Virtual Elastic Tether: A New Approach for Multi‐Agent Navigation in Confined Aquatic Environments

ABSTRACT Underwater navigation is a challenging area in the field of mobile robotics due to inherent constraints in self‐localization and communication in underwater environments. Some of these challenges can be mitigated by using collaborative multi‐agent teams. However, when applied underwater, the robustness of traditional multi‐agent collaborative control approaches is highly limited due to the unavailability of reliable measurements. In this paper, the concept of a Virtual Elastic Tether (VET) is introduced. VET introduces the concept of a virtualised tether to connect multiple robots by innovatively using dual camera views for two‐sided visual servoing. This enables individual robots to perform autonomous maneuvers while maintaining mutual proximity. The concept of VET is formulated and validated through an AUV‐ASV multi‐agent underwater system. Within this framework, a vision‐based leader‐follower approach for an autonomous underwater vehicle and an autonomous surface vehicle is developed. The proposed system has been tested in both simulation and physical experiments, with performance benchmarks against the traditional single Image‐Based Visual Servoing approach. Results indicate that while the leader‐follower formation of the baseline system failed under external perturbations, the VET‐enhanced system's formation recovered to its pre‐perturbation state within 5 s. Moreover, the VET‐enhanced system successfully navigated a confined water pond where the baseline approach failed to perform adequately.