Uncertain information combination for decision making in smart grid BDI agent systems

In a smart grid SCADA (supervisory control and data acquisition) system, sensor information (e.g. temperature, voltage, frequency, etc.) from heterogeneous sources can be used to reason about the true system state (e.g. faults, attacks, etc.). Before this is possible, it is necessary to combine information in a consistent way. However, information may be uncertain or incomplete while the sensors may be unreliable or conflicting. To address these issues, we apply Dempster-Shafer (DS) theory to model the information from each source as a mass function. Each mass function is then discounted to reflect the reliability of the source. Finally, relevant mass functions (after evidence propagation) are combined using a context-dependent combination rule to produce a single combined mass function used for reasoning. We model a smart grid SCADA system in the belief-desire-intention (BDI) multi-agent framework to demonstrate how our approach can be used to handle the combined uncertain sensor information. In particular, the combined mass function is transformed into a probability distribution for decision-making. Based on this result, the agent can determine which state is most plausible and insert a corresponding AgentSpeak belief atom into its belief base. These beliefs about the environment affect the selection of predefined plans, which in turn determine how the agent will behave. We also identify conditions when a combination should occur to ensure the reactiveness of the agent

A Formal Approach to Embedding First-Principles Planning in BDI Agent Systems

The BDI architecture, where agents are modelled based on their beliefs, desires, and intentions, provides a practical approach to developing intelligent agent systems. However, these systems either do not include any capability for first-principles planning (FPP), or they integrate FPP in a rigid and ad-hoc manner that does not define the semantical behaviour. In this paper, we propose a novel operational semantics for incorporating FPP as an intrinsic planning capability to achieve goals in BDI agent systems. To achieve this, we introduce a declarative goal intention to keep track of declarative goals used by FPP and develop a detailed specification of the appropriate operational behaviour when FPP is pursued, succeeded or failed, suspended, or resumed in the BDI agent systems. Furthermore, we prove that BDI agent systems and FPP are theoretically compatible for principled integration in both offline and online planning manner. The practical feasibility of this integration is demonstrated, and we show that the resulting agent framework combines the strengths of both BDI agent systems and FPP, thus substantially improving the performance of BDI agent systems when facing unforeseen situations

Hybrid POMDP-BDI: An Agent Architecture with Online Stochastic Planning and Desires with Changing Intensity Levels

Partially observable Markov decision processes (POMDPs) and the belief-desire-intention (BDI) framework have several complimentary strengths. We propose an agent architecture which combines these two powerful approaches to capitalize on their strengths. Our architecture introduces the notion of intensity of the desire for a goal’s achievement. We also define an update rule for goals’ desire levels. When to select a new goal to focus on is also defined. To verify that the proposed architecture works, experiments were run with an agent based on the architecture, in a domain where multiple goals must continually be achieved. The results show that (i) while the agent is pursuing goals, it can concurrently perform rewarding actions not directly related to its goals, (ii) the trade-off between goals and preferences can be set effectively and (iii) goals and preferences can be satisfied even while dealing with stochastic actions and perceptions. We believe that the proposed architecture furthers the theory of high-level autonomous agent reasoning

A hybrid POMDP-BDI agent architecture with online stochastic planning and plan caching

This article presents an agent architecture for controlling an autonomous agent in stochastic, noisy environments. The architecture combines the partially observable Markov decision process (POMDP) model with the belief-desire-intention (BDI) framework. The Hybrid POMDP-BDI agent architecture takes the best features from the two approaches, that is, the online generation of reward-maximizing courses of action from POMDP theory, and sophisticated multiple goal management from BDI theory. We introduce the advances made since the introduction of the basic architecture, including (i) the ability to pursue and manage multiple goals simultaneously and (ii) a plan library for storing pre-written plans and for storing recently generated plans for future reuse. A version of the architecture is implemented and is evaluated in a simulated environment. The results of the experiments show that the improved hybrid architecture outperforms the standard POMDP architecture and the previous basic hybrid architecture for both processing speed and effectiveness of the agent in reaching its goals

Iterative Online Planning in Multiagent Settings with Limited Model Spaces and PAC Guarantees

Methods for planning in multiagent settings often model other agents ’ possible behaviors. However, the space of these models – whether these are policy trees, finite-state controllers or inten-tional models – is very large and thus arbitrarily bounded. This may exclude the true model or the optimal model. In this paper, we present a novel iterative algorithm for online planning that consid-ers a limited model space, updates it dynamically using data from interactions, and provides a provable and probabilistic bound on the approximation error. We ground this approach in the context of graphical models for planning in partially observable multiagent settings – interactive dynamic influence diagrams. We empirically demonstrate that the limited model space facilitates fast solutions and that the true model often enters the limited model space

Incorporating PGMs into a BDI Architecture

In this paper, we present a hybrid BDI-PGM framework, in which PGMs (Probabilistic Graphical Models) are incorporated into a BDI (belief-desire-intention) architecture. This work is motivated by the need to address the scalability and noisy sensing issues in SCADA (Supervisory Control And Data Acquisition) systems. Our approach uses the incorporated PGMs to model the uncertainty reasoning and decision making processes of agents situated in a stochastic environment. In particular, we use Bayesian networks to reason about an agent's beliefs about the environment based on its sensory observations, and select optimal plans according to the utilities of actions defined in influence diagrams. This approach takes the advantage of the scalability of the BDI architecture and the uncertainty reasoning capability of PGMs. We present a prototype of the proposed approach using a transit scenario to validate its effectiveness. © 2013 Springer-Verlag.Peer Reviewe