Design and Research Sowing Devices for Aerial Sowing of Forest Seeds with UAVs
Round 1
Reviewer 1 Report
The authors have investigated the practical use of UAVs as seed planters to both authomate and expedite the seed planting process.
The work carried out will be of great significance to both commercial and subsistence farm practice.
The topic explores and exploits the current trends of finding new applications for autonomous machines and vehicles. This is a novelty in and of itself; hence, the patenting of the UAV payload designs as detailed in the paper.
It opens up new queries about the use of collaborative UAVs for seed planting. This is a topic many UAV and UAS researchers will be keen on investigating.
A suggestion:
In Section 2.3, the details in Table 1 and lines 265 to 314 appear to be somewhat similar. Table 1 can be made more self-contained so that lines 265 to 314 be can either be better summarised (i.e., shortened) or removed completely to avoid redundancy.
Author Response
Response to Reviewer 1 Comments
Point 1:
A suggestion:
In Section 2.3, the details in Table 1 and lines 265 to 314 appear to be somewhat similar. Table 1 can be made more self-contained so that lines 265 to 314 be can either be better summarised (i.e., shortened) or removed completely to avoid redundancy.
Response 1:
In accordance with the comment of the reviewer, the text was shortened to avoid duplication of information.
Line 294-312.
Concept 1 used central shutter mechanism has a high speed of action and in the open state forms an almost round hole. This enables batch feeding by periodically opening and closing the metering mechanism. Sowing material of various sizes and shapes can be used, including mixtures of seeds of different size groups. The uniformity of distribution is low and a mixing mechanism is required for poorly flowing seeds.
Concept 2 can be equipped with various types of roller, which allows it to be used for sowing small and medium seeds. Provided that the mixing mechanism is installed, it can work even with unfinished seeds. Carries out row sowing with seed distribution only due to the forces of gravity and the movement of air masses. With a high simplicity and reliability of the design, it can cause damage to seeds and their artificial covers.
Concept 3, through the use of an air flow distribution mechanism, significantly improves the uniformity of distribution and the width of the sowing strip. At the same time, with an increase in the weight of seeds, the efficiency of distribution decreases markedly. Energy consumption and weight of the structure are increased due to the need to install an additional motor that creates an air flow in the distributor.
Concept 4 has a centrifugal distributor that ensures even distribution and significantly increases the width of the sowing strip. Energy consumption and weight of the constructions are also increased due to the installation of an additional motor that rotates the spreader disc.
Сoncept 5 can be used for sowing small and medium-sized seeds that are sufficiently uniform in size. The main disadvantage is the need to create a vacuum, without which the construction becomes completely inoperative, as well as the complexity of additional acceleration of seeds.
Сoncept 6 has a simple and reliable design that does not require a vacuum. Has a wide range of sown seeds in size and shape. The distribution system is also gravitational.
Concept 7 differs in that it has a pneumatic system that gives the seeds the additional acceleration necessary to penetrate into the surface layer of the soil. The uniformity of seed distribution in the row also increases significantly. It is used only with special pelleted seeds of a spherical shape with slight deviations in size and shape.
Concept 8 has an optional vacuum seed capture system. This improves the uniformity of sowing. At the same time, in contrast to concept 5, the sowing device remains operational even in the absence of a vacuum source, working like a sowing device 7. It is also used only with special pelleted seeds of a spherical shape with a slight variation in size.
Reviewer 2 Report
The presented paper discusses the development of sowing devices for drone-based reforestation of hard-to-reach and difficult-to-access areas.
The paper sounds interesting, but the authors can consider the following points:
- The script is unclear and not well-organized (the current state of the article is more similar to a technical report).
- There are many broken sentences and paragraphs.
- The article's layout should be improved.
- Figures 1 and 2 should be changed to make them more presentable. Also, it seems they are from presentation slides.
- Figure 3 and Figure 4 : it would be better if more information are added into the mentioned figures; they only show the shapes of the seeds.
- Table 4 is unclear.
- The style of Figure 20 should be aligned with the rest of the paper.
- In the reference section, the format of citations should be improved.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The work is interesting but it is incomplete. The authors explain in great detail their concept and all the related simulations, but the work lacks validation. In my opinion, a field experiment using a built prototype must be performed and presented in the same paper otherwise the functionality of the designed device can hardly be assessed.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear authors, thank you for the opportunity to get acquainted with the manuscript of the article. The initial interest in the annotation of the research topic, stated by the authors, was indeed confirmed by a sufficiently high-quality article.
