Study on Pulling Dynamic Characteristics of White Radish and the Optimal Design of a Harvesting Device

Round 1

Reviewer 1 Report

To optimize the structure of the harvesting device and improve the performance of the harvesting operation, according to the growth characteristics of white radish in the field, the discrete element method (DEM) was used to simulate the pulling process in the manuscript. Then, the structure and operating parameters of the harvesting device were designed, and the white radish harvesting performance tests were carried out in the field. The paper is well organized and described. Subject of the study is in the scope of the journal. This work is interesting and may be accepted for publication on Agriculture.

The comments for the improvement of this manuscript are as follows:

(1) The clamping position of leaves will affect the holding force, and whether it will affect the stability of radish pulling performance.

(2) Please further explain why the relative position of the release shovel and clamping wheel is selected as a design parameter.

(3) Why choose EEPA model for dynamics simulation and how to determine the model parameters.

(4) Fig. 13 gives the instantaneous velocity change of the soil particles around the radish fruit. How to choose the moment.

(5) Is the pulling angle determined by the actual field? Please explain why θ is 0 to 10 degrees.

(6) The English language should be edited by a native speaker. Minor improvements are needed.

Author Response

Response to Reviewer 1 Comments

We would like to sincerely thank your valuable suggestions that help us to improve the quality of this manuscript. Our manuscript has been revised carefully. We mark the modified content with a red font. Below are our detailed responses to your comments.

(1) The clamping position of leaves will affect the holding force, and whether it will affect the stability of radish pulling performance.

Response: Yes, the clamping position of leaves will affect the stability of white radish pulling performance. In the design of harvester, the diameter of the clamping wheel was 90 mm, and its center height was about 100 mm above the soil bed. The clamping force of the belts was controlled by a set of springs, which was greater than 100 N. The test results show that this can ensure the stability of the white radish pulling. This is now explained in the Section 3.5 in the revised manuscript.

(2) Please further explain why the relative position of the release shovel and clamping wheel is selected as a design parameter.

Response: The main function of the shovel is to reduce the pulling force. As the installation position L moves forward, the loosening time to the soil bed increases and the pulling force decreases more significantly. On the other hand, during the soil bed loosening process, the radish is subjected to an additional force in the forward direction. This force will increase with the increase of the installation position L, and will affect the posture of the radish and the stability of the leaf gathering. So, a suitable installation position L should be in the range of 50 – 70 mm, and the maximum pulling force can be effectively reduced to less than 65 N. This is now explained in the Section 3.4 in the revised manuscript.

(3) Why choose EEPA model for dynamics simulation and how to determine the model parameters.

Response: Compared with the Hertz-Mindlin model with bonding and the Hertz-Mindlin model with JKR contact, EEPA model has advantages in capturing the stress-history-dependent responses and the cohesive forces. Recently, EEPA model has been successfully used in many fields of soil dynamics research [Refs. 23–25].

This is now explained in the Section 2.1 in the revised manuscript.

(4) Fig. 13 gives the instantaneous velocity change of the soil particles around the radish fruit. How to choose the moment.

Response: At the moment when the white radish is pulled up, the pulling force increases rapidly to the maximum value. The instantaneous moment corresponds to the moment of maximum pulling force, shown in Figure 9.

(5) Is the pulling angle determined by the actual field? Please explain why θ is 0 to 10 degrees.

Response: The pulling force is mainly generated by the disturbance of the radish fruit to the soil bed. This disturbance is not only dependent on the pulling speed and soil compactness, but also closely related to the pulling angle. In the actual harvesting tests, it is also necessary to pull the radishes at a vertical angle as much as possible. Therefore, in the DEM simulations, the range of θ was chosen from 0 to10º. This is now explained in the Section 3.3 in the revised manuscript.

(6) The English language should be edited by a native speaker. Minor improvements are needed.

Response: The paper has been checked by a native English speaking colleague, and some minor grammatical errors have been corrected.

If the reviewer have any question about this paper, please don’t hesitate to let me know.

