Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript introduces a mobile robot system designed for detecting hazardous explosives in parking lot environments. The system comprises three types of robots: Type 1 for preliminary sniffing and analyzing chemicals in the air to indicate the presence of explosives; Type 2 for visual recognition of common explosives (based on a database) and analyzing vehicle license plates for threat assessment; and Type 3 for precise chemical analysis using advanced sensors. These robots operate collaboratively to identify and respond to potential threats.

 

The manuscript is structurally sound and relatively comprehensive, with experimental sections demonstrating preliminary functional validation, indicating certain application prospects. However, significant improvements are needed in theoretical depth, clarity of contributions, and writing presentation.

 

Firstly, the manuscript fails to clearly articulate whether this work addresses knowledge gaps unresolved by previous studies. A critical review of the relevant literature is lacking, resulting in insufficient prominence of its innovative aspects.

 

Secondly, the current draft reads more like a conceptual system design rather than a research paper with clearly defined original contributions. Key elements relating to the authors' actual contributions are missing, and the derivation and validation of critical content are inadequate, lacking sufficient theoretical foundation. Consequently, the specific contributions remain unclear.

 

Additionally, there is considerable repetition and overlap between different sections of the manuscript. The logical flow is not sufficiently clear, which challenges readers in following the authors' line of reasoning.

 

In summary, I recommend major revisions. The manuscript should be resubmitted for review after addressing the core issues mentioned above. The authors are advised to focus more on clarifying the specific contributions of their work and improving the organizational structure, thereby allowing the value of this research to be more fully demonstrated.

Author Response

Dear Reviewer

Thank you very much for all your comments and feedback on our article.

All changes in the article are marked in color.

 

„This manuscript introduces a mobile robot system designed for detecting hazardous explosives in parking lot environments. The system comprises three types of robots: Type 1 for preliminary sniffing and analyzing chemicals in the air to indicate the presence of explosives; Type 2 for visual recognition of common explosives (based on a database) and analyzing vehicle license plates for threat assessment; and Type 3 for precise chemical analysis using advanced sensors. These robots operate collaboratively to identify and respond to potential threats.”

Thank you for your comment. It's encouraging and motivates us to continue our work.

 

„ The manuscript is structurally sound and relatively comprehensive, with experimental sections demonstrating preliminary functional validation, indicating certain application prospects. However, significant improvements are needed in theoretical depth, clarity of contributions, and writing presentation.”

 Thank you for your comment. We've tried to incorporate the comments from all the reviews into this revised version.

 

„Firstly, the manuscript fails to clearly articulate whether this work addresses knowledge gaps unresolved by previous studies. A critical review of the relevant literature is lacking, resulting in insufficient prominence of its innovative aspects.”

Thank you for your feedback. We've added relevant descriptions of the new features presented in our work to the article. The introduction has been completely rewritten to highlight the proposed solutions.

 

„Secondly, the current draft reads more like a conceptual system design rather than a research paper with clearly defined original contributions. Key elements relating to the authors' actual contributions are missing, and the derivation and validation of critical content are inadequate, lacking sufficient theoretical foundation. Consequently, the specific contributions remain unclear.”

Thank you for your comment. The authors' contribution has been further structured and expanded upon in the introduction. Descriptions of the individual solutions developed by the authors can be found in the following chapters of the article.

 

„Additionally, there is considerable repetition and overlap between different sections of the manuscript. The logical flow is not sufficiently clear, which challenges readers in following the authors' line of reasoning.”

Thank you for your valuable feedback. We've updated the article's content and removed unnecessary repetition.

 

„In summary, I recommend major revisions. The manuscript should be resubmitted for review after addressing the core issues mentioned above. The authors are advised to focus more on clarifying the specific contributions of their work and improving the organizational structure, thereby allowing the value of this research to be more fully demonstrated.”

Thank you for your comment. We hope the changes we've made address all the suggestions in the review.

Thank you again for all your valuable comments and suggestions.