Before proceeding with recommendations to improve the quality of the results provided, please pay attention to the following note (duplicated and for editors), - Special note: Please check the application number PI2020005912, - as there is already another publication mentioning this number. Although this may be just a coincidence [https://www.mdpi.com/2411-5134/6/2/38/htm].
Suggestions and recommendations for improving the manuscript of the article:
1) Without denying the importance of the statements indicated by the authors in the field of ecology in general, it is possible that the issue of aerial seeding by UAVs should be presented more specifically in the introduction.
a) Methods of reforestation. The role and place of the methods used by the authors in comparison with other known methods. It is advisable to indicate both strengths and weaknesses for identifying significant limitations to focus on implementation problems.
b) The authors claim that an extremely limited number of specialized devices are available to them to solve new problems. A more detailed patent review should be conducted, since the topic has extensive development (for example, - URL: https://airseedtech.com / ;
as well as direct examples with subsequent clarifications, -
< https://patents.google.com /?q=UAV+Seeder&oq=UAV+Seeder >).
c) More clearly highlight the key purpose of the work - the implementation of which unique function is proposed by the authors.
2) The abstract should be reduced to be within 200 words maximum.
At the same time, one should not superficially combine the problematic issues of the development of specialized devices (that is, adapted for UAVs) and their subsequent implementation. Since the number of subsequent implementation tasks using UAVs in practice is much more than is considered in this work.
At the same time, it is important to present strong arguments for the discussion of the main results in a balanced and convincing way.
3) Engagement with sources as well as recent scholarship. Also, the authors should pay attention to the review of works previously published in the MDPI publishing house on selected and related issues (even with a more detailed consideration of the tasks, - for example, "Design and Experimentation of an Aerial Seeding System for Rapeseed Based on an Air-Assisted Centralized Metering Device and a Multi-Rotor Crop Protection UAV", DOI 10.3390/app10248854 [https://www.mdpi.com/2076-3417/10/24/8854]).
It may well make sense to indicate the existing experience of your university, including previously obtained patents. Along with the "Federal State Budgetary Educational Institution of Higher Education "Voronezh State Forestry University named after G.F. Morozov"", the organization "Federal State Budgetary Educational Institution of Higher Professional Education "Kuban State Agrarian University"" has comparable experience on current patents in this topic. … and many others.
4) Academic Soundness. Discrete Element Method (DEM) was used to simulate the workflow. This will require supplementing the paper with a section (subsection), a more detailed literature review on the current state of knowledge in this scientific area.
The authors are recommended to disclose in more detail the question with an emphasis on novelty: whether this and other applicable new methods are described in sufficient detail to allow any other competent researcher to reproduce these results for tasks in their chosen industry.
5) The authors claim many additional possibilities for the use of UAVs in forestry in general. - That's right. However, even though the use of drones for the needs of forestry improves some indicators (this is more significant where there is no need to contact harmful substances), in many countries there are bans on spraying fertilizers from the air, as well as laws to combat terrorism that do not allow drones to transport cargo. First of all, we are talking about limiting the range of the UAV flight within the line of sight. This means that the costs of manufacturing and using new devices may be unreasonably high in comparison with traditional methods.
In this regard, it should be most advantageous to present the broader contribution of the authors to the development of the problem of the use of UAVs for the agricultural industry in the context of the multifunctionality-specialization dilemma.
6) The feasibility study of innovation is of immutable importance in patenting. So, even in the Russian market there are analogues. In particular, the hexacopter "OSA HEXA S-1" is designed for automated seeding or spreading of granular fertilizers and other substances. As declared by its developers, it can also be used for ultra-early sowing of small-seeded cold-resistant crops, including forage grasses, as well as for early spring fertilizing of winter crops with nitrogen mineral granular fertilizers [https://russiandrone.ru/catalog/bespilotnye-kompleksy/multirotornye/kopter-seyalka-osa-hexa-s-1/]. And this is just one of many products on the market.
- How are the developments proposed by the authors better? [- URL: https://youtu.be/IaJzMf1FyDc].
… As a result, the seeding machine most suitable for a specific given technology was selected. So, taking account the specific result, namely, "row sowing of pelleted seeds with penetrating into the surface soil layer", the authors are invited to consider other options and more correctly formulate the title of the article per its content (of course, within the generalization of practical significance).
Comments for author File: Comments.pdf
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thank you for the author's response.
Reviewer 3 Report
The authors mostly disagreed with my remarks and did not carry out the changes/improvement requested. The manuscript remains incomplete and insufficient for publication. I insist that the authors should improve their work following my suggestions given in the first round of review.
