A CONTROL MODEL FOR DETECTING DEADLOCKS IN AN AUTOMATED MACHINING CELL

Process interactions in concurrent manufacturing systems can result in deadlocks which are difficult to detect during the controller program design stage. This paper reports on the application of a Control Mode l for detecting deadlocks in an Automated Machining Cell consisting of a CNC lathe and a service robot. The Control Model is generated from a list of Programmable Logic Controller events using the theory of Pet ri Nets. The model is tested for deadlocks that could possibly occur d ue to the concurrent nature of activities in the cell. The applicabili ty of the model is demonstrated on an Automated Machining Cell install ed in the Manufacturing Automation Laboratory at Rutgers University. T he results show a promising perspective of Control Model applications in debugging Programmable Logic Controller programs.