Reviewer 2 Report

Comments and Suggestions for Authors

The research presents a novel and multi-layered concept for a low-cost mobile robot swarm aimed at enhancing security in airport parking lots. The proposed system is commendable for its practical application potential and its comprehensive approach, which integrates preliminary screening, detailed verification, chemical sensing, machine vision, and database cross-referencing. The manuscript is well-structured, and the experimental section provides a basic validation of the robot's core functionalities. This paper requires further modifications for improvement.

1. The abstract identifies operation in a dynamic environment as a key challenge, yet the experimental section barely addresses this. The ANPR tests were conducted on "stationary or low-speed" vehicles, and there is no mention of the robot's ability to navigate, avoid obstacles, and execute tasks in complex scenarios with moving pedestrians and other vehicles. This leaves one of the core challenges of the research largely unaddressed.
2. Section 1. Introduction. The literature review lists related works on mobile robots, Under-Vehicle Inspection Systems (UVIS), and HAZMAT detection but fails to provide a critical analysis. The authors do not clearly articulate the specific limitations of existing systems in terms of cost, scalability, stealth, and their ability to counter widespread, distributed threats. Consequently, the necessity and novelty of the proposed low-cost swarm approach are not sufficiently justified by the literature.
3. The threat probability model constructed in this paper does not carry out parameter sensitivity analysis. For example, when P_ANPR(license plate matching risk) changes from 0.5 to 0.8, is the magnitude of the change in the final threat probability reasonable? Are the weights of each parameter in the model validated? The lack of this analysis will lead to doubts about the robustness of the model, and its reliability cannot be judged when the parameters fluctuate.
4. Sections 3.2, 3.4.The vision techniques employed, such as ANPR via OpenCV, background subtraction, and HAAR cascade classifiers, are well-established and widely used technologies. While the authors have integrated them into a novel system, the paper should clearly state that its contribution lies in system integration and application innovation, not in the novelty of the algorithms themselves.
5. The paper consistently uses the term "swarm." In academic literature, "swarm intelligence" typically refers to decentralized systems where complex collective behaviors emerge from simple, local interactions between individuals. However, the architecture described in this manuscript is strictly centralized and hierarchical. A level 1 robot detects an anomaly, reports it, and a central system (or logic) then "summons" a level 2 or 3 robot. This is fundamentally a "multi-robot team" or "robot fleet," not a swarm. This terminological inaccuracy is misleading and overstates the system's level of intelligence.
6. The paper presents an ambitious application but gives insufficient consideration to the challenges of large-scale, real-world deployment. Critical issues such as battery life and autonomous charging strategies, operational reliability under adverse weather (rain, snow) and lighting (night) conditions, and the long-term maintenance and management costs for a fleet of hundreds of robots are pivotal to the system's feasibility but are not discussed in depth.

Author Response

Dear Reviewer

Thank you very much for all your comments and feedback on our article.

All changes in the article are marked in color.

 

„The research presents a novel and multi-layered concept for a low-cost mobile robot swarm aimed at enhancing security in airport parking lots. The proposed system is commendable for its practical application potential and its comprehensive approach, which integrates preliminary screening, detailed verification, chemical sensing, machine vision, and database cross-referencing. The manuscript is well-structured, and the experimental section provides a basic validation of the robot's core functionalities. This paper requires further modifications for improvement.”

Thank you for your comment. It's encouraging and motivates us to continue our work.

 

„The abstract identifies operation in a dynamic environment as a key challenge, yet the experimental section barely addresses this. The ANPR tests were conducted on "stationary or low-speed" vehicles, and there is no mention of the robot's ability to navigate, avoid obstacles, and execute tasks in complex scenarios with moving pedestrians and other vehicles. This leaves one of the core challenges of the research largely unaddressed.”

Thank you for your valuable feedback. The system described is not yet fully operational. In our article, we focused primarily on describing threat detection procedures, along with estimating the probability of hazardous events. In future work, we will test our solutions in a public parking lot. The preliminary results presented in this article were obtained in simulated hazardous situations, the purpose of which was to test the detection system's operational assumptions. In further work, we will expand on issues related to navigation in the variable environment of an airport parking lot.

