Research On The Key Technology Of Virtual Assembly And Simulation Applications

Virtual assembly, based on virtual reality technology, could make the operator carry on the perceived verification research diametrically aimed at the the rationality and specification of the product design, and feasibility and ease of assembly and other factors by building virtual prototypes of products in an immersive virtual environment. It has the important significance to improve product development speed, lower assembly testing and training costs. At present, however, there are no engineering semantic information such as tolerance and assembly planning auxiliary information in most virtual assembly system, which results in the phenomenon of’like but do not really" and’assembly disorder’existing ubiquitously and the system could not be large-scale promotion and practical application. In this paper, the key technologies of virtual assembly are studied and various study contents proposed are simulated and tested based on application background of certain marine engine.The construction method of part model with tolerance information and the visualization method of tolerances information have been studied. The layers of tolerance and engineering auxiliary information are proposed based on traditional layer structure of part model and the methods of extracting information and establishing map relationship aimed at each layer are elaborated. The expression mode and application scope of static and dynamic tolerance are discussed and the follower transform calculation method of the static tolerance and parts is given. The collision detection method of part model with tolerance information is discussed. The expression method of the space hierarchical bounding volume based on the volume decomposition is proposed and redundant space compressing algorithm of the bounding volume is demonstrated. The overlap region of bounding boxes is detected rapidly by traversing assembly local space partition cell which is divided by the technology of space subdivision. The method of calculating collision penetration depth is provided and according to comparing this depth value with the tolerance range of the part, different collision response strategies are obtained. The part positioning method based on constraint and multi-constraint dynamic management approach are studied. The correspondence relationship between the constraint and geometrical element of part, the distance and angel calculation method between geometric elements constrained, the criteria of constraint recognition, and the methods of degree of freedom reduction and detecting the redundant constraint are elaborated. The positioning methods of three kinds of composite constraints are explained and the dynamic management approach of constraint is proposed. The combination method of intelligent assembly sequence planning and assembly simulation is studied. The hybrid algorithm based on ant colony and genetic algorithms is proposed to solve the assembly sequence planning. The ant colony and generatic algorithms are scheduled dynamically by the best algorithm fusion strategy. The concept of integrated assembly costs is proposed and the changes of the tool and the direction, and some custom assembly factors are taken into account in the calculation of integrated assembly costs.The method of combination between optimal sequence and assembly simulation system is illustrated and the problems generated in the assembly simulation could be as assembly criterion to feedback to the optimizing algorithm for influencing the follow-up calculation.