Analysis of Mechanical Characteristics of Stereolithography Soft-Picking Manipulator and Its Application in Grasping Fruits and Vegetables

Round 1

Reviewer 1 Report

The authors have carried out an intense work on the analysis of the mechanical characteristics of soft-picking grippers. The paper has a well-designed research and technical infrastructure. But in order to have a final decision, the author(s) should do the following minor revisions:

v The FEM model requires an expansion and explanation as the abbreviation has been mentioned in the abstract session.

v The abstract can be refined such that the methodology and the outcome can be justified quantitively.

v At the end of the introduction, authors can highlight the outline of the paper in addition to the contribution of the work.

v The main heading for section 2 finds to be incomplete.

v Authors have tested the mechanism based on the pressure metrics. Depending on the application the authors can include the performance metrics with respect to the slippage, success rate, stability, completion time and so on with quantitative measures.

v The results can be compared with the other models and discussions can be given on each.

v Capture some limitations spanning the intermediate results.

v The paper should indicate how the current work can be scaled up or can prove to be utilitarian for other kinds of work. The authors can suggest limitations while indicating the same.

v The authors can include few more references.

v Usage of personal pronouns can be removed while writing a research article. Overall English correction is required.

Author Response

Thank you for your letter and the Reviewers’ comments concerning our manuscript

entitled “Mechanical characteristics analysis and grasping experiment study of stereolithography soft-picking manipulator”. (ID: agronomy-2576407). Those comments are all valuable and very helpful for revising and improving our paper and have great guiding significance to our researches. We have studied the comments carefully and have made corresponding corrections which can meet with your approval hopefully. The main corrections in the paper and the responses to the Reviewer’s comments are as following:

 

Responses to the Reviewer’s comments:

Reviewer #1:

1. The FEM model requires an expansion and explanation as the abbreviation has been mentioned in the abstract session.

 

Response 1: First of all, thank you for your careful work. Considering the Reviewer’s suggestion, we have extended and explained the finite element model in the abstract.

 

2. The abstract can be refined such that the methodology and the outcome can be justified quantitively.

 

Response 2: Thanks for your valuable suggestion. Considering the Reviewer’s suggestion, we have added the results of the grasping test (grasping force and grasping completion time, etc) to the abstract.

 

3. At the end of the introduction, authors can highlight the outline of the paper in addition to the contribution of the work.

 

Response 3: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have revised the introduction and added the contribution of this paper in the field of agricultural picking to the revised manuscript. (Line 128)

 

4. The main heading for section 2 finds to be incomplete.

 

Response 4: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have changed the main heading of section 2 of the manuscript to "Materials and Methods".

 

5. Authors have tested the mechanism based on the pressure metrics. Depending on the application the authors can include the performance metrics with respect to the slippage, success rate, stability, completion time and so on with quantitative measures.

Response 5: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have included the performance of the output force change under slippage, success rate, and completion time in the quantitative measurements and added them to the revised manuscript.

 

6. The results can be compared with the other models and discussions can be given on each.

 

Response 6: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have compared the SLA soft manipulator designed in this paper with other forming methods, including output force, materials, complexity of manufacturing process, manufacturing cost and characteristics (Table 2). It is also analyzed and discussed in this paper. (Line 423)

 

7. Capture some limitations spanning the intermediate results.

 

Response 7: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have added some limitations of SLA soft manipulators and their solutions (such as sun aging and force sensing, etc.) to the manuscript. (Line 423)

 

8. The paper should indicate how the current work can be scaled up or can prove to be utilitarian for other kinds of work. The authors can suggest limitations while indicating the same.

 

Response 8: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have added some limitations, such as aging in sunlight, and pointed out that in agricultural production, SLA soft manipulators should be kept away from light when not in use to avoid surface cracking caused by prolonged exposure to sunlight.

 

9. The authors can include few more references

 

Response 9: Thanks for your valuable question. Considering the Reviewer’s suggestion, we have added relevant references to the section comparing the introduction and the final test results.

 

We appreciate for Editors and Reviewers’ diligent work and inspiring opinions earnestly.  We hope that the corrections will meet with your approval. Once again, thank you very much for your comments and suggestions.

 

Yours sincerely,

Yu Zhuang

E-mail: [email protected]

Author Response File: Author Response.docx

Reviewer 2 Report

 

In this paper, a pneumatically driven soft-picking manipulator for fruit and vegetables were developed. Overall, this manuscript is well written and can be consider for publication after well addressing following issues.

1.     Introduction.

·         In line 95,”design a soft……without support during printing”, can you explain more detail about “without out support”?

·         Fruit and vegetables picking is hot research issue, and many kinds of mechanisms can be applied or potentially applied in fruit picking. Authors should make a more comprehensive introduction by including introduction of a special mechanisms-constant force mechanism which have been widely used in the fields of precision polishing, and vibration isolation. constant force mechanism can maintain a constant force output within a certain motion range. Thus, it suitable for force sensitive fruits and vegetables. Introduction and application of constant force mechanism, authors can refer, “Modular quasi-zero-stiffness isolator based on compliant constant-force mechanisms for low-frequency vibration isolation”, “Design of a spatial constant-force end-effector for polishing/deburring operations”.

·         In practical applications, the required force to pick target fruit may different. In this manuscript, authors adjust clamping force by controlling pneumatically pressure. For constant force mechanisms, the variable output constant force can be obtained by changing the preloading conditions on the positive structures” Configuration design and experimental verification of a variable constant-force compliant mechanism”. Authors also can develop a soft passive constant force gripper for fruit picking.

