762 research outputs found
Scalable Planning and Learning for Multiagent POMDPs: Extended Version
Online, sample-based planning algorithms for POMDPs have shown great promise
in scaling to problems with large state spaces, but they become intractable for
large action and observation spaces. This is particularly problematic in
multiagent POMDPs where the action and observation space grows exponentially
with the number of agents. To combat this intractability, we propose a novel
scalable approach based on sample-based planning and factored value functions
that exploits structure present in many multiagent settings. This approach
applies not only in the planning case, but also in the Bayesian reinforcement
learning setting. Experimental results show that we are able to provide high
quality solutions to large multiagent planning and learning problems
Learning for Multi-robot Cooperation in Partially Observable Stochastic Environments with Macro-actions
This paper presents a data-driven approach for multi-robot coordination in
partially-observable domains based on Decentralized Partially Observable Markov
Decision Processes (Dec-POMDPs) and macro-actions (MAs). Dec-POMDPs provide a
general framework for cooperative sequential decision making under uncertainty
and MAs allow temporally extended and asynchronous action execution. To date,
most methods assume the underlying Dec-POMDP model is known a priori or a full
simulator is available during planning time. Previous methods which aim to
address these issues suffer from local optimality and sensitivity to initial
conditions. Additionally, few hardware demonstrations involving a large team of
heterogeneous robots and with long planning horizons exist. This work addresses
these gaps by proposing an iterative sampling based Expectation-Maximization
algorithm (iSEM) to learn polices using only trajectory data containing
observations, MAs, and rewards. Our experiments show the algorithm is able to
achieve better solution quality than the state-of-the-art learning-based
methods. We implement two variants of multi-robot Search and Rescue (SAR)
domains (with and without obstacles) on hardware to demonstrate the learned
policies can effectively control a team of distributed robots to cooperate in a
partially observable stochastic environment.Comment: Accepted to the 2017 IEEE/RSJ International Conference on Intelligent
Robots and Systems (IROS 2017
Arena: A General Evaluation Platform and Building Toolkit for Multi-Agent Intelligence
Learning agents that are not only capable of taking tests, but also
innovating is becoming a hot topic in AI. One of the most promising paths
towards this vision is multi-agent learning, where agents act as the
environment for each other, and improving each agent means proposing new
problems for others. However, existing evaluation platforms are either not
compatible with multi-agent settings, or limited to a specific game. That is,
there is not yet a general evaluation platform for research on multi-agent
intelligence. To this end, we introduce Arena, a general evaluation platform
for multi-agent intelligence with 35 games of diverse logics and
representations. Furthermore, multi-agent intelligence is still at the stage
where many problems remain unexplored. Therefore, we provide a building toolkit
for researchers to easily invent and build novel multi-agent problems from the
provided game set based on a GUI-configurable social tree and five basic
multi-agent reward schemes. Finally, we provide Python implementations of five
state-of-the-art deep multi-agent reinforcement learning baselines. Along with
the baseline implementations, we release a set of 100 best agents/teams that we
can train with different training schemes for each game, as the base for
evaluating agents with population performance. As such, the research community
can perform comparisons under a stable and uniform standard. All the
implementations and accompanied tutorials have been open-sourced for the
community at https://sites.google.com/view/arena-unity/
Conflict-Based Model Predictive Control for Scalable Multi-Robot Motion Planning
This paper presents a scalable multi-robot motion planning algorithm called
Conflict-Based Model Predictive Control (CB-MPC). Inspired by Conflict-Based
Search (CBS), the planner leverages a similar high-level conflict tree to
efficiently resolve robot-robot conflicts in the continuous space, while
reasoning about each agent's kinematic and dynamic constraints and actuation
limits using MPC as the low-level planner. We show that tracking high-level
multi-robot plans with a vanilla MPC controller is insufficient, and results in
unexpected collisions in tight navigation scenarios. Compared to other
variations of multi-robot MPC like joint, prioritized, and distributed, we
demonstrate that CB-MPC improves the executability and success rate, allows for
closer robot-robot interactions, and reduces the computational cost
significantly without compromising the solution quality across a variety of
environments. Furthermore, we show that CB-MPC combined with a high-level path
planner can effectively substitute computationally expensive full-horizon
multi-robot kinodynamic planners
Solving Common-Payoff Games with Approximate Policy Iteration
For artificially intelligent learning systems to have widespread
applicability in real-world settings, it is important that they be able to
operate decentrally. Unfortunately, decentralized control is difficult --
computing even an epsilon-optimal joint policy is a NEXP complete problem.
