Designing and Implementing a Versatile Agricultural Robot: A Vehicle Manipulator System for Efficient Multitasking in Farming Operations

Round 1

Reviewer 1 Report

The article presents the design of a mobile skid-steering platform with four wheels, together with a serial Cartesian manipulator (PPP) mounted on it. The authors claim that the designed platform can perform several tasks in the agricultural process, since it can move heavy materials in the agricultural field. The conceptual mechanical design and dynamic properties were evaluated using specialized software. Simulation of the dynamic behavior of the platform was carried out, mathematical models and results are presented. Motion control analyzes are also shown in the results and, finally, experimental evaluations were performed to assess the dynamic behavior of the parallel mechanism in the end-effectors.

The text is very descriptive and tries to contextualize a project planning and its importance for agriculture. However, it does not make it clear why the constructed platform is as flexible as the authors propose, since it was designed to only support the harvesting of fruits and vegetables that can be grabbed by the designed grips. As far as modeling and presentation of results is concerned, it is somewhat obscure. In this regard, the following can be mentioned:

-          - Lines 192-194: several variables are cited (B´, x-axis, wheel C) that cannot be seen in Figure 2 as referred.

-        - Lines 237-239: “Each limb consists of one prismatic joint and three revolute joints, and all the joint axes are parallel to each other”, and that could be seen in Figure 6. However, it is not possible to see that in Figure 6. The three revolute joints cannot be located or imagined.

-          - In Section 6, Figures 7 and 8 and Tables 1 and 2 are supposed to describe the coordinate transformations between motion axes using the D-H notation. However, it is not possible to derive these transformations from the tables and figures, which refer to axes and movements that are not clearly specified.

-         - Figures 9, 10 and 11 show graphs of the dynamic behavior of the variables shown in the graph legend, but there is no reference in the text or in any figure to what these variables mean and why they are important.

-     - Figure 15 is a graph of the response to a force of 200N, but there is no reference to what this force is (direction) and where its point of application is.

-         - Figures 15 and 16 are difficult to understand.

 The article concludes with the statement that the system was constructed to possibly move muskmelons and watermelons. Therefore, it obviously lacks the versatility that the article tries to demonstrate in its introductory part.

 In summary, the article is the description of a 4-wheel skid-steering mobile robot project that carries a Cartesian manipulator and a grip for grabbing fruits with a closed kinematic chain mechanism with actuation by parallel and symmetrical bars. The dynamic model is not clearly described and the graphics and information on how they were built need more clarity. The article's contribution as a novelty is quite questionable. For a publication it will be necessary to meet the criticism and improvements suggested.

Author Response

The responses are submitted as an attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

An agricultural robot is developed in this manuscript, and simulation and experimental studies are performed to validate it performance. Overall, this paper is well written and can be considered for acceptance after addressing following issues.

1, This paper presents a whole process of developing an agricultural robot and introduce its potential applications. However, more experimental studies should be performed in real applications to validate it performance in harness fruits.

2, Similar figures should be clustered in a panel. Like Fig11 and Fig12, Fig15 and Fig16, Fig17, 18, 19 and 20.

3, Some references should be added to in the Section of 5 to make the paper looks more like a research paper rather than a scientific report. For example, “Minimum-jerk trajectory planning pertaining to a translational 3-degree-of-freedom parallel manipulator through piecewise quintic polynomials interpolation” and “Multi-objective dimensional optimization of a 3-DOF translational PKM considering transmission properties” both reported kinematic analysis for parallel robot manipulator.

4, Previous studies about this kind of machine should be reviewed in the Introduction part, in order to highlight the novelty of this manuscript. Motivation should be added in the introduction section.

5, How much does it cost to develop this kind of machine? If it is cheaper than other types with better performance, it may have a big market.

6, What kind of terrain is suitable for this machine? Hills or flat ground?

Good

Author Response

The responses are submitted as an attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper presents the design of a wheeled robot equipped with a Cartesian manipulator, used in agricultural operations. In general, the work is well written, but there are some aspects that should be considered

Comments:

1) The authors of the paper frequently use the name "parallel robot" for what is actually a "Cartesian robot". In the theory and practice of manipulators/robots, there is a clear difference between parallel and Cartesian topology. I recommend the authors to take this into account, including in the title of the paper.

2) In Abstract at line 9: What is the meaning of "using solid work modeling"?

3) The introduction should include more information about autonomous robots used in agriculture. Possibly a comparative analysis from the structural point of view. Also, the authors should point out how their robot differs from other robots used in agriculture.

4) The authors state that one of the contributions is "Integration of Robotic Sensor and Visual Feedback". But in the content of the work, this aspect is not analyzed.

5) Apparently figures 2 and 3 look the same. This is due to the small size of the labels.. I think the labels should be enlarged and possibly placed on the same figure.

6)  What is the purpose of figure 14? Also, Figures 15 and 16 are hard to read.

7) Probably the CAD models in figures 17...20 can be made bigger compared to the table containing the description of the components

8) The conclusions are quite general and do not clearly show the contributions of the authors or the advantages of the proposed robot

Based on the above comments, I think that the work needs some improvements to be published

Author Response

The responses are submitted as an attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

A skid-steering mobile platform with four wheels and a Cartesian serial (PPP) manipulator is presented. The platform is designed to perform various tasks in the agricultural process, such as harvesting heavy fruits. The parallel manipulator can handle heavy materials in the agricultural field. The platform was simulated on undulating terrain profiles using ADAMS software. Proportional derivative control and proportional derivative-like conventional sliding surface control were applied to the model. A structural analysis was performed to ensure minimal deformation and the highest safety factor for important components. Calibration tests were conducted at various X, Y, and Z-axis frame mounting stages to minimize the lateral and longitudinal deviation between the parallel linear motion rails.

Field testing was carried out, and all mechanical movements in the lateral and longitudinal directions functioned according to the desired commands. The grippers utilizing parallel mechanisms were also subjected to testing, demonstrating their ability to handle different cylindrical and spherical fruits, and other relevant objects.

The paper has formulated a clear and relevant research question. The methodology is appropriate, comprehensible and well described. The paper is well written, and the figures and tables are illustrative. The structure is logical and clear. The sources are current but more of them could be cited. The argumentation is convincing and based on the simulation results. Disadvantages of the proposed methods are not stated and there is a lack of experimental testing in real harvesting scenarios. Overall, the paper is of good quality and has a value for the research field, but there is also room for improvement and further investigation. After correcting the minor typographical errors, the paper could be published.
A good idea would be a link to a video to see the robot working.

Line                     Hints / Typos

219                      you have obtained -> obtained

431                      and as -> and is

436                      and as -> and is

443                      and as -> and is

Author Response

The responses are submitted as an attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Authors well respond the reviewer's comments. This manuscript can be considered for publication in current form.

Reviewer 3 Report

The content of the work has been  improved, compared to the previous version. The authors also took into account all the suggestions I made

I have no further comments