Best Regards,

Yours sincerely,

Zhao Zhan

Reviewer 2 Report

This study is good, but needs significant improvement in the structure. Discussion is missing.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

We would like to sincerely thank your valuable suggestions that help us to improve the quality of this manuscript. Our manuscript has been revised carefully. We mark the modified content with a red font. Below are our detailed responses to your comments.

(1) Novelty and need of the study statement is missing.

Response: In the revised paper, novelty and need of the study statement is added in Introduction.

(2) It looks like the part of methodology.

Response: In the revised paper, this part has been modified in Introduction.

(3) Discussion is missing.

Response: The harvester in this paper has been optimized in terms of structure and operating parameters. Compared with the previous harvester, the operating performance has been effectively improved. These optimization efforts are closely related to the analysis of the pulling dynamic characteristics of white radish. At present, there are few researches on the pulling dynamic characteristics and the harvesting device design of white radish. It is difficult to find similar harvesters for performance comparison.

Due to the unstable operational performance of the previous prototype, a comparative analysis was not performed in the revised paper. Instead, the performance of harvester under different working environment and parameters is discussed. Combined with the DEM simulation results, the reasons for the variation of operational performance are analyzed (Section 4.2).

(4) Should be part of methodology and results must be presented in Results part.

Response: We have restructured the paper. The description of the harvester structure has been moved to Section 2.2. Optimization of structural parameters has been moved to Section 3.5.

If the reviewer have any question about this paper, please don’t hesitate to let me know.

Best Regards,

Yours sincerely,

Zhao Zhan

Reviewer 3 Report

The article is focused on modeling, device design, and testing in laboratory conditions. The mechanized harvesting of said crop is nothing new. However, the authors did not mention practical experience and losses in field conditions in the introduction. The article, on the other hand, is quite interesting, but in the submitted state it is not suitable for publication in Q1.

For the quality of the publication, I suggest the following:

In the abstract - it is necessary to add why the research was carried out, the main results and what it will bring for practice, the main results are listed only for statistical evaluation

Introduction - it is necessary to expand with practical and scientific experience of the issue of interest

Material and methods - we suggest adding a more detailed description of the applied equipment - measuring devices, collection machine, technical parameters, operational parameters, Add applied statistical methods

Results and discussion - they are written in a simple formulation without statistical evaluations, except for regression, I suggest expanding the statistical evaluations, more detailed descriptions of the designed device, individual components with dimensions, type of material, etc.

Authors should discuss the results and how they can be interpreted in the perspective of previous studies and working hypotheses. They should discuss their results and highlight the differences in their research.

Conclusions - stating that according to the properties and state of growth... how many different modifications did you describe in the methodology?

Author Response

Response to Reviewer 3 Comments

We would like to sincerely thank your valuable suggestions that help us to improve the quality of this manuscript. Our manuscript has been revised carefully. We mark the modified content with a red font. Below are our detailed responses to your comments.

(1) In the abstract - it is necessary to add why the research was carried out, the main results and what it will bring for practice, the main results are listed only for statistical evaluation.

Response: We have revised the Abstract. The purpose of the research, the main results and what it will bring for practice are further explained.

(2) Introduction - it is necessary to expand with practical and scientific experience of the issue of interest.

Response: In the revised manuscript, the growth state of white radish, the problem in the pulling harvest and the purpose of dynamic research are further explained in Introduction.

(3) Material and methods - we suggest adding a more detailed description of the applied equipment - measuring devices, collection machine, technical parameters, operational parameters, Add applied statistical methods.

Response: This section introduces the method of DEM simulation, the structure and working process of the harvester. Detailed optimization of harvester parameters are introduced in the Sections 3.5.

(4) Results and discussion - they are written in a simple formulation without statistical evaluations, except for regression, I suggest expanding the statistical evaluations, more detailed descriptions of the designed device, individual components with dimensions, type of material, etc.

Response: In the revised manuscript, Figure 5 gives the statistical test results of the leaf breaking force of five different varieties of white radish. The sensor parameters and the actual measurement method are introduced.

