A Fixture Assembly Sequence Planning Method Based On Ant Colony Algorithm

Assembly quality affects various behaviors of products to a great extent. Assembly costs are also a huge factor of the whole product manufacturing costs. Thence, assembly sequence planning is of great importance to improve product quality, shorten production cycle and decrease product costs.Assembly sequence planning is a combinatorial optimization problem. In the paper, according to the principle that a part can be assembled if it can be disassembled, the disassembling relations between fixture parts are used to establish a multi-objective mathematical model and an integrated disassembling interference matrix. The matrix determines the disassembling directions of the fixture parts. A disassembling table describes the tools used in part disassembling process. Direction change factor and tool change factor are used to modify the status transition probability equation. The update of global pheromone guides the algorithm to find the optimal solution quickly.In Matlab, the improved ant colony algorithm is programmed to realize fixture assembly sequence optimization. Several instances are used to verify the feasibility and practicability of the algorithm. By comparisons with the results of examples in literature, the advantage of the improved algorithm of the paper is validated.The factors of the ant colony algorithm affect the optimization results greatly. A series of simulation experiments are carried out in Matlab. The results are analyzed to determine the spans of the factors. The rationality of factor selection is also verified by fixture examples.