好,计算简洁.     

基于偏置补偿的6自由度腕部偏置机器人逆解算法

串联6自由度腕部偏置机器人一般没有实用的封闭形式位置逆解.根据几何特征分析,以对应的腕部无偏置机器人的封闭解为基础,通过对腕部偏置量的平移补偿和对手腕位置点坐标的迭代修正,得到了腕部偏置机器人位置逆解的数值解.算法保证了末端姿态的正确性.根据末端位置精度要求控制迭代次数,可以得到任意精度的位置逆解.逆解过程中各关节变量的计算采用腕部无偏置机器人的封闭解,使得程序具有通用性.大量的数据试验表明,该算法可以满足实时控制要求.     

基于Matlab的六自由度工业机器人运动学逆解分析及仿真

在Matlab环境下对六自由度工业机器人进行运动学逆解研究,以ER7B-C10机器人为研究对象,使用D-H法进行各关节坐标系建立及参数设计,推导出正运动学方程。鉴于目前应用较为广泛的解析法求逆解仍然存在不足之处,运用几何法求解逆运动方程,在Matlab中利用Robotics Toolbox搭建仿真结构,直接调用Robotics Toolbox工具箱中ikine函数。由于迭代过程的收敛性导致验证过程中存在无解或少解的情况,因此对所求逆解的可靠性增加验证设计来证明几何法求逆解方法可行。对机器人模型在空间轨迹及各关节的位移、速度和加速度等内容进行了仿真分析,结果验证了ER7B-C10机器人运动的可行性,为后续分析机器人动力学、轨迹规划提供了运动学参考。     

机器人逆运动学的微分进化与粒子群优化BP神经网络求解

针对采用传统反向传播(BP)神经网络算法进行逆运动学求解收敛速度慢的问题,提出将微分进化(DE)与粒子群优化(PSO)算法相结合,对用于机器人逆运动学求解的BP神经网络进行优化。基于机器人正解映射建立优化算法的目标函数,在PSO过程中,引入DE操作优化粒子进化方向,并将此混合算法用于BP神经网络权值与阈值的优化。对KUKA机器人进行仿真实验,结果表明:采用该文方法对机器人逆运动学问题的求解精度高,求得的关节角度误差小于0.1°;逆运动学求解结果所对应位姿矩阵的位置误差在0.1 mm数量级,具有较好的泛化能力。该文方法满足机器人位置和姿态方面的精度要求。     

采用Matlab的六自由度机器人三维运动学仿真

对SA1400型六自由度工业机器人进行三维的运动学建模与仿真,建立机器人的正逆运动学方程,并得到正逆解.为验证方程及所求解的正确性,首先,使用Solidworks建立机器人各个部件三维模型;然后,用Matlab将所求得的正逆解编写为程序,导入机器人各部件,利用Matlab的三维绘图功能,以显示机器人的三维模型,并对机器人按轨迹运动的过程进行动态仿真,记录运动过程中机器人各关节角度值的变化,提示求解得到的不合理角度值和奇异点.结果表明:仿真过程较真实地模拟了实际机器人的运动情况,仿真结果达到预期目标,证明根     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.