Development of a Combined Orchard Harvesting Robot Navigation System
Round 1
Reviewer 1 Report
General comments
The paper reports the results on development and test of a dual robot, intended for apple harvesting.
In my opinion, the study’s topic is suitable for Remote Sensing. However, the paper needs to be more concise and organized among the different sections. In some cases, paper resulted to me either not easy to read nor clear. There are typographical errors along the text that suggest that the authors did not re-read the text submitted for review.
Specific comments
Abstract, lines 12-14. At the beginning of the abstract, Authors introduce the problem to solve, However, this problem is not discussed and deepen in the paper, with the exception of the last part of conclusions. Could the authors better explain this concept in the introduction?
Keywords: typographical errors (there are numbers).
Material and methods. The first part of this section should be moved to the Introduction.
Figure 2. This figure is similar to others (see for example fig. 17) and it is probably useless. Please, consider reducing the number of figures.
Line 277-278-279: check the references.
Lines 290-291. I don’t agree with this affirmation, also in agriculture and forest there are many studies.
Line 309: m/s2
Line 345: check the word “figure”
Line 396: check the reference
Figure 15 caption: (and Table1) Apple tree root diameter measurement is incorrect. I think you measured the trunk diameter at the soil level (=the diameter of the collar trunk).
Tables 2, 3, 4 and 5: summarize the results and remove the tables. Then, revise the text in discussion section according to the new presentation of the results.
Author Response
Dear reviewer:
I am very grateful for your comments on the manuscript on 17 Jan 2022. According to your advice, we amended the relevant part of the manuscript. Some of your questions were answered below.
1)
The reviewer’s comment:
Abstract, lines 12-14. At the beginning of the abstract, Authors introduce the problem to solve, However, this problem is not discussed and deepen in the paper, with the exception of the last part of conclusions. Could the authors better explain this concept in the introduction?
The author’s answer:
Thanks to the reviewer's comments, this section is explained in the study of the purpose of the study and the navigation model in the introduction.
It has now been changed to” As early as 2004, Noguchi et al. proposed the concept of master-slave navigation based on the combined harvesting method for hay in large fields, and he divided master-slave navigation into two modes: command navigation and follow navigation [13,14] And a review of the literature reveals that the earliest record of master-slave navigation robots in orchards is the orchard spraying robots proposed by Moorehead et al. in 2012, which used a centralized controller as the master and operated the spraying robots with commanded navigation in the planned operation area. Similarly, Gonzalez-de-Santos, et al. [15]， Kim et al. [16] first used a UAV to acquire ground information and then used command navigation ground-based on ground images to operate the ground robot along the planned operation path. Ju et al [17]used two UAVs and a ground robot to monitor the environment in an orchard, with the ground robot traveling ahead as the master and the UAV following as the slave, and the experimental results showed that the master-slave robot could maintain a stable formation under this navigation mode. These studies all use one navigation mode, either command navigation or follow navigation. In a single master-slave navigation mode, the robots can only achieve continuous path tracking or maintain a fixed formation, which is not very flexible.”
2)
The reviewer’s comment:
Keywords: typographical errors (there are numbers).
The author’s answer:
Because I was using a word template, the format of the sample in the template was keywords followed by numbers, which I thought was a requirement of the submission template, so I didn't remove it.
It has now been changed to” go to navigation; following navigation; autonomous combined harvesting; pure pursuit control”.
3)
The reviewer’s comment:
Material and methods. The first part of this section should be moved to the Introduction.
The author’s answer:
Thanks to the reviewer's comments, the section on the literature cited in Materials and Methods has been placed in the Introduction.
It has now been changed in lines 96-136 to” In terms of master-slave robot cooperative navigation, the problem of autonomous navigation of the master robot needs to be addressed first. The current research on autonomous navigation of orchard robots mainly focuses on automatic travel between rows of fruit trees, especially the use of light detection and ranging (LiDAR) to extract tree rows or detect trees and labels, among others, which is regarded as a reliable method of autonomous navigation. For example, Zhang, et al. [20] set the landmarks at the ends of the rows of fruit trees and used a laser scanner to detect the landmark information and build a local map of the orchard to ensure the robot's autonomy in the orchard. Bergerman, et al. [21] fused the 2D laser scanner, whee, and steering encoder sensor data, and then used the laser scanner to detect the landmarks at both ends of the orchard rows to realize the vehicle's straight and cross-row turns in the orchard……”.
