The Design and Application of a Vectored Thruster for a Negative Lift-Shaped AUV

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1.The resolution of the velocity and pressure maps at Figure 6 is insufficient, and it is recommended to export the corresponding high-resolution vector maps. Meanwhile, in order to better represent the structural damage caused by the pressure difference between the upper and lower structures during the motion of the first type of vector thruster, the pressure maps at different speeds should be considered to be placed here, and the local structure of the vector thruster should be analyzed with more detailed maps.

 

2.This paper 3.2 cosine theorem only from the two-dimensional plane to illustrate the relationship between the motion of the structure of the vector thruster, while the rotation of the work of the three-dimensional motion of the work surface and the relevant theoretical analysis is not comprehensive enough, and the lack of vector thruster mechanism on the dynamics of the theoretical basis of the support, it is recommended to supplement the dynamics of the thrust and the mechanism between the drive transfer relationship and thrust control analysis

 

3.At 3.3 of this paper, there is no error analysis for the data fitting effect, and it is suggested to increase the error analysis for the fitting curve to increase the credibility of the fitted data, and to analyze whether the underwater motion situation will have an effect on the mapping relationship between the control parameters and the thrust.

 

4.At 4.1 of this paper, it is proposed to show the physical structure of the vector thruster designed in this paper and its localized detail drawing display.

Comments on the Quality of English Language

No comments.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The overall impression of the article is positive, with an interesting problem and promising, accurate results. However, there are some issues that need addressing. To improve the article's quality, I suggest considering the following remark:

1/ The motivation and practical applications of the theoretical results should be clearly emphasized to facilitate readers' understanding.

2/ The authors have provided a comprehensive review of previous works in the introduction. However, the literature review is more of a summary than a critical analysis. The authors should highlight research gaps and propose solutions in their work. The authors could enrich the reference section by discussing some new works related to your system. For example, robust position control of an over-actuated underwater vehicle under model uncertainties and ocean current effects using dynamic sliding mode surface and optimal allocation control, station-keeping control of a hovering over-actuated autonomous underwater vehicle under ocean current effects and model uncertainties in horizontal plane, design and experimental tests of a buoyancy change module for autonomous underwater vehicles.

3/ In section 2, the reviewer thinks that a picture of the AUV system with the reference frames (earth-fixed and body-fixed frames) used in the paper should be added. This reviewer thinks it is necessary to define and explain each coordinate system.

4/ The reviewer thinks that a detailed explanation of dynamics of an AUV need to be explained more in kinematics and dynamic. All assumptions and physical constraints (constraints of speed and heading angle) should be provided.  How many degrees of freedom applied to AUV?

5/ Since control forces and torques are constrained; actual control inputs should be effectively saturated. However, I cannot see how to realize constraints for the control forces/torques? Explain this aspect in detail.

6/ There is a lack of detailed implementation information. Please provide specifications of the hardware, software, configuration, and settings, and the sensors used for the experiment of the approach.

7/ In this paper, the author used the PID controller, please give some information and formulations of the proposed controllers and the control gains of the proposed controller.

8/ Did authors consider the disturbance forces acting on the vehicle such as model uncertainties and ocean current?  How control parameters of proposed trajectory tracking control module are determined under unknown uncertainty and disturbance?

9/ If you focus on figure 25, I think that some chattering is observable. What is your strategy for elimination of chattering ‎of propeller rotation?

10/ The reviewer suggests that the authors include the simulation results in the paper and compare them with the experimental results. This comparison will enhance the quality of the analysis.

11/ The conclusion is ok. But the future scope of the work should also be included.

 

12/ The overall writing of the article needs improvement. Carefully check the grammar and typos. There were errors in capitalization, punctuation, spelling, figure captions, and paragraphing that should be addressed.

Comments on the Quality of English Language

Carefully check the grammar and typos

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper studies the design of a vector thruster for AUVs. The paper looks good from the design perspective but needs more work on the analysis of results and discussion from a scientific view.

 

The major issues are as follows.

1. In Line 39, the authors mention that "few engineers have focused on the propulsion systems." I don't think this is true. The propulsion systems have been one of the most popular topics in the past decades. Before the current trend of research on autonomy, research on propulsion systems led to a lot of papers. The authors are suggested to do a more in-depth literature review of this problem before making this statement.
2. The literature review is not well-organized. It would be good if it could be rewritten to form a clear storyline.
3. It would be good if the major contributions of this work could be included in Section 1 as one independent paragraph.
4. The authors listed several equations in Section 2. Where are these equations used?
5. Several figures were included in Section 2. Please provide some analysis for these plots and explain how they help the design process.
6. It would be helpful to provide some videos of the field tests to demonstrate the effectiveness and mechanism of working.
7. In Figure 22, the fluctuation around the reference depth and yaw angle is too large.
8. It seems the linear actuator angle in Figure 23 is saturated. 
9. Is the result in Figure 25 from field experiments? Do the chattering signals cause any problems?

 

Some typos in the manuscript hinder the understanding of the content. For example, is "Open-hoop" in Line 18 supposed to be "Open-loop"? 

Comments on the Quality of English Language

Some typos exist.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I have no further comments.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed all my previous comments. Even though some responses are not perfectly as expected, they are acceptable at this point.  I have no further questions.