Real time control of multilevel manufacturing systems using colored Petri nets

A colored Petri net (CPN) model of a cell controller capable of real-time control and monitoring of multiple workstations is described. The need to incorporate the ideas of both computer integrated manufacturing (CIM) and flexible manufacturing systems (FMS) is discussed, and the controller is based on these concepts. The CPN for the cell controller is presented and described. The controller in this case controls two workstations: the Cincinnati Milacron 5VC machining center and a robotic assembly workstation using an Adept robot. An analysis of the net is performed, and relevant portions are presented. A data structure for implementing this type of a CPN is given. The code for the controller is divided into application-dependent and -independent code. An execution algorithm is provided. The conclusions emphasize the advantages of CPNs in modeling and analysis for discrete-event control of manufacturing systems