Sliding mode control with power-type barrier function for autonomous aerial refueling based on disturbance observer

Area of Science:

• Aerospace Engineering
• Control Systems Theory
• Robotics

Background:

• Autonomous aerial refueling (AAR) requires precise control, especially during docking.
• Abrupt atmospheric disturbances, like wind gusts, significantly degrade control accuracy and safety.

Purpose of the Study:

• To develop an advanced disturbance-rejection sliding mode control (SMC) strategy for receiver aircraft in AAR.
• To improve the robustness and tracking accuracy of AAR systems under abrupt external disturbances.

Main Methods:

• An estimator-based disturbance observer was developed for feedforward compensation and chattering mitigation in SMC.
• A single-power barrier function-based SMC (SPBFSMC) was introduced for rapid compensation of estimation errors.
• A dual-power barrier function-based SMC (DPBFSMC) was proposed, combining two SPBFSMC methods for enhanced convergence and accuracy.

Main Results:

• The disturbance observer effectively compensates for time-varying disturbances without needing prior knowledge of their bounds.
• SPBFSMC ensured rapid convergence and avoided gain overestimation under abrupt disturbances.
• DPBFSMC achieved a smaller final convergence region, significantly improving tracking accuracy.

Conclusions:

• The proposed barrier function-based SMC strategy enhances AAR control precision and robustness against abrupt disturbances.
• The dual-power approach offers superior tracking accuracy by minimizing the convergence region.
• Lyapunov stability analysis confirmed the closed-loop system's stability, validated by simulations.