Distributed 3D Leader-Follower Formation Control with Field-of-View Safety via Control Barrier Functions

2026-05-17

AI Summary

This study addresses the challenge of maintaining visual connectivity in three-dimensional leader-follower multi-UAV formations, where limited onboard camera fields of view (FOV) can cause followers to lose sight of the leader, jeopardizing formation safety and stability. To resolve this, the authors propose a distributed control framework that, using only local relative state information, integrates a relative motion model formulated in the line-of-sight coordinate frame, a distributed tracking controller, and a safety filter based on control barrier functions solved via quadratic programming (CBF-QP). This architecture structurally guarantees that the leader remains within each follower’s visual frustum. The approach effectively balances formation tracking accuracy with visual visibility constraints. Validation through Gazebo simulations and real-world experiments with Crazyflie quadrotors demonstrates its capability to preserve FOV constraints while achieving high-precision trajectory tracking, even in conflict-prone scenarios.

Abstract

This letter proposes a distributed 3D leader-follower formation (3D-LFF) control framework for multi-UAV systems that achieves formation tracking while enforcing perception safety constraints. Maintaining safe, vision-based 3D-LFF is challenging because onboard cameras impose strict Field-of-View (FOV) limitations, and demanding formation commands can drive the leader outside the follower's camera frustum, resulting in loss of visibility. To address this issue, we develop a perception-aware safe control architecture that guarantees visibility by construction. First, we derive a relative kinematic model in a line-of-sight coordinate representation and design a distributed 3D-LFF tracking controller using only locally available relative states. Next, we embed the nominal formation controller within a Control Barrier Function-based Quadratic Program (CBF-QP) safety filter that minimally modifies the commanded velocities to maintain the leader inside the follower's camera frustum while preserving formation tracking whenever feasible. Gazebo simulations and Crazyflie hardware experiments validate the proposed approach, demonstrating accurate formation tracking and effective FOV enforcement, including scenarios in which the nominal desired formation conflicts with visibility constraints.

Problem

• 3D leader-follower formation
• Field-of-View safety
• perception constraints
• multi-UAV systems
• visibility maintenance

Innovation

• Control Barrier Functions
• Field-of-View Safety
• Distributed Formation Control
• 3D Leader-Follower
• Perception-Aware Control