A Review of the Various Control Algorithms for Trajectory Control of Unmanned Underwater Vehicles

Round 1

Reviewer 1 Report

Please read the attachment. Thank you.

Comments for author File: Comments.pdf

Author Response

Answers to the Reviewers’ Comments

Manuscript: sustainability-2563421

 

The following represent point-by-point answers to the reviewers’ comments. Appropriate revisions are made in the revised manuscript, as explained hereunder. In the revised version of the manuscript, all the revisions are highlighted in yellow.

 

Reviewer 1 Comments:

• Figure 1: Please connect those separate shapes.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the separate shapes in Figure 1 have been connected.

 

• All equations should be marked with numbers and aligned. They should be mentioned or explained in the main text.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, all equations have been aligned and marked with numbers. Moreover, all equations have been mentioned/explained in revised version of the manuscript and highlighted in yellow.

 

• Sections 2-3 should be combined.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, sections 2 & 3 have been combined.

 

• Please add a section introducing wireless communications and cyber security applications for UUVs.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the discussion about the wireless communications and cyber security is added on pages 2 & 3 and is highlighted in yellow.

 

• Citations in the main text. Please format following the journal template.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, citations have been formatted as per journal format.

 

• Related works: Please discuss the other missing methods in this literature review. The following works could be helpful for the authors to enrich the references.

1. Wireless Communications for Data Security: Efficiency Assessment of Cybersecurity Industry—A Promising Application for UAVs
2. Multi-agent task planning and resource apportionment in a smart grid

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the suggested references have been discussed in the introduction section and are highlighted in yellow on pages 2 and 3.

 

• Methodology Section: The manuscript lacks a dedicated section describing the methodology used to review and compare control system algorithms. It should outline the criteria used for evaluation, the selection process of algorithms, and the sources of simulation and experimental data.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, a separate methodology section has been added on page 4 and is highlighted in yellow.

 

• Please provide the flowchart of the study process.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the flowchart of the study process is added on page 4 of the revised manuscript.

 

• Conclusion: Please add a summary of the study process. Then, give brief findings, the limitations, and trends-driven for further studies.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, a summary of the study process, brief findings, the limitations, and trends-driven for further studies are discussed in the conclusion section on page 21 and 22 of the revised manuscript.

 

• References: they have a shortage. Please improve.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, new references have been added.

 

Constructive Questions:

 

• How did the authors select the control system design algorithms for review in this manuscript, and what criteria were used to evaluate their reliability, robustness, precision, and ability to handle non-linearity in UUV missions?

Answer: The authors are thankful to the reviewer for the valuable comment. The authors have more than 15 years of the experience of the design and construction of unmanned and manned sea going platforms, based on the experience of the authors, the control system design algorithms were selected. The major factors that were kept in mind during the selection of these algorithms were their ease of hardware construction, reliability and cost-effectiveness. As the UUVs are subjected to the hostile environment of the sea, so reliability is a key component. The reliability of the control system depends upon how effectively it handles the disturbances. Algorithms are evaluated on the basis of the mathematical models to get insight of the disturbance effects. It is pertinent to highlight that all disturbances cannot be fully mitigated as the sea environment is very unpredictable. However, selecting right algorithm, based on the mission profile will ensure maximum compensation of the disturbances.

 

• Could the authors elaborate on the challenges UUVs face due to ocean currents, propulsion systems, and uncertainties, and how these challenges were considered while designing the control systems? How did the different control algorithms perform under these challenging conditions in the simulation and experimental studies?

Answer: The authors are thankful to the reviewer for the valuable comment. The environment of the sea is very unsympathetic and one of the major factors that affect the motion of the UUVs is the sea current. Depending upon the condition of the ocean, these currents can be of 3, 4 or 5 Kn. One interesting factor about these currents is that they are directional and predictable so, they can be mitigated using thrusters and control surfaces. Sea currents have maximum impact on slow moving UUVs. From the previous experience, authors found that in order to overcome the issue of the sea currents, a self-adaptation hybrid control system can be utilized. The problem of the sea currents can also be mitigated if the design of the vehicle has thrusters, each for six degrees of freedom i.e. surge, heave, sway, roll, pitch, and yaw. Other uncertainties of the sea will be handled by the robust control scheme. 

