1、#Theoretical Computer Science 253 (2001) 6193#Developing a Hybrid Programmable Logic Controller Platform for a Flexible Manufacturing System#Henning Dierks 1#University of Oldenburg, Fachbereich Informatik, Postfach 2503, 2900 Oldenburg, Germany#Abstract:# In this article, we present the design and
2、implementation of a flexible manufacturing system (FMS) control platform based on a programmable logic controller (PLC) and a personal computer (PC)-based visual man-machine interface (MMI) and data acquisition (DAS) unit. The key aspect of an FMS is its flexibility to adapt to changes in a demandin
3、g process operation. The PLC provides feasible solutions to FMS applications, using PC-based MMI/DAS, whereby PLCs are optimized for executing rapid sequential control strategies. PCs running MMI/DAS front-ends make intuitive operation interfaces, full of powerful graphics and reporting tools. Infor
4、mation from the PC can be distributed through a companys local area network or web using client-server technologies. Currently, with the convergence of underlying microprocessor technology and software program-ming techniques, many users find that PLCs provide a cost-effective solution to real-time
5、control in small- to medium-sized process plants, especially when combined with supervisory PCs using hybrid systems. The major work of this article demonstrates that PLCs are responsive to rapid and repetitious control tasks, using PCs that present the flow of information automation and accept oper
6、ator instructions, thereby providing the user a tool to modify and monitor the process as the requirements change.#Key Words:# PLC、FMS、PC.#1. Introduction#In a variety of product manufacturing industries, the most automated form of production is a Flexible manufacturing system(FMS),first introduced
7、in 1970s. Since the FMSs can providea high potential for productivity improvement in batch manufacturing, the number of FMSs is growing substantially (Groover and Zimmers, 1984). The acceleration throughout the world is due to increased global competition, reduced manufacturing cycle times, and cuts
8、 in production costs.#Generally, an FMS consists of a group of machines or other automated work stations, which form into modular subsystems, such as CNC machines, robots, vision systems, and a process station. These are interconnected by a materials handling system and usually driven by a computer(
9、Maleki,1991).Each modular system requires an individual modular control system, with different components being controlled by individual controller units. All of the modular subsystems are controlled by computers as usual. These controllers perform their intended tasks under supervision of a higher
10、level controller. To the system, both the control devices as well as the flow of information need to be automated. The key aspect of an FMS is its ability to adapt to changes in the control tasks. Thisflexibility includes the quantities andvarieties of part types which it can produce, the order in w
11、hich operations may be performed, and its ability to reroute parts back into flow paths. In the end, the control platform should have the capability to automate the flow of information.#Typically, therearethreetypes ofcontrol platformsusedin FMSs:# minicomputers, microcomputers, and PLCs (Maleki, 19
12、91). The minicomputers are best suited for complex large-scale, continuous ,regulatory control applications . The PLCs are used for rapid and repetitious logic control. Personal computers (PCs) are suited for operator interface functions. Primarily, PLCs are designed to replace hardwiring relays, to
13、 operate in an industrial environment, to be easilymodified by plant engineers and maintenance personnel, and to be maintained by plant electricians. Currently, with the convergence of underlying microprocessor technology and software programming, many users find that PLCs provide a cost-effective s
14、olution to#real-time control in small-to medium-sized process plants, especially when combined with supervisory PCs using hybrid systems.#The purpose of this article is to address the state-of-the-art technology of FMSs. The design and construction of an FMS using PLC-controlled and PC-based visual
15、man-machine interface(MMI) and data acquisition system(DAS)are presented. It is organized as follows. Section 2 begins with the description of the FMS on the factory floor of the Center for Manufacturing System sat the NewJersey Institute of Technology(NJIT).Section 3 shows the operational descripti
16、on of the FMS. Sections 4 and 5 present the applications of PLC-controlled and PC-based MMI/DAS for the FMS at NJIT. Section 6 contains a summary of the advantages of this PLC-controlled and PC-based MMI/DAS for FMS application.#2. Description of the FMS#SI handling conveyor system#This consists of four carts, A, B, C, and D, with fixtures mounted on each, two transfer tables,TT1 and TT2 , and dual conveyors which tran
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