Capture Dynamics and Control of a Flexible Net for Space Debris Removal

Round 1

Reviewer 1 Report

The paper ‘Capture Dynamics and Control of a Flexible Net Robot for Space Debris Removal’ focus on the process of capturing irregular and rotating debris via a flexible net robot and proposes an active control scheme is applied for designing the controllers of the flexible net robot. The simulation results show that the wrapping of the debris is stable, and the debris can be dragged away along the expected trajectory, thus feasible for future missions.

The theme of the paper is very interesting, the results of the simulations are good, anyway some aspects should be clarified:

- How did you get the simulation parameters of the debris shown in Table 1? How the simulation results are modified if the parameters are modified? Please explain it.

- From Figure 11 and 12 it seems that the contact forces on the debris and on the actuators are very low and that the chosen actuators (maximum force 100 N) are noticeably oversized. Is it correct? Could you choose  much more reduced actuators? Please explain it.

- Pag. 10 you write that if there no control applied to the actuators, the open area will decrease to zero and the four actuators would collide each other. But, is it necessary to use a robust control to avoid this condition, could not be enough to fix some limits to the actuators elongation? Please explain it.

- What about the effects of the possible delay of the experimental controller on the performance of the proposed flexible net robot? Please specify it.

Author Response

Dear reviewer,

Thank you for your valