基于Pa~2运动副的移动并联机器人的综合与分析

发布时间：2018-05-09 00:35

本文选题：移动并联机器人 + Pa~2运动副　；参考：《天津科技大学》2017年硕士论文

【摘要】：并联机器人以其负载高、精度高以及刚度好等一系列优点获得了人们越来越多的关注,也成为各国学者研究的前沿课题。但是,并联机构的型综合问题始终没有得到很好的解决,特别地,低自由度并联机构的机型综合仍然是并联机器人研究领域的热点问题。低自由度并联机构,尤其是能够生成平移运动的并联机构,在工业生产中有着重要的应用价值。通过借助于位移子群综合法,本文提出了两类基于Pa2运动副的移动并联机器人,并且对他们进行了综合分析(自由度分析与机构学分析)。广义运动副Pa2是平行四杆机构的衍生机构,它不仅具有能够提供2自由度平移运动的能力,还可以作为被动自由度生成平移运动。与应用被动的移动副相比,在生成平移运动上,Pa2更有优势,那是因为浮动的移动副很难产生稳定的平移运动。而且,Pa2的数学模型可以直接应用在此类并联机构的分析中。应用空间封闭向量的方法,本文成功地解决了 3-PPa2并联机器人的正、逆运动学问题,并得到了正、逆运动学解的个数。在求解正逆运动学的过程中,得到了 3-PPa2的工作空间,是由空间三个圆柱所围成的空间几何体。同时,论文分析解决了 3-PPa2的速度问题,得到了机构的速度方程,并由此定义了三类雅克比矩阵:正运动学雅克比矩阵、逆运动学雅克比矩阵和增加运动性雅克比矩阵。通过对雅克比矩阵的分析,论文研究了 3-PPa2并联机器人的三种奇异位形:正运动学奇异、逆运动学奇异和增加运动性的奇异位形。其中,逆运动学奇异位形最简单,它是末端执行器处于工作空间的内外边界时所发生的一种奇异状态。通过分析,3-PPa2的正运动学奇异相当复杂,很难用一个奇异曲面来表示所有的奇异位形。但是,本文得到了 3-PPa2在一些特殊位置时发生奇异的状态,并得到了相应的奇异面。本文首次分析了支链中含有复杂闭链的并联机构,表明了广义副Pa2在并联机构的型综合中具有较大的应用前景,拓展了可用于合成并联机构的运动副类型。文中提出的3-PPa2机构不仅结构紧凑,而且有着简洁的运动学解。3-PPa2的出现丰富了并联机构的机型种类,进一步完善了并联机器人相关的理论知识。
[Abstract]:Parallel robot has attracted more and more attention because of its high load, high precision and good stiffness. However, the problem of type synthesis of parallel mechanism has not been well solved, especially, the model synthesis of low degree of freedom parallel mechanism is still a hot issue in the field of parallel robot research. The low degree of freedom parallel mechanism, especially the parallel mechanism which can generate translation motion, has important application value in industrial production. By means of displacement subgroup synthesis method, two kinds of mobile parallel manipulators based on Pa2 kinematic pair are proposed in this paper, and they are analyzed synthetically (degree of freedom analysis and mechanism analysis). The generalized kinematic pair Pa2 is a derivative mechanism of parallel four-bar mechanism. It not only can provide 2-DOF translation motion, but also can be used as passive freedom to generate translation motion. Compared with the passive pair, Pa2 has more advantages in generating the translational motion because it is difficult for the floating pair to produce a stable translational motion. Moreover, the mathematical model of Pa2 can be directly applied to the analysis of this kind of parallel mechanism. Using the method of closed space vector, this paper successfully solves the forward and inverse kinematics problems of 3-PPa2 parallel manipulators, and obtains the number of forward and inverse kinematics solutions. In the process of solving forward and inverse kinematics, the workspace of 3-PPa2 is obtained, which is a spatial geometry formed by three cylinders of space. At the same time, the velocity problem of 3-PPa2 is analyzed and solved, the velocity equation of mechanism is obtained, and three kinds of Jacobian matrices are defined: positive kinematics Jacobian matrix, inverse kinematics Jacobian matrix and adding kinematic Jacobian matrix. Based on the analysis of Jacobian matrix, three singular configurations of 3-PPa2 parallel manipulators are studied: positive kinematics singularity, inverse kinematics singularity and kinematic singular configuration. The inverse kinematics singular configuration is the simplest one. It is a kind of singular state when the end actuator is in the inner and outer boundary of the workspace. By analyzing the positive kinematic singularities of 3-PPa2, it is very difficult to express all singular configurations with one singular surface. However, in this paper, we obtain the singular states of 3-PPa2 in some special positions, and obtain the corresponding singular surfaces. In this paper, the parallel mechanism with complex closed chain in the branch chain is analyzed for the first time. It is shown that the generalized pair Pa2 has a great application prospect in the type synthesis of the parallel mechanism, and extends the type of kinematic pair that can be used to synthesize the parallel mechanism. The proposed 3-PPa2 mechanism is not only compact in structure but also has a concise kinematics solution. The appearance of .3-PPa2 enriches the types of parallel mechanisms and further improves the relevant theoretical knowledge of parallel manipulators.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP242;TH112

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