4)
The reviewer’s comment:
Figure 2. This figure is similar to others (see for example fig. 17) and it is probably useless. Please, consider reducing the number of figures.
The author’s answer:
Thanks to the reviewer's comments, Figure 17 is indeed similar to Figure 2, which was intended to explain the overall design of the system more visually to the reader, and has been removed here due to the revised introductory section.
5)
The reviewer’s comment:
Line 277-278-279: check the references.
The author’s answer:
Thanks to the reviewers' comments. This is caused by cross-referencing, when using Word templates for typesetting drafts, some numbers and formulas were cross-referenced incorrectly. This error caused reading inconvenience due to my carelessness and has now been changed.
6)
The reviewer’s comment:
Lines 290-291. I don’t agree with this affirmation, also in agriculture and forest there are many studies.
The author’s answer:
Thank you for your suggestion, and I apologize for the error in the formulation of this sentence. It has now been changed in lines 335-344.to “In recent years, there have been a large number of studies on ground point cloud extraction and segmentation algorithms. For example, some scholars segmented ground point clouds based on the ground measurement model of LiDAR [45,46], or used RANSAC to fit the ground like a piece of a plane for segmentation [47-49], or distinguished ground and vegetation based on the threshold between ground point clouds [50] These methods are simple and effective to operate, but considering that the ground point cloud changes continuously above and below the horizontal plane when the robot is driving continuously in the orchard, the principle of clot simulation filter (CSF) algorithm [51] is more indicative of the current terrain features than the methods that rely on the height of laser beam and sensor or set thresholds.”
7)
The reviewer’s comment:
Line 309: m/s2
The author’s answer:
Thank you for your careful review, this symbol has been changed.
8)
The reviewer’s comment:
Line 345: check the word “figure”
The author’s answer:
Thank you for your careful review, which was caused by the formatting in the legend. All relevant figures in the text have been checked and similar issues have been changed together.
9)
The reviewer’s comment:
Line 396: check the reference
The author’s answer:
This has been changed as well as the previous cross-reference.
10)
The reviewer’s comment:
Figure 15 caption: (and Table1) Apple tree root diameter measurement is incorrect. I think you measured the trunk diameter at the soil level (=the diameter of the collar trunk).
The author’s answer:
Thank you for your patience. The description of the root diameter of apple trees in Fig. 15 (changed to Fig. 14) and Fig. 1 is an error in the author's choice of words in the translation. After checking books on fruit tree growing, a more accurate description here would be the ground diameter. I have replaced the vocabulary in Figure 14 and Table 1.
11)
The reviewer’s comment:
Tables 2, 3, 4, and 5: summarize the results and remove the tables. Then, revise the text in discussion section according to the new presentation of the results.
The author’s answer:
Thanks to the reviewer's suggestion, I have placed Tables 2, 3, 4 and 5 in the Supplementary Information and summarized the phenomena occurring in the data in the tables in the original results. Then the summarized phenomena were analyzed and discussed in the discussion. In addition, a table has been added to the additional material that includes the results of calculating the maximum, minimum, mean and standard deviation of the values in Table 3, Table 4 and Table 5.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper is interesting, easily comprehensible and relevant to the field of this journal. I would be happy to see it published. Before this, the authors should make some improvements to the manuscript in order to be suitable for publication.
English language and style are fine/minor spell check required.
The abstract does not provide the reader with information about the results obtained. It has not any numerical values. It needs to be improved, giving more numeric values for the results.
Avoid lumping references (e.g. [17-26]) and similar. Instead, summarize the main contribution of each referenced paper in a separate sentence and/or cite the most recent and/or relevant one.
