Unmanned Aerial Vehicle Routing Problems: A Literature Review
Round 1
Reviewer 1 Report
My major concerns are the fact that authors have not considered the fleet type in their categorizations and have not studied the vehicle routing problem with profits in their classifications.
Author Response
Authors’ Responses to the Referee’s Comments
Applied Sciences
Unmanned Aerial Vehicle Routing Problems: A literature review
Authors: Amila Thibbotuwawa, Grzegorz Bocewicz, Peter Nielsen, Banaszak Zbigniew
The authors would like to thank the reviewers for very helpful, kind and careful comments and suggestions. The authors have incorporated all the reviewers’ comments in the revised manuscript.
Responses to the Reviewers Comments
Reviewer #1
Remark:
My major concerns are the fact that authors have not considered the fleet type in their categorizations and have not studied the vehicle routing problem with profits in their classifications.
Response: Thank you very much for the comments and remarks.
We added the fleet type of UAVs used in the literature into the categorization in the revised version of the Table 3 and 4. There is seldom research done for heterogeneous fleet of UAVs and most of the existing literature focuses on homogeneous fleet of UAVs. We included the VRP with profits to the classification. (Line 119 to line 122)
Once again, thank you very much for your careful comments.
Yours sincerely,
Amila Thibbotuwawa, Grzegorz Bocewicz, Banaszak Zbigniew, Peter Nielsen
Author Response File: 
Author Response.docx
Reviewer 2 Report
This is a review paper at which the state of Unmanned Aerial Vehicles (UAV) routing research area is reviewed. The topic is interesting to many readers and it is well structured and written. The followings are my comments:
References are adequate and most of them are recent.
Abstract lacks of key findings of the review.
The introduction should include types of UAVS and their applications, you may find this useful:
- Klippstein, A. Diaz De Cerio Sanchez, H. Hassanin, Y. Zweiri, and L. Seneviratne, Advanced Engineering Materials, 2018, 20(2), 1700552.
Although the paper is 26 pages it only has 5 figures which are the authors own figures. Figures from literature must be added after getting permission to use and in many of the cases is free of charge. Additional 5-15 figures and their analysis should be added.
L74 AGVs was mentioned without definition should be automated guided vehicles.
L100: Based on modes of transport: you listed land and maritime and did not include air as a mode of transport, check this?
What are the types of UAVs that use VRP approaches? Is there is a away to add a column of the UAV type in table 3.
L271 to L286 and table 5 the presentation of this section is not useful. Find a better way to represent these references in the paper and avoid to list them like that. I think it needs to be rewritten.
Author Response
Authors’ Responses to the Referee’s Comments
Applied Sciences
Unmanned Aerial Vehicle Routing Problems: A literature review
Authors: Amila Thibbotuwawa, Grzegorz Bocewicz, Peter Nielsen, Banaszak Zbigniew
The authors would like to thank the reviewers for very helpful, kind and careful comments and suggestions. The authors have incorporated all the reviewers’ comments in the revised manuscript.
Responses to the Reviewers Comments
Reviewer #2
This is a review paper at which the state of Unmanned Aerial Vehicles (UAV) routing research area is reviewed. The topic is interesting to many readers and it is well structured and written. The followings are my comments:
References are adequate and most of them are recent.
Remark 1:
Abstract lacks key findings of the review.
The introduction should include types of UAVs and their applications, you may find this useful:
Klippstein, A. Diaz De Cerio Sanchez, H. Hassanin, Y. Zweiri, and L. Seneviratne, Advanced Engineering Materials, 2018, 20(2), 1700552.
Response: Thank you very much for the comments and remarks and the provided reference.
We have modified the abstract adding the key findings of the review. (Line 11 to Line 23).
We have included the types of UAVs and their applications into the introduction with the support of relevant references. (Line 36 to Line 47)
Remark 2:
Although the paper is 26 pages it only has 5 figures which are the authors own figures. Figures from literature must be added after getting permission to use and in many of the cases is free of charge. Additional 5-15 figures and their analysis should be added.
Response: Thank you very much for the comments and remarks. We have added several figures from literature with analysis. (Line 193 to Line 208), (Line 223 to Line 233), (Line 241 to line 247), (line 252 to Line 261), (Line 269 to Line 289), (Line 321 to Line 332)
The revised version of the work includes 8 figures (6 from the literature references) and 4 tables which cover over 8 pages of whole text with 18 pages (not including bibliography). Taking into account the suggestion presented, reference is made to literature presenting rich illustrations of the issues discussed, e.g. Kimon P. Valavanis, George J. Vachtsevanos Eds. Handbook of Unmanned Aerial Vehicles, Springer Dordrecht 2015, DOI 10.1007/978-90-481-9707-1 (With 1228 Figures and 233 Tables). Such a solution will allow us to keep the right proportions of work while focusing on results of own research (study).
