Actuators and Sensors for Application in Agricultural Robots: A Review
Round 1
Reviewer 1 Report
This manuscript presents a review of the existing work related to actuators in agricultural robots. The different systems used in agricultural robot motion are presented, and the control techniques used to control these systems.
Section 3.1 presents end-effector applications in agricultural robots, which are given some examples. The clamping mechanism subsection referred to more works than the other mechanisms subsections. The reason behind this difference could be mentioned.
In a work where so many references are used, perhaps, there should be a discussion section of the results obtained during the research to relate the different related works found.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewers
September 18 2022
On behalf of my co-authors and myself, we would like to thank you for your thoughtful and constructive comments in manuscript number 1914438, entitled “Actuators for applications in agricultural robots: A comprehensive review”. We believe they have improved this manuscript significantly
This letter accompanies the online resubmission of our manuscript, with the updated title “Actuators and Sensors for applications in agricultural robots: A review”, to be considered for publishing in MDPI Machines.
First and foremost, we would like to thank all the comments and suggestions from the three reviewers and the editor regarding our manuscript, which helped to improve our work. Further, we appreciate the value of our study and the opportunity to resubmit our revised manuscript.
All the issues noted are listed below and addressed individually.
All new changes made to the paper are highlighted with red underlining.
Sincerely Yours,
Dongbo Xie
Issue 1: “This manuscript presents a review of the existing work related to actuators in agricultural robots. The different systems used in agricultural robot motion are presented, and the control techniques used to control these systems.
Section 3.1 presents end-effector applications in agricultural robots, which are given some examples. The clamping mechanism subsection referred to more works than the other mechanisms subsections. The reason behind this difference could be mentioned.”
R.: Many thanks to the reviewers for their valuable comments and for the high level of condensation of the article. As the experts say, this paper focuses on the application of actuators and sensors in agricultural robots. Indeed, the manuscript does not analyze the reasons for the more work involved in the clamping structure compared to other mechanisms. This revision is according to the expert opinion on the reasons for adding discrepancies. Additional descriptions are provided in lines 406-420, 752-761 of the text, which is highlighted by red underlining.
Issue 2: “In a work where so many references are used, perhaps, there should be a discussion section of the results obtained during the research to relate the different related works found.”
R.: Many thanks to the reviewers for recognizing our workload. The article is really not too much discussed. Based on your suggestions for this revision, we have added a discussion section to the text. Related content is added in Section 5, article lines 734-777, and is marked by red underlining.
In addition, in response to the problems pointed out by the reviewers in the attachment, the authors have checked and revised the whole text, and the revised parts are highlighted in red underlining.
Author Response File: Author Response.pdf
Reviewer 2 Report
The reviewer finds the paper does not have an appropriate constitution that introduce studies technological developments confined in agricultural fields.
Introduction is too lengthy. The paper is a survey paper. Therefore the introduction should be devoted to explain how kind of order the following chapters is formed not surveying literatures.
Agricultural works extremely differs depending on their environments and species of crop. However the paper does not much take a consideration for them.
It classifies with types of actuator, types of control, mechanism of end-effector and sensors. This classification is absolutely the same as those of any other survey paper of another fields.
It should categolizes according to what kind of works are especially involved in agricultural works , which should be explained in the introduction. The paper should be reordered based on it.
Some grammatical errors should be corrected.
Author Response
Response to Reviewers
September 18 2022
On behalf of my co-authors and myself, we would like to thank you for your thoughtful and constructive comments in manuscript number 1914438 entitled “Actuators for applications in agricultural robots: A comprehensive review”. We believe they have improved this manuscript significantly
This letter accompanies the online resubmission of our manuscript, with the updated title “Actuators and Sensors for applications in agricultural robots: A review”, to be considered for publishing in MDPI Machines.
First and foremost, we would like to thank all the comments and suggestions from the three reviewers and the editor regarding our manuscript, which helped to improve our work. Further, we appreciate the value of our study and the opportunity to resubmit our revised manuscript.
All the issues noted are listed below and addressed individually.
All new changes made to the paper are highlighted with red underlining.
