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| Orientation workspace and global orientation capability analysis of the Gough-Stewart parallel mechanism |
| LI Bao-kun1,2, GUO Yong-cun1, WANG Chuan-li1, CAO Yi3,4 |
1. School of Mechanical Engineering, Anhui University of Science and Technology, Huainan 232001, China;
2. Postdoctoral Research Station of Mechanical Engineering, Anhui University of Science and Technology, Huainan 232001, China;
3. School of Mechanical Engineering, Jiangnan University, Wuxi 214122, China;
4. State Key Laboratory of Mechanical System and Vibration, Shanghai 200240, China |
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Abstract Singular configuration seriously affects the performance of the Gough-Stewart parallel mechanism. It is necessary to obtain the distributing chart of the singularity-free workspace of the parallel mechanism, which can guarantee the mechanism to avoid the singularities. Based on the Jacobian matrix, the expression for representing the oriantaion-singularity locus for a given position was constructed. The method for the constraint orientation workspace determination was established by using the inverse displacement analysis. The orientation singularityfree workspace was obtained by synthetically considering the influence of the singularities of the mechanism. The minimal inscribed sphere of the orientation singularityfree workspace boundary was called the practical orientation-capability which was used as the performance index of the practical orientation singularity-free size. The average practical orientation-capability of the all positions inside the position-workspace was defined as the global orientation-capability (GOC), and then the influence of the moving platform's shape and fixed platform's shape on the GOC was studied. The exploration further expands the workspace determination theory of the parallel mechanisms, and the proposed novel performance index called the global orientation capability has important reference value for the structural parameter optimization.
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Received: 20 April 2015
Published: 28 October 2015
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Gough-Stewart并联机构姿态空间与全局姿态能力分析
奇异位形严重影响Gough-Stewart并联机构的性能.有必要得到机构无奇异工作空间的分布，使机构在工作过程中避免出现奇异位形.基于机构的雅可比矩阵，得到机构位于固定位置时的姿态奇异轨迹表达式.利用机构位置反解建立机构的约束姿态空间求解方法.综合考虑机构奇异位形影响，进一步得到机构无奇异姿态空间.将无奇异姿态空间边界的最小内切球作为衡量机构实际无奇异姿态空间大小的性能参数，称之为实际姿态能力.定义约束位置空间内各个位置点的平均实际姿态能力为全局姿态能力，并研究机构动、定平台形状对全局姿态能力大小的影响情况.研究进一步丰富了并联机构工作空间求解理论，提出的全局姿态能力这一新的性能指标对机构的结构参数优化亦具有重要的参考价值.
关键词：
并联机构,
奇异位形,
姿态空间,
无奇异工作空间,
全局姿态能力
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