8-UPS并联机器人的工作空间求解

为了满足自动化大作业空间的生产需求,提出了一种面向大型工件加工(如机翼铆接)和大作业空间的工业机器人概念——8-UPS并联机器人。提出了8-UPS并联机器人整体及支链构型,支链中低副等价支链的巧妙配置确保了机器人的步行功能,通过逆运动学模型求解了驱动杆长变化,同时基于三维搜索法,用Matlab求解了并联机构加工状态下的工作空间,并利用姿态工作空间分析了并联机构杆长对工作空间的影响。研究发现,工作空间的截面积沿z轴方向是先增大后减小,空洞则逐渐消失,当z=2 700 mm时,动平台工作空间的面积达到最大值;随着最小杆长的增加,转动中心在垂直空间的范围逐渐增大,这样可以保证并联机器人有足够的加工空间。     

Delta并联机器人的参数优化设计研究

结构参数优化是并联机器人运动学设计的最终目标。本文针对Delta机器人提出了一种结构参数优化设计方法。首先对机构进行运动学分析得到局部灵活度的性能评价指标,其次将局部性能评价指标综合为全域性能指标,将尺度综合问题归结为一类参数优化问题。该方法对这类以及其他并联机构的运动学设计理论有一定指导意义。     

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.     

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。     

3-TPT并联机器人的动力学研究

运用凯恩方程对3-TPT并联机器人进行了动力学分析,建立了动力学方程,为进一步机构动态特性分析提供了依据。     

基于模糊控制的并联机器人系统研究

针对一般模糊控制器无法消除稳态误差、易产生极限环振荡的问题,设计了并联机器人变参数调节模糊积分控制器,并进行了轨迹跟踪仿真试验,且利用VC＋＋设计了并联机器人的计算机控制软件。实验结果表明,该模糊控制算法的实际控制效果较好,并联机器人能在其工作空间内顺利完成给定的轨迹运动,且具有一定的控制精度。     

并联机器人运动学标定方法综述

运动精度限制了并联机器人的应用,而运动学标定是提高并联机器人运动精度的有效手段。并联机器人的运动学标定方法有三种：传统标定方法、自标定方法和第三类标定方法。这三种标定方法各有特色,在应用这些方法对并联机器人进行运动学标定时需要充分考虑具体机构的特点。     

并联机器人逆运动学模型及高效并行算法研究

充分考虑机构并行特征，运用影响系数法建立了并联机器人逆运动学模型，研究了模型的并行算法。并行算法的计算量分析表明该算法具有显著的并行性和高效性。     

并联机器人在机械工程实验教学中的应用

在控制工程基础、机器人技术及单片机等课程教学中,充分利用六自由度并联机器人平台进行实验教学,可解决机械工程实验教学中先进机器人技术教学难的问题。结合控制工程基础、机器人技术及单片机等课程的具体教学实例,对六自由度并联机器人在机械工程实验教学中的应用进行了探索与实践。实验结果证明,该方法提高了学生对控制工程基础、机器人技术及单片机等课程的理解,培养了学生动手能力,实验教学效果良好,为控制工程基础、机器人技术以及单片机等课程的实验教学提供了一种新的方法。     

平移型3-UPU并联机构的工作空间分析

To determine workspace and relationship between the workspace and geometry of parallel manipulator is important for optimum design of parallel manipulators. In this paper, the workspace and the relationship between the workspace and the geometry of 3-UPU parallel manipulators with pure translation axe investigated. Geometric and non-geometric constraints are defined and taken account of in determining the workspace of the translation 3-UPU manipulators. A direct average condition number is used as the global performance index of the workspace. This research shows that there exists an optimal value of the direct average condition number favorable for a good design of parallel mechanisms. The results presented in this paper are useful for the optimum design of 3-UPU parallel manipulators.     

