Research On Assembly Sequence Planning Based On MIPS And Subassembly Identification

The generation of all feasible assembly sequences for given products is the keyof assembly sequences planning (ASP) and also an NP-hard problem. The traditionalmethods for ASP either have the problem of combinatorial explosion, or can't guaranteeto generate the optimal sequences. In view of the good performance of Model CheckingIntegrated Planning System (MIPS) for general domain planning, the author researcheson solving the ASP problems based on MIPS and subassembly identification. The workdone in this paper includes:(1) How to establish the interference matrix and analyze the geometrical feasi-bility of assembly/disassembly sequences and how to deduce the feasible disassemblydirections of parts in the disassembly process are explained. The relevant theory anal-ysis on stability of parts in the disassembly process is expatiated, too. Finally, theauthor discusses how to judge the stability of assembly sequences from the viewpointof disassembly based on the sustain matrix.(2) The ASP problems are represented formally in the framework of the formula-tion of general intelligent planning problems, and the hard constraints and soft con-straints in mechanical assembly are formulated using predicate logic and temporal logicformulae. The ASP domain and instances are also defined, and the procedures to solvethe ASP problems using MIPS are presented. The experimental results show thatMIPS scheme reveals good performance on assembly sequence planning.(3) According to the definitions of the connection types, the weighted undirectedliaison graph of the assembly is presented to identify the subassembly automaticallyand effciently. In the weighted undirected liaison graph model, the identification al-gorithms are designed and implemented for the two kinds of subassembly based onthe interference matrix and sustain matrix. The results of experiments show that thescheme works well in the subassembly identifications.(4) The planner, called MASP-Planner, for ASP is designed and implemented.The functions which include the automatic generation of the problem definition files,subassembly identification and invoking MIPS are integrated in the planner. Theplanner provides a friendly and uniform UI, and makes the planning work easier. Theexperimental results show that MASP-Planner can solve large-scale ASP problemseffectively.