Control of a conveyor system for a reconfigurable manufacturing cell

[摘要] ENGLISH ABSTRACT: This work entails a study of the control software of transportation systemsfor use in recon gurable manufacturing systems (RMSs). Various control approachesare considered, with the focus on enhancing recon gurability. Thework is unique in the sense that the RMS is designed to manufacture smallparts/products and is meant to be used in developing countries. Manufacturingsystems that can ensure product quality and delivery, are a critical needin countries where the bulk of manufacturing systems function with manuallabour. RMSs and holonic manufacturing systems (HMSs) are identi ed asconcepts that can potentially compete with manual manufacturing systems.The competing system must thus have a low initial adoption risk, be able toadapt to changing product functionality and demands, and have a comparablethroughput rate. IEC61311-3, IEC64199 function block and agent-basedcontrol architectures are evaluated. The control software is tested on an experimentalconveyor system.The thesis shows that IEC61131-3 and IEC64199 architectures are advantageousin lower levels of control. IEC64199 function blocks provide humaninterface and development tools and simpli es the distribution of control. Thehuman interface and development tools of IEC64199 function blocks may provebene cial in providing system monitoring and rapid low skilled adaptation ofthe control system, increasing recon gurability of systems in under-developedcountries. Unfortunately, the low maturity of the development environmentsfor IEC64199 function blocks is a limitation. It is shown that an IEC64199function block controller becomes complex as the actuator/sensor count exceed10. Agent-based systems o er reliable control and powerful communication tools but requires a higher level of expertise than IEC64199 function blocks.Agent-based systems are proposed for the core high level control. Complexsystems can be controlled with agents and intelligence can be added to controlsystems in a recon gurable way. For the recon gurable control of large manufacturingsystems, agent-based control was found to be superior to IEC64199function blocks.

[发布机构] Stellenbosch University