In the revised manuscript, with the soil bed compactness SC of 1.0 – 4.5 MPa, Figure 11 gives the effect of pulling speed on maximum pulling force. With the pulling speed of 0.1 – 0.5 m/s, Figure 13. Effect of pulling angle on maximum pulling force. With the forward speed of 0.2 – 0.4 m/s and the soil compactness of 3.0 – 4.0 MPa, Figure 15 gives the variation of the maximum pulling force with the installation position. They are statistical evaluations of multiple sets of simulation results, and the distribution ranges are added. It is difficult to construct an accurate theoretical model describing Eqs. 7-9. We have tried to fit the relationships with different models, and the results show that the index model presented in the paper has the highest fitting accuracy.

Detailed component dimensions are added in Section 3.5 in the revised manuscript.

(5) Authors should discuss the results and how they can be interpreted in the perspective of previous studies and working hypotheses. They should discuss their results and highlight the differences in their research.

Response: The harvester in this paper has been optimized in terms of structure and operating parameters. Compared with the previous harvester, the operating performance has been effectively improved. These optimization efforts are closely related to the analysis of the pulling dynamic characteristics of white radish. At present, there are few researches on the pulling dynamic characteristics and the harvesting device design of white radish. It is difficult to find similar harvesters for performance comparison.

Due to the unstable operational performance of the previous prototype, a comparative analysis was not performed in the revised paper. Instead, the performance of harvester under different working environment and parameters is discussed. Combined with the DEM simulation results, the reasons for the variation of operational performance are analyzed (Section 4.2).

(6) Conclusions - stating that according to the properties and state of growth... how many different modifications did you describe in the methodology?

Response: Five typical white radish varieties were selected as test samples. Parameters such as geometry, weight, depth of fruit in the soil bed, and leaf breaking force were statistically analyzed. This is now explained in the Section 2.1 in the revised manuscript.

If the reviewer have any question about this paper, please don’t hesitate to let me know.

Best Regards,

Yours sincerely,

Zhao Zhan

Round 2

Reviewer 2 Report

Comments are given in the file.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer:

    We would like to sincerely thank your valuable suggestions that help us to improve the quality of this manuscript. We have tried our best to carefully revise the manuscript according to your comments. The resubmitted manuscript is now in a much better shape.

    There is a question we hope to receive your understanding. We have searched many databases, but did not find any suitable research work for comparison. We have explained it in our Response and hope to get your approval.

    We mark the modified content with a red font. Below are our detailed responses to your comments.

(1) Novelty and need of the study statement is missing. This paragraphs should summarize the problems/issues making a problem statement. A novelty statement describes one line solution without describing detailed methodology. Methodology should not be mentioned here.

Response: In the revised paper, this paragraph has been reorganized (The last paragraph of the Introduction).

(2) Discussion is missing.

(3) Discussion means comparing your results with the results of previous studies. Previous studied should be referred. Authors should compare the current design with present harvesters showing the improvement. Without comparison no reader can judge the improvement in design. So, there must be some discussion regarding improvement. The DEM simulation results are ok and do not need any discussion.

Response: Dear reviewer, this is a very valuable suggestion. We also deeply know that the value of this study can be better reflected by comparing with previous work. We have searched CNKI, Science Direct, SPRINGER LINK, MDPI and other databases, but we really did not find any research reports on the pulling dynamic characteristics of white radish and optimal design of harvesting device.

    The objective of this paper was to analyze the pulling dynamic characteristics of white radish using DEM method, and to provide a basis for the optimal design of the pulling device and the operating parameters. We feel that it is not appropriate to compare the current design with our previous work. On the one hand, the working principle of the machine has not changed, the optimization is mainly for structural and operational parameters. On the other hand, compared with the prototype with unstable performance and unreasonable structure design, it is difficult to reflect the research value of this paper.

    Therefore, we respectfully request your understanding!

    If the reviewer have any question about this paper, please don’t hesitate to let me know.

Best Regards,

Yours sincerely,

Zhao Zhan

Reviewer 3 Report

I did not receive a cover letter for the submitted article. I propose to supplement the article.

In the abstract – there is no statistical evaluation of the measurement results

Introduction - was supplemented

Material and methods - technical parameters of the harvester are missing - table, operating parameters, question: Were statistics used to evaluate the measured results?

Results and discussion - detailed statistical evaluations are missing, the Optimization of structural parameters section was added - are these the parameters you have already set?

