Modeling and Optimization Algorithm of FMS Logistics System Based on Petri Nets and PSO - Advanced Research on Computer Education, Simulation and Modeling - page 361

2.2 FMS Logistics Subsystem Model
The prototype FMS (Figure 3)is designed and produced
Fig. 3. FMS prototype
In the warehouse unit of logistics system, the processing flow chart of warehousing
request [10] is shown in Figure 4 (left), and the processing flow chart of ex-
warehousing request is similar.
According to the flow chart showing and the rules of Petri net modeling ,the Petri
net model of the storage unit is established and shown in Figure 4(right).
Fig. 4. Processing flow chart request and the Petri model of warehouse
The meaning of some symbols in the figure as follows. M104: storage request from
the delivery objects; M105: allowing delivery object into the storage unit; M106:
workpiece has been transported to the storage unit.; T104: applying AGV to perform
tasks; T106: AGV begins to perform the tasks; T107: AGV finished the tasks; T108:
workpiece on storage unit is removed by AGV, the station is released; T109: booking
storage space station, allowing the delivery object into the storage units; T110: arrival
on the storage unit. The processing flow chart of one AGV and its Petri model were
shown in Figure 5.
The meaning of some symbols in the figure as follows:M10:AGV requested to pro-
vide transport services queue; M11:AGV in the delivery state; M12:AGV is in wait or
idle state; P08:AGV receives transportation requests; P11:AGV sent storage requests
to the warehouse object; P12:AGV receives the feedback message from the ware-
house; T8:requesting AGV to transport workpiece; T9:AGV convery parts; T10:AGV
finished transporting the workpiece; T11:responses received from the warehouse.
With VS2008. AGV class , storage class and algorithms are established. The logis-
tics system simulation interface is shown in Figure 6.