Hierarchical Task Assignment for Multi-UAV System in Large-Scale Group-to-Group Interception Scenarios

Round 1

Reviewer 1 Report

 

 

To solve the task allocation problem of multiple UAVs in large-scale group-to-group interception scenarios, this paper proposes a hierarchical task allocation framework and an effective evaluation model, and proves by mathematics and simulation that, as the scale increases, the runtime can be reduced.

 

This paper has several limitations.

First, the paper only considers cases where the number of UAVs is larger than the number of targets and the speed of the targets is faster than the speed of the UAVs. However, in the real world, there are many other situations.

 

Second, the paper assumes two-dimensions for UAVs and targets, but UAVs and targets can make three-dimensional movements.

 

Third, in the proposed method, the number of clusters in the targets(Ns) is set up by a human (i.e. a user). However, the number of targets that can be various. 

 

Therefore, the proposed method in this paper should be more generalized to handle more various situations.

 

In addition, I suggest several improvement points in the revision of this paper.

 

1. Section 1 (Introduction), page 1: It was hard to understand the situations to be handled. So, to help readers’ understanding, please explain the concepts of Counter UAVs and interceptions in the introduction.

 

2. Section 3 (Model Decomposition), page 4: There are symbols that are not defined but used. For example, I in Equation (1) is not defined. "U" is used even before "U" is defined. 

 

3. Section 3 (Model Decomposition), page 5: The authors did not explain the criteria and reasons why set up the threshold α to 5 m/s and 10 m/s.

 

4. Section 5 (Results and Analysis, page 13: The authors mentioned MATLAB R2017a, but did not explain the hardware environment where the experiment was conducted. Specifying the hardware environment, which could help the replication of the experiment.

 

Rather than limiting to the quality of English language, there are some improvement points to revise the paper, as mentioned in the comments.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper is focused on addressing the multi-UAV task assignment problem in scenarios involving large-scale group-to-group interception by introducing an evaluation model and a hierarchical task assignment framework. The proposed evaluation model takes into account the specific dynamic constraints associated with fixed-wing UAVs to enhance the Apollonius circle model and provide a more accurate description of how multiple UAVs cooperate to effectively intercept targets. 

Simulation results are provided to demonstrate the feasibility and effectiveness of the proposed approach, demonstrating a substantial reduction in runtime. 

 

Overall, the paper offers new and interesting insights into effectively solving the challenges posed by large-scale multi-UAV group-to-group interception scenarios. The model's conceptualization is robust, and the presentation and technical descriptions are clear and satisfactory.

 

The paper is well-written and engaging to read, it provides sufficient details and presents the results in an appropriate manner. 

However, some minor issues should be resolved before publishing it:

 

- The introduction is quite comprehensive and covers the essential aspects of the problem. However, it could be helpful to elaborate the section a bit more.

The authors might consider adding more about why this problem is critical. Moreover, if possible, including a brief summary of the findings or methods of previous works (e.g., "Gao et al.", "Sun et al.", "Wang et al.", etc.) could provide more context for readers.

Additionally, towards the end of the introduction, the authors could clearly state the research objectives of the paper by emphasizing the innovative aspects of the work. Highlight how the proposed hierarchical task assignment scheme differs from existing methods and its potential benefits in terms of efficiency and scalability.

 

- It would be interesting to include videos as supplemental materials to help readers appreciate the benefits of the proposed approach.

 

- In the Conclusions section, briefly discuss how the proposed scheme and findings could be applied practically. This could include potential real-world scenarios or industries that could benefit from this approach.

Remember that the goal of the "Conclusions" section is not just to summarize the work but to emphasize its significance and potential impact. It's also a place to discuss, suggest avenues for future research, highlight practical applications, and reflect on the broader implications of specific findings.

 

To sum up, the paper is promising but requires some revision and improvement.

Please carefully proof-read spell check to eliminate typos and repetitions (es. line 171 and Algorithm 1 Md ,Md ,Mθ   instead of Md, Mv, Mθ).

A minor revision is needed to improve the quality of English.

In line 127 The sentence “This paper transforms the task assignment problem” is unclear. What does the expression “The paper transforms the task assignment problem” means?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

I agree with the authors that the multi-UAV task assignment problem in large-scale group-to-group interception scenarios presents challenges in terms of large computational complexity and the lack of accurate evaluation models. At the same time, the authors should be aware of recent works, even published in MDPI where multi-UAV models have been given: A semi-physical platform for guidance and formations of fixed-wing unmanned aerial vehicles. This suggetion is relevant because the semi-physical platform incorporates the dynamics constraints specific to fixed-wing UAVs, as in this manuscript (quote "The evaluation model incorporates the dynamics constraints specific to fixed-wing UAVs and improves the Apollonius circle model..."); in addition, the semi-physical platform is about fixed-wing UAVs, as in this manuscript. The authors are free to judge if this suggestion is appropriate. Concerning the methodology, let me quote the authors

 

"

This paper proposes an effective evaluation model and hierarchical task assignment framework to address these challenges. The evaluation model incorporates the dynamics constraints specific to fixed-wing UAVs and improves the Apollonius circle model to accurately describe the cooperative interception effectiveness of multi-UAVs. By evaluating the interception effectiveness during the interception process, the assignment scheme of the multi-UAVs could be given based on the model. To optimize the configuration of UAVs and targets, a hierarchical framework based on the network flow algorithm is employed.

"

 

The methodology seems appropriate and complete, yet a few questions arise

 

- The authors write "This framework utilizes a clustering method based on feature similarity and interception advantage to decompose the large-scale task assignment problem into smaller, complete submodels." This is ok, however, when reading the manuscript it is unclear what the computational savings are. Is it possible to elaborate on how faster this approach is?

 

- Related to the previous comment, it is true that the authors write "With the increase of the model scale, the proposed scheme has a greater descending rate of runtime. In a large-scale scenario involving 200 UAVs and 100 targets, the runtime is reduced by 84.86%." However, a question arises. Does the descending rate of runtime happen because of parallel computation with multiple processors? Or the the descending rate of runtime happens also when a single processor is in charge of the computations? Please explain

 

- The authors write "Following the assignment, Dubins curves are planned to the optimal interception points, ensuring the effectiveness of the interception task." It is unclear why Dubins curves should be optimal? Can the authors elaborate on this point

 

In general, I support the work subject to the comments above

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

none.

There are many passive forms. Please, use active forms, as much as possible. Do not mix the subjects of the sentences between "this paper" and "we."

Reviewer 2 Report

This reviewer believes the authors have adequately addressed the reviewers' comments in the revised version of the manuscript. As a result, I find no further comments necessary.

Reviewer 3 Report

All comments have been addressed