Precision Variable-Rate Spraying Robot by Using Single 3D LIDAR in Orchards
Round 1
Reviewer 1 Report
The manuscript presented matches the current situation of the spraying technology evolution that uses mobile platforms and technologies allowing variable rate application. The description of the technology used is enough detailed.
As a reviewer, I think the line between precision spraying and the technique provided on the manuscript is very thin. From my point of view, using Lidar systems and PWM valves, I could expected a PWM valve per each nozzle actuating independently.
Two main concerns appear to me reading the manuscript. First is the description of the spraying technology. It is no clear to me if there is only one single valve that controls the flow rate or there are several valves. And no information related to the nozzle is provided being very important to justify the spray distribution and loses.
The second concern is related to drift mythology. Please review the drift methodology used according ISO 22688. Last time I have used this methodology, the vertical poles must be placed at a distance of 5 and 10 meters of the edge of the row trees, and at least, 20 meters perpendicular to the edge of the field must be sprayed. Wind must be around 1 m/s perpendicular to the tree row.
In addition, in this ISO, measurements of ground drift must be taken. On the manuscript this measurements are not mentioned.
In this sense, I miss a lot of information regarding drift measurements and weather conditions allowing the acceptance of the trials.
If you are able to provide this information, please do it, if not, I suggest to remove this data or, at least, mention that the methodology is an adaptation of the 22866.
Last but not least, authors used many abbreviations that are used along the manuscript. I suggested to add a list of abbreviations and the meanings to facilitate the existence of the readers.
Particular comments are below:
L 187: MOS tube, what is it?
Section 2.4 Spraying Systems.
In this section, authors describe the spraying system. No information regarding forward speed or working width is provided. No information about the nozzles characteristics is provided. This is an important aspect to consider due to the influence on spray distribution, and as a consequence, quality of the VRA systems.
L211: full cone nozzles or hollow cone nozzles?
L212: piston pump instead of plunger pump
L240. Authors assume that in all air outlets, the air speed is around 20 m/s. Since my experience, I have never seen an axial fan providing a homogeneous air speed distribution across the section.
L371: you should mention how this 0.1 L/m3 is achieved.
L426: add the characteristics of the filter paper
L 446: I have never seen a methodology where authors used the filter papers with atrazine to assess spray coverage with a software as Dropletscan. Furthermore, I suggest to remove it as no references are included on the manuscript supporting this methodology of measuring spray coverage.
From 464 to 473, does not belong to results sections. Is part of methodology for the tests.
L 506: suggest to modify the title for: spray pesticide application
Table 3: the information provide in terms of Volume applied is insufficient. I suggest to add a volume rate in terms of volume/surface. This will allow to contextualize the application technology in orchard field.
L 514: the title of the section 5.3 is confusing. As I understand, the values expressed are related to coverage of the collector (sample) or to the number of droplet impacts per cm2. In both cases, the title must be modified i.e. Droplets impacted.
L 521: Sentence starts as “The percentage of DD on the inner side…..” indicates to me that authors are discussing about the percentage of coverage, but the truth is that they are discussing about Spray deposition on the collector. Try to be more precise on the description.
Table 5: the title of the table is insufficient. You must add how the values are expressed. How the deviation is expressed? As SEM? Standard deviation? Please, clarify it.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors address the problem that automatic navigation and precise variable spraying are not yet closely integrated. A single 3D LIDAR was used to implement automatic navigation and precise variable spraying. This has important implications for smart orchard operations. However, there are some problems in the authors' study.
(1) RTK GNSS was used to measure robot trajectory and fruit tree row position in the paper. How accurate RTK GNSS is, please check.
(2) The borders of the pictures in Figure. 2, Figure. 10 and Figure. 17 are missing, please check and correct them.
(3) In Figure 8, there is cluttered information, and the authors should check the format of the paper.
(4) In Figure 16, the text is too small, and the authors are requested to correct the images for the convenience of readers.
(5) The table header in Table 5 is in a different format from the headers of other tables, please check it.
(6) The spray in the keyword is suggested to be changed to spraying.
(7) The text of the label in Figure 1 is too large.
(8) In the second chapter, it is suggested that the author attach the URL of the module. Instead of writing the company and model number.
(9) The deflectors which are deflector1 and deflector8, deflector4 and deflector7 should be combined in Figure 3, but they are not in the figure.
(10) The red dotted line in Figure 17 should be above all icons.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear authors, I recognize the efforts carried out during the review.
I am still not comfortable with the description of the methodology to measure airborne drift. In fact the reference that supports the field test, is written on a language that I'm not able to understand, so it is difficult to verify the acceptance of this methodology to measure drift.
In this sense, you provide precise information in relation of the description of the electronic system, but regarding the methodology of drift measurements, it is no as precise. I suggest to add more detailed information as it is required on the ISO.
On the other hand, I have checked the information regarding the nozzles. First of all, the link provided on the manuscript does not work. So I checked the Teejet catalogue, and the information provided on the manuscript (L 222) does not coincide with the catalogue. What I have found is: nozzles disc and core D6 - DC56 at 5 bar is 5.9 L/min. Please review it
L 459: I think there is a typo error in " Nº6".
Author Response
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Author Response File: Author Response.docx
