Risk Analysis of Autonomous Underwater Vehicle Operation in a Polar Environment Based on Fuzzy Fault Tree Analysis
Round 1
Reviewer 1 Report
1. FFTA relies on the subjective judgment of experts to define fuzzy sets and membership functions. This may lead to differences in the analysis results between different experts. Please explain how to avoid the subjectivity of expert opinions.
2. This paper combines the fuzzy evaluation method and the fault tree method, and uses the FFTA to diagnose underwater robot faults. What are the innovations of this method? Please explain in detail.
3. The computational complexity of the FFTA is relatively high, especially for underwater robots in extreme environments such as the polar regions. How to solve computationally intensive problems and improve solution efficiency and accuracy,
4. In actual application scenarios, there must be partial connections between different fault events. FFTA is based on the independence of events. How to solve this problem, please explain it.
5. It is recommended to add relevant experiments or real cases to verify the effectiveness of the methods in this article.
Format related
1. There are deficiencies in the layout of the table
2. The format of some formulas is not clear enough
3. There is a problem with the serial numbers of small and medium titles in section 2.3.2
4. Some of the subtitles in the text are not uniformly formatted in section 3
Moderate editing of English language required,
There are some long sentences that are difficult to understand
Author Response
Thank you very much for taking the time to review this manuscript. The detailed responses to each of your comments and questions have been compiled in a separate file, which is attached for your convenience. The corresponding revisions and corrections in the manuscript are marked in red in the re-submitted files. Most format-related queries have been addressed and incorporated into the revised manuscript, except for issues related to formulas due to technical difficulties with MDPI. These are expected to be resolved prior to publication.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work is presented as a risk analysis of the operation of autonomous underwater vehicles in polar conditions using fuzzy fault tree analysis, although the work itself has a lot of theoretical part and also considers a probabilistic approach to estimating the probability of loss of an underwater autonomous object;
On the one hand, the topic is relevant, but due to the poor development of such technologies it is difficult to talk about solving any serious applied problems, rather a review of theoretical possibilities and limitations;
Rather, the novelty lies in the fact that a risk tree has been proposed as a known approach, i.e. old conditions on a new research subject;
In terms of methodology, it is sufficient to present the structure and describe the approach without atomizing or delving into known theoretical frameworks;
References are OK.
Detail Comments:
1. In my opinion, no abbreviations should be included in either the abstract or the conclusions;
2. It would be more logical to move the text from line 117 to the main text of the article and to conclude the introduction with a definition of the degree of relevance and applied significance of this work;
3. The authors seem to be more focused on the principles of fuzzy logic than on the research objectives. A significant part of the theoretical material could be omitted as it is poorly related to the research topic;
4. Section 3 Materials and Methods is overloaded and needs to be optimized in terms of presentation of methods by means of which it is proposed to solve the set tasks;
Author Response
Thank you very much for taking the time to review this manuscript. The detailed responses to each of your comments and questions have been compiled in a separate file, which is attached for your convenience. The corresponding revisions and corrections in the manuscript are marked in red in the re-submitted files
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors work shows a method for assessing the risk of operating AUVs in high risk environments, such as under different types of sea ice. The use a fault tree method, which has been modified to include fuzzy data. The method is applied to an AUV operating in ice covered waters. The outcome can contribute to a better understanding of risk involved in operating AUVs in ice covered waters.
The paper is very well written, with excellent spelling, grammar, etc.
The authors should consider the following suggestions for improving the paper.
1. In tables 8 & 10, and figures 5 & 6, the authors should clarify the period over which the probability of failure was calculated. Examples might be per day, per mission, per year, etc.
2. The weighting score in table 5 seems a little simplistic. Perhaps a matrix which reflects the combination of degree of formal training and practical experience would be a better system. It can be imagined that a skilled technician with a lot of practical operating experience could assess the risks as competently as an academic.
3. Other researchers, such as Brito et al. (2010) and Chen et al. (2023) predict that the level of risk changes with time. In their models, the risk starts relatively high with an inexperienced team, reduces as the team gains experience, and increases again as the AUV systems age. However the authors only present a single number for risk. Perhaps they could discuss their work in the context of time variation of risk, combined with the skill and experience of the operating team.
Author Response
Thank you very much for taking the time to review this manuscript. The detailed responses to each of your comments and questions have been compiled in a separate file, which is attached for your convenience. The corresponding revisions and corrections in the manuscript are marked in red in the re-submitted files
Author Response File: Author Response.pdf
Reviewer 4 Report
In this paper, the environmental factors affecting the loss of autonomous underwater vehicle (AUV) are investigated by employing an expert recruitment method. The influence degree of environmental factors on the probability of AUV loss is obtained through aggregation and fuzzy logic processing of the evaluation of several experts. The results show that the deterioration of certain environmental conditions will significantly increase the probability of AUV loss. This study provides an important reference for the risk assessment of AUVs. There are several problems, which must be solved before it is considered for publication. If the following questions are well addressed:
(1) The title “Risk analysis of autonomous underwater vehicles operation in polar environment using fuzzy fault tree analysis” is recommended as “Risk analysis of AUV operation in polar environment based on fuzzy fault tree analysis”;
(2) It is recommended to rewrite the introduction. It should provide an overview of the related researches in the table form, and the advantage and disadvantages of the work are suggested to be highlighted in comparison with previous studies or methods. Also, It is recommended to highlight the main contribution of the proposed algorithm.
(3) It should be better to add some figures to depict the data other than tabular form Additionally, incorporating figures of the proposed algorithm principles is recommended.
(4) In Table 5, it is necessary to discuss the validity of the four experts to be quantitatively weighted.
(5) As mentioned in Figure 2, the inherent failure probability of the system is based on historical data. Therefore, it is imperative to discuss the origin source and reliability of the historical data.
(6) In the section of discussion, the analysis of the factors causing AUV loss in polar regions is not comprehensive, it is necessary to discuss the factors of failure caused by polar environment?
The standardization of paper writing requires further enhancement. The English writing is not qualified for presentation and should be thoroughly checked and improved.
Author Response
Thank you very much for taking the time to review this manuscript. The detailed responses to each of your comments and questions have been compiled in a separate file, which is attached for your convenience. The corresponding revisions and corrections in the manuscript are marked in red in the re-submitted files
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
It has stressed all the concerns, and can be accept with this version.
The English quality of the manuscript has been enhanced, however, further revision is still necessary.
