Abstract. It is generally accepted that the environment is an essential compound of multiagent systems (MASs). Yet the environment is typically assigned limited responsibilities, or even neglected entirely, overlooking a rich potential for the paradigm of MASs. Opportunities that environments offer, have mostly been researched in the domain of situated MASs. However, the complex principles behind the concepts and responsibilities of the environment and the interplay between agents and environment are not yet fully clarified. In this paper, we first give an overview of the state-of-the-art on environments in MASs. The survey discusses relevant research tracks on environments that have been explored so far. Each track is illustrated with a number of representative contributions by the research community. Based on this study and the results of our own research, we identify a set of core concerns for environments that can be divided in two classes: concerns related to the structure of the environment, and concerns related to the activity in the environment. To conclude, we list a number of research challenges that, in our opinion, are important for further research on environments for MAS. 1

Abstract not found

Abstract. In situated multi-agent systems (situated MASs), agents are explicitly placed in an environment. A situated agent does not not use long-term planning to decide what action sequence should be executed, but selects actions on the basis of its current position, the world it perceives and limited internal state. Situated agents exploit the environment to coordinate their behavior and to reach a common goal. In a recent project, we applied situated MASs to the control of an automated transportation system that uses automatic guided vehicles (AGVs) to transport loads in a warehouse. In contrast to traditional approaches where the AGVs are controlled by a central server, in this project we model the AGVs as agents in a situated MAS, aiming to improve flexibility and openness. Since the physical environment of AGVs is very restricted, it offers little opportunities for agents to use the environment. We introduce a virtual environment for agents to live in. This virtual environment (1) offers a medium that agents can use to exchange information and coordinate their behavior, and (2) serves as a suitable abstraction to shield low-level physical processing from the AGV agents. Since the only infrastructure available to the AGVs is a wireless network, the virtual environment is necessarily distributed over the AGVs. Synchronization of the state of the virtual environment is provided by ObjectPlaces, a middleware infrastructure that offers support to exchange and share information among nodes in mobile and ad-hoc networks. In this paper, we demonstrate how the environment is used creatively in the design of a MAS solution, helping to manage the complexity of engineering a complex real-world application. 1

Abstract. A reference architecture integrates a set of architectural patterns that have proven their value for a family of applications. Such family of applications is characterized by specific functionality and quality requirements. A reference architecture provides a blueprint for developing software architectures for applications that share that common base. As such, a reference architecture provides a means for large-scale reuse of architectural design. This paper gives an overview of a reference architecture for situated multiagent systems we have developed in our research. We discuss various architectural views of the reference architecture. Per view, we zoom in on the main view packets, each of them containing a bundle of information of a part of the reference architecture. For each view packet we explain the rationale for the design choices that were made and we give built-in mechanisms that describe how the view packet can be exercised to build a concrete software architecture. We illustrate the use of the reference architecture with an excerpt of the software architecture of an industrial AGV transportation system. 1

Abstract. Automatic Guided Vehicles (AGVs) are unmanned vehicles that can transport loads in a warehouse. AGVs are instructed by on-board AGV control software. As multiple AGVs operate in a decentralized manner in the warehouse environment, conflicts may arise. Consequently, it is crucial to test thoroughly whether the AGV control software actually handles the potential conflicts in the appropriate way. In this paper, we employ a simulated warehouse environment to test the AGV control software. The AGV control software is embedded and activated in the simulated warehouse environment. The simulated warehouse environment provides support for testing by means of (1) representing dynamism in the warehouse environment in an explicit manner, and (2) detecting conflicts of dynamism in an automated way. The approach is illustrated for the case of testing collision avoidance. 1

Abstract. We investigate the application of a logic-based framework representing an agent environment as a composite structure that evolves over time. Such a complex structure contains the interaction between two main classes of entities: agents and objects. Interactions between these entities are specified in term of events whose occurrence is governed by a set of physical laws specifying the possible evolutions of the environment, including how these evolutions are perceived by agents and affect objects and processes in the environment. We illustrate the work using GOLEM, a protype platform whose aim is to implement the framework to build situated cognitive agents in a distributed environment. 1

Abstract. Research on situated multi-agent systems investigates how to model a distributed application as a set of cooperating autonomous entities (agents) which are situated in an environment. Many fundamental issues remain unrevealed in this research area. A profound understanding of these issues, however, is necessary before situated multi-agent systems can be applied to industry-strength applications. We use the abstract application called the Packet-World quite extensively as a test bed for investigating, experimenting and evaluating fundamental concepts and mechanisms. Examples are active perception, decision making of situated agents, synchronization of simultaneous actions and indirect coordination. The Packet-World has direct connections with real-world applications, such as the decentralized control of a warehouse transportation system through unmanned vehicles. In this article, we describe the Packet-World and we give an overview of our research for which we have used the Packet-World as a test bed.

Abstract. Engineering non-trivial open multi-agent systems is a challenging task. Our research focusses on situated multi-agent systems, i.e. systems in which agents are explicitly placed in a context – an environment – which agents can perceive and in which they can act. Two concerns are essential in developing such open systems. First, the agents must be adaptive in order to exhibit suitable behavior in changing circumstances of the system: new agents may join the system, others may leave, the environment may change, e.g. its topology or its characteristics such as throughput and visibility. A well-known family of agent architectures for adaptive behavior are free-flow architectures. However, building a free-flow architecture based on an analysis of the problem domain is a quasi-impossible job for non-trivial agents. Second, multi-agent systems developers as software engineers require suitable abstractions for describing and structuring agent behavior. The abstraction of a role obviously is essential in this respect. Earlier, we proposed statecharts as a formalism to describe roles. Although this allows application developers to describe roles comfortably, the formalism supports rigid behavior only, and hampers adaptive behavior in changing environments. In this paper we describe how a synergy can be reached between freeflow architectures and statechart models in order to combine the best of both worlds: adaptivity and suitable abstractions. We illustrate the result through a case study on controlling a collection of automated guided vehicles (AGVs), which is the subject of an industrial project. 1

In this paper we propose an approach for flexible and decentralized task allocation based on a negotiation protocol and applicable in case of delayed commencement of tasks. Delayed task commencement arises when an agent has to make some e#ort in order to start the task, e.g. a robot first has to move towards the starting position of its task of moving a packet before the task can be performed.

In this paper we present a generic model for active perception in situated multi-agent systems. Active perception enables an agent to direct its perception at the most relevant aspects in the environment according to its current task. The model decomposes perception into three functionalities: sensing, interpreting and ltering.