 

• In the "Advantages and Disadvantages" section, the authors briefly discuss the strengths and weaknesses of each control system algorithm. Could they provide more detailed analysis and real-world examples where each algorithm excels or falls short? Furthermore, what are the potential strategies to address the limitations identified in the study and improve the overall performance of UUV control systems?

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, more details have been provided in the “Advantages and Disadvantages” section on pages 20 and 21. The pros and cons of each algorithm is explained in the Table 1 of the manuscript. The tabulated form is easier to comprehend for the reader. Real world example of the model predictive control algorithm is in drones made by UZH robotics group. Nonlinear model predictive control (NMPC) algorithm has recently shown promising results for agile quad rotor control but it has a disadvantage as it relies on highly accurate models for maximum performance. Adaptive control is used in the real-world road vehicles. Adaptive cruise control (ACC) is designed to help cars maintain a safe following distance and stay within the speed limit. This system adjusts a car's speed automatically. One of the main disadvantages of ACC is that this control system algorithm is not entirely autonomous, it still requires driver’s intervention. Moreover, poor weather conditions like snow, rain, or fog might confuse the system's sensors, as well as environmental factors such as driving through tunnels etc. H-Infinity control algorithm is under research in NASA to be used in large space structures in real world. One of the properties of this control scheme is that it can handle multiple variables, which made it suitable for space applications. Limitation of this control algorithm is that it requires too much computational work load and it also requires extremely precise model. Fuzzy control algorithm has been used in numerous applications in real world such as facial pattern recognition, air conditioners, washing machines, vacuum cleaners, antiskid braking systems, transmission systems, control of subway systems and unmanned helicopters, knowledge-based systems for multi-objective optimization of power systems, weather forecasting systems etc.  The key advantage of the fuzzy based control system is that it is robust system that works with vague inputs but it requires a lot of testing for validation and verification. PID controllers are widely used for process control applications, such as chemical processing, power generation, and manufacturing. The controller measures the process variables, such as flow rate, pressure, or level, and adjusts the input to maintain the desired process conditions. The main advantage of PID is that it provides precise and stable control. The major drawback of the PID is that it has very low robustness. Backstepping control system design algorithm has been applied to control the attitude and altitude of spacecraft, to design active suspension systems for cars, and to stabilize chemical reactors. The versatility of backstepping control makes it a popular choice for controlling nonlinear systems. Major disadvantage of this algorithm is that it has large steady state error.

 

Finally, the authors wish to thank the reviewer for his constructive remarks, which are well-taken and implemented to improve the clarity and quality of the manuscript.

 

Author Response File: Author Response.docx

Reviewer 2 Report

This paper mainly presents a complete review of different control system design algorithms for UUVs. The basis logic designs of several control system algorithms are also presented. The entire content is sufficient and attractive to the audience. However, there are several questions and problems the authors should be addressed and solved.

 

(1) .The introduction is prolix and long. Authors need to summarize and reduce this part to make it more clear and logical.  

(2) .For control system part, authors need to categorize all the existed works. It seems the current version is not sufficient and summarized.

 

(3) .Authors need to describe and discuss more for the future development of the UUV.

Moderate editing of English language required

Author Response

Answers to the Reviewers’ Comments

Manuscript: sustainability-2563421

 

The following represent point-by-point answers to the reviewers’ comments. Appropriate revisions are made in the revised manuscript, as explained hereunder. In the revised version of the manuscript, all the revisions are highlighted in yellow.

 

Reviewer 2 Comments:

• The introduction is prolix and long. Authors need to summarize and reduce this part to make it more clear and logical.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the introduction section has been reduced and summarized.

 

• For control system part, authors need to categorize all the existed works. It seems the current version is not sufficient and summarized.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, in the control system part, most of the existing works have been included and are summarized.

 

• Authors need to describe and discuss more for the future development of the UUV.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the future development of the UUVs has been discussed on page 22 of the revised manuscript.

 

• Moderate editing of English language required.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, the revised version of the manuscript is thoroughly checked and all English language mistakes have been removed.

 

Finally, the authors wish to thank the reviewer for his constructive remarks, which are well-taken and implemented to improve the clarity and quality of the manuscript.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The article publishes data for control algorithms for trajectory control of unmanned underwater vehicles. The publication methodically describes the sequence and possibilities of modern control tools. The authors reach up to 83 literary sources related to this subject.

