MoRoCo: An Online Topology-Adaptive Framework for Multi-Operator Multi-Robot Coordination under Restricted Communication

Abstract

Fleets of autonomous robots are increasingly deployed with multiple human operators in communication-restricted environments for exploration and intervention tasks such as subterranean inspection, reconnaissance, and search-and-rescue. In these settings, communication is often limited to short-range ad-hoc links, making it difficult to coordinate exploration while supporting online human-fleet interactions. Existing work on multi-robot exploration largely focuses on information gathering itself, but pays limited attention to the fact that operators and robots issue time-critical requests during execution. These requests may require different communication structures, ranging from intermittent status delivery to sustained video streaming and teleoperation. To address this challenge, this paper presents MoRoCo, an online topology-adaptive framework for multi-operator multi-robot coordination under restricted communication. MoRoCo is built on a latency-bounded intermittent communication backbone that guarantees a prescribed delay for information collected by any robot to reach an operator, together with a detach-and-rejoin mechanism that enables online team resizing and topology reconfiguration. On top of this backbone, the framework instantiates request-consistent communication subgraphs to realize different modes of operator-robot interaction by jointly assigning robot roles, positions, and communication topology. It further supports the online decomposition and composition of these subgraphs using only local communication, allowing multiple requests to be serviced during exploration. The framework extends to heterogeneous fleets, multiple teams, and robot failures. Extensive human-in-the-loop simulations and hardware experiments demonstrate effective and reliable coordination under restricted communication.

Figures (19)

• Figure 1: Illustration of the considered scenario, where multiple operators and robots are deployed in an unknown and communication-restricted environment for exploration and task execution. (a) Simulation of 2 operators and 8 robots collaboratively exploring a large-scale environment, while accomplishing 5 tasks via splitting and merging embedded communication graphs; (b) Hardware experiments of 2 operators and 4 robots, with ad-hoc network devices for local communication in close proximity; (c) Intermittent communication protocol that ensures bounded-latency information flow between operators and robots; (d)-(e) Online request fulfillment via changing the communication topology for video streaming and teleoperation.
• Figure 2: Overall framework of MOROCO for multi-team human--robot coordination under restricted communication. Multiple teams of operator and robots simultaneously explore the environment and fulfill several online requests, following the embedded communication graphs under the intermittent communication protocol (Left); The embedded graph is optimized and matched against different targeted graphs given the current graph and the set of active requests (Middle); The resulting subgraphs are realized by the proposed detach-and-rejoin mechanism via only local coordination (Right).
• Figure 3: The measured signal strength in an office environment via the ad-hoc communication network (Top) at different robot positions (Bottom).
• Figure 4: Top: the joint-wheel communication graph over time; Bottom: the pairwise meeting events (black vertical lines) and return events (blue lines).
• Figure 5: The proposed pairwise coordination scheme via intermittent communication. Top: return event to the operator is determined first; Bottom: the next meeting event is optimized given the current exploration tasks.

Theorems & Definitions (22)

• Definition 1
• Remark 1
• Definition 2
• Definition 3
• Remark 2
• Remark 3
• Definition 4
• Remark 4
• Definition 5
• Definition 6