Title
Directed graphs, decompositions, and spatial linkages
Abstract
The decomposition of a linkage into minimal components is a central tool of analysis and synthesis of linkages. In this paper we prove that every pinned d-isostatic (minimally rigid) graph (grounded linkage) has a unique decomposition into minimal strongly connected components (in the sense of directed graphs), or equivalently into minimal pinned isostatic graphs, which we call d-Assur graphs. We also study key properties of motions induced by removing an edge in a d-Assur graph - defining a sharper subclass of strongly d-Assur graphs by the property that all inner vertices go into motion, for each removed edge. The strongly 3-Assur graphs are the central building blocks for kinematic linkages in 3-space and the 3-Assur graphs are components in the analysis of built linkages. The d-Assur graphs share a number of key combinatorial and geometric properties with the 2-Assur graphs, including an associated lower block-triangular decomposition of the pinned rigidity matrix which provides modular information for extending the motion induced by inserting one driver in a bottom Assur linkage to the joints of the entire linkage. We also highlight some problems in combinatorial rigidity in higher dimensions (d=3) which cause the distinction between d-Assur and strongly d-Assur which did not occur in the plane.
Year
DOI
Venue
2013
10.1016/j.dam.2013.06.004
Discrete Applied Mathematics
Keywords
Field
DocType
2-assur graph,3-assur graph,central building block,kinematic linkage,unique decomposition,bottom assur linkage,entire linkage,d-assur graph,spatial linkage,minimal component,block-triangular decomposition,directed graph,strongly connected component,mechanical engineering,algorithms,decomposition
Discrete mathematics,Modular decomposition,Indifference graph,Combinatorics,Clique-sum,Chordal graph,Cograph,Graph product,Pathwidth,1-planar graph,Mathematics
Journal
Volume
Issue
ISSN
161
18
0166-218X
Citations 
PageRank 
References 
4
0.49
12
Authors
3
Name
Order
Citations
PageRank
Offer Shai1417.48
Adnan Sljoka240.83
Walter Whiteley345032.34