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Toward Self-Reconfiguration of Manufacturing Systems Using Automation Agents

The reconfiguration of control software is regarded as an important ability to enhance the effectiveness and efficiency in future manufacturing systems. Agent technology is considered as a promising approach to provide reconfiguration abilities, but existing work has been focused mainly on the reconfiguration of higher layers concerned with production scheduling and planning. In this paper, we present an automation agent architecture for controlling physical components that integrates “on the fly” reconfiguration abilities on the low-level layer. Our approach is combined with an ontological representation of the low-level functionality at the high-level control layer, which is able to reason and initiate reconfiguration processes to modify the low-level control (LLC). As current control systems are mostly based on standards and principles that do not support reconfiguration, leading to rigid control software architectures, we base our approach on the promising Standard IEC 61499 for the LLC, extended by an innovative reconfiguration infrastructure. We demonstrate this approach with a case study of a reconfiguration process that modifies the LLC functionality provided by the automation agent of a physical component. Thereby, we obtain the ability to support numerous different LLC configurations without increasing the LLCs complexity. By applying our automation agent architecture, we enhance not only the flexibility of each components control software, but also achieve the precondition for reconfiguring the entire manufacturing system.

Application of an ontology in a transport domain

This paper presents an application of an ontology in combination with multi-agent technologies in a transport domain. The need for flexibility and agility in this domain is continuously growing due to the increasing complexity in the processes where this domain is used. The ontology, we propose, is shared among agents and provides the common agreement and understanding about the used concepts. This approach offers a convenient way for design and control of distributed systems reducing their complexity, increasing flexibility and enhancing fault tolerance.

Decentralized Reconfiguration of a Flexible Transportation System

This paper presents a decentralized approach for the local reconfiguration of control software, which is based on a multiagent system with ontology-driven reasoning. We apply this approach to a transportation system and demonstrate improvements on efficiency, fault tolerance and stability with several experiments. One key element to achieve these results is the use of ontologies to ensure the consistency of local reconfiguration of the control software with the desired global behavior of the system. To show the feasibility of our approach in a realistic industrial setting, we implemented the multiagent system on the “Testbed for Distributed Holonic Control” at the Automation and Control Institute. We also used simulation to analyze its impact on the system performance. The simulation results as well as the real system experiments indicate that our approach is able to cope with the dynamic nature of the transportation domain thereby enhancing reconfigurability, robustness, and fault tolerance.

Integrating software agents and IEC 61499 realtime control for reconfigurable distributed manufacturing systems

The need for agility in manufacturing systems is continuously growing. This is caused by increasing complexity and decreasing life cycles of the produced goods. This paper proposes a modular, reconfigurable manufacturing system, based on a distributed three layer architecture, consisting of mechatronic components, an IEC 61499 based distributed low level control and on top a multi agent system as high level control. Adaptivity to new demands is added by the inclusion of knowledge in the top layer. Agents are able to understand the structure of the manufacturing system and the produced goods. This enables the high level control to reconfigure the underlying system. To gain most value of this combination, agents and the low level control have to work together in an integrated environment. An interface for connecting distributed low level control and the multi agent system is presented.

An automation agent architecture with a reflective world model in manufacturing systems

Manufacturing systems have become very complex, and the traditional hierarchical and centralized approaches are not adequate any more. Decentralized approaches are considered promising, but they are not yet sufficiently understood for widespread industrial application. In particular, agent-based control has not yet achieved its potential, so that more research is still required. Therefore, we propose a new architecture of automation agents. Such an agent is composed of a hardware component and a software component, where the hardware component can be viewed as an embodiment of this software component in its manufacturing environment. An important part of the software component is a world model repository of the automation agent. As a special innovation, the world model is reflective in the sense, that it contains a symbolic representation of the automation agent and of its relations to its environment as well. The world model repository is made up of representations of situations and activities. In summary, we propose an automation agent architecture with a reflective world model for use in manufacturing systems.

Monitoring and diagnostics of industrial systems using automation agents

An agile monitoring and diagnostic system plays a vital role in manufacturing, since it can considerably increase its robustness and efficiency. Applying agent technology to such systems is recognised as an appropriate approach, providing fault-tolerance and means for failure recovery in the case of sudden anomalies. In this article, we present an automation agent approach with agents comprising a software component with an integrated world model repository besides the related hardware. The world model is an explicit representation of the external surroundings and internals of the agent, and is used to detect anomalies in its own behaviour. We use an ontology to formalise the agents knowledge. Applicability and functionality of our approach are presented in an example employing a real system.

Integration of a heterogeneous Low Level Control in a multi-agent system for the manufacturing domain

Currently employed manufacturing systems are very often historically grown systems that can comprise several different technologies of control software. Linking these diverse control subsystems in the manufacturing domain is therefore of vital importance to ensure the systems functionality. In this paper we introduce an agent-based approach with agents that integrate a high level control layer and a low level control layer using a generic interface. Three use-cases are presented that illustrate the application of existing low level control solutions. The shown communication concept offers a feasible way for integrating these different types of low level control in a multi-agent system for the manufacturing domain. This allows to reduce the domains complexity and to handle its heterogeneous nature.

Towards ontology-based automated disassembly systems

The disassembly of products is a key process in the treatment of Waste Electrical and Electronic Equipment. When performed efficiently, it enables the maximization of resources re-usage and a minimization of pollution. However, currently employed automation solutions are mainly custom-oriented and not quite suited to cope with the dynamic nature of the disassembly environment resulting from the wide variety of products to be disassembled as well as their general shape at their disposal (e.g., scratches and fractions). To overcome these limitations we present an ontology-based automated disassembly system that integrates distributed multiagent based machine control as well as vision-based real-time path planning and robot automation. On the one side, the usage of ontologies in combination with intelligent agents provides the system with agility and the ability to autonomously perform soft-and hardware modifications in order to perform a particular activity (e.g., by selecting a specific tool). On the other side, the flexible semantic coupling of the ontology with the vision system supports the “understanding” of the captured image and enables an automated and robust realization of the individual disassembly operations as well as their coordination.

Simulation of workflow scheduling strategies using the MAST test management system

Workflow simulation is an effective approach to investigate dynamic workflow scheduling and evaluate system performance. In this paper we report on a test management system for the evaluation of a range of workflow scheduling strategies based on multi-agent negotiation, where each resource agent performs local scheduling using dispatching rules. The newly developed test management system runs test cases on the manufacturing agent simulation Tool (MAST), which provides comprehensive support for performance measurement and data analysis reporting.

Performance evaluation of workflow scheduling strategies considering transportation times and conveyor failures

Workflow simulation is an effective approach to investigate dynamic workflow scheduling strategies and evaluate system performance. In this paper we report on a series of performance tests run on our workflow scheduling and quality measurement system. Traditional calculations for workflow scheduling strategies focus only on machine service duration; however, in some contexts the variation of transport time is a significant scheduling factor. In this paper we augment the scheduling calculations to explicitly consider the transportation durations between the machines. In addition, we introduce scenarios with failures of the transport system, e.g. conveyors, which influence the variation of transport durations and evaluate the robustness of workflow scheduling strategies regarding these variations.