Sincerely Yours,
Dongbo Xie
Issues highlighted by Reviewer 2
Issue 1: “The reviewer finds the paper does not have an appropriate constitution that introduce studies technological developments confined in agricultural fields.
Introduction is too lengthy. The paper is a survey paper. Therefore the introduction should be devoted to explain how kind of order the following chapters is formed not surveying literatures. ”
R.: Many thanks to the reviewers for their valuable comments. This paper aims to discuss the actuator applications in agricultural robots and to give an outlook on their future development. According to the author's understanding of this aspect, the paper firstly classifies actuator systems according to drive components, control systems and environmental sensing. Secondly, it considers the situation in different operating environments in agriculture, and analyzes its specific application cases in agricultural tillage, sowing, plant protection and harvesting, etc. Finally, it concludes and discusses. This is the main structure of this paper. We are grateful to the reviewers for their comments, and perhaps the above logical relationships were not very clearly presented in the previous manuscript. In this revision, the authors have simplified the introductory section. On the one hand, the paragraphs introduced in chapter order are added, and in addition, the authors add images of typical agricultural robots to label and explain the drive components, control systems, and sensing systems involved in their actuators to help readers better understand and thus comprehend the structure of the text. The revised parts are highlighted in the text with red underlining.
Issue 2: “Agricultural works extremely differs depending on their environments and species of crop. However the paper does not much take a consideration for them.”
R.: Many thanks to the reviewers for their valuable comments, as I mentioned in the previous question, this paper is mainly about the application of actuators in agricultural robots and the outlook on their future development. It is true that the consideration of the environment and crop types are not too much, because there may be many different forms if the consideration of crop types is subdivided. So, we have mainly provided specific case studies in the text on different agronomic aspects of agriculture. In this revision, the authors fully considered the comments of the reviewers and provided additional explanations in lines 115-122, 374-380 of the text. The revised sections are highlighted in red underlining.
Issue3: “It classifies with types of actuator, types of control, mechanism of end-effector and sensors. This classification is absolutely the same as those of any other survey paper of another fields.
It should categolizes according to what kind of works are especially involved in agricultural works , which should be explained in the introduction. The paper should be reordered based on it.”
R.: Many thanks to the reviewers for their valuable comments. This paper has similarities to such articles in other fields in actuator types, controls, etc. The author's main consideration is that agricultural robots are one of the hot issues that many scholars around the world have focused on in recent years. Therefore, we would like to summarize and conclude the development of actuators in the field of agricultural robots, and propose some aspects of future development to give some reference to the colleagues who carry out such research. Thus, this paper starts with the existing more mature structure, from the types of actuators, control systems, and sensing systems, etc. However, this paper differs from similar articles in other fields, because it addresses different aspects of agricultural production and the applications of different types of crops and then elaborates on them to highlight the theme of agricultural robots more. This revision is mainly focused on highlighting the application of actuators and sensors in agricultural robots. Also, to respond to the problem of unclear classification in the introduction, the authors added chapters and pictures to introduce the basis of classification in the introduction, and additional explanations were provided in lines 56-64 of the text. The modified parts are highlighted in red underlining.
Issue4: “Some grammatical errors should be corrected.”
R.: Many thanks to the reviewers for their valuable comments. The authors have checked and revised the whole text; the revised parts are highlighted with red underlining.
Author Response File: Author Response.pdf
Reviewer 3 Report
This is an interesting study, and the authors have collected strong literature. The paper is generally well written and structured. However, in my opinion, what is covered in the entire text is not only focused on actuators in agricultural robots. Mostly, the authors talked about sensors, actuators, and robots' abilities and challenges. By that, I mean the title is not appropriate to the manuscript, and it should be broader because the text is broader than focusing on actuators in robots. Also, some spelling errors should be , modified. Citation style should be constant for all references. In addition, if there were more flow amount sentences, it would be easier to follow the text and story.
Although minor revision is required to improve the entire manuscript, the required revision would be major if the title is not modified and become more relevant to what is covered in the text.