 

„Section 1. Introduction. The literature review lists related works on mobile robots, Under-Vehicle Inspection Systems (UVIS), and HAZMAT detection but fails to provide a critical analysis. The authors do not clearly articulate the specific limitations of existing systems in terms of cost, scalability, stealth, and their ability to counter widespread, distributed threats. Consequently, the necessity and novelty of the proposed low-cost swarm approach are not sufficiently justified by the literature.”

Thank you for your valuable feedback. Appropriate changes have been made to the Introduction. The order of the research problems described has been largely changed, improving readability and allowing for a better highlighting of unresolved issues related to threat detection in airport parking lots.

 

„The threat probability model constructed in this paper does not carry out parameter sensitivity analysis. For example, when P_ANPR(license plate matching risk) changes from 0.5 to 0.8, is the magnitude of the change in the final threat probability reasonable? Are the weights of each parameter in the model validated? The lack of this analysis will lead to doubts about the robustness of the model, and its reliability cannot be judged when the parameters fluctuate.”

Thank you for your comment. Vehicle detection and recognition is based on correlating the recognized license plate number with data contained in a government database (in Poland, this is the CEPIK database). Recognizing license plate markings is practically nonexistent. Only in the absence of a corresponding record in the database can the vehicle be considered unrecognizable. In such a case, the standard procedure will be to place the vehicle under special surveillance and first inspect it for potential threats. We will explore this issue in more detail in the next article.

 

„Sections 3.2, 3.4.The vision techniques employed, such as ANPR via OpenCV, background subtraction, and HAAR cascade classifiers, are well-established and widely used technologies. While the authors have integrated them into a novel system, the paper should clearly state that its contribution lies in system integration and application innovation, not in the novelty of the algorithms themselves.”

Thank you for your valuable comment. We agree that the image recognition technologies used in our robots are widely known. The goal of our work was not to develop a (new) technology for recognizing information from images (photos), but to use it in the designed robot system. Image recognition is performed by type 2 robots (the system's operational diagram includes this information). Examples of potential threat recognition are shown in Figure 11.

 

 

„The paper consistently uses the term "swarm." In academic literature, "swarm intelligence" typically refers to decentralized systems where complex collective behaviors emerge from simple, local interactions between individuals. However, the architecture described in this manuscript is strictly centralized and hierarchical. A level 1 robot detects an anomaly, reports it, and a central system (or logic) then "summons" a level 2 or 3 robot. This is fundamentally a "multi-robot team" or "robot fleet," not a swarm. This terminological inaccuracy is misleading and overstates the system's level of intelligence.”

Thank you for this valuable comment. Our goal was to correctly use the terms describing the characteristics of our threat recognition system. Our system also features direct communication between robots. We would like to note that animal swarms also have an element of central control. For example, a queen bee programs the behavior of individual worker bees through the production of chemical compounds. A separate issue in describing the behavior of collective biological systems is the example of a school of fish. Central control cannot be distinguished in such a set of beings. Because our system resembles a swarm of insects more than a school of organisms, we have used the term "robot swarm" to describe it.

 

„The paper presents an ambitious application but gives insufficient consideration to the challenges of large-scale, real-world deployment. Critical issues such as battery life and autonomous charging strategies, operational reliability under adverse weather (rain, snow) and lighting (night) conditions, and the long-term maintenance and management costs for a fleet of hundreds of robots are pivotal to the system's feasibility but are not discussed in depth.”

Thank you for this valuable comment. We are aware that the example we're describing is not yet a final implementation and requires resolving many practical issues. In future work, we will attempt to present and expand on the issues not addressed in this article.

 

Thank you again for all your valuable comments and suggestions.

