Obstacle-Aware Multi-UAV Formation Coordination via a Hierarchical Guiding Vector Field with Adaptive Virtual Coordinates

This paper presents a hierarchical guiding vector field (HGVF) with adaptive virtual coordinates for multi-UAV formation coordination in a two-dimensional workspace containing known static circular obstacles. The outer layer modifies the original closed path in its normal direction to construct an obstacle-aware coarse manifold. Based on the estimated obstacle risk, a shared formation variable continuously interpolates the tangential virtual-coordinate offsets and physical normal offsets between circular and line formation parameters. A distributed virtual-coordinate law coordinates the shifted virtual coordinates using neighboring scalar virtual-coordinate information. The inner layer guides each UAV along its individual reference and combines the resulting tracking field with local obstacle and inter-UAV repulsive corrections to generate bounded velocity commands. Numerical comparisons and CoppeliaSim results show positive obstacle clearances, temporary tracking and coordination deviations during formation reconfiguration, and transitions between the circular and line configurations in the considered scenario.