Fuzzy Monitoring Approach Based on P-time Petri Nets of manufacturing Systems with Time Constraints

Abstract

Manufacturing job-shops can have uncertainties related to different operations. A time interval is associated with each operation compose of two limits: the minimum time required to perform the operation and a maximum time not to exceed in order to ensure the quality of the manufactured products. The fuzzy sets can be applied to many fields in which uncertainty plays a key role [1]. The uncertain knowledge associated with these discrete event system with time constrains requires specific reasoning and modeling methods. Fuzzy logic provides a framework for the exploitation of fuzzy knowledge, which from a qualitative point of view gives finer results than classical logic. The paper proposes a new approach for monitoring and maintenance of manufacturing systems with time constraints that integrates fuzzy logic and P-time Petri nets (P-TPN) tool. So, in this context, we propose a new fuzzy Petri net able to analyze monitoring and recovery tasks of a discrete event system with time constraints, using a temporal fuzzy approach. The monitoring module is consists of P-time PNs and fault tree. The first is used as modeling tool of normal behavior of the system. The second model corresponds to monitoring model. Finally, to illustrate the effectiveness and accuracy of proposed monitoring approach an application to a winding unit is outlined.