Hostile UAV Detection and Neutralization Using a UAV System
, Andrius Laučys 1, Paulius Ragulis 1, Rimvydas Aleksiejūnas 1, Karolis Stankevičius 1, Martynas Kinka 1, Matas Razgūnas 1, Domantas Bručas 2,3, Dainius Udris 4 and Raimondas Pomarnacki 4,*
Round 1
Reviewer 1 Report
The paper presents a solution for detecting aerial, land or marine elements, based on the integration of a radar system on a fixed-wing drone. It thus adds a complementary solution for the neutralization of intruder drones. The work is based on a patent registered by the authors on 30 July 2022. The work needs to be more detailed in some points of the document, especially in the description of the field experiment conducted and the results obtained. It presents an applicable solution that can be improved in different aspects through future modifications, integrations and developments.
Summary. The abstract should be rewritten in a way that more clearly indicates the experiment developed.
Line 17 “the smallest of which are privacy invasion or flights above crowded areas”. It is a value judgement, it does not seem appropriate in the introduction.
Line 18. “Much more damage…..”, I rewrote the sentence, UAVs can do a lot of damage but I don't see the right way to introduce it, maybe the consequences of an accident with UAVs in an airport could involve fatalities and a lot of material damage...
Line 30. “Means of neutralization are reviewed in [5, 7, 8]” Sería conveniente ampliar sobre el contenido de estas referencias o al menos dar más detalle de ello.
Line 48 “Detection (up to 150 m range) of small UAVs from the ground using mm-wave MIMO radar was presented in the work of the authors of [9].”. Another way to introduce the contributions of a work can be: In Klare, J. et al, lograron la detection, up to 150 m range, of small UAVs from the ground using mm-wave MIMO radar. Please note in the manuscript
Line 49-51. Does it work over long distances? How much effectiveness does the system lose? Is not clear from the sentence.
Line 57. It would be useful to expand the content of the work [17].
Line 93. “The ability to detect UAVs….” It would be interesting to elaborate further on the content of the above-mentioned reference, proposal and conclusions at least.
Figure 9. The "Hunter drone" has not been shown in pictures 4 and 5, it is clear from the paragraph in lines 221-231 that this integration has not been effective in the developed prototype. This should be made clear in the document from the beginning. In the document it is stated that the experimental drone weighs 25 kg, had the weight of the "Hunter drone" been taken into account, this is a key factor in terms of operability, it is a question that needs to be discussed.
Experimental Results.
· Does not detail the flight parameters (flight altitude or route) of both the drone developed by the authors and the drones they intend to identify. Neither the size of these drones nor the type of route they were flying, whether they were in recreational or programmed flight, etc., are specified. These details are important in order to establish the range of use of the spy drone. An important factor would be to have carried out tests with both fixed wing and multi-rotor intruders in different types of flights and to the maximum of their capabilities in the event of evasive manoeuvres to avoid being identified or shot down. The number of drones detected is not detailed, nor is there a statistical summary of the results, it is only mentioned that drone detection is improved by integrating elements in the wings of intruder drones, this should be detailed and the number of drones detected, not detected, etc. should be explained. These aspects should be integrated in the manuscript to show more detail of the experiment performed, as well as the positive and negative results and proposals for improvement.
· At the beginning of the paper it is stated that the experiment tested a spy drone carrying a hunter drone. In fact, on the one hand a spy drone was developed and on the other hand a hunter drone solution was tested with commercial equipment; this should be clear from the summary. It is clear that a combined option of both drones can be developed, but this was not the case in the work presented.
· At this point, mention should be made of the flight mode of the hunter drone, mentioned in the discussion section.
Conclusions (and general comments)
· The paper presents a solution for intruder drone detection but in the conclusions it mentions marine surveillance against different intrusions as the first item of use. This point is interesting and can be a correct use of the technology. I suggest modifying the document and presenting a surveillance drone beyond monitoring intruder drones or other elements.
