Research And Application Of Virtual Assembly Sequence Planning On EMU Bogies

With the aid of computer technology and the virtual reality technology, the pre-assembly /pre-disassembly can be realized within the stage of product design, and then it can verify the correctness of the assembly/disassembly process. It can provide research platforms and tools for the product designers and craftsmen, as well as training methods for manufacturers and maintainers. This is particularly important for the complex products such as the bogie of EMU.Assemble sequence planning is one of the principle research contents in virtual assembly. This paper focuses on the generation of assembly optimizing sequence and dynamic simulation of the assembly process.In order to solve the combinatorial optimization problem of assembly/disassembly sequence planning, this paper follows the principle of "assembled as disassembled". A multi-objective mathematical model was established which was expressed by matrixes and contains geometric constraint, stability constraint and disassembly tools constraint. Interference matrix was used to analyze the feasible disassembly direction, support matrix was used to analyze the stability, and disassembly tools list was used to analyze the tools used during operations. In order to find the optimal disassembly sequence more quickly, redirection factor, tool change factor and stability factor were added to the state-transition rule. Local and global pheromone were updated after operations so as to avoid the searching gets into a local optimal solution, to accumulate pheromone according to the quality of solutions and to guide ant colony in searching the approximate/optimal solutions quickly. Achieved the optimized sequence based on the bogie of EMU finally. Taking the bogie of EMU as an instance, this paper verified the validity and correctness of the algorithm.Based on Qt and OSG, the assembly sequence planning module was realized. In the assembly sequence tree established with Qt, the craftsmen not only can do animated simulation according to the sequence based on ACA, but also can reconstructed the disassembly sequence based on experience to build a more fitting disassembly sequence, and then defined the disassembly time, distance and tools of the parts to realized visualization of the disassembly sequence based on OSG.. Taking the bogie of EMU as an instance, this paper verified the practicality of assembly sequence planning module and forecasted the prospect for the future research work.