Augmented safety guarantee-based area keeping control for an underactuated USV with environmental disturbances

Area of Science:

• Marine robotics
• Control systems engineering
• Autonomous navigation

Background:

• Underactuated unmanned surface vessels (UUSVs) face challenges in maintaining stability and safety during area keeping maneuvers, especially under environmental disturbances.
• Existing methods like Weather Optimal Control (WOC) may not fully address nonlinear safety constraints.

Purpose of the Study:

• To develop an accurate area keeping control method for UUSVs with augmented safety guarantees.
• To ensure both safety and stability during UUSV area keeping operations in the presence of environmental factors.

Main Methods:

• An augmented safety guarantee was constructed using control barrier functions (CBFs) on general manifolds to handle nonlinear safety constraints.
• Stability constraints were formulated by integrating control Lyapunov functions (CLFs) and a Weather Optimal Control (WOC) method.
• A quadratic program (QP) was employed to unify safety and stability constraints, creating an optimal area keeping controller.

Main Results:

• The proposed method successfully integrates safety considerations into the optimal area keeping control of UUSVs.
• Simulation results demonstrated the feasibility of the developed control strategy.
• The new method showed superiority compared to the conventional WOC approach.

Conclusions:

• The proposed accurate area keeping control method with augmented safety guarantee is effective for UUSVs operating under environmental disturbances.
• The integration of CBFs and CLFs provides a robust framework for balancing safety and stability.
• This approach offers a significant advancement for autonomous marine navigation systems.