· It also talks about other monitoring and geomatics applications. This point is interesting because current lidar systems are not carried on fixed-wing drones, so map production is limited to the autonomy and flight capacity of the multirotors. The accuracy of the coordinates acquired is very important here, and if the order of magnitude is known, this should be included.
· The possibilities for improvement and advances are important, both in accuracy and in the placement of the radar sensor, the decrease in weight or the integration of the hunter drone, this can be highlighted.
· In the item "It is possible to use UAVs up to 20 kg mass" I suggest indicating the mass of 25 kg, as this is the mass indicated throughout the document and also the legal limit of the category in which it would be implemented. You could also add "In a UAV in the 10 to 25 kg category".
Author Response
Review Report 1 (Round 1)
- Reviewer. The abstract should be rewritten in a way that more clearly indicates the experiment developed.
Answer. Thank You for Your useful comments. The abstract has been updated.
- Reviewer. Line 17 “the smallest of which are privacy invasion or flights above crowded areas”. It is a value judgement, it does not seem appropriate in the introduction.
Answer. The sentence has been changed to “like privacy invasion or flights above crowded areas.”
- Reviewer. Line 18. “Much more damage…..”, I rewrote the sentence, UAVs can do a lot of damage but I don't see the right way to introduce it, maybe the consequences of an accident with UAVs in an airport could involve fatalities and a lot of material damage...
Answer. The sentence has been changed to “Lots of damage can be done by UAVs …”
- Reviewer. Line 30. “Means of neutralization are reviewed in [5, 7, 8]” Sería conveniente ampliar sobre el contenido de estas referencias o al menos dar más detalle de ello.
Answer. The sentence has been changed to “The possibilities to neutralize the detected drones are examined in [6,13,14].”
- Reviewer. Line 48 “Detection (up to 150 m range) of small UAVs from the ground using mm-wave MIMO radar was presented in the work of the authors of [9].”. Another way to introduce the contributions of a work can be: In Klare, J. et al, lograron la detection, up to 150 m range, of small UAVs from the ground using mm-wave MIMO radar. Please note in the manuscript
Answer. The sentence has been updated to “In [15] the authors achieved detection up to 150 m range of small UAVs from the ground using mm-wave MIMO radar.”
- Reviewer. Line 49-51. Does it work over long distances? How much effectiveness does the system lose? Is not clear from the sentence.
Answer. We are sorry, but we cannot provide such information, as the referenced article did not mention anything regarding this issue.
- Reviewer. Line 57. It would be useful to expand the content of the work [17].
Answer. The article has been updated.
- Reviewer. Line 93. “The ability to detect UAVs….” It would be interesting to elaborate further on the content of the above-mentioned reference, proposal and conclusions at least.
Answer. The article has been updated.
- Reviewer. Figure 9. The "Hunter drone" has not been shown in pictures 4 and 5, it is clear from the paragraph in lines 221-231 that this integration has not been effective in the developed prototype. This should be made clear in the document from the beginning. In the document it is stated that the experimental drone weighs 25 kg, had the weight of the "Hunter drone" been taken into account, this is a key factor in terms of operability, it is a question that needs to be discussed.
Answer. The article has been updated. “killer drone” has been changed to “hunter drone.”
The detailed description of the “hunter drone” is given in line 274. Now the parts of the text connected in one chapter.
As described in the original lines 274-278, the hunter drone in the described experiment is mounted on the different “Spartan” UAV (which is slightly smaller than the radar carrier UAV), but it can be mounted on the radar carrier UAV in the future (if required).
- Reviewer. Does not detail the flight parameters (flight altitude or route) of both the drone developed by the authors and the drones they intend to identify. Neither the size of these drones nor the type of route they were flying, whether they were in recreational or programmed flight, etc., are specified. These details are important in order to establish the range of use of the spy drone. An important factor would be to have carried out tests with both fixed wing and multi-rotor intruders in different types of flights and to the maximum of their capabilities in the event of evasive manoeuvres to avoid being identified or shot down. The number of drones detected is not detailed, nor is there a statistical summary of the results, it is only mentioned that drone detection is improved by integrating elements in the wings of intruder drones, this should be detailed and the number of drones detected, not detected, etc. should be explained. These aspects should be integrated in the manuscript to show more detail of the experiment performed, as well as the positive and negative results and proposals for improvement.