Author Response
Response to Reviewers
September 18 2022
On behalf of my co-authors and myself, we would like to thank you for your thoughtful and constructive comments in manuscript number 1914438 entitled “Actuators for applications in agricultural robots: A comprehensive review”. We believe they have improved this manuscript significantly
This letter accompanies the online resubmission of our manuscript, with the updated title “Actuators and Sensors for applications in agricultural robots: A review”, to be considered for publishing in MDPI Machines.
First and foremost, we would like to thank all the comments and suggestions from the three reviewers and the editor regarding our manuscript, which helped to improve our work. Further, we appreciate the value of our study and the opportunity to resubmit our revised manuscript.
All the issues noted are listed below and addressed individually.
All new changes made to the document are highlighted in red.
Sincerely Yours,
Dongbo Xie
Issues highlighted by Reviewer 3
Issue 1: “This is an interesting study, and the authors have collected strong literature. The paper is generally well written and structured. However, in my opinion, what is covered in the entire text is not only focused on actuators in agricultural robots. Mostly, the authors talked about sensors, actuators, and robots' abilities and challenges. By that, I mean the title is not appropriate to the manuscript, and it should be broader because the text is broader than focusing on actuators in robots.”
R.: Thank you very much for your recognition of our work. Your encouragement means a lot to us. We have carefully analyzed the problem you raised about the title not matching the manuscript. The scope of the content discussed in the article is indeed broader than the title, and with your suggestion, we have rethought and formulated a new title. The new title is: "Actuators and Sensors for applications in agricultural robots: A review". We would appreciate your comments on the rationality of our new title in your busy schedule.
Issue 2: “Also, some spelling errors should be , modified. Citation style should be constant for all references. In addition, if there were more flow amount sentences, it would be easier to follow the text and story. ”
R.: Many thanks for your valuable comments, which have been very helpful in improving the quality of the manuscript. We apologize for the errors caused by carelessness, and according to your comments, we have thoroughly checked the spelling of words and the format of quotations in the paper and corrected them. In addition, based on your comments, we have made many changes to the sentences in the article and used more flow of sentences to make the article easier to understand.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors made many changes to the manuscript that increased its quality.
However, there seem to be some comments that have been ignored. Therefore, it is requested to either make the suggested changes or provide a response to the following comments (which were previously made in the pdf file):
"An actuator-based drive system is associated to move on land in a motor vehicle, it concerns the movement of the vehicle. However, in the subsequent section are given some examples of systems that are not related to the movement of a vehicle but to another type of movement. In order to be consistent the term drive should be replaced by a more general term, e.g. movement or motion. Another option is to delete the examples that are not consistent with the drive term."
"This subsection is part of a section related to actuator-based motion systems. However, as the authors wrote, the neural networks are used to "extract and classify crop details and local features". This technique is used as a perception system, not a control system. "
"Why should the end-effector have the function of absorbing these errors and not the robotic arm itself?"
"The caption could be more detailed." - related to table 2
"The end-effector doesn't comprise all these mechanisms. These mechanisms are different examples of end-effectors, according to the application."
"Shouldn't there be a section "Disc weeding knife", in the same way as was done for the other mechanisms? "
Author Response
Response to Reviewers
September 30 2022
On behalf of my co-authors and myself, we would like to thank you for your thoughtful and constructive comments in manuscript number 1914438, entitled “Actuators and Sensors for applications in agricultural robots: A review”, to be considered for publishing in MDPI Machines. We believe these comments have greatly improved the manuscript.
First and foremost, we would like to thank all the comments and suggestions from the three reviewers and the editor regarding our manuscript, which helped to improve our work. In addition, we appreciate the opportunity to resubmit our revised manuscript.
All the issues noted are listed below and addressed individually.
All new changes made to the paper are marked in blue.
Sincerely Yours,
Dongbo Xie
Issues highlighted by Reviewer 1
The authors made many changes to the manuscript that increased its quality.
