Virtual Assembly & Simulation Based On Geometric Probability Set And Touching Constraint

Virtual Assembly is a key technology for the digital design and virtual manufacturing. Assembly process plays an important role in Virtual Assembly. This paper investigates the process of virtual assembly & simulation and relevant technologies based on National 973 Program. In this paper, the solving process via geometric constraints is analyzed and a solution for improving the efficiency of assembly through the construction of probability set is presented. Last but not least, a solution for the assembly based on touching constraints is proposed. As an example, I developed a prototype system ConVAS.In the first chapter, paper summarizes the definition and research significance of Virtual Assembly, as well as the state of the art. The main content and the structure of this article are presented.In the second chapter, mathematical expressions under each constraint mating condition are deduced in detail. The process of constraint evaluation and DOF analysis are introduced. Parts can be assembled statically by interactively specify or remove constraint by users. Several algorithms are advanced to improve implementation.The third chapter studies the process of dynamic simulation and assembly based upon geometric constraints and probability set. Improvements of the constraint recognition and confirmation, as well as movement navigation are proposed. Real time interference detection is implemented. This chapter also illustrates the approach for the generation of assembly path by recording the key points during the assembly process.The fourth chapter demonstrates the process of the dynamic simulation and assembly based on the touching constraints. Firstly, the problem of interference detection is studied and a solution to the interference response is proposed. Secondly, the definition of touching points and its calculation are given, the touching relationships are categorized according to the touching points, DOF of each kind of touching constraint is analyzed. Further, an approach for assembly navigation based on touching constraints is proposed. Finally, concluding remarks for the flow of assembly navigation are presented.Based on the above four chapters, the fifth chapter describes the design architecture and implementation of the ConVAS system. System functionalities are validated via several assembly examples and the demonstration of the instances are also given.Conclusions are made in the sixth chapter, which includes the improvements of the algorithms, the functionalities provided in ConVAS as well as the advantages and disadvantages of it. Future directions for the research are also presented.