Answer. The article has been updated.
Precise research of the catching of hostile drone probability was not in the scope of this work, the main focus was on the proof of concept, and further research will follow. Nonetheless, according to the experiments performed, it might be stated:
- The UAV vehicles flying at the speed of up to 120 km/h can be caught;
- Altitude of the target vehicle doesn’t play a major role in catching;
- Evasive maneuvers by the hostile vehicle were not considered, since it was assumed that the interception should take place at long distances without hostile drone operator physically observing the action, i.e. hostile drone being controlled in automatic mode or over FPV.
- From the number of experiments which were performed, for the moment it might be stated that is takes 2-3 tries to catch the hostile drone (though those results are preliminary).
The number of the drones detected by the radar is not limited by any means. The detection of the drone or a fixed vehicle detection is in details analyzed (by the same authors) in the paper [11]
- Reviewer. At the beginning of the paper it is stated that the experiment tested a spy drone carrying a hunter drone. In fact, on the one hand a spy drone was developed and on the other hand a hunter drone solution was tested with commercial equipment; this should be clear from the summary. It is clear that a combined option of both drones can be developed, but this was not the case in the work presented.
Answer. The article has been updated.
- Reviewer. At this point, mention should be made of the flight mode of the hunter drone, mentioned in the discussion section.
Answer. The article has been updated.
- Reviewer. I suggest modifying the document and presenting a surveillance drone beyond monitoring intruder drones or other elements.
Answer. The article has been updated. The following sentence was added to the Discussion section: “The radar embedded into the fixed wing vehicle can be used for tracking other objects too, especially maritime vehicles.”
Yes, the surveillance drone can monitor other vehicles too (especially maritime vehicles), nonetheless, the goal of this particular work is tracking and neutralizing other UAV vehicles.
- Reviewer.The accuracy of the coordinates acquired is very important here, and if the order of magnitude is known, this should be included.
Answer. Authors decided to not include information related to GNSS coordinates receivers and accuracy. If Reviewer decides, authors would add it to experimental setup and discussion sections.
Two ArduSimple RTK2B boards with uBlox ZED-F9P were used in the moving base scenario to obtain heading and position data. GNSS Antennas of the RTK GPS modules were placed on 20 cm x 20 cm square metal plates on each end of the airplane’s wing as recommended by uBlox [https://content.u-blox.com/sites/default/files/ZED-F9P-MovingBase_AppNote_%28UBX-19009093%29.pdf]. Baseline between antennas was around 2.5 meters which is enough to achieve more than 0.3 deg heading accuracy [https://content.u-blox.com/sites/default/files/ZED-F9P-04B_DataSheet_UBX-21044850.pdf]. Heading direction this method is calculated as a line from Base antenna to Rover antenna, therefore it needs to be rotated by 90 degrees to face the front of the plane. Roll values were obtained from the airplane's autopilot module. Heading, roll and position data were collected at 10 Hz rate in the Raspberry Pi computer, stored and sent to the ground station laptop together with the data from the radar. Microhard nVIP5800 pair was used as a long range Wi-Fi 5.8GHz datalink with the ground station laptop. A slightly modified Open-source software OpenCPN with a radar-pi plugin [https://github.com/opencpn-radar-pi/radar_pi] was used to control the radar and to draw and observe its data in real time.
Block diagram of winged-radar system.
- Reviewer. The possibilities for improvement and advances are important, both in accuracy and in the placement of the radar sensor, the decrease in weight or the integration of the hunter drone, this can be highlighted.
Answer. Dear reviewer, further development and modification should be performed in future research:
- redesigning the airframe of the radar carrier vehicle: moving the wing with the radar constructively higher or to the side of fuselage to decrease the interference with the fuselage itself;
- redesigning the radar unit to decrease its mass;
- installing the hunter drone on the same vehicle as the radar (implementing the same concept with the magnet held drone, which proved itself reliable and simple enough);
- performing additional tests on the vehicle neutralizing, using different vehicles at different conditions, controlled in different modes.
