Vibration Response of Walnuts under Vibration Harvesting
Round 1
Reviewer 1 Report
The reviewer is not able to check all the analytical equations and the numerical analysis. Therefore, the following comments are done by studying the general equations and the graphical results. Publication of the manuscript is recommended, provided that the following points are considered by the authors and make necessary modifications. The paper is quite clear and the main ideas are well developed.
In my opinion, this paper should be accepted but I think that some explanations/integrations might be useful.
1. The reviewer unable to find any proper validation of the results, explain.
2. The reviewer feels that the theoretical model explained in the manuscript is not appropriate, it needs to be addressed properly.
3. There are some grammatical and spelling errors found in the manuscript, correction required.
Author Response
Dear Reviewers and Editors,
The referees' comments are very helpful. Thank you for your detailed comments. We accepted all of them because we believe that the paper will be more readable to the general readers after these revisions.
Response to Reviewer 1 Comments
Point 1: The reviewer unable to find any proper validation of the results, explain.
Response 1:
Answer：
In this paper, we have established the theoretical model and obtained the motion morphology (motion trajectory and dropping position) and the relationship between the detachment force and the vibration frequency and amplitude. Through the field experiments and observation of the actual motion trajectory and dropping position in the vibration harvesting progress, it is proved that the motion trajectory and dropping position in the theoretical derivation is the same as that in the actual vibration harvesting, and proved the correctness of the theoretical model, which including the motion morphology and detachment force.
For motion morphology, the article shows several motion moments in a motion cycle in Figure 5 and Figure 6 to prove the results. For the detachment force, the equation established in this paper is not the calculation formula of the detachment force and the frequency and amplitude, but the macroscopic relationship between the detachment force and the frequency and the amplitude. Therefore, it can only be established through theoretical derivation. Since the correctness of the theoretical model can be proved by the motion morphology, and the dropping position and the motion process in Figure 5 and Figure 6 can also be used as evidence.
I have made more detailed supplementary explanations for the above contents.
Revision：
The sentence “In Figure 4 and Figure 5, the motion trajectory of walnut is the motion track of walnut centroid drawn by comparing with the motion video recorded by high-speed camera. And in Figure 5, by intercepting several positions of the walnut in one motion cycle, the motion of walnut recorded by high-speed camera is approximately reflected, which intuitively shows that the motion trajectory of the walnut resembles an ellipse. The dropping position of walnut is determined by drawing the motion trajectory of walnuts and observing the fruit’s motion position when fracture occurs between the fruit and the fruit handle through the video recorded by the high-speed camera. As in Figure 6, it shows several moments before and after the dropping moment of walnuts. By determining the position of walnut before and after dropping, the dropping moment of walnut can be determined, and the position of this moment is at both endpoints of the walnut motion trajectory can be further obtained. The conclusion that the dropping position of walnuts is at the endpoints is consistent with the theoretical model that the maximum detachment force appears at the end point and walnuts are most likely to drop.” has been added in page 9-10, line 323-337.
The sentence “And the dropping position of walnuts is concentrated at both endpoints of the motion trajectory, which is because the fracture occurs at the moment of maximum detachment force, and the moment when the detachment force is maximum is when the fruit moves to the end point” has been added in page 12, line 366-370.
The sentence “And the theoretical model was verified, which including the motion morphology and detachment force.” has been added in page 12, line 376-377.
Point 2: The reviewer feels that the theoretical model explained in the manuscript is not appropriate, it needs to be addressed properly.
Response 2:
Answer：
I have added an explanation of the theoretical model in the theoretical part and made a more detailed explanation of the unclear parts in the theoretical analysis.
Revision：
The sentence “In the actual measurement of fruit response acceleration, the method is usually using sensors to measure the acceleration of fruit vibration response in x, y and z directions, and then sum their vectors to obtain the synthesized response acceleration of fruit to explore the vibration response. Therefore, in this paper, the method of synthesis and decomposition of motion and forces was used to establish a theoretical model to study the vibration response of walnut.” has been added in page 3, line 109-114 .
The sentence “Therefore, this equation shows from the relationship level that to obtain high harvesting rate, the vibration parameters of frequency and amplitude should be comprehensively consider. Only when vibration frequency and amplitude both reach the appropriate combination, the fruit vibration response will be the best.”has been added in page 8, line 255-258
The sentence “From the above theoretical analysis of the synthesized motion and decomposition motion in the vertical and horizontal direction.”has been added in page 8, line 259-260
The sentence “This result indicates that in order to achieve better vibration response and improve fruit harvesting rate, vibration frequency and vibration amplitude should be considered comprehensively.” has been added in page 13, line 420-422
Point 3: There are some grammatical and spelling errors found in the manuscript, correction required.
Response 3:
Answer：
The manuscript has checked by a native English-speaking colleague, and I have corrected some grammatical and spelling errors in the article.
