The Method Of 3D Clustering And Reconstruction And Its Application In Mechanism Design

With the development of computer technology and increasingly high requirements of design tasks,it becomes a trend to utilize computers to aid conceptual design.In mechanical conceptual design,for overcoming the shortage of conceptual design based on the Function-Behavior-Structure(FBS)model in obtaining the creative conceptual design results,the 3D clustering of basic operations in the structure layer based on quotient structure and quotient attribute can fully realize the potential of multi-functions for kinematic compound mechanisms,and generate compositional schemes with constituent mechanisms whose kinematic behaviors coordinate with each other temporally and spatially.More specifically,this paper defines basic operations with quotient space(X,f,T)three-dimensionally,and constructs a quotient space model of basic operations,taking the decomposed basic operations as domain X,and representing the attribute of basic operations with f as well as the relations of basic operations with T.In the function layer,decomposing the overall function into multiple sub-functions,the finest basic operations are obtained after further decomposition.Then matching the basic operations obtained from functional decomposition in the function layer to structure layer.Clustering the matched operations in the structure layer into one group,then partitioning and reconstructing the basic operations divergently based on cell division.Introducing the idea of bionics,the innovation through grouping of basic operations in the structure layer,which lays the foundation for the next clustering.Divergent partition implements the grouping of basic operation set and preliminary innovation.Adopting the rule-based clustering method and introducing attribute rules and structure rules,through the partition of quotient attribute[T] and quotient structure[T],then representing the attribute clustering with parameter-based DSM and the structure clustering with task-based DSM,this paper constructs the 3D-DSM model for the 3D clustering.Matching the quotient space model into the 3D-DSM model and clustering the operations in terms of domain,attribute and structure based on the synthesis principle in quotient space,the 3D clustering results which are complete behaviors having order relations and meeting the clustering requirements of attribute and structure are obtained.Traversing each group of behaviors,and searching the satisfying mechanisms to match them.After evaluating the matched mechanisms,the mechanisms whose main and secondary functions are made full use of and whose behaviors are continuous temporally and spatially are obtained,thus implementing the innovation process.Based on the above theory,this paper proposes a computational method for implementing the whole process of 3D clustering and develops a prototype system for the mechanical conceptual design,including the construction of database,functional decomposition,divergent partition of basic operations,3D clustering,generation of schemes and selection of multi-function mechanisms.Through the system,a case study of the design of a simple flatbed printer system is given to obtain the feasible conceptual design schemes.