Reviewer 3 Report

Comments and Suggestions for Authors

The article, titled "A Mobile Robot Designed to Detect Hazardous and Explosive Materials in Airport Parking Lots", refers to an attempt to design a mobile robot that will detect hazardous and explosive materials in airport parking lots. The article, as the authors themselves state, describes the preliminary findings of the research and focuses on the dual problem of, on the one hand, movement through other moving bodies, and on the other hand, the actual detection of explosive materials at an airport. The development of aerial robotics is in an excellent phase of development and constitutes, for electronics and not only, an evolving and promising scientific field. The organization of aerial robotics essentially covers three phases. In Phase A, the topics of aerial robotics are mentioned, focusing on movement, as well as the types of robots that can be used in formal and informal sensing environments. In Phase B, the possibilities of programming moving robots in dynamic environments are presented, along with the issue of their programming. At the same time, the aim is to familiarize readers with flight environments and the capabilities that are integrated into the same application. In phase C, the sensing part is placed according to the relevant examples described in the article. Basically, in this study, the authors present three distinct types of mobile robots, each designed with varying levels of physical, technical, and cost-related complexity and equipped with different embedded software configurations. Although the text focuses on an interesting topic, several parts require substantial revisions to improve the clarity, structure, and overall presentation of your research. From the formal part of the paper, we note some specific comments that we consider important for improving the overall image of the publication.

1) Initially, we would say that authors should revise their introductory text as a whole. We recommend that they avoid excessive paragraphing, correctly number the references with a scale in accordance with the journal's proposals, and limit themselves to the academic context of scientific publications. We would suggest that they reconsider the functionality of the introduction and remove any information or data that can and should be presented later. The Introduction can extend to five pages but the following should be formulated as an introductory text: 1) the only framework of the problem, 2) the purpose of the researchers, 3) the scientific questions, 4) the research questions 5) the codified objective of the study, 6) the rough approach to the methodology, 7) the design tools and finally 8) the main findings, results and contribution. All this with simple, concise, and focused sentences. 

2) There is no need for excessive paragraphing. A minimum of three paragraphs per page or page section is sufficient. At least three paragraphs per page or page section is sufficient.

3) After the contributions, the authors should cite the individual chapters of the article with a precise description and justification. In this citation, they will explain in detail the connection between the parts and the scientific and research questions. In this particular article, as the development issues are not only interdisciplinary but also approach risk forecasts, we would strongly recommend a flowchart regarding the flow of the text.

4) We don't understand the gap from line 208 to 209. Is it the publisher's fault, or the writers' choices?

5) Between 2. "Threat detection system" (line 209) and 2.1 "Description of System Components and Structure" (line 210), write a short introductory text that will familiarize readers with the content of the chapter, and explain the separation of parts. In any case, (3-3.1) between the titles of the chapters and subchapters, a short introductory text should be written, which will concern the justification of the parts.

6) Be careful with abbreviations. Explain acronyms everywhere before using them. We don't write "ANPR (Automated Number Plate Recognition)", but "Automated Number Plate Recognition" (ANPR), and then use the abbreviation where necessary. Note: at the end of the article, write down a table with all the abbreviations.

7) Figure 2. Robot models used, type 1: (a) right side, (b) top view, (c) left side. Do not take the photo tag to another page. Move the text.

8) Describe the technical terms of photography. How were the photos taken?

9) Figure 8. Robot sensor diagram: What exactly do the microcontrollers?

10) The whole 2.2 Incident probability needs more analysis.

11) The transition from 2.2 to 2.3 is extremely abrupt for the reader. Place textual bridges.

12) What is the meaning of "Vision technique"?

13) In what ways was the diagram in Figure 9 created? What type of statistical analysis was applied? Explain everything. 

14) Figure 11: It is impossible to accept such a long caption. Note something characteristic and transfer the rest.

15) Figure 12 and Figure 13, document justifications and references to construction tools are completely absent.

16) Figure 16 - Figure 20: The most important parts of the article are left significantly uncovered. Please provide details of the applied methodology, metrology, and weighting tools. Documentation measurements cannot be accepted without all of the above.

17) Table 2. Example of calculating the probability: how are those numbers calculated? 

