一种四自由度并联机构运动学分析及尺寸参数优化

发布时间：2018-09-17 11:33

【摘要】：空间少自由度非对称并联机构与以Stewart平台为代表的六自由度并联机构相比具有结构简单、性能好、易于控制和性价比高等诸多优点,有广阔的应用前景和潜力。但也由于其各个分支不全相同,导致对新机型的构型研究有限,从而影响了对这类机构的研究分析。随着其他机构研究的相对成熟,各国的机构学者开始将目光转移到对空间少自由度非对称并联机构的研究。2TPS/2TPR并联机构是一种空间少自由度非对称并联机构,串联一个转动副就可以成为五自由度的混联机构,具有很大的应用前景。本文对新型2TPS/2TPR空间少自由度非对称并联机构进行结构尺寸参数设计并作了深入的研究。首先,详细描述2TPS/2TPR并联机构的结构,分析了机构的运动性质,计算了机构的自由度。建立了机构的完整雅克比矩阵,它包括运动子矩阵和约束子矩阵。对机构的奇异位形进行了定性分析；其次,详细分析了机构的两个重要性能评价指标,即工作空间体积与机构自身的体积之比和全域条件数。建立工作空间体积与机构自身的体积之比这一性能评价指标与机构尺寸参数间的内在关系；基于完整雅克比矩阵求得了机构的全域条件数指标与机构尺寸参数间的内在关系；再次,对机构各尺寸参数进行了灵敏度分析,建立了各尺寸参数变化对各项性能指标的影响关系曲线,分析了各参数变化对机构各性能指标的影响,为机构的尺寸设计提供了理论依据；最后,简要介绍了遗传算法的原理和相关的基本概念。基于遗传算法及尺寸参数对机构性能的影响,对2TPS/2TPR并联机构进行尺寸设计优化,并利用MATLAB计算软件编写程序获得了各尺寸参数的最佳组合并通过实例验证优化结果的有效性；最后根据优化结构建立了机构的实体模型。
[Abstract]:Compared with the six-degree-of-freedom parallel mechanism represented by Stewart platform, the space-less-degree-of-freedom asymmetric parallel mechanism has many advantages, such as simple structure, good performance, easy control, high cost performance and so on. It has broad application prospects and potential. However, due to its different branches, the research on the configuration of the new model is limited, which has an impact on it. With the relative maturity of other mechanisms, scholars in various countries began to turn their attention to the study of asymmetric parallel mechanisms with few degrees of freedom in space. 2TPS/2TPR parallel mechanism is a kind of asymmetric parallel mechanism with few degrees of freedom in space, and one rotating pair in series can become five degrees of freedom parallel mechanism. The mechanism has great application prospects.
In this paper, a new type of 2TPS/2TPR spatial asymmetric parallel mechanism with few degrees of freedom is designed and studied.
Firstly, the structure of 2TPS/2TPR parallel mechanism is described in detail, the kinematic properties of the mechanism are analyzed, and the degree of freedom of the mechanism is calculated.
Secondly, two important performance evaluation indexes of the mechanism are analyzed in detail, i.e. the ratio of workspace volume to the volume of the mechanism itself and the global condition number. The internal relationship between the global condition number index and the size parameters of the mechanism.
Thirdly, the sensitivity of each dimension parameter of the mechanism is analyzed, and the influence curve of each dimension parameter change on each performance index is established. The influence of each parameter change on each performance index of the mechanism is analyzed, which provides a theoretical basis for the dimension design of the mechanism.
Finally, the principle and basic concepts of genetic algorithm are briefly introduced. Based on genetic algorithm and the influence of dimension parameters on the performance of mechanism, the dimension design optimization of 2TPS/2TPR parallel mechanism is carried out. The optimum combination of dimension parameters is obtained by programming with MATLAB software and the validity of optimization results is verified by an example. Finally, according to the optimized structure, the entity model of the mechanism is established.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH112

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