SNATUS: Safe Navigation with Accurate Tracking for Underactuated Slender-body Autonomous Underwater Vehicles

Abstract

In underwater navigation, precise trajectory tracking and reliable obstacle avoidance are crucial for the safe and efficient operation of Autonomous Underwater Vehicles (AUVs), especially in cluttered or complex environments. This paper introduces a novel framework SNATUS that integrates Nonlinear Model Predictive Control (NMPC) with Control Barrier Functions (CBF) to address these needs for slender-body AUVs. These AUVs face unique challenges due to underactuation and actuator limitations. To ensure smooth control transitions and respect actuator constraints, a regularization term is added to the NMPC cost function that helps avoid abrupt changes in control actions. Safe navigation around obstacles is further enhanced through higher-order CBFs, providing a robust barrier against potential collisions. Additionally, ocean currents are introduced as external disturbances to test the robustness of the proposed approach under real-world conditions. Through a series of simulations, SNATUS architecture demonstrates the AUV’s capability to handle these disturbances, avoid obstacles effectively, and stay on course, proving its effectiveness for reliable underwater navigation. © 2025 IEEE.