T. Masood, Riaz-ur-Rehman, and M.H. Sahir (Pakistan)
Flexible Manufacturing Systems [FMS], Modeling,Supervisory Control, Petri Nets [PN], ComputerIntegrated Manufacturing [CIM], Deadlock, ControlSoftware, Dynamic Behavior.
Flexible Manufacturing System [FMS] is a totally automated manufacturing system and a key part of Computer Integrated Manufacturing [CIM] system. All manufacturing activities take place in FMS. For independent and unattended operation of an FMS, flexible control software is necessary. The main objective of supervisory control of FMS is to plan and execute the task at the cell or work processing centre levels for the safe and unattended processing of a work order. Petri Nets [PN] is a state-transition graph used to model the event control system of manufacturing system. In this paper, PN Models of supervisory control of FMS have been modeled and verified for their liveliness, safety, and deadlock free operation, Job Processing, Material Transportation and Tool flow control. The FMS equipment may work in casually independent manner and work parts may face conflicts. These characteristics of equipment and work parts have been modeled using PN. The basic purpose of the modeling activity has been to synthesize control logic for the full system and examine this control logic for its liveliness and being free of deadlocks through PN development and verification software. The approach adopted here has been to develop a modular architecture of model for supervisory control system to ensure the flexibility, in terms of addition of new products and equipment. The modules resemble the physical equipment and model their dynamic behavior. Mathematical formulation of PN models has also been provided in this paper for implementation through computer software for the control of FMS.
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