Remark 3:
L74 AGVs was mentioned without definition should be automated guided vehicles.
Response: Thank you very much for the comments and remarks. We have included the definition accordingly. (Line 87)
Remark 4:
L100: Based on modes of transport: you listed land and maritime and did not include air as a mode of transport, check this?
Response: Thank you very much for the comments and remarks. We have included air as a mode of transport in section 2.2 (Line 127 to Line131) as UAV routing falls under the domain of air transport along with typical airplanes used in airline industry.
Remark 5:
What are the types of UAVs that use VRP approaches? Is there is a away to add the UAV type in table 3.
Response: Thank you very much for the comments and remarks.
We added the fleet type of UAVs used in the literature into the categorization in the revised version of Table 3.
Remark 6:
L271 to L286 and table 5 the presentation of this section is not useful. Find a better way to represent these references in the paper and avoid to list them like that. I think it needs to be rewritten.
Response: Thank you very much for the comments and constructive remarks.
We modified the way we presented L271 to L286 and We have rewritten the section addressing your insightful comments and removed the Table 5. (Line 268 to Line 287)
Once again, thank you very much for your careful comments.
Yours sincerely,
Amila Thibbotuwawa, Grzegorz Bocewicz, Banaszak Zbigniew, Peter Nielsen
Author Response File: Author Response.docx
Reviewer 3 Report
Abstract:
The abstract is of good quality, arouses interest, consists of the goals, and the ability to use the results.
Introduction:
The introduction is of sufficient scope and not just general.
Cost savings only appear for take-off and landing infrastructure, however, airspace surveillance and air traffic control require significant and expensive improvements.
How do airspace usage rules affect UAV route planning?
(prohibited, restricted airspace)
The examination of the range of the UAV is missing.
The range is not the same as fuel consumption, as the extent of this depends on many other conditions.
Chapter 2.1 is only a list, the description is missing.
Due to the layout of the table on pages 8-14, it is difficult to review, it would be useful to compare the cited articles in another form.
Figure 5 illustrates the grouping of references very well.
It contains 142 references, the quantity of which corresponds to the classification of the article.
Conclusion:
The conclusions part appropriately summarizes the previous chapters and identifies further research opportunities.
I can't judge the English level of the article, it was written in a language I understand.
Comments for author File: 
Comments.pdf
Author Response
Authors’ Responses to the Referee’s Comments
Applied Sciences
Unmanned Aerial Vehicle Routing Problems: A literature review
Authors: Amila Thibbotuwawa, Grzegorz Bocewicz, Peter Nielsen, Banaszak Zbigniew
The authors would like to thank the reviewers for very helpful, kind and careful comments and suggestions. The authors have incorporated all the reviewers’ comments in the revised manuscript.
Responses to the Reviewers Comments
Reviewer #3
Abstract: The abstract is of good quality, arouses interest, consists of the goals, and the ability to use the results.
Introduction: The introduction is of sufficient scope and not just general.
Figure 5 illustrates the grouping of references very well.
It contains 142 references, the quantity of which corresponds to the classification of the article.
Conclusion: The conclusions part appropriately summarizes the previous chapters and identifies further research opportunities.
Remark 1:
Cost savings only appear for take-off and landing infrastructure, however, airspace surveillance and air traffic control require significant and expensive improvements. How do airspace usage rules affect UAV route planning? (prohibited, restricted airspace)
Response: Thank you very much for the comments and remarks. We have included the various aspects of airspace usage rules and how it affects UAV routing in section 5.2. (Line 340 to Line 351)
Remark 2:
The examination of the range of the UAV is missing.
The range is not the same as fuel consumption, as the extent of this depends on many other conditions.
Response: Thank you very much for the comments and remarks. We have included the range in the section 5 and elaborated the factors linked to the range of a UAV and the importance in giving attention to the range in future research avenues. (Line 362 to Line 372)
Remark 3:
Chapter 2.1 is only a list, the description is missing.
Response: Thank you very much for the comments and remarks. We added a description at the beginning of section 2.1. (Line 90 to Line 100)
Remark 4:
Due to the layout of the table on pages 8-14, it is difficult to review, it would be useful to compare the cited articles in another form.
Response: Thank you very much for the comments and remarks. We have modified the table arrangement and added additional information such as the fleet type of UAVs where it is relevant in the revised versions of the table 3 and the table 4.
Once again, thank you very much for your careful comments.
Yours sincerely,
Amila Thibbotuwawa, Grzegorz Bocewicz, Banaszak Zbigniew, Peter Nielsen
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors addressed all the raised comments and the paper can be accepted in the current form