Revision：
The modified parts are marked in the text.
Reviewer 2 Report
The article deals with an interesting topic related to the vibrational response of walnuts to improve their mechanised harvesting. It structures a theoretical framework which it validates with a controlled field trial. However, there are a few formatting issues and observations about the article that I would like to point out to you:
- From line 30 to 32 it should be clarified that, although selective picking is not generally performed as indicated, there are cases where selective picking has been performed by regulating machine parameters [20,27] or by using the ripening time of the fruit, performing different passes of the machine as in cherry (He et al., 2013) or coffee (Silva et al., 2013).
- Equations should be presented before they appear in the text, as you do with figures, even if you then describe the variables involved.
- On line 249 change "3kW" to "3 kW" with a space between the figure and the unit.
- On line 267 change "2048 * 1024 pixels" to "2048 x 1024 pixels" or "2048 by 1024 pixels".
- On line 289 change "drop,dropping" to "drop, dropping" leaving a space between the comma and the next word.
- On line 290 replace "In the figures" with "In the figures above (Fig. 4, 5 and 6)" or similar text to clarify the reference.
- Figure 2 should bold the letters (a) and (b) indicating the subgraphs, as has been done for figure 8.
- Figure 7 and figure 8b should use the International System for the units of acceleration (m/s^2 instead of g).
- The title of figures 4, 6 and 7 should indicate the subgraphs that make up each figure, as indicated in figures 2 and 8.
- The methodology indicates that the sensor is placed on the branch, measuring the acceleration close to the fruit. Although close to the fruit, the branch does not necessarily behave exactly like the fruit, being an approximate indication. This is shown in the quote in the text [21]. However, these conclusions were obtained by taking the acceleration measurement inside the fruit and using a vibration system based on localised vibration with direct contact by means of a canopy shaker. This vibration system is different from the method presented in this work, which is closer to a branch shaker, with a medium-high frequency and a lower amplitude compared to the canopy shaker.
- Some of the conclusions drawn are based on well-studied and well-founded physical models and, although these models are experimentally tested in the paper, they may be self-evident.
He, L., Zhou, J., Zhang, Q., & Karkee, M. (2013). Evaluation of multi-pass mechanical harvest on sweet cherry. In 2013 Kansas City, Missouri, July 21-July 24, 2013 (p. 1). American Society of Agricultural and Biological Engineers.
Silva, F. D., Rodrigues, R. F., & Martin, W. G. (2000). Desempenho operacional da colheita mecanizada com varias passadas da colhedora de café. In CONGRESSO BRASILEIRO DE PESQUISAS CAFEEIRAS (Vol. 26, pp. 345-347).
I thank you for your efforts and contribution to scientific progress in the area of mechanised harvesting of fruit trees. I hope that my observations can enrich your work.
Best regards.
Author Response
Dear Reviewers and Editors,
The referees' comments are very helpful. Thank you for your detailed comments. We accepted all of them because we believe that the paper will be more readable to the general readers after these revisions.
Response to Reviewer 2 Comments
Point 1: From line 30 to 32 it should be clarified that, although selective picking is not generally performed as indicated, there are cases where selective picking has been performed by regulating machine parameters [20,27] or by using the ripening time of the fruit, performing different passes of the machine as in cherry (He et al., 2013) or coffee (Silva et al., 2013).
Response 1:
Answer：
I have added the further explain about the cases where selecting picking has been performed.
Revision：
The sentence “except for some special cases, such as the need to harvest some fruits of certain maturity when there are fruits of different maturity on the same tree.” has been added in page 1, line 31-32.
Point 2: Equations should be presented before they appear in the text, as you do with figures, even if you then describe the variables involved.
Response 2:
Answer：
I have modified the parts related to the error you mentioned. Thank you for your detailed comments. In this article, some explanations of variable are given to the variables appearing in the diagram, and some explanations of variables are explained for the further derivation and simplification of the above formulas. In addition, the explanation of variables not appearing in the following part of some formulas is to avoid repetition with the explanation mentioned in the previous article, and is not intended to put the formula behind the explanation of variables.
Revision：
The modified parts around the equation (4) (9) (11) (12) were marked in the text. ( page 5, line 164; page 6, line 202-203, line 206, line 208)
Point 3: On line 249 change "3kW" to "3 kW" with a space between the figure and the unit.
Response 3:
Answer：
I have corrected this error in the article.
Revision：
The modified part is marked in the text. ( page 8, line 277)
Point 4: On line 267 change "2048 * 1024 pixels" to "2048 x 1024 pixels" or "2048 by 1024 pixels".
Response 4:
Answer：
I have corrected this error in the article.
Revision：
The modified part is marked in the text. ( page 8, line 295)
Point 5: On line 289 change "drop,dropping" to "drop, dropping" leaving a space between the comma and the next word.
