Application domain: SMART CONVEYORS

Airport Baggage Handling Systems could be considered a potential application domain for the application of IEC 61499 technologies.

Here is an extract from 'The IEC 61499 Function Block Standard: Launch and Takeoff', by Thomas Strasser et al.

Airport Baggage Handling Systems (BHS) are a classic example of complex automation systems combining requirements for modularity and distribution with high performance, reliability, and flexibility. Using smart modules with embedded intelligence is a possible and very promising approach for the realisation of BHS. Such modules will integrate sensors, actuators, and embedded control devices with open software architecture, allowing for easy plug­and­play integration with other modules and machines into complex self­configurable systems. Each machine will be controlled by an intelligent agent – the software that combines traditional low level control functions with communication and collaboration with related devices.

Using the IEC 61499 reference model for the realisation of the corresponding control architecture is very promising. In a first realisation an IEC 61499 application for the complete automation of a small airport BHS has been created. It consists of dozens of identical FBs – one per conveyor section. Each FB is internally structured according to the Layered Model­View­Control (MVC) design pattern for IEC 61499. An overview of the resulting IEC 61499 control application is depicted in the figure.

To test the feasibility of distributed control implementation deployed on a network of embedded control devices, a testbed consisting of more than 50 networked control nodes has been constructed, corresponding in complexity to a medium­sized airport . The hardware is heterogeneous, comprising platforms from four different vendors and including 48 lightweight IEC 61499 ­based modules, each of which could be embedded into a conveyor or a motor drive.

Application of IEC 61499 to an airport Baggage Handling System

Various simulations and experiments with the testbed have shown the ability of the IEC 61499 approach to meet the required levels of modularity, distribution, reliability and flexibility. Runtime flexibility has been achieved through the use of agent­based control that includes dynamic distributed routing of every piece of baggage. This imparts active fault tolerance to the BHS, whereby it is capable of continued operation even in case of breakdowns in some conveyor sections. This study has demonstrated the feasibility of implementing a variety of BHS control functions in a truly distributed manner, and has illustrated a systematic pattern for structuring agent­based control and deploying it onto a distributed network of IEC 61499 devices.

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