Theory And Application Of Automatic Decomposition Of Complex Mechanisms Structure

Mechanism structural decomposition is an important part of structural analysis.The decomposition of the mechanism structure means to decompose multi-loop mechanism into some simple basic components,so as to achieve the purpose of simplifying the complexity.The traditional manual dividing method is inefficient ?easy to make mistakes and can not meet the automation requirements of structural.This paper proposes an efficient algorithm for the automatic decomposition of the mechanism structure based on the theory of the pole group proposed by the former Soviet Union scholar Assur,the loop theory proposed by the American School,and the order-opening chain theory proposed by Mr.Yang Tingli of China.Firstly,according to the similar connection principle between graph and mechanism diagram in graph theory,the mechanism diagram can be transformed into topological graph.Description of Planar Mechanism Information Using Correlation Matrix and Adjacency Matrix.For space agencies,the four matrixes are used to describe the types and Position and Orientation relationships of the pairs of movements on each branch,and the Position and Orientation relationships of each branch and the dynamic and static platforms.Secondly,Automatic Dividing of Assur Groups from Planar Linkages.The judgment criteria of basic Assur groups are given,through the analysis and summary of the structural characteristics of the common Assur groups.In addition,the algorithm for automatic dividing of Assur groups from planar linkages is presented,after imposing the composition principle of planar mechanism and the connection forms and transmission route between each group.Automatic Dividing of Assur Groups from Planar loops.Simplify the mechanism through the topological map and give the criteria for the existence of the loop according to the definition of the loop.According to the principle of topology diagram and considering the connection between loops,an automatic loop splitting algorithm is proposed.Automatic Dividing of single open chain from Planar Linkages.Taking the basic loop matrix as input,the optimal splitting route is found by finding the minimum value of the coupling degree.The splitting efficiency is improved according to the upper bound of the coupling degree theorem.Then,Automatic Dividing of single open chain from Parallel mechanism,the Position and Orientation Characteristics can be viewed as a vector.Classification of structural by differences in dimension and direction of the Position and Orientation Characteristics sets.In order to get the least split route,different types of structural correspond to different split methods.According to the coupling degree algorithm,the splitting route with the smallest coupling degree is found and the splitting efficiency is improved according to the upper bound of the coupling degree.Finally,the feasibility of the four automatic decomposition algorithms for the mechanism structure is verified by examples.The experimental results show that the algorithm is accurate,simple and efficient.Compared with traditional decomposition methods,the algorithm of automatic dividing does not need a multitude of dividing trials,and it can reflect the connection forms and the transmission route of each basic unit.