These results will be presented in a future article and the results will be compared with those of this article.
- Reviewer. In the item "It is possible to use UAVs up to 20 kg mass" I suggest indicating the mass of 25 kg, as this is the mass indicated throughout the document and also the legal limit of the category in which it would be implemented. You could also add "In a UAV in the 10 to 25 kg category".
Answer. The article has been updated. It is a technical error. Yes, it should be 25 kg.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript puzzled me very much. The title of the manuscript is a concept, which makes the reader think it is a theoretical research paper, but the author gives a lot of experimental parts. This should be adjusted.
At the same time, the manuscript lacks a global map. In fact, the author proposes a method of integrating the radar antenna and the wing of the fixed wing UAV to reduce the load. At the same time, in the experimental part, the author proposes to use the airborne rotor UAV with better mobility to carry out the final reaction.
The author needs to rewrite and comb the manuscript. In particular, the experiment part needs to be subtitled. Enhance the logic of the experiment.
Overall, the manuscript is quite innovative, but needs to be rewritten. Focus on the innovation and logic of the article. I think with such innovation and rich experiments, the article should be more perfect.
Author Response
Review Report 2 (Round 1)
- Reviewer. This manuscript puzzled me very much. The title of the manuscript is a concept, which makes the reader think it is a theoretical research paper, but the author gives a lot of experimental parts. This should be adjusted.
Answer. Thank You for Your useful comments.
From the authors’ point of view, the investigation of the concept involves both the theoretical research and practical proof of concept of the ideas. As can be seen from the paper, the practical part focuses on the proof of the concept of the theoretical ideas without moving to the possible product (which requires much more researches to develop).
Authors propose a new article title:
“Hostile UAV detection and neutralization using a UAV system”
- Reviewer. At the same time, the manuscript lacks a global map. In fact, the author proposes a method of integrating the radar antenna and the wing of the fixed wing UAV to reduce the load. At the same time, in the experimental part, the author proposes to use the airborne rotor UAV with better mobility to carry out the final reaction.
Answer. The article has been updated.
The radar is integrated into the fixed wing UAV to reduce the weight, size, increase endurance etc. The vehicle with the radar is supposed to have long range, long endurance high speed. Agility is not an important issue in this case.
For the physical neutralizing of the hostile UAVs, agility is critical. Therefore, for the final part of the mission – physical neutralizing of the hostile UAV, a small multirotor vehicle (carrying catching equipment) is used. This multirotor vehicle does not carry any radar.
- Reviewer. The author needs to rewrite and comb the manuscript. In particular, the experiment part needs to be subtitled. Enhance the logic of the experiment.
Answer. The section of Experimental results has been updated.
- Reviewer. Overall, the manuscript is quite innovative, but needs to be rewritten. Focus on the innovation and logic of the article. I think with such innovation and rich experiments, the article should be more perfect.
Answer. The article has been significantly updated.
Author Response File: Author Response.docx
Reviewer 3 Report
Dear authors,
I believe that your manuscript can be published in the "Drones" journal after making the changes mentioned below in the text. You presented an extremely interesting idea of radar integration on a UAV, however, the presentation of the results themselves could be done better. Please, make the following suggestion..
The title should be grammatically checked, I think it is a bit clumsily composed, and formatted in accordance with the journal's instructions...
· Line 5 - The problem of conventional means of neutralization IS short range - correct it
· Line 7 - “2m” to “2 m”
· Line 8 - “into” or “on the” - check which meaning is more accurate
The abstract should contain a few sentences about the results and contribution of the research. In this case, this has been left undefined. Authors must expand the abstract with a few sentences about methodology, research results, contribution, and/or future research.
· Add literature for line 15 “extremely complex scientific or military applications”
· Line 25 - remove double-space
· Line 27 - “suggested in the world” is unnecessary. Delete it.
