Research On Virtual Assembly Technology For Large Scientific Facility

Large scientific facility with compact internal space is huge and has a complex structure.Its construction process which involves a huge number of resources and relations to coordinateis very complex. The difficulty and complexity of construction program designing areconsiderably increased. Virtual assembly technology provides an efficient, fast and reliablemeans to plan construction process and validate the construction programs for relevant staff.This paper study virtual assembly technology for large scientific facility construction and themain work are as follows.In order to assist decision-making, virtual assembly technology is introduced intoconstruction programs planning and evaluation. This thesis analysis the characteristics ofconstruction and compares the differences between construction process and assembly processof mechanical products as well as the virtual assembly technology for each one. And then, avirtual assembly framework for large scientific facility construction is set up and its functionmodules are described.An improved artificial potential field algorithm is researched based on automaticadjustment strategy for3D assembly path planning. At first, a3D assembly space is structurallydescribed by Configuration space. The assembly objects are abstracted as particles with acertain position and pose in configuration space. The artificial potential field algorithm isextended to three-dimension and an automatic adjustment strategy is proposed to make theparticle move along the directions of axises for avoiding obstacles to reach its target point.Multi-DOF tool is defined as a complete object by using object-oriented method. Amovement component hierarchy for unified modeling and management of multi-DOF tool isintroduced based on composition and driven form analysis. A node cell structure is designed tobuild the tool model in virtual environment and a general modeling template is constructed formulti-DOF tool. Characteristics and strategy of virtual simulation for multi-DOF tool are alsoanalyzed and described.A virtual prototype system for large scientific facility assembly modeling, simulationand process planning is developed by using Visual C++6.0and Open Inventor6.0. Taking avirtual assembly scene with crane as an example, the thesis describe the implementationprocess of3D path planning, scenario modeling, multi-DOF tool assembly planning andsimulation, and the feasibility and effectiveness of the proposed methods are verified.