BotNet: A Simulator for Studying the Effects of Accurate Communication Models on Multi-agent and Swarm Control

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ABSTRACT:
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Decentralized control in multi-robot systems is dependent on accurate and reliable communication between agents. Important communication factors, such as latency and packet delivery ratio, are strong functions of the number of agents in the network. Findings from studies of mobile and high node-count radio-frequency (RF) mesh networks have only been transferred to the domain of multi-robot systems to a limited extent, and typical multi-agent robotic simulators often depend on simple propagation models that do not reflect the behavior of realistic RF networks. In this paper, we present a new open source swarm robotics simulator, BotNet, with an embedded standards-compliant time-synchronized channel hopping (6TiSCH) RF mesh network simulator. Using this simulator we show how more accurate communications models can limit even simple multi-robot control tasks such as flocking and formation control, with agent counts ranging from 10 up to 2500 agents. The experimental results are used to motivate changes to the inter-robot communication propagation models and other networking components currently used in practice in order to bridge the sim-to-real gap.

What you need to know:

Multi-agent control has historically been dominated by central control where each agent is sent a command from an all-knowing central station. The practicality of this approach is falling off a cliff as more practitioners are interested in deploying a) real world systems (where ideal communications is a challenging research problem) and b) high agent-count systems (often called swarms) where scaling laws come into effect. Centralized control breaks down simply because it is hard to get all the commands through the network and computation load increases dramatically.

The common solution is decentralized control. In centralized control, agents decide how to act based on signal from their neighbors. In reality, the concept of neighbors of a networked robot is not as stable as the concept of distance between the two. Communication connections drop and re-emerge, and the control systems of the future must be able to accomodate this.

In this paper, we released a new tool for studying the effects of and building new tools to empower decentralized or partially-centralized control in high-agent count settings. The paper describes these problems and future directions in great detail!

Citation

@inproceedings{selden2021BotNet,
 title={BotNet:  A  Simulator  for  Studying  the  Effects  of  AccurateCommunication  Models  on  Multi-agent  and  Swarm  Contro},
 author={Selden, Mark and Zhou, Jason and Campos, Felipe and Lambert, Nathan and Drew, Daniel and Pister, Kristofer S. J.},
 booktitle={IEEE International Symposium on Multi-Robot and Multi-Agent Systems)},
 year={2021},
 organization={IEEE}
}