The authors should change all the sentences in the text which are written in the first plural (lines 448, 452 and 455).
The Conclusion is not suitable, should give more useful conclusions. This section should include numerical values for the results.
Author Response
Dear reviewer:
I am very grateful for your comments on the manuscript on 17 Jan 2022. According to your advice, we amended the relevant part in the manuscript. Some of your questions were answered below.
1)
The reviewer’s comment:
English language and style are fine/minor spell check required.
The author’s answer:
I have improved some words, tense, and some of the sentences that do not make sense in the article, and I hope you will be satisfied when you see it
2)
The reviewer’s comment:
The abstract does not provide the reader with information about the results obtained. It has not any numerical values. It needs to be improved, giving more numeric values for the results.
The author’s answer:
Thanks to your suggestion, the abstract has been revised and the test results have been redescribed in the summary results section by adding maximum, minimum, mean, and standard deviation.
It has been changed to “The experimental results show that the data packet loss rate is less than 1.2% when the robot communicates in the orchard row within 50 m, which meets the robot orchard communication requirements. The master-slave robot can achieve repeated stops in the row using follow navigation, which meets the demand of joint orchard harvesting. The maximum, minimum, mean and standard deviation of the position deviation of the master robot is 5.3 cm, 0.8 cm, 2.4 cm, and 0.9 cm, respectively; the position deviation of the slave robot is larger than that of the master robot, with the maximum, minimum, mean and standard deviation of 39.7 cm, 1.1 cm, 4.1 cm, and 5.6 cm, respectively; the maximum, minimum, mean and standard deviation of the following error between the master-slave robot is The maximum, minimum, mean and standard deviation of the following error between master and slave robots are 4.4cm, 0cm, 1.3cm, and 1cm respectively. In the ground head turn, the command navigation method can turn continuously, but the lateral deviation between robots is more than 0.3 m and less than 1m, and the heading deviation is more than 10° and less than 90°”.
3)
The reviewer’s comment:
Avoid lumping references (e.g. [17-26]) and similar. Instead, summarize the main contribution of each referenced paper in a separate sentence and/or cite the most recent and/or relevant one.
The author’s answer:
Thanks to your suggestion, I have changed the references to the last 10 years and have given a brief description of the methodology for these references.
It has changed in line 96 -126 to” In terms of master-slave robot cooperative navigation, the problem of autonomous navigation of the master robot needs to be addressed first. The current research on autonomous navigation of orchard robots mainly focuses on automatic travel between rows of fruit trees, especially the use of light detection and ranging (LiDAR) to extract tree rows or detect trees and labels, among others, which is regarded as a reliable method of autonomous navigation. For example, Zhang, et al. [20] set the landmarks at the ends of the rows of fruit trees and used a laser scanner to detect the landmark information and build a local map of the orchard to ensure the robot's autonomy in the orchard…….”
4)
The reviewer’s comment:
The authors should change all the sentences in the text which are written in the first plural (lines 448, 452 and 455).
The author’s answer:
Thank you for your comments, I have revised the sentence with the first person plural.
It has changed in lines 493-494. to” To verify the reliability of information interaction of the combined harvesting robot in an orchard environment, based on the minimum tracking distance (0.35 m) between the two robots measured in the field and the longest distance (47.4 m) of the fruit tree rows in the test area, an orchard communication test of the combined harvesting robot was designed in this paper concerning the literature[55], and the test protocol is shown in Figure 15 (a).”
It has also changed in lines 504-508 to “Then, the number of packets received by the slave machine was checked and the packet loss rate was calculated. This test was repeated five times independently. The IP address of the master robot at the time of the test was 192.168.62.2, and the IP address of the slave robot was 192.168.62.30.”
5)
The reviewer’s comment:
The Conclusion is not suitable, should give more useful conclusions. This section should include numerical values for the results.
The author’s answer:
Thanks to the reviewer's suggestion, I have rewritten the conclusion section. The conclusion section now includes the methods, experimental results, and discussion, and you can see the quantitative experimental results in the conclusion.
