Mathieu Vallée

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.

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.

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.

A real-time reconfiguration infrastructure for distributed embedded control systems

During the last decades production automation research has been focused on improving the flexibility and adaptability in order to cope with the arising challenges of mass customization. Much work was devoted to the higher—planning and scheduling—levels of automation systems. However, the lower level real-time control infrastructure was widely neglected. Therefore, we are currently faced with an adaptive flexible high level control connected to a rigid low level control. This work presents a dynamic reconfiguration architecture for the low level control of industrial automation systems. This architecture allows to reconfigure real-time control applications during full operation of the controlled plant. In an example implementation we prove that this is also possible on small embedded control devices as they are typically used as field devices in industrial automation systems.

Self-Representation for Self-Configuration and Monitoring in Agent-Based Flexible Automation Systems

Automation systems become more and more complex, and their traditional hierarchical and centralized control may not be able to deal with this ever-increasing complexity satisfactorily. 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. Our approach is based on the concept of an automation agent composed of a hardware (HW) component and a software (SW) component, where the HW component can be viewed as an embodiment of this SW component. These agents represent the parts of a flexible automation system. In particular, we propose that each such agent has an explicit symbolic representation of itself and of its relations to its environment. More precisely, this new agent architecture contains a reflective world model that includes a representation of this same agent and of its relations to its environment. In addition, the world model contains representations of situations and activities. We show that and how such a self-representation can be used for self-configuration, as well as monitoring, including failure detection in automation systems. The agent performs this self-configuration without any human intervention and just based on a brief specification of the HW configuration. The monitoring is based on automatically raised expectations for the systems behavior and allows failure detection without any specific failure detection code.

Online reconfiguration of the low level control for automation agents

Addressing changing market conditions and customer needs requires more flexible and reconfigurable manufacturing systems. Distributed intelligent control systems based on agent technologies are seen as a promising approach to provide reconfiguration abilities. Existing work has been focused on the reconfiguration of higher layers concerned with production planning and scheduling. However, a different approach is needed for reconfiguration of the control software at a lower level closer to physical components, in order to enable a better adaptation to changes and disturbances in the local environment. In this paper, we investigate the feasibility of online reconfiguration of the low level control for automation agents. Our approach relies on a reconfiguration infrastructure for real-time control software based on the IEC 61499 standard. We detail the features of this infrastructure as well as its integration within the architecture of an automation agent. We also describe an implementation example with timing measurements showing the ability for rapid reconfiguration. Using our approach, reconfiguration can be performed locally without the need to restart the control system.

Detection of anomalies in a transport system using automation agents with a reflective world model

Manufacturing systems need to become more flexible and agile in order to address permanently changing requirements. Agent-based manufacturing control systems are envisioned as a relevant solution. However, designing and deploying such systems is complex, and raises some concerns regarding safety, robustness and emergence of unforeseen behaviors. To address these concerns, we propose an approach in which automation agents are created by extending existing hardware and real-time control software with advanced capabilities for cooperation and run-time diagnosis. The main feature of an automation agent is the reflective world model - a symbolic model of the agents world, including the agent itself. In this paper, we present the application of a reflective world model for automation agents to detect some anomalies in a pallet transport system. This work shows the suitability of the proposed approach for designing advanced run-time diagnosis capabilities, while preserving existing hardware and control software.

A Layered Manufacturing System Architecture Supported with Semantic Agent Capabilities

Manufacturing control systems are a mission-critical application domain for semantic agents systems. While multi-agent systems have been explored in the manufacturing systems domain, there is very little work on semantically enabled agent systems. This chapter introduces a layered architecture for manufacturing systems based on agent systems and discusses relevant capabilities of the semantic agents based on real-world use cases.