Forward Position Analysis of 5-DOF Parallel Mechanism

Forward position analysis is one of the importantand difficult issues in the kinematic analysis of paral-lel manipulators and has been extensively investiga-ted[1—3]. Most of the approaches for solving forwardposition problems of parallel manipulators with six de-grees of freedom (6-DOF), the Stewart platform forinstance, can be classified into two categories, i.e.closed-form analytical method using polynomial ap-proach and numerical method using iterative algo-rithm. Although the polynomial…     

Architecture Singularity Analysis of 4-U■S/U■U 5-DOF Parallel Mechanism

Architecture singularity of a parallel mechanism with five degrees of freedom (DOF) is analyzed. Such mechanism consists of a movable platform connected to the base by five active limbs. Four of them are identical 6-DOF limbs and the last one has the same DOF as the specified DOF of the movable platform. Based on the kinematics analysis, two categories of architecture singularities for such mechanism are proposed. Then the sufficient condition for each singularity is researched. Results show that the mechanism is singular when it employs each category of the proposed architecture, provided that it satisfies the corresponding sufficient condition. It can be concluded that the proposed two categories of architecture singularities should be avoided with the following dimensional synthesis of such mechanism.     

GPU并行计算的CUDA架构浅析

本文阐述了GPU并行运算的一种主流架构——CUDA架构,包括CUDA编程模型、程序的运行模式、线程架构、存储器结构、指令结构等。     

一种冗余并联机器人的运动学及工作空间分析

针对一种平面冗余2-DOF并联机器人,分析了其运动学正解和反解,并在运动学反解的基础上讨论了该机构工作空间的约束条件;提出了运用Matcom将Matlab和VC＋＋结合起来进行混合编程的方法,探讨了并联机构工作空间的形状,并得到基于VC＋＋开发的该并联机器人控制系统;仿真结果表明,该机构具有较好的工作空间,可广泛应用于工业装配机器人、虚拟轴并联机床和多维减振平台等领域。     

6-SPS型并联六坐标测量机位置分析与研究

根据6-SPS并联机构特点,合理地定义了支杆和动平台的方位及位置坐标,研究了6-SPS型并联六坐标测量机运动学正反向求解方法,提出了一种正向数值求解的方法以及正解迭代格式。     

Research on the operating characteristics of parallel 4-DOF electric platform with 4TPS-PS structure

The 4TPS-PS parallel platform designed for a stabilization and automatic tracking system is a novel lower-mobility parallel mechanism. In the first part of this paper, the structure of the platform is described and the kinematics model is built. The workspace of the platform is defined as the full reachable rotation workspace when the Z coordinate dimension of the upper plate varies continuously. A fast searching method of the full reachable workspace is presented, after which the inverse kinematics of the platform is deduced. The forward and inverse solutions of the speed and force of the platform are deduced. According to the characteristic of the 4TPS-PS platform’s structure, a fast searching algorithm of the maximum generalized speed and maximum generalized force output by the upper plate is put forward based on the forward and inverse solutions of the platform’s speed and force. The 4TPS-PS platform prototype built by the State Key Laboratory of Fluid Power Transmission and Control of China is taken as the research subject. The full reachable rotation workspace of the prototype is computed out and analyzed. The curves of maximum generalized speed and maximum generalized force of the prototype are computed out and plotted. Finally, the com- puting and analyzing results of the operating characteristics are confirmed through the experiment.     

并行计算机系统浅析

并行计算机一直是世界各国计算机界研究的热点，是当代计算机技术的制高点。本通过构建一个并行处理双机系统分析了计算机并行系统的关键技术。     

仿生关节3A由度并联机构运动分析

自由度仿生关节并联机构具有结构紧凑、承载能力大和易于实现的特点。对3-DOF（RRS型）仿生关节并联机构进行结构原理设计，建立机构位移方程，设计仿生关节机构的结构参数并对其结论作出分析。     

IC芯片粘片机并联焊头机构的动刚度分析

针对所设计的IC芯片粘片机的并联焊头机构,建立了机构的振动方程和动刚度模型,使用Matlab软件得出了机构在整个工作空间的动刚度特性曲线,并对其分布进行了分析.根据这些曲线,说明所设计的并联焊头机构的动刚度能满足IC芯片粘片机的工作要求.     

平面并联机构的动力学建模及自适应控制

Dynamic model and control strategy of parallel mechanism have always been a problem in robotics research. In this paper, different dynamics formulation methods are discussed first. A model of redundant driven parallel mechanism with a planar parallel manipulator is then constructed as an example. A nonlinear adaptive control method is introduced. Matrix pseudo-inversion is used to get a desired actuator torque from a desired end-effector coordinate while the feedback torque is directly calculated in the actuator space. This treatment avoids forward kinematics computation that is very difficult in a parallel mechanism. Experiments with PID together with the descibed adaptive control strategy were carried out for a planar parallel mechanism. The results show that the proposed adaptive controller outperforms conventional PID methods in tracking desired input at a high speed.     