18) In the conclusions, they do not conclude. In addition to the detailed answers to the scientific and research questions, note the overall added value of the article, the difficulties in implementing parts of the research, and finally, suggestions for future research work.

 

Author Response

Dear Reviewer

Thank you very much for all your comments and feedback on our article.

All changes in the article are marked in color.

„The article, titled "A Mobile Robot Designed to Detect Hazardous and Explosive Materials in Airport Parking Lots", refers to an attempt to design a mobile robot that will detect hazardous and explosive materials in airport parking lots. The article, as the authors themselves state, describes the preliminary findings of the research and focuses on the dual problem of, on the one hand, movement through other moving bodies, and on the other hand, the actual detection of explosive materials at an airport. The development of aerial robotics is in an excellent phase of development and constitutes, for electronics and not only, an evolving and promising scientific field. The organization of aerial robotics essentially covers three phases. In Phase A, the topics of aerial robotics are mentioned, focusing on movement, as well as the types of robots that can be used in formal and informal sensing environments. In Phase B, the possibilities of programming moving robots in dynamic environments are presented, along with the issue of their programming. At the same time, the aim is to familiarize readers with flight environments and the capabilities that are integrated into the same application. In phase C, the sensing part is placed according to the relevant examples described in the article. Basically, in this study, the authors present three distinct types of mobile robots, each designed with varying levels of physical, technical, and cost-related complexity and equipped with different embedded software configurations. Although the text focuses on an interesting topic, several parts require substantial revisions to improve the clarity, structure, and overall presentation of your research. From the formal part of the paper, we note some specific comments that we consider important for improving the overall image of the publication.”

Thank you for your opinion

 

„Initially, we would say that authors should revise their introductory text as a whole. We recommend that they avoid excessive paragraphing, correctly number the references with a scale in accordance with the journal's proposals, and limit themselves to the academic context of scientific publications. We would suggest that they reconsider the functionality of the introduction and remove any information or data that can and should be presented later. The Introduction can extend to five pages but the following should be formulated as an introductory text: 1) the only framework of the problem, 2) the purpose of the researchers, 3) the scientific questions, 4) the research questions 5) the codified objective of the study, 6) the rough approach to the methodology, 7) the design tools and finally 8) the main findings, results and contribution. All this with simple, concise, and focused sentences. „

Thank you for your comment. The introduction has been edited. We hope that its current form meets the expectations of all the reviewers.

 

 

„There is no need for excessive paragraphing. A minimum of three paragraphs per page or page section is sufficient. At least three paragraphs per page or page section is sufficient.”

Thank you for your comment. We've revised our article in this regard. We've reduced the number of new paragraphs. The text in the first chapter has also been reduced.

 

„After the contributions, the authors should cite the individual chapters of the article with a precise description and justification. In this citation, they will explain in detail the connection between the parts and the scientific and research questions. In this particular article, as the development issues are not only interdisciplinary but also approach risk forecasts, we would strongly recommend a flowchart regarding the flow of the text.”

Thank you for your comment. Because our project is not yet complete, we anticipate making some modifications to the final block diagram, which represents a comprehensive approach to building a robotic threat detection system. Therefore, we wanted to avoid presenting a block diagram that is not yet final. If we absolutely must do this at this stage of the project, please provide more detailed information.

 

„We don't understand the gap from line 208 to 209. Is it the publisher's fault, or the writers' choices?”

This is an unintended effect – we will try to avoid such errors in the final version of the article.

 

 

„Between 2. "Threat detection system" (line 209) and 2.1 "Description of System Components and Structure" (line 210), write a short introductory text that will familiarize readers with the content of the chapter, and explain the separation of parts. In any case, (3-3.1) between the titles of the chapters and subchapters, a short introductory text should be written, which will concern the justification of the parts.”

Thank you for your comment. We have made changes to the article based on it.

 

„ Be careful with abbreviations. Explain acronyms everywhere before using them. We don't write "ANPR (Automated Number Plate Recognition)", but "Automated Number Plate Recognition" (ANPR), and then use the abbreviation where necessary. Note: at the end of the article, write down a table with all the abbreviations.”

