Modeling of a discrete event manufacturing plant and design and implementation of controller using LabVIEW and programmable logic controller

Abstract

<p>Control of discrete event systems has been discussed widely in the literature in the past 10-15 years; however, little has been published that discusses real-life implementation of these control systems. The goal of this project is to model a manufacturing plant as a discrete event system and manually synthesize a maximally permissive controller using the supervisory control technique. The manufacturing plant used in this work consists of seven sensors and five actuators which are used to assemble plastic rings on metal pegs. Inputs to the system are pegs and rings on a conveyor belt and the output of the system is a sequence of pegs and rings that are either assembled or unassembled. Modeling of the manufacturing plant is done using the rules-based modeling technique. The controller we developed is then implemented using LabVIEW with a PC interface card to the manufacturing plant. The LabVIEW implementation allows a cyclic output sequence of arbitrary length. We also implement a restricted version of the control algorithm using a programmable logic controller (PLC) with ladder logic. The PLC implementation is restricted to output a sequence that is cyclic with length four. We present the controller implementation in a manner that is well suited to formal analysis for possible future work, including formal verification of the controller model. Other future work could include the development of a fault-tolerant and real-time controller.</p>