Browsing by Author "Masendeke, Darlington M."
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- ItemEvaluation of labview based control for a reconfigurable manufacturing subsystem(Stellenbosch : Stellenbosch University, 2015-03) Masendeke, Darlington M.; Basson, A. H.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: This thesis considers the evaluation of LabVIEW based control for reconfigurable manufacturing systems (RMSs), and in particular for an RMS subsystem. The evaluation used a rivet feeder station as a case study. The architecture of the rivet feeder station included a vibratory bowl feeder, a singulation device, a pick-n-place mechanism and an XYZ positioning table. The objective of the research was to determine whether LabVIEW is a suitable development environment for implementing holonic control. The motivation for considering LabVIEW in this thesis was that other control approaches, such as IEC 61499 function blocks, agent-based control and object-orientated control, that have been used in most RMS research, have not found favour with industry. The PROSA holonic reference architecture was adopted here, with the following holons: Coms Holon, Request Manager Holon, Order Holon, Product Holon Manager, Pick-n-Place Holon and XYZ Table Holon. The holons, constituting the controller, were designed based on LabVIEW’s producer/consumer and state machine architectures. The controller was aimed at making the rivet feeder station reconfigurable. Furthermore, the controller was interfaced with a cell controller through a TCP/IP connection and an XML format of messaging was adopted for communication. The main limitations and disadvantages of LabVIEW, for the implementation of holonic control systems, were found to be: the graphical programming which makes the block diagram cumbersome to follow, for complex applications; and that dynamic instantiation of objects or memory cannot be achieved in LabVIEW. However, LabVIEW holds the following advantages: shared variables and TCP/IP components simplify communication over a network; easy construction of the graphical user interface using controls and indicators on LabVIEW front panels; the XML standard format in LabVIEW provides flexibility to create your own unlimited tags; and immediate compilation of LabVIEW programs. Furthermore, LabVIEW easily can be integrated with hardware such as the compactRIO with a CANopen card. The reconfigurability assessment of the rivet feeder station included three experiments which involved changing the product type, adding new devices and performing station diagnostics. From these experiments, it was concluded that the key characteristics of reconfigurable manufacturing systems were achieved, thereby demonstrating the suitability of LabVIEW for implementing holonic control.