·         How to detect the contact/interactive force beteem gripper fingers and target object for the proposed design, by experience or sensing? The output force of the constant force mechanism is predefined, thus avoid using tactile sensors.

2.     Experiments

·         In part 2.2, line 123, it said the air flows through the channel, but the channel part can’t be seen in Fig.3.

·         Also in part 2.2, the author said the air fill the chamber to make the actuator bend or deform, when the air pressure is increased. So, in Figure 8, when the air pressure increased, how could the author keep the actuator in the same angle? Didn’t the variable air pressure change the angle of the actuator?

3.     Results

·         As shown in Figure 10, most of the target fruits and vegetables are spherical. How about picking bananas? In addition, all these target objects are convex shape, did the gripper can pick concave shape objects?

·         How about the footprint of the prototype? Authors suggest deleting Fig.12a, it looks like toy car. If possible authors can mount their design in assemble line for further research.

Need improve

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

This article describes the design process and testing of a soft fruit and vegetable picking manipulator structure, manufactured by printing SLA technology. The design was tested by simulation, using Abacus FEM software and the printed prototype was tested through a testing bench, composed of a mobile test platform as well as a set of pneumatic circuit and an electronic control circuit.

The topic of the research project described in the article presents scientific interest. The research process has been performed adequately and the results are promising and are well supported by the research. The paper is well written, although the English language could be improved.

Additionally, some minor issues should be addressed by the authors prior to publication:

1)      The state of the art revision is very concise in SLA technology and should be expanded.

2)      In the same context, the contributions of the present research to the scientific knowledge, specially, with respect to the revised bibliography, would be of interest and, hence, more insight in this topic should be provided.

3)      The results of the experiments and the performance of the manipulator with different types of fruits, should be compared to other types of manipulators built with different technologies, as well as the costs of manufacturing of them, to clarify the potential of this tool in the fruit and vegetables picking industry.

4)      The conclusions section could be completed by describing possible improvements of the design, as well as future research lines that could be developed from the research project, presented in this article.

The English language is understandable and easy to read. However, minor mistakes could be addressed and corrected.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

This manuscript presented a stereolithography soft-picking manipulator and analysis the mechanical characteristics and grasping performance. The bending deformation and the final output force characteristics were tested, while the correctness of the mathematical model was verified. Several fruits and vegetables of different qualities and sizes were used to test the manipulator. The topic is meaningful for relative research and applications. However, the analysis of the result were not detailed enough. With revision, this work would be greater.

Specific comments:

1 It’s better to give more details of why the actuator structure was designed in current way.

2 It would be more friendly to the readers to explain why the mesh was selected as triangular one.

3 3.1 was more like the method instead of the result, so do some part of the 3.2 section.

4 It’s better to improve the title of table 1.

5 More analysis of the date of table 1 should be addressed.

6 The damage condition of the fruit should be evaluated.

7 The data of the table 1 should be the average value of parallel test.

8 The conclusion section should generate the highlights results of this work instead of stating the work.

9 The manuscript was a little bit short than others.

10 If the English writing could be polished, the manuscript would be a greater work. 

 If the English writing could be polished, the manuscript would be a greater work.

Author Response

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Author Response File: Author Response.docx

Reviewer 5 Report

The paper carried out mechanical characteristics test of a self-designed soft gripping actuator, and it is of certain applicaiton values. However, the study lacks innovation and need further revision.

1. How the results of equations 1 to 4 are applied to the design of the gripping mechanisms is unclear in the article. At present, the equation derivation results are disconnected from the design, as there are no specific parameter values in the formula.

2. This article claims to have designed a soft actuator, but its design is very ordinary and there is not any improvement or optimization for a specific fruit or vegetable objectives. Instead, a universal clamping mechanism was printed using a 3D printer, and the research work lacks innovation. 

3. The paper only provids the schematic diagram of the soft-picking manipulator control system. However, how the various parts are connected and the control methods are not introduced.

4. The bending deformation ability is depend on the material and shape of the actuator. This study only proves the partial consistency between theoretical analysis and actual objects, which the practical significance is not significant. Also, the relationship between the  actuator's size and its bending deformation ability is not tested.

Author Response

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Round 2

Reviewer 2 Report

Authors well addressed the concerns, this manuscript can be considered for publication in current form.

English writing is good.

Author Response

Thank you for your valuable and constructive comments on our manuscript (ID: agronomy-2576407). 

Reviewer 4 Report

The revisions were acceptable.

Minor editing of English language required

Author Response

Response: Thank you for your valuable and constructive comments on our manuscript (ID: agronomy-2576407). Following your suggestions, we have carefully revised our manuscript with the help of a native speaker. The corrected section of the manuscript is marked in red in the revised manuscript.

Reviewer 5 Report

1. Equation 1 is the starting equation, and its source needs to be provided. In addition, equation 4 in this article is derived, and from the process, all parameters are independent of the structure of this design. Therefore, equation 4 should have been obtained in the previous research by other scientists.

2. This study conducted testing around a flexible clamping mechanism, but the design of the clamping mechanism itself lacked innovation.

3. In the first review, it was clearly stated that this design did not consider the specific situation of a certain fruit or vegetable, and it is unrealistic to use a fixture to adapt to multiple objects.

The English writing of this paper is acceptable.

Author Response

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Round 3

Reviewer 2 Report

Authors well addressed my concerns. This manuscript can be recommended for publication in current form.

Well

Author Response

Thank you for your valuable and constructive comments on our manuscript (ID: agronomy-2576407). 

Reviewer 5 Report

Since it has been revised three times, it could be considered for publication.