Browsing by Author "Van den Berg, Christopher Sean"

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    Evaluation of Erlang for a stigmergy holonic routing controller
    (Stellenbosch : Stellenbosch University, 2018-03) Van den Berg, Christopher Sean; Basson, A. H.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: A reconfigurable manufacturing system (RMS) is a manufacturing paradigm aimed to be able to react to manufacturing uncertainty caused by hardware failures and changes in the global market. Transport systems for RMSs should be able to easily adapt the routing of parts between manufacturing stations, while making optimal use of the transport infrastructure to maximise the RMS's throughput. In this thesis, a holonic routing controller with stigmergy, aimed at a palletised conveyor for an RMS, is developed using Erlang. The objective is to evaluate the suitability of Erlang in implementing a holonic control architecture where a large number of concurrent processes is required within one controller. The routing controller is adapted from architectures found in literature, and uses elements from the product, resource, order, staff architecture (PROSA). The routing controller is a conveyor controller that transfers a pallet from a source to a destination within the conveyor system based on an instruction given by an outside source, such as a user. The conveyor controller makes use of order, resource, feasibility and ant holons to perform the pallet transfer. Order, feasibility and ant holons were each implemented in their own Erlang process within the conveyor controller, while resource holons used three Erlang processes. The conveyor controller was tested in the Mechatronics, Design and Automation Research Group (MADRG) at Stellenbosch University. Higher-level control was performed by interfacing the conveyor controller, described in this thesis, with previously developed lower-level controllers. The results of the testing proved that the controller possessed all the required characteristics of an RMS and could successfully manage pallet traffic within the conveyor system, including avoiding bottlenecks and changing a previously decided route when conveyor segments unexpectedly become available or unavailable. It was found that Erlang is an appropriate programming language to use in implementing the conveyor controller. Erlang possesses built-in functionality that was found to be convenient and useful. With Erlang, it was possible to create and run processes with ease, even when the system was running.