机械原理课程设计中机器人机构的动力学建模与仿真

为培养学生的机构分析能力,在机械原理课程设计中对3-PRR并联机器人机构动力学建模分析进行研究.推导出3-PRR并联机构位置反解、速度反解和加速度反解等方程.基于第2类拉格朗日方程建立3-PRR并联机器人机构逆动力学模型,据此求出各驱动关节的驱动力.在空载和负载两种情况下进行数值计算,经过与Adams仿真结果对比分析,...     

基于分布式算法的串/并混合构架FIR滤波器设计

研究基于分布式算法的并行度为2的串/并混合构架FIR数字滤波器设计,提出了一种新的FPGA实现结构。该结构引入一个新的移位累加模块,用于实现2查询表输出的累加运算,采用移位寄存器构建相关控制电路。设计输入精度为8位的FIR滤波器,通过Quartus II 7.1及Modelsim 6.0SE的综合与仿真,以及在EPF10K70RC240-4FPGA目标器件上的实现。结果表明:该结构有效缩减关键路径且简化模块化设计流程,性能获得显著提升。     

SF5CF3与H反应机理的理论研究

采用量子化学QCISD（ T）／6－311＋＋G（ d, p）／／B3LYP／6－311＋G（ d, p）方法研究了SF5 CF3与H自由基的反应机理,对于反应势能面上的各驻点的几何构型进行了全参数优化,过渡态的真实性通过振动分析和内禀反应坐标（ IRC）分析的结果得到了证实,共找到3条可能的反应通道．结果表明,SF5CF3＋H→TS1→P1（CF3SF4（a）＋HF）是最佳的反应通道．该反应通道需要克服的能垒高度为73．5 kJ／mol,生成的产物CF3SF4（a）＋HF的能量低于反应物SF5CF3＋H的能量,属于放热反应,无论从热力学上还是从动力学上分析都是最有利的．     

集群式创新网络的治理机制分析

治理环境的变化使治理形式发生改变,相应地,治理机制也在发生变动。正如市场的治理机制是价格、科层的治理机制是权威控制一样,集群武创新网络治理机制的核心是信任机制。作为信任机制的两种类型,制度化信任和人际关系的信任之间是相互加强而非相互排斥的。无论是基于人际关系的信任还是基于制度的信任,都是嵌入到一定结构下的,并且都有其作用的极限。在现实的组织运行中,价格机制、权威控制和信任机制的交叉并行往往是一种常态。彼此的交互作用,降低了交易成本,提高集群的整体运作效率和创新效率。     

新型四自由度并联机构工作空间特性分析

在建立新型四自由度机构2RRS-2RUS逆运动学模型的基础上,运用单开链法和支链子空间形成的包络面法求解确立该机构的可达位置工作空间和姿态工作空间,并利用雅克比矩阵的代数特征定义约束条件,导出机构奇异位形曲面的方程,据此求解出特定参数下该机构的奇异位形的边界曲线,确定系统在特定参数下出现奇异位形的可能性.     

微进给机构的柔性铰链设计与有限元分析

设计一套以音圈电机为驱动电机,柔性铰链为支承元件,碟形弹簧为减震机构的微进给机构.柔性铰链采用双平行四杆机构的结构形式,计算了柔性铰链在音圈电机峰值推力作用下的最大输出位移和最大应力值.通过有限元分析柔性铰链在不同推力作用下的应力、应变图,发现在音圈电机最大推力800 N作用下,柔性铰链的最大应变为224．67μm.分析结果证明,所设计的直圆形双平行四连杆柔性铰链能够满足微进给机构的往复进给行程要求.     

黑格斯机制与SU(5)大统一场理论

较为详细地叙述了对称性自发破缺的概念,给出哥德斯通定理和Higgs机制,进一步讨论了黑格斯机制在G-W-S及SU(5)中的应用.     

美军研究生教育激励约束机制分析及其借鉴

创新提出针对激励约束机制的RAP分析法,从角色、目标、途径等三方面对美军研究生教育激励约束机制进行了详细分析;阐释了对我军研究生教育的借鉴作用:军队研究生教育必须有效把握军队长远需要与现实需要的均衡,必须注重深化军事特色与学术水平的融合,必须更好实现军队建设需求与军官职业发展的统一,促进高层次人才培养质量提升。     

猪Klf4、Klf5和Egr2基因内含子的克隆及进化分析

从猪肝脏提取基因组作为模板,分别扩增了Klf4、Klf5和Egr2的第3、第2和第1内含子,长度分别为916、1027和1342bp,并通过其两端连接的部分外显子序列与Genbank序列比对加以确认,并和人相应基因内含子作长度和序列同源性比较。结果表明,由内含子比对得出的这些基因在人和猪间的保守程度与这些基因在氨基酸水平上比对得出的保守程度相一致。     

SO4^2--/La2 O3-ZrO2-HZSM-5催化合成柠檬酸酯

首次合成了固体超强酸催化剂SO4^2--/La2O3-ZrO2-HZSM-5,并用其合成了六种柠檬酸酯,分析了催化剂用量、焙烧温度、反应时间、醇酸比等因素对酯化率的影响。结果表明：500℃焙烧3 h所得催化剂活性最好,柠檬酸酯的酯化率可达91.5%以上,高碳醇的酯化率高于低碳醇的酯化率,且该催化剂具有良好的重复使用和再生能力。