A Synergistic Fractional-Order Control for Precise Helical Trajectory Tracking and Formation Stability in Multi-Agent Quadrotor UAVs

The present study introduces a cohesive hybrid control strategy designed to improve helical trajectory tracking accuracy and formation stability for quadrotor unmanned aerial vehicles (QUAVs) in multi-agent, real-world environments. In these applications, accurate trajectory tracking and stable formation maintenance are interrelated issues, as disturbances and uncertainties in dynamic environments can compromise both individual path-following precision and group coordination. To tackle these interrelated challenges, we present a fractional-order proportional–integral–derivative (FOPID) controller that enhances transient response, minimises overshoot for accurate helical trajectory tracking and improves robustness against disturbances, thereby benefiting the overall stability of the formation. Furthermore, our methodology incorporates a decentralised nonlinear formation control strategy grounded in consensus and vector field path following. This enables QUAVs to sustain adaptable and dependable circular forms without necessitating fixed placements, hence facilitating flexible coordination in dynamic settings. The stability of trajectory tracking and formation control is assured by Lyapunov's direct technique and the Grönwall–Bellman lemma, ensuring global asymptotic stability for the entire system. Through the validation of the hybrid control framework via simulation and hardware tests, we illustrate its efficacy in attaining accurate trajectory tracking and resilient formation maintenance as interdependent goals. This study enhances UAV control for intricate multi-agent applications, including aerial surveillance, environmental monitoring, and search and rescue operations, by providing a unified and flexible control solution adept at managing interrelated tracking and formation tasks in practical scenarios.