Research Of Automatic Logistics System's Control System Based On Decomposition Of Petri Nets Techniques

The research platform of this thesis is the automatic logistics system in Subjects Experimental Center of XUST (Xi'an University of Science and Technology). Aiming at this automated logistics system task planning, a new decomposition method of Petri net is given in this paper. Through decomposing the Petri net model of the logistics system by the new decomposition method, a conclusion is drawn:this logistics system's task planning is reasonable and without globally or local deadlocks. Based on this conclusion,the development of this automatic logistics system's control system is completed, and functions of warehouse discharge and moving are accomplished.The hardware of the automatic logistics system in Subjects Experimental Center of XUST is introduce and analysed. Based on understanding each core part's structure and parameters, a model based on Petri nets theory of Automated Logistics System is presented and defined.Aiming at the automated logistics system task planning, a new decomposition method of Petri net based on the index of transition and index of places fusion is given in this paper. The relationship of repeatability and boundedness between minimum subnets and the original Petri net model is deduced, and some corresponding reasonings are proposed and proved. Through decomposing the Petri net model of the logistics system by decomposition method of Petri net based on the index of transition subnets which physical meaning is clear are gotten. Then through decomposing these subnets by decomposition method of Petri net based on index of places minimum subnets which fuse characteristics of T-net and S-net are gotten. According to the analysis of the minimum subnet the activity and boundedness of this Automated Logistics System is inferred. Then, according to the result of the analysis a conclusion is drawn:this logistics system's task planning is reasonable. Using his method greatly reduced the calculation of analyzing the subnets or original Petri nets model directly, without globally or local deadlocks which provides a basis of good working for this system.On the basis of that conclusion, through designing database, designing interface, developing functions of warehouse discharge and moving based on the established Petri nets model E this automatic logistics system's control system is completed. After many commissioning and experiments, it is proved that this control system of the automatic logistics system can work very well. The stacker can executive instructions of warehouse discharge and moving accurately (Warehouse entry function is accomplished in the paper of graduate student Qin GuoZhu).