Forward displacement analysis of a redundant parallel manipulator by approximation algorithms

This paper presents the forward displacement analysis of an 8-PSS （prismatic-spherical-spherical） redundant parallel manipulator whose moving platform is linked to the base platform by eight kinemtic chains consisting of a PSS joint and a strut with fixed length. A general approximation algorithm is used to solve the problem. To avoid the extraction of root in the approximation process, the forward displacement analysis of the 8-PSS redundant parallel manipulator is transformed into another equivalent problem on the assumption that the strut is extensible while the slider is fixed. The problem is solved by a modified approximation algorithm which predicates that the manipulator will move along a pose vector to reduce the difference between the desired configuration and an instantaneous one, and the best movement should be with minimum norm and least quadratic sum. The characteristic of this modified algorithm is that its convergence domain is larger than that of the general approximation algorithm. Simulation results show that the modelified algorithm is general and can be used for the forward displacement analysis of the redundant parallel manipulator actuated by a revolute joint.     

Traversing the singularity hypersurface by applying the input disturbances to 6-SPS parallel manipulator

The singular points of a 6-SPS Stewart platform are distributed on the multi-dimensional singularity hypersurface in the task-space, which divides the workspace of the manipulator into several singularity-free regions. Because of the motion un- certainty at singular points, while the manipulator traverses this kind of hypersurface from one singularity-free region to another, its motion cannot be predetermined. In this paper, a detailed approach for the manipulator to traverse the singularity hypersurface with its non-persistent configuration is presented. First, the singular point transfer disturbance and the pose disturbance, which make the perturbed singular point transfer horizontally and vertically, respectively, are constructed. Through applying these disturbances into the input parameters within the maximum loss control domain, the perturbed persistent configuration is transformed into its corresponding non-persistent one. Under the action of the disturbances, the manipulator can traverse the singularity hypersurface from one singularity-flee region to another with a desired configuration.     

Optimum calibration of a parallel kinematic manipulator using digital indicators

This paper presents a calibration method for parallel manipulators using a measurement system specially installed on an external fixed frame. The external fixed frame is important as an error reference for calibration in certain operations, such as in the configuration of a parallel manip- ulator functioning as a machine tool where the workpiece is fixed to a worktable. The pose of the end-effector is mea- sured using three digital indicators installed on the external fixed frame. To enable measurement, the end-effector is assumed to be a plane large enough that all digital indicators could touch. The error is defined as the difference between the theoretical and actual readings of the digital indicators. The geometric parameters of the parallel manipulator are optimized to minimize this error. This calibration method is low cost and feasible for compensating geometric parameter errors for a parallel manipulator. Optimal pose selection for the calibration is achieved using a swarm intelligence search algorithm. The method is implemented on a prototype of a six degrees-of-freedom （DOFs） Gough-Stewart platform constructed to function as a machine tool.     

论社会资本的运作空间

在竞争空前激烈、信息爆炸的现代社会，社会资本的运作空间非常之大，因而使作为一种事实存在的社会资本运作空间被学术界所忽视，但作为一种理论工具的社会资本运作空间的存在是不能被忽视的，因为它是一个非常有解释能力的概念工具，本文在对社会资本的本质特征分析的基础上，提出了社会资本运作空间这一概念，并针对社会资本功能发挥和工具性使用的特点，构建了社会资本运作的空间模型，最后，文章运用社会资本的运作空间这一理论工具分析了当前中国社会的就业机制。     

基于.NET平台的作业空间管理系统

系统主要提供在计算机实验课程中文件服务器的学生作业帐号建立、空间目录分配以及教师对学生作业浏览检索等功能,摆脱传统学生帐号、空间建立和安全设置等繁琐过程。系统基于.NET技术,分管理员、教师、学生三个子平台,采用教师-课程-班级-学生的层次结构建立服务器物理目录,建立了合理有效的实验室作业空间管理平台。     

Pressure observer based adaptive robust trajectory tracking control of a parallel manipulator driven by pneumatic muscles

This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.     

平行研究之我见

本文从平行研究的定义、存在依据、研究途径三方面来论述作为比较文学研究方法之一的平行研究 ,从民间文学等学科的研究成果为平行研究的存在提供了合理性依据 ,在操作层面上 ,应当强调开放性、兼容性 ,注意深入了解两国的历史文化语境 ,借鉴外学科的研究成果 ,把握好同、异因素与比较的关系。