Autonomous helicopter aerial refueling: controller design and performance guarantees

2025-02-21

AI Summary

This work addresses key challenges in autonomous helicopter aerial refueling: strong position–attitude coupling arising from the off-center fuel probe, high uncertainty in drogue motion induced by rotor wake turbulence, and poor stability during high-speed probe–drogue docking. To this end, we propose a novel outer-loop position control framework. Our method directly incorporates probe position and velocity into the feedback loop, establishing a coupled dynamics model linking attitude, angular rates, and probe pose. We further derive, for the first time, an analytical performance bound on docking error with respect to drogue uncertainty and helicopter angular acceleration, and guarantee robust stability via ultimate boundedness of the closed-loop tracking error. Evaluated on a high-fidelity UH-60 simulation incorporating wind-induced drogue dynamics, the proposed controller reduces the L₂-norm docking error by 36% compared to a standard baseline, significantly enhancing docking accuracy and reliability under complex aerodynamic conditions.

Technology Category

• Intelligent Robots: State Estimation
• Planning, Routing, and Scheduling: Replanning and Plan Repair
• Search and Optimization: Sampling/Simulation-based Search

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Search and Retrieval-Augmented AI: Agentic search
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

In this paper, we present a control design methodology, stability criteria, and performance bounds for autonomous helicopter aerial refueling. Autonomous aerial refueling is particularly difficult due to the aerodynamic interaction between the wake of the tanker, the contact-sensitive nature of the maneuver, and the uncertainty in drogue motion. Since the probe tip is located significantly away from the helicopter's center-of-gravity, its position (and velocity) is strongly sensitive to the helicopter's attitude (and angular rates). In addition, the fact that the helicopter is operating at high speeds to match the velocity of the tanker forces it to maintain a particular orientation, making the docking maneuver especially challenging. In this paper, we propose a novel outer-loop position controller that incorporates the probe position and velocity into the feedback loop. The position and velocity of the probe tip depend both on the position (velocity) and on the attitude (angular rates) of the aircraft. We derive analytical guarantees for docking performance in terms of the uncertainty of the drogue motion and the angular acceleration of the helicopter, using the ultimate boundedness property of the closed-loop error dynamics. Simulations are performed on a high-fidelity UH60 helicopter model with a high-fidelity drogue motion under wind effects to validate the proposed approach for realistic refueling scenarios. These high-fidelity simulations reveal that the proposed control methodology yields an improvement of 36% in the 2-norm docking error compared to the existing standard controller.

Problem

• Designing a controller for autonomous helicopter refueling
• Addressing aerodynamic interactions and drogue motion uncertainty
• Improving docking performance under high-speed conditions

Innovation

• outer-loop position controller
• feedback loop integration
• analytical docking guarantees