· Line 27 - “4” replace with “four”
· Line 28 - 29 - “optical in various bands, passive acoustic, passive radio - receiving emitted radio radiation from UAV, and active radio- using radars.” Number each method like this: “(a)”, (b)”, “(c)”, and for each method add literature/papers where that specific method is analyzed.
· Line 47 - MIMO acronym is here the first time mentioned. Please define it.
· Line 53 - replace “drones” with “UAV”
· Line 56 - 65 - This subchapter needs a detailed grammar check. The authors have a good idea, but they don't communicate it effectively. The sentences are sometimes disjointed.
· Line 71 - “The paper is structured in the following manner…
· Line 75 - 77 - Please, restructure this sentence to be grammatically correct.
· Line 77 - remove double space
· Line 85 - 86 - Add examples or literature for this “Radars currently implemented on UAVs are heavy, bulky, expensive or not effective for large distances.”
· Line 102 - 103 - “using is mentioned two times in one sentence, restructure the sentence.
· Line 194 - check double space
· Line 201 - correct “in” into “In”
· Line 201 -“the authors do not go into” rephrase this
· Line 255 - the sentence is unclear
· Line 317 - “minimisation task3” - correct this
Author Response
Review Report 3 (Round 1)
- Reviewer. The title should be grammatically checked, I think it is a bit clumsily composed, and formatted in accordance with the journal's instructions...
Answer. Thank You for Your useful comments. The article title has been updated.
Authors propose a new article title:
“Hostile UAV detection and neutralization using a UAV system”
- Reviewer. Line 5 - The problem of conventional means of neutralization IS short range - correct it
Answer. The article sentence has been updated to “The main problem of conventional UAV countermeasures is the short detection and neutralization range.”
- Reviewer. Line 7 - “2m” to “2 m”
Answer. This has been updated.
- Reviewer. Line 8 - “into” or “on the” - check which meaning is more accurate
Answer. The sentence has been updated to “embedded into the wing.”
- Reviewer. The abstract should contain a few sentences about the results and contribution of the research. In this case, this has been left undefined. Authors must expand the abstract with a few sentences about methodology, research results, contribution, and/or future research.
Answer. The article abstract has been updated to:
The technologies of Unmanned Aerial Vehicles (UAVs) saw extremely rapid development in recent years. UAV technologies are developing much faster than means of their control. There are many means of UAV detection and neutralization suggested in the world, nonetheless, all of them have serious disadvantages. The essential problem in the detection of UAVs is – the small size of UAVs, weak radio wave reflection, weak radio signal and sound emitting The main problem of conventional UAV countermeasures is the short detection and neutralization range. Authors propose the concept of the airborne counter-UAV platform with radar. We use low-cost marine radar with a high resolution 2 m wide antenna, embedded into the wing. Radar scanning is implemented by changing the attitude of aircraft. For the countermeasures authors suggest to use a small rotorcraft UAV carried by a bigger fixed-wing one. A mathematical model that allows to calculate the coordinates of the detected drone while scanning the environment in a moving UAV with radar was created. Furthermore, the results of integrated radar performance with a detected drone and the results of successful neutralization experiments of different UAVs were achieved.
- Reviewer. Add literature for line 15 “extremely complex scientific or military applications”
Answer. An additional reference has been added.
- Reviewer. Line 25 - remove double-space
Answer. The article has been updated.
- Reviewer. Line 27 - “suggested in the world” is unnecessary. Delete it.
Answer. The article has been updated.
- Reviewer. “4” replace with “four”
Answer. The article has been updated.
- Reviewer. Line 28 - 29 - “optical in various bands, passive acoustic, passive radio - receiving emitted radio radiation from UAV, and active radio- using radars.” Number each method like this: “(a)”, (b)”, “(c)”, and for each method add literature/papers where that specific method is analyzed.
Answer. The reference list and article have been updated.
- Reviewer. Line 47 - MIMO acronym is here the first time mentioned. Please define it.
Answer. The article has been updated.
- Reviewer. Line 53 - replace “drones” with “UAV”
Answer. The article has been updated.