The article is very well laid out and ready for publication, I have two comments:

1.      The quality of fig. 7 and 8 to improve;

2.      Table 1 should be formatted to fit the width of the page.

Author Response

Answers to the Reviewers’ Comments

Manuscript: sustainability-2563421

 

The following represent point-by-point answers to the reviewers’ comments. Appropriate revisions are made in the revised manuscript, as explained hereunder. In the revised version of the manuscript, all the revisions are highlighted in yellow.

 

Reviewer 3 Comments:

• The quality of fig. 7 and 8 to improve.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the quality of Figures 7 and 8 has been improved.

 

• Table 1 should be formatted to fit the width of the page.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, Table 1 is formatted to fit the width of the page.

 

Finally, the authors wish to thank the reviewer for his constructive remarks, which are well-taken and implemented to improve the clarity and quality of the manuscript.

 

Author Response File: Author Response.docx

Reviewer 4 Report

 

The topic is interesting. However, there are some minor comments that should be revised. The detailed comments are as follows:

1. The organization of the review lacks clarity. Consider using subheadings to categorize the literature and provide a clear structure for readers.

2. The figures appear pixelated and lack sufficient resolution for clear interpretation. Please provide higher resolution versions.

3. Certain studies are overrepresented in the review, while others receive limited attention. Aim for a balanced distribution of citations across relevant works.

4. Include references to studies that have explored similar methodologies or concepts to provide a broader perspective, like, https://doi.org/10.3390/jmse11081538, https://doi.org/10.1016/j.isatra.2021.02.045, https://doi.org/10.1016/j.oceaneng.2023.115050, etc.

 

5. Check the formatting of citations and references to ensure consistency and accuracy with the journal's guidelines.

 

Quality of English Language must be improved.

Author Response

Answers to the Reviewers’ Comments

Manuscript: sustainability-2563421

 

The following represent point-by-point answers to the reviewers’ comments. Appropriate revisions are made in the revised manuscript, as explained hereunder. In the revised version of the manuscript, all the revisions are highlighted in yellow.

 

Reviewer 4 Comments:

• The organization of the review lacks clarity. Consider using subheadings to categorize the literature and provide a clear structure for readers.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the organization of the manuscript has been improved.

 

• The figures appear pixelated and lack sufficient resolution for clear interpretation. Please provide higher resolution versions.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the quality of the figures has been improved.

 

• Certain studies are overrepresented in the review, while others receive limited attention. Aim for a balanced distribution of citations across relevant works.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, all the relevant studies are discussed in detail and new references are also added. However, from some of the studies, figures have been added in the manuscript that require the discussion of those studies in more detail.

 

• Include references to studies that have explored similar methodologies or concepts to provide a broader perspective, like,

https://doi.org/10.3390/jmse11081538,

https://doi.org/10.1016/j.isatra.2021.02.045,

https://doi.org/10.1016/j.oceaneng.2023.115050, etc.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, the mentioned reference related to UUVs have been added.

 

• Check the formatting of citations and references to ensure consistency and accuracy with the journal's guidelines.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, in the revised version of the manuscript, citations have been formatted as per journal format.

 

• Quality of English Language must be improved.

Answer: The authors are thankful to the reviewer for the valuable comment. As suggested, the revised version of the manuscript is thoroughly checked and all English language mistakes have been removed.

 

Finally, the authors wish to thank the reviewer for his constructive remarks, which are well-taken and implemented to improve the clarity and quality of the manuscript.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Editor and Authors:

Thank you for providing the point-to-point response.

The authors have answered all questions and suggestions. The revised manuscript has been improved significantly and could be accepted for publications as it is.

Please feel free to contact me if you have any further questions or concerns.

Thank you for reading.

Reviewer 2 Report

The current version looks good. Accept as is now.

minor revision for English 

Reviewer 3 Report

      This is my second review of this article, and my comments from the first review have been taken into consideration by the authors. Perhaps after the many revisions, the only thing I notice at the moment are confusions in the figure numbers. Let the authors pay attention before the final and layout.

Reviewer 4 Report

No more concerns