Introduction:
This article presents two multi-level control strategies aimed at tackling the guidance and control challenge of underwater vehicles. The strategies discussed are an outer-loop path-following algorithm and an outer-loop trajectory tracking algorithm. Both algorithms provide reference commands for a generic submarine to adhere to a three-dimensional path. Additionally, an inner-loop adaptive controller is utilized to determine the necessary actuation commands. Furthermore, the article introduces a reduced order model of a generic submarine, which incorporates depth dependence and the influence of waves on the craft. The model is validated using computational fluid dynamics (CFD) results, and the procedure to obtain its coefficients is discussed.
Guidance and Control Strategies:
The article outlines two multi-level control strategies to address the guidance and control problem faced by underwater vehicles.
Outer-Loop Path-Following Algorithm:
The first strategy discussed is the outer-loop path-following algorithm. This algorithm provides reference commands that enable a generic submarine to follow a predetermined three-dimensional path. By utilizing an inner-loop adaptive controller, the required actuation commands are determined to ensure the submarine maintains its desired path.
Outer-Loop Trajectory Tracking Algorithm:
The second strategy presented is the outer-loop trajectory tracking algorithm. Similar to the path-following algorithm, this strategy also provides reference commands for the generic submarine. However, it aims to enable the submarine to track a given trajectory, which may be more complex than a straight path. The inner-loop adaptive controller is again employed to determine the appropriate actuation commands needed to achieve accurate trajectory tracking.
Reduced Order Model:
In addition to the control strategies, the article introduces a reduced order model of a generic submarine. This model takes into account depth dependence and the impact of waves on the craft. Computational fluid dynamics (CFD) results are utilized to validate the model’s accuracy. The process of obtaining the model coefficients is also discussed, and the article provides examples of the data used for this purpose.
Analysis and Expert Insights:
The presented multi-level control strategies offer promising solutions to the guidance and control challenges faced by underwater vehicles. By employing outer-loop algorithms with reference commands and inner-loop adaptive controllers, these strategies enable submarines to follow both predefined paths and complex trajectories accurately.
The reduced order model of the generic submarine, which considers depth dependence and the influence of waves, is a significant contribution. This model’s accuracy is validated through computational fluid dynamics (CFD) results, enhancing confidence in its reliability for control system design and analysis.
Looking ahead, further research could focus on refining and optimizing the presented control strategies. Exploration of additional factors that affect underwater vehicle behavior, such as underwater currents and obstacles, would also enhance the practicality of these strategies. Additionally, the development of real-time implementation techniques and experimental validation would be valuable to assess the strategies’ performance in realistic underwater scenarios.
Conclusion:
This article introduces two multi-level control strategies for guiding and controlling underwater vehicles. The outer-loop path-following algorithm and outer-loop trajectory tracking algorithm enable a generic submarine to adhere to a three-dimensional path and track complex trajectories, respectively. Computational fluid dynamics (CFD) results validate a reduced order model of the submarine, which considers depth dependence and wave effects. This work opens opportunities for enhancing underwater vehicle guidance and control through further optimization, considering additional factors, and experimental validation.