- Reviewer. Line 56 - 65 - This subchapter needs a detailed grammar check. The authors have a good idea, but they don't communicate it effectively. The sentences are sometimes disjointed.
Answer. The article has been updated.
Our proposed idea is integrating a radar into a UAV and turning the unmanned aircraft into a radar itself. A similar concept is most widely studied in [23]. However, our proposed case will scan the area in a 360-degree rotation like a conventional ground-based radar, thus leaving no blind spots. An additional solution is integrated to allow to track and disrupt the mission of detected drones, and in the best case, physically neutralize the unwanted drone. There are not many studies of systems that use drones to track and eliminate other drones, and as an example, the control concept for the drone swarm is presented [5], in which a swarm of drones surrounds the intruder and can limit the intruder’s operational capabilities more safely, but this is only implemented at the level of conceptual and control algorithms.
- Reviewer. Line 71 - “The paper is structured in the following manner…
Answer. The paragraph has been updated to:
The paper is structured in the following manner: A mathematical model of the detected UAV coordinates estimation, UAV embedded radar solution, experimental setup, results with discussion and conclusions. In the paper authors reveal the characteristics of implementing the countermeasure system and the results obtained.
- Reviewer. Line 75 - 77 - Please, restructure this sentence to be grammatically correct.
Answer. The paragraph has been updated to
In this paper, the authors want to present a solution that allows integrating the radar into a fixed-wing UAV structure, thus not adding radar externally to the plane, but building the radar into the plane structure and performing the rotation of the radar by maneuvering the plane itself.
- Reviewer. Line 77 - remove double space
Answer. Thank You for Your useful comments. The article has been updated.
- Reviewer. Line 85 - 86 - Add examples or literature for this “Radars currently implemented on UAVs are heavy, bulky, expensive or not effective for large distances.”
Answer. Sentence and reference updated as “Radars currently implemented on UAVs are heavy, bulky, expensive [27] or not effective at long distances (X band radars)”
- Reviewer. Line 102 - 103 - “using is mentioned two times in one sentence, restructure the sentence.
Answer. The sentence updated to: “The methodology for the determination of all three coordinates of the target using simple 2D radar with a special flat curved flight pattern has been presented in the co-authors’ patent application [20].”
- Reviewer. Line 194 - check double space
Answer. The article has been updated.
- Reviewer. Line 201 - correct “in” into “In”
Answer. The article has been updated.
- Reviewer. Line 201 -“the authors do not go into” rephrase this
Answer. The sentence has been updated to: “In this paper, authors presents only general information about the used antenna. A antenna model simulation results shown in Fig. [8]”
- Reviewer. Line 255 - the sentence is unclear
Answer. The sentence has been updated to: “As a result, it can be seen that the data obtained from the developed radar and the AIS system exactly match after their images are combined.”
- Reviewer. Line 317 - “minimisation task3” - correct this
Answer. The sentence has been updated to: “in proposed expression 3.”
Author Response File: Author Response.docx
Reviewer 4 Report
The paper is well written and can be published in present form.It will be helpful for the readers if the authors can descript the caption of figure1 from(a) to (c) in the text.
Author Response
Review Report 4 (Round 1)
Reviewer. The paper is well written and can be published in present form. It will be helpful for the readers if the authors can descript the caption of figure1 from(a) to (c) in the text.
Answer. Thank You for Your useful comments. The caption description of Figure 1 has been updated.
Figure 1. Fixed-wing UAV with embedded radar possible manoeuvring routes, where (a) – periodical UAV scanning-circling in-route, (b) – half circle rotation with 180o degrees scanning in-route, and (c) – 90o degree scanning in flight direction with quick turns of UAV
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The review has been satisfactory. The modifications allow a better understanding of the whole document, clarifying the initial doubts.
Congratulations
Best regards
Reviewer 2 Report
My problem has been basically solved. In general, the article is very practical. The team made the prototype and carried out experiments. But I always feel that the author should write better, which may be shown in future achievements. thank you!