However, there seem to be some comments that have been ignored. Therefore, it is requested to either make the suggested changes or provide a response to the following comments (which were previously made in the pdf file):
Issue 1: "An actuator-based drive system is associated to move on land in a motor vehicle, it concerns the movement of the vehicle. However, in the subsequent section are given some examples of systems that are not related to the movement of a vehicle but another type of movement. To be consistent the term drive should be replaced by a more general term, e.g. movement or motion. Another option is to delete the examples that are not consistent with the drive term."
R.: Thank you very much for giving us another opportunity to revise the manuscript. I apologize to you for my carelessness as we repeatedly revised the manuscript and missed replies to the attached questions, and I will reply to your corrections one by one.
Many thanks to the reviewers for their valuable comments. When writing the manuscript, the author used the term "drive" to describe the mechanical structure (device) of the power transmission system of various actuators in agricultural robots. The author then considered the reviewer's comments and replaced the term "drive" with "motion" in this case, and also repeatedly considered the term "drive" used elsewhere in the text. In addition, the author repeatedly considered the use of "drive" in other parts of the paper and modified and replaced the term "drive" according to the specific context of the manuscript, and the modified part is marked in blue.
Issue 2: "This subsection is part of a section related to actuator-based motion systems. However, as the authors wrote, the neural networks are used to "extract and classify crop details and local features". This technique is used as a perception system, not a control system. "
R.: Many thanks to the reviewers for their valuable comments. When writing the manuscript, the author considered that in the field of agricultural robotics, many experts and scholars use neural network control algorithms for extracting and classifying target features of operation objects with the help of various advanced sensor technologies to provide control strategies for the next step of actuator drive systems, and thus categorized neural network control algorithms as control strategies. As experts said, neural network control algorithms are commonly used to extract job objects' target features and not directly for actuator drive systems. So, the author has trimmed this section.
Issue 3: "Why should the end-effector have the function of absorbing these errors and not the robotic arm itself?"
R.: Many thanks to the reviewers for their valuable comments. When designing robotic arms or end-effectors for agricultural robots, it is necessary to consider the effects of subtle differences in color, shading, position, and maturity that may exist on the sensors, therefore, causing errors in the control accuracy of the robotic arms or end-effectors. In the face of the complexity and delicacy of the operating object, the end-effector is usually mounted on the end of the robotic arm and works flexibly directly with the operating object. If the control accuracy of the robotic arm generates errors, the end-effector absorbs or eliminates such errors, so the agricultural robot can still perform flexible operations in non-structured environments. In addition, when agricultural robots need to complete fruit picking tasks, when faced with differences in the size and weight of the fruit and the material force characteristics of the skin, they still cannot effectively complete the picking operation by relying only on the robotic arm to absorb the positional errors existing in itself and the end-effector. However, the end-effector equipped with a mechanics sensor can adjust to the size and mechanics of the fruit in time to complete the flexible operation. Thus, the author thinks the end-effector is needed to absorb or eliminate possible ground errors.
Issue 4: "The caption could be more detailed." - related to table 2
R.: Many thanks to the reviewers for their valuable comments. The title of Table 2 has been changed and marked with blue font.
Issue 5: "The end-effector doesn't comprise all these mechanisms. These mechanisms are different examples of end-effectors, according to the application."
R.: Many thanks to the reviewers for their valuable comments. As mentioned by the reviewer, the examples of the end-effectors are given here in the paper in the context of specific application scenarios of agricultural robots, so the author has made changes here in the paper and marked them in blue.
Issue 6: "Shouldn't there be a section "Disc weeding knife", in the same way as was done for the other mechanisms? "
R.: Many thanks to the reviewers for their valuable comments. The author adds other types of end-effectors to this section based on the "disc type hoe knife" to elaborate on the application of end-effectors in agricultural robots.
Author Response File: Author Response.pdf
Reviewer 2 Report
The introduction was well revised in explaining the classification of researches that the paper takes in the subsequent chapters.
Author Response
Thank you very much for your recognition of our work.
Reviewer 3 Report
The revised version is acceptable
Author Response
Thank you very much for your recognition of our work.
Round 3
Reviewer 1 Report
Thank you to the authors for considering all the comments. The revised version is now acceptable.