Response 5:
Answer：
I have corrected this error in the article.
Revision：
The modified part is marked in the text. ( page 9, line 320)
Point 6: On line 290 replace "In the figures" with "In the figures above (Fig. 4, 5 and 6)" or similar text to clarify the reference.
Response 6:
Answer：
I have corrected this error in the article.
Revision：
The modified part is marked in the text. ( page 9, line 321)
Point 7: Figure 2 should bold the letters (a) and (b) indicating the subgraphs, as has been done for figure 8.
Response 7:
Answer：
I have corrected this error in the article.
Revision：
The modified part is marked in the text. ( page 7, line 236-237)
Point 8: Figure 7 and figure 8b should use the International System for the units of acceleration (m/s^2 instead of g).
Response 8:
Answer：
I have modified the unit in the pictures.
Revision：
The revised picture is shown in Figure 7 and Figure 8b in the article ( page 12-13, line 390-394; page 14, line 423-424)
Point 9: The title of figures 4, 6 and 7 should indicate the subgraphs that make up each figure, as indicated in figures 2 and 8.
Response 9:
Answer：
I have added the explanations of the subgraphs of figures 4, 6 and 7
Revision：
The modified parts are marked in the text. ( page 10, line 343-344; page 11, line 348-350; page 12, line 395-396)
Point 10: The methodology indicates that the sensor is placed on the branch, measuring the acceleration close to the fruit. Although close to the fruit, the branch does not necessarily behave exactly like the fruit, being an approximate indication. This is shown in the quote in the text [21]. However, these conclusions were obtained by taking the acceleration measurement inside the fruit and using a vibration system based on localised vibration with direct contact by means of a canopy shaker. This vibration system is different from the method presented in this work, which is closer to a branch shaker, with a medium-high frequency and a lower amplitude compared to the canopy shaker.
Response 10:
Answer：
First of all, because the acceleration sensor used in this paper wants to explore the relationship equation between the detachment force and the frequency and amplitude, and not the calculation equation of the detachment force can be calculated by the input frequency and amplitude. Secondly, from the vibration harvesting device input end to the fruit, there is also an error in the transmission of vibration in this process, and it may reach 50% [19]. Therefore, although there is attenuation of vibration transmission between branches and fruits, the error caused by this reason is small compared with the error of vibration transmission from the input end to the fruit because the position of the sensor is close to the fruit, which can be ignored. Therefore, the sensor is placed in the branch near the fruit in this paper, which has a small effect on the linear relationship between detachment force and variables. I added a more detailed description at the setup of the experiment and the result of the sensor.
Revision：
The sentence “Because the maximum difference between the fruits’ input frequency and response frequency can exceed 53%[19] and the distance from the location of vibration input to the fruit is far greater than the distance from the sensor to the fruit, the experiment in this paper approximately considers that the response of the branches near the fruit is the same as that of the fruit.” added in page 12, line 381-385.
The revisions are shown as follows in red.
“The sensor was fixed to the branches near the walnuts using tie-wraps, and the distance from the walnut fruit is within 10 cm.” (in page 8, line 287)
Point 11: Some of the conclusions drawn are based on well-studied and well-founded physical models and, although these models are experimentally tested in the paper, they may be self-evident
Response 11:
Answer：
As for conclusion 1, the article shows several motion moments in a motion cycle in Figure 5 and Figure 6 to prove the results of the motion morphology in the actual vibration harvesting. And it is the same as the theoretical model.
As for conclusion 2, although the relationship between input frequency and response frequency, input amplitude and response amplitude in the conclusion may be self-evident, we do not know the exact linear relationship between them, which is worth exploring. Through the field experiments, the exact relationship was obtained.
As for conclusion 3, the equation established in this paper is not the calculation formula of the detachment force and the frequency and amplitude, but the macroscopic relationship between the detachment force and the frequency and the amplitude. This equation shows from the relationship level that to obtain high harvesting rate, the vibration parameters of frequency and amplitude should be comprehensively consider. So that, in this paper, the correctness of the theoretical model is proved through the motion morphology, which including the motion morphology and detachment force.
I have revised the conclusions of the article
Revision：
The revisions are shown as follows in red.
Theoretical and experimental results both showed that ( in page 15, line 471)
For vibration harvesting of walnuts under actual harvesting conditions, the response amplitude of the walnuts is proportional to the vibration amplitude of the device. ( in page 15, line 474)
Using the theoretical model and extending the experiment, the relationship between the detachment force and the vibration response and amplitude was obtained, which shows the detachment force is proportional to the vibration amplitude and the square of the vibration frequency. This relationship further reflects that in order to achieve better vibration response and improve fruit harvesting rate, vibration frequency and vibration amplitude should be considered comprehensively. ( in page 15, line 484-487)