What were the original ones? – add to the methodology

Discussion - the title has been added, but the question is: Who are you discussing with? Until today, no one has described the measurements with the presented harvester?

Conclusions - probably not changed.

Author Response

Dear Reviewer:

    We would like to sincerely thank your valuable suggestions that help us to improve the quality of this manuscript. We have tried our best to carefully revise the manuscript according to your comments. The resubmitted manuscript is now in a much better shape.

    There is a question we hope to receive your understanding. We have searched many databases, but did not find any suitable research work for comparison. We have explained it in our Response and hope to get your approval.

   We mark the modified content with a red font. Below are our detailed responses to your comments.

(1) I did not receive a cover letter for the submitted article. I propose to supplement the article.

Response: This is supplemented in the resubmitted paper.

(2) In the abstract – there is no statistical evaluation of the measurement results.

Response: The white radish harvesting tests were carried out in different fields. Statistical results show that when the soil compaction was increased from 1.47 MPa to 2.21 MPa, the average loss rate increased from 0.68 % to 1.75% and the average damage rate increased from 2.41 % to 2.70 %. Sim-ilarly, when the forward speed was increased from 0.18 to 0.47 m/s, the average loss rate in-creased from 1.08% to 1.30% and the average damage rate increased from 2.34 % to 2.74 %. Over-all, the maximum loss rate and the maximum damage rate could be controlled below 2.0 % and 3.0 %, respectively. In the hard soil bed, the loss rate can be effectively reduced from 15% to 2.5% by installing a loosening shovel. This is now explained in the Abstract.

The data are all statistical results at different fields and forward speeds

(3) Introduction - was supplemented

Response: Thank you for your positive comments on our work.

(4) Material and methods - technical parameters of the harvester are missing - table, operating parameters, question: Were statistics used to evaluate the measured results?

(5) Results and discussion - detailed statistical evaluations are missing, the Optimization of structural parameters section was added - are these the parameters you have already set?

Response: Please allow us to answer these two questions together, because they have something in common.

The most important structural and operational parameters of the harvester include rated power, forward speed, pulling angle, diameter of the clamping wheel, clamping force, diameter of the leaf cutter and the rotational speed, etc. Among these parameters, the forward speed is controlled in real time, the clamping force is adjustable, and the structural parameters are fixed. These parameters are given in detail in Section 3.5.

The results given in Table 2 were obtained by repeated experiments in different fields with different parameters. They are all obtained by statistical calculations.

(6) What were the original ones?  – add to the methodology

Response: The basic structure and operating principle of the harvester has not changed, which is described in Section 2.2. Optimization is mainly for structural and operational parameters, for example, 1:0.866 linear speed ratio to ensure the stability of the pulling angle, the adjustment of the clamping force, and the structural parameters of other components. These are given in Section 3.5. The objective of this paper was to analyze the pulling dynamic characteristics of white radish using DEM method, and to provide a basis for the optimal design of the pulling device and the operating parameters. Due to the unstable operational performance and unreasonable structural design of the previous prototype, they are not introduced in the paper.

(7) Discussion - the title has been added, but the question is: Who are you discussing with?  Until today, no one has described the measurements with the presented harvester?

Response: Dear reviewer, this is a very valuable suggestion. We also deeply know that the value of this study can be better reflected by comparing with previous work. We have searched CNKI, Science Direct, SPRINGER LINK, MDPI and other databases, but we really did not find any research reports on the pulling dynamic characteristics of white radish and optimal design of harvesting device.

    The objective of this paper was to analyze the pulling dynamic characteristics of white radish using DEM method, and to provide a basis for the optimal design of the pulling device and the operating parameters. We feel that it is not appropriate to compare the current design with our previous work. On the one hand, the working principle of the machine has not changed, the optimization is mainly for structural and operational parameters. On the other hand, compared with the prototype with unstable performance and unreasonable structure design, it is difficult to reflect the research value of this paper.

   Therefore, we respectfully request your understanding!

(8) Conclusions - probably not changed.

Response: The introduction of the optimization of structural parameters is added to the Conclusion.

    If the reviewer have any question about this paper, please don’t hesitate to let me know.

Best Regards,

Yours sincerely,

Zhao Zhan