Design of Discrete–Event Controllers for Flexible Manufacturing System using Informal Product Requirements

This approach collects informal product requirements (customer needs), determines the highest hierarchical functional requirement (FR) for a product to satisfy the stated needs and generates the corresponding recipe procedure for a coordination level of a flexible manufacturing cell. Then, an axiomatic system design methodology is applied to decompose hierarchically the FR and to generate a corresponding design parameter (DP) for each FR. DP are components able to enable–disable their respective FR to generate an acceptable process cell operational sequence that represents the “functional specifications” of the manufacturing process. Thus, a discrete–event system class of controllers for flexible manufacturing system can be constructed using the output of the axiomatic design methodology to built “elementary components” that contains the discrete-event behaviour of the functional specifications. These elementary components are the building blocks of the “open-loop model” from which the discrete–event controller is synthesized for the coordination control layer. Finite state machines (FSM) are extended to state–labelled to facilitate the detection of behaviour properties and forbidden states. An example of the approach is presented; a customer requires the design of some similar products and their respective processes. The example emphasizes the structured design process.