Thank you for your comment. The changes have been made to the content. A table with essential explanations of the abbreviations used is included at the end of the article.

 

„Figure 2. Robot models used, type 1: (a) right side, (b) top view, (c) left side. Do not take the photo tag to another page. Move the text.”

Thank you for your comment. The final proof will be formatted according to the journal's guidelines.

 

„Describe the technical terms of photography. How were the photos taken?”

The photos were taken using a camera mounted on the robot. Technical details are less important for object detection than the ability to recognize it. Importantly, no additional lighting was used to capture the photos.

 

„Figure 8. Robot sensor diagram: What exactly do the microcontrollers?”

The diagram shows the modular structure of the sensor connections to the microcontroller inputs. This allows for changes to the sensor configuration, which is currently being tested.

 

„The whole 2.2 Incident probability needs more analysis.”

Thank you for your comment. Please let us know if you feel there are any elements of the description of the use of probability theory that need to be added.

 

„The transition from 2.2 to 2.3 is extremely abrupt for the reader. Place textual bridges.”

Following review comments, a few introductory sentences have been added at the beginning of Chapter 2.

 

„What is the meaning of "Vision technique"?”

This term refers to a method used in robots to detect threats based on visual recognition. A similar term is used for chemical detection: "Chemical technique." If such terms are incorrect, please explain why.

 

„In what ways was the diagram in Figure 9 created? What type of statistical analysis was applied? Explain everything. „

Figure 9 shows a histogram of the ground clearance height distribution for the analyzed group of 500 vehicles. The most popular models operated in the EU were selected for analysis. Based on this analysis, the maximum height of the robot that must fit under the vehicle was determined.

 

„Figure 11: It is impossible to accept such a long caption. Note something characteristic and transfer the rest.”

Thank you for this comment – ​​the description under the drawing has been shortened.

 

„Figure 12 and Figure 13, document justifications and references to construction tools are completely absent.”

Figures 12 and 13 show examples of fuel leak detection during robotic inspection. These results are obtained for simulated leaks.

 

„Figure 16 - Figure 20: The most important parts of the article are left significantly uncovered. Please provide details of the applied methodology, metrology, and weighting tools. Documentation measurements cannot be accepted without all of the above.”

Thank you for your valuable advice. The results presented in the article refer to raw readings from sensors used in our robots, which will primarily monitor the parking lot. Threat detection itself is not linked to determining the concentration of a hazardous substance. The difficulty lies in the fact that accidental leaks, such as fuel, can range widely, so we don't focus on determining the actual concentration value, but only on detecting a potentially hazardous substance. The applied probability analysis indicates the direction in which detection will proceed, minimizing false alarms.

 

„Table 2. Example of calculating the probability: how are those numbers calculated? „

Table 2 presents the results obtained using the formulas described in Section 2.2. This is an example showing how a parking lot threat assessment can be performed using raw results from robot sensors. It is important to note that a single detection can always be confirmed by neighboring robots to reduce detection errors.

 

„In the conclusions, they do not conclude. In addition to the detailed answers to the scientific and research questions, note the overall added value of the article, the difficulties in implementing parts of the research, and finally, suggestions for future research work.”

Thank you for your comment. A paragraph on the overall scientific value has been added to the summary.

 

Thank you again for all your valuable comments and suggestions.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The paper has been revised and it can be accepted

Author Response

Thank you very much for your acceptance of our article.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors of the article generously addressed our observations and comments, and through a structural restructuring of the article's content, rendered it in an acceptable form. The introduction has been edited, and the current form meets our expectations. The authors revised their article accordingly to our suggestions; they have reduced the number of new paragraphs, and the text in the first chapter has been reduced. The authors fixed the manuscript, photos, and diagrams. A new material and a new paragraph on the overall scientific value have been added to the end of the manuscript. 

      We believe that transforming the manuscript through targeted suggestions can make the article publishable.

Author Response

Thank you again for your previous tips and suggestions, which helped improve our article.

Thank you for accepting our article.