Browsing by Author "Kruger, Karel"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Control of the feeder for a reconfigurable assembly system
    (Stellenbosch : Stellenbosch University, 2013-03) Kruger, Karel; Basson, A. H.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: This thesis documents the research conducted into the control of the feeder subsystem of a Reconfigurable Assembly System (RAS). The research was motivated by a new set of modern manufacturing requirements associated with an aggressive and dynamic global market. The motivation can be more specifically attributed to the need for selective automation, through the installation of reconfigurable systems, in the South African manufacturing industry. The objective of the research was to implement and evaluate Multi-Agent Systems (MASs) and IEC 61499 function block systems as potential control strategies for reconfigurable systems. The control strategies were implemented for the control of the feeder subsystem of an experimental RAS at Stellenbosch University. The subsystem's hardware consisted of a singulation unit with a machine vision camera, part magazines and a six DOF pick-'n-place robot. The structure of the control strategies is based on the ADACOR holonic reference architecture. The mapping of the subsystem holons to the structures of the control strategies is explained. The development and implementation of the control strategies, along with the accompanying lower level software, is described in detail. A system reconfigurability assessment was performed and the results are discussed. The assessment was performed at two levels – the Higher Level Control (HLC) (where the control strategies were implemented) and the low level control and hardware. The assessment was done through four reconfiguration experiments. The evaluation of the HLC was done through both quantitative and qualitative performance measures. The implications of the reconfiguration, involved in each of the respective experiments, on the low level software and hardware are discussed. The experimental results show that agent-based control adds more reconfigurability to the feeder subsystem than IEC 61499 function block control, and that agents have more advantages regarding customizability, convertibility and scalability than IEC 61499 function blocks. Also, the ability of agent-based control to implement reconfiguration changes during subsystem operation makes it more suitable to the case study application.
  • Thumbnail Image
    Item
    The development and evaluation of an Erlang control system for reconfigurable manufacturing systems
    (Stellenbosch : Stellenbosch University, 2018-03) Kruger, Karel; Basson, A. H.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
    ENGLISH ABSTRACT: The dynamic and highly competitive nature of the modern manufacturing environment has introduced a new set of challenges, urging researchers and industry to formulate new and innovative solutions. The concepts of holonic and reconfigurable manufacturing systems showed great promise to address the challenges. While these concepts could not achieve significant industry adoption, they will play an important role in the latest emerging paradigm in manufacturing – the fourth industrial revolution, or Industry 4.0. Industry 4.0, can potentially have a significant impact on all aspects of the manufacturing industry, aiming to enhance individualization of products through highly flexible production, extensively integrate customers and businesses in valueadded processes and link production and high-quality services to deliver hybrid products. To achieve these goals, Industry 4.0 relies on Cyber-Physical Production Systems (CPPSs) to enhance the connectedness throughout all levels of the manufacturing enterprise. CPPSs aim to enhance the intelligence, connectedness and responsiveness of manufacturing systems. These goals closely resemble those of holonic and reconfigurable manufacturing systems, indicating the relevance of research on these topics to the development and implementation of CPPSs. The objective of this dissertation is to evaluate the suitability of the Erlang programming language as an alternative for the implementation of holonic control in manufacturing systems. The dissertation presents an Erlang-based holonic control implementation for a manufacturing cell. The Erlang implementation is evaluated through a comparison with an equivalent implementation using Multi- Agent Systems (MASs), which is considered as the status quo for holonic control implementation in manufacturing systems research. To accomplish the evaluation of the holonic control implementations, evaluation criteria is formulated. The evaluation criteria focusses on both the development of control implementations and the adoption of the implementations by industry. The criteria identifies a set of quantitative and qualitative performance measures that are indicative of seven critical requirements for holonic control implementations. The Erlang and MAS implementations are evaluated and compared according to these performance measures and requirements. The comparison shows that the Erlang implementation matches the functionality of the MAS implementation and even offers some advantages for the desired characteristics for the holonic control of manufacturing systems. The advantages in availability and supportability can be attributed to the enhanced modularity and fault tolerance of the Erlang implementation. The Erlang implementation also allows for increased development productivity through a reduction in software complexity and simplification of software verification. The findings of the evaluation confirms the inherent suitability of the Erlang programming language for the implementation of holonic control. It is recommended that further research be conducted on the refinement of the architecture and the development of a framework for holonic control implementations in Erlang.