Research Of Assembly Process Planning Based On Object-oriented Knowledge Petri Nets

Researches on assembly efficiency of products are highly valued since development cycle, development cost and assembly quality are affected by assembly efficiency. It was found that there exists deficiency of expression on process knowledge related to assembly. In this paper, process knowledge were expressed based on object-oriented approach, process knowledge rule database was built, then knowledge Petri net was constructed combine with Petri net. Assembly process planning system was set up based on UG platform and automatic generation of optimized assembly sequence was implemented eventually. Specific contents of this paper are as follows.(1) The expression method of assembly process knowledge was determined. As the characteristics of the assembly process knowledge of mechanical and electrical products were analyzed, object-oriented approach was chosen to express assembly process knowledge. Then the assembly process knowledge database was built and the generation of unreasonable assembly sequence was reduced effectively. Thus, there exists data basis for the following selection of assembly sequence.(2) Knowledge Petri net was built and optimized assembly sequences were generated. Associating the establishment of hierarchy tree with connect diagrams, the corresponding hierarchy connect diagram was obtained. Feasible assembly sequence were generated by using cut set algorithm, knowledge Petri net was constructed with the help of assembly process knowledge and Petri net. Optimized assembly sequence was filtered after knowledge Petri net was executed.(3) Software development platform of assembly process planning system was established. The assembly process knowledge database was programmed by VC ++ language on UG platform. Combined with SQL Server database, the establishment of the desired platform was completed. As assembly process planning system run, optimized assembly sequence and three-dimensional process documents were generated automatically, assembly efficiency of products was improved.