A Novel Underwater Vehicle With Orientation Adjustable Thrusters: Design and Adaptive Tracking Control

TL;DR

The paper tackles limited 6-DOF maneuverability and disturbance sensitivity in underwater vehicles by introducing the Orientation Adjustable Thruster AUV (OAT-AUV) with four independently tiltable vector thrusters, enabling full 6-DOF motion and reduced coupling. A novel feedforward adaptive model predictive controller (FF-AMPC) integrates real-time parameter adaptation with MPC to robustly track trajectories under uncertain dynamics and disturbances. Key contributions include the four-vector-thruster design with 23.8% cost reduction and the FF-AMPC achieving up to ~68–69% improvements in trajectory tracking and resilience to disturbances, validated through simulations and lab pool experiments showing unique composite maneuvers like helical/spiral trajectories. The approach has practical impact for marine exploration and research by delivering higher maneuverability, stability, and adaptive control in dynamic underwater environments.

Abstract

Autonomous underwater vehicles (AUVs) are essential for marine exploration and research. However, conventional designs often struggle with limited maneuverability in complex, dynamic underwater environments. This paper introduces an innovative orientation-adjustable thruster AUV (OATAUV), equipped with a redundant vector thruster configuration that enables full six-degree-of-freedom (6-DOF) motion and composite maneuvers. To overcome challenges associated with uncertain model parameters and environmental disturbances, a novel feedforward adaptive model predictive controller (FFAMPC) is proposed to ensure robust trajectory tracking, which integrates real-time state feedback with adaptive parameter updates. Extensive experiments, including closed-loop tracking and composite motion tests in a laboratory pool, validate the enhanced performance of the OAT-AUV. The results demonstrate that the OAT-AUV's redundant vector thruster configuration enables 23.8% cost reduction relative to common vehicles, while the FF-AMPC controller achieves 68.6% trajectory tracking improvement compared to PID controllers. Uniquely, the system executes composite helical/spiral trajectories unattainable by similar vehicles.

Figures (12)

• Figure 1: Overview of OAT-AUV.
• Figure 2: Mechanical design of OAT-AUV. (a) Mechanical configuration; (b) Detailed mechanism of orientation adjustable thruster; (c) Illustration of CFD simulation (using SOLIDWORKS).
• Figure 3: Schematic of the OAT-AUV electrical system.
• Figure 4: Configuration of the OAT-AUV's thrust vector.
• Figure 5: Analysis of force and moment from vector thrusters in 2-D. OAT-AUV data is denoted as red, while AURORA data is presented as blue. (a) $F_x-F_y$; (b) $F_y-F_z$; (c) $F_x-F_z$; (d) $M_x-M_y$; (e) $M_y-M_z$; (f) $M_x-M_z$.