Research on re-entrant system scheduling problem based on petri net and ant colony algorithm

Many types of small quantities re-entrant system has a lot of characteristics such as re-entrant process flows, multi-constrain and flexible processing paths. In this paper a generic HCTPN scheduling model is presented to optimize this type of system. This model creates the corresponding sub-modules for different scheduling features with hierarchical and modular theory. The model of re-entrant systems with such characteristics can be established by simply splicing module, which reduces the complexity of system modeling. Improved ant colony algorithm has been applied to solve the model, the solutions construction and pheromone update mechanism operate with transitions of the model, which can be used in a wider range. Finally, the method is applied to the scheduling problem of biochemistry analyzer equipment with reentrant features. The simulation results prove the effectiveness of this method.