Nevertheless, a recently rediscovered insight -- that a team of agents can
coordinate via common knowledge -- has given rise to algorithms capable of
finding optimal joint policies in small common-payoff games. The Bayesian
action decoder (BAD) leverages this insight and deep reinforcement learning to
scale to games as large as two-player Hanabi. However, the approximations it
uses to do so prevent it from discovering optimal joint policies even in games
small enough to brute force optimal solutions. This work proposes CAPI, a novel
algorithm which, like BAD, combines common knowledge with deep reinforcement
learning. However, unlike BAD, CAPI prioritizes the propensity to discover
optimal joint policies over scalability. While this choice precludes CAPI from
scaling to games as large as Hanabi, empirical results demonstrate that, on the
games to which CAPI does scale, it is capable of discovering optimal joint
policies even when other modern multi-agent reinforcement learning algorithms
are unable to do so. Code is available at https://github.com/ssokota/capi .Comment: AAAI 202
Emergence and resilience in multi-agent reinforcement learning
Our world represents an enormous multi-agent system (MAS), consisting of a plethora of agents that make decisions under uncertainty to achieve certain goals. The interaction of agents constantly affects our world in various ways, leading to the emergence of interesting phenomena like life forms and civilizations that can last for many years while withstanding various kinds of disturbances. Building artificial MAS that are able to adapt and survive similarly to natural MAS is a major goal in artificial intelligence as a wide range of potential real-world applications like autonomous driving, multi-robot warehouses, and cyber-physical production systems can be straightforwardly modeled as MAS. Multi-agent reinforcement learning (MARL) is a promising approach to build such systems which has achieved remarkable progress in recent years. However, state-of-the-art MARL commonly assumes very idealized conditions to optimize performance in best-case scenarios while neglecting further aspects that are relevant to the real world.
In this thesis, we address emergence and resilience in MARL which are important aspects to build artificial MAS that adapt and survive as effectively as natural MAS do. We first focus on emergent cooperation from local interaction of self-interested agents and introduce a peer incentivization approach based on mutual acknowledgments. We then propose to exploit emergent phenomena to further improve coordination in large cooperative MAS via decentralized planning or hierarchical value function factorization. To maintain multi-agent coordination in the presence of partial changes similar to classic distributed systems, we present adversarial methods to improve and evaluate resilience in MARL. Finally, we briefly cover a selection of further topics that are relevant to advance MARL towards real-world applicability.Unsere Welt stellt ein riesiges Multiagentensystem (MAS) dar, welches aus einer Vielzahl von Agenten besteht, die unter Unsicherheit Entscheidungen treffen müssen, um bestimmte Ziele zu erreichen. Die Interaktion der Agenten beeinflusst unsere Welt stets auf unterschiedliche Art und Weise, wodurch interessante emergente Phänomene wie beispielsweise Lebensformen und Zivilisationen entstehen, die über viele Jahre Bestand haben und dabei unterschiedliche Arten von Störungen überwinden können. Die Entwicklung von künstlichen MAS, die ähnlich anpassungs- und überlebensfähig wie natürliche MAS sind, ist eines der Hauptziele in der künstlichen Intelligenz, da viele potentielle Anwendungen wie zum Beispiel das autonome Fahren, die multi-robotergesteuerte Verwaltung von Lagerhallen oder der Betrieb von cyber-phyischen Produktionssystemen, direkt als MAS formuliert werden können. Multi-Agent Reinforcement Learning (MARL) ist ein vielversprechender Ansatz, mit dem in den letzten Jahren bemerkenswerte Fortschritte erzielt wurden, um solche Systeme zu entwickeln. Allerdings geht der Stand der Forschung aktuell von sehr idealisierten Annahmen aus, um die Effektivität ausschließlich für Szenarien im besten Fall zu optimieren. Dabei werden weiterführende Aspekte, die für die echte Welt relevant sind, größtenteils außer Acht gelassen.
In dieser Arbeit werden die Aspekte Emergenz und Resilienz in MARL betrachtet, welche wichtig für die Entwicklung von anpassungs- und überlebensfähigen künstlichen MAS sind. Es wird zunächst die Entstehung von emergenter Kooperation durch lokale Interaktion von selbstinteressierten Agenten untersucht. Dazu wird ein Ansatz zur Peer-Incentivierung vorgestellt, welcher auf gegenseitiger Anerkennung basiert. Anschließend werden Ansätze zur Nutzung emergenter Phänomene für die Koordinationsverbesserung in großen kooperativen MAS präsentiert, die dezentrale Planungsverfahren oder hierarchische Faktorisierung von Evaluationsfunktionen nutzen. Zur Aufrechterhaltung der Multiagentenkoordination bei partiellen Veränderungen, ähnlich wie in klassischen verteilten Systemen, werden Methoden des Adversarial Learning vorgestellt, um die Resilienz in MARL zu verbessern und zu evaluieren. Abschließend wird kurz eine Auswahl von weiteren Themen behandelt, die für die Einsatzfähigkeit von MARL in der echten Welt relevant sind
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