Geometrical distribution of rotational axes of 3-[P][S] parallel mechanisms
Geometrical distribution of rotational axes of 3-[P][S] parallel mechanisms
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DOI：
10.1016/j.mechmachtheory.2013.02.007
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发表时间：
2013-07
影响因子：
5.2
通讯作者：
Qinchuan Li;Qiaohong Chen;Chuanyu Wu;Zhen Huang
中科院分区：
文献类型：
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作者：
Qinchuan Li;Qiaohong Chen;Chuanyu Wu;Zhen Huang
3-[P][S]并联机构由三个分支组成，每个分支都能生成一个平面-球面（[P][S]）运动键。通常，3-[P][S]并联机构族包括四种类型的架构，即3-RPS、3-PRS、3-RRS和3-PPS，其中R表示转动副，P表示棱柱副，S表示球铰。3-[P][S]并联机构由于其潜在的实用价值而受到广泛的关注。但对3-[P][S]并联机构两个转动自由度轴线的几何分布知之甚少。因此，虽然3-[P][S]并联机构的运动学推导是正确的，但实际瞬时转动的解释不清楚。这一事实可能会妨碍其适用。本文主要研究3-[P][S]并联机构在不同的杆位布置下的转动轴线的识别问题。首先，利用旋量理论讨论了受力约束的刚体的可行转动轴的几何条件。然后，根据3-[P][S]并联机构的杆面和球铰中心的几何条件，将3-[P][S]并联机构分为4类7亚类，并利用倒螺旋理论确定了这7亚类3-[P][S]并联机构的瞬时转动轴和有限转动轴。结果适用于所有3-[P][S] PM。
A 3-[P][S] parallel mechanism consists of three limbs and each limb can generate a planar-spherical ([P][S]) kinematic bond. Typically, the 3-[P][S] parallel mechanism family includes four types of architectures, namely, 3-RPS, 3-PRS, 3-RRS and 3-PPS, where R denotes a revolute pair, P a prismatic pair, and S a spherical joint. The 3-[P][S] parallel mechanism has received extensive attention due to its practical potential. But little is known about the geometrical distribution of the axes of the two rotational DOF (degrees of freedom) of the 3-[P][S] parallel mechanism. Consequently, although the kinematic derivations of the 3-[P][S] parallel mechanism are correct, the interpretation of the actual instantaneous rotation is not clear. This fact may hinder its application. This paper concentrates on the identification of the rotational axes of the 3-[P][S] parallel mechanism with different limb arrangements. First, the geometrical condition for the axis of a feasible rotation of a rigid body constrained by a force is discussed using screw theory. Then, the 3-[P][S] PMs are classified into four categories and seven subcategories based on the geometrical condition of their LPs (limb planes) and spherical joint centers, The instantaneous and finite rotational axes of the seven subcategories of 3-[P][S] parallel mechanism are identified using reciprocal screw theory. The results apply to all 3-[P][S] PMs.