It has also changed in lines 704-724 to “The experimental results show that the packet loss rate of the communication system is less than 1.2% when the interval distance of the joint harvesting robots is within 50m, which meets the communication requirements of the master and slave robots in the orchard. …… And the error value gradually decreases after changing the master-slave navigation method and can be used for in-row cooperative operations. The maximum value of the position error of the master robot is 0.053m, the minimum value is 0.008m, the mean value of the error is 0.024m, and the standard deviation of the error is 0.009m. The maximum value of the position error of the slave robot is 0.397m, the minimum value is 0.011m, the mean value of the error is 0.041m, and the standard deviation of the error is 0.056m. The safety distance between master and slave robots is basically within the set threshold (0.35 m), where the maximum value of the following error is 0.044 m, the mean value of error is 0.013 m, and the standard deviation of error is 0.01 m. ……..”.
Author Response File: Author Response.docx
Reviewer 3 Report
The content of the article is consistent with the scientific area of the Journal Remote Sensing. The subject raised by the authors is current and so far rarely noticed by other authors publishing in this area.
The paper has an original, scientific character: for a better clarification, please edit your paper as follows:
- Enlarge the Introduction with current results reported in the world and Europe
- define better the scientific results
- Improve the reference list
Author Response
Dear reviewer:
I am very grateful for your comments on the manuscript on 17 Jan 2022. According to your advice, we amended the relevant part in the manuscript. Some of your questions were answered below.
1)
The reviewer’s comment:
Enlarge the Introduction with current results reported in the world and Europe
The author’s answer:
Thanks to your suggestion, I did a literature search in Google Scholar and "Engineering Village" using keywords like "orchard collaboration", "orchard robot collaboration", and "orchard mobile robot communication". However, I could find very little literature related to the research work in this paper. Currently, I have placed the relevant literature I searched in the article.
In addition, I have placed the literature that was originally mentioned in Materials and Methods (based on suggestions from other reviewers) and have provided a brief review of that literature. I hope you will be satisfied with the changes made to this section.
For example, it has changed in lines 96-126 to” In terms of master-slave robot cooperative navigation, the problem of autonomous navigation of the master robot needs to be addressed first. The current research on autonomous navigation of orchard robots mainly focuses on automatic travel between rows of fruit trees, especially the use of light detection and ranging (LiDAR) to extract tree rows or detect trees and labels, among others, which is regarded as a reliable method of autonomous navigation. For example, Zhang, et al. [20] set the landmarks at the ends of the rows of fruit trees and used a laser scanner to detect the landmark information and build a local map of the orchard to ensure the robot's autonomy in the orchard…….”.
2)
The reviewer’s comment:
Define better the scientific results
The author’s answer:
Thank you for your comments. In the results and conclusions section of the text, the experimental results are summarized in terms of the maximum, minimum, mean, and standard deviation of the experimental data, and the experimental phenomena are described.
For example, It has been changed in the abstract. to “The experimental results show that the data packet loss rate is less than 1.2% when the robot communicates in the orchard row within 50 m, which meets the robot orchard communication requirements. The master-slave robot can achieve repeated stops in the row using follow navigation, which meets the demand of joint orchard harvesting. The maximum, minimum, mean and standard deviation of the position deviation of the master robot is 5.3 cm, 0.8 cm, 2.4 cm, and 0.9 cm, respectively; the position deviation of the slave robot is larger than that of the master robot, with the maximum, minimum, mean and standard deviation of 39.7 cm, 1.1 cm, 4.1 cm, and 5.6 cm, respectively; the maximum, minimum, mean and standard deviation of the following error between the master-slave robot is The maximum, minimum, mean and standard deviation of the following error between master and slave robots are 4.4cm, 0cm, 1.3cm, and 1cm respectively. In the ground head turn, the command navigation method can turn continuously, but the lateral deviation between robots is more than 0.3 m and less than 1m, and the heading deviation is more than 10° and less than 90°.”
3)
The reviewer’s comment:
Improve the reference list
The author’s answer:
Thank you for your comments. References and cross-references to tables, formulas, and figures have been updated.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
None
