Research On Key Technologies Of Virtual Assembly Process Planning Based On Semantic-Associated Models

Production assembly process planning is an important stage ofproduction development. With the transform of manufacturing mode andgrowing complexity of productions in function and structure，fast andcorrect assembly process planning becomes to be a more difficult task.Virtual assembly process planning based on interactive virtual assemblysimulation provides a better solution. However, current virtual assemblyprocess planning systems have some demerits, such as incompleteproduction model, inefficient and fallible interactive assembling,imcomplete planning results, etc., which have limited the application ofvirtual assembly process planning technologies.In order to solve the problems above, assembly semantic isintroduced, and a virtual assembly process planning solution based onsemantic-associated models is brought forward. This solution can makefull use of engineering information contained in assembly semanticmodel, and can support product and assembly tool information expression,efficient and correct interactive virtual assembly simulation, andassembly process information extraction. It makes it possible to do product assembly process planning in3D virtual environment。Mainworks and conclusions of this thesis are listed as follows:1. A solution for virtual assembly process planning based onsemantic-associated models is proposed, and the detailed implementationprocesses and key technologies are introduced. In this solution, takingassembly semantic model as centre, product assembly information modeland unified assembly tool model are built. It can support interactivevirtual assembly based on semantic reasoning method and assemblyprocess information extraction from virtual assembling operation. Thesolution makes it possible to do assembly process planning throughreal-time interactive assembling simulation in virtual environment.2. Assembly semantic model is proposed, and semantic-associatedmodels are built. The definition, expression and reasoning methods forassembly semantic model are researched, and an interactive generationmethod for assembly semantic model in CAD environment is proposed.Based on assembly semantic, a multi-leveled product assemblyinformation model and a unified assembly tool model are built, and theirsub-models are detailedly discussed.3. Real-time collision detection algorithm during interactiveassembling is improved, and interactive assembling methods with bothhands and assembly tools based on semantic reasoning methods areproposed. Real-time collision detection method based on bounding boxhierarchy trees is researched and improved. Dealing rules for interactiveassembly in virtual environment with both hands are built, and based on semantic reasoning methods including recognition, confirmation,navigation, and solving. Logics for grasping, moving, and releasingobjects with both hands are proposed. Interactive assembly process withassembly tools is divided into selection, orientation, driving, and logicsfor these operations in virtual environment are researched.4. Assembly process planning methods based on assembly semanticand interactive virtual assembly are researched. Basic Assembly Motions,and Standard Assembly Operations are brought forward, and the mappingrelationships between them is built. An assembly operation extractionmethod based on this mapping reletionship is proposed. A method forassembly operation time extraction based on interactive assemblyoperation and standard assembly process is proposed.5. A prototype named Virtual Assembly Process PlanningEnvironment (VAPPE) based on above researches is developed, andassembly process planning for typical parts of automobile motor is takenas an application to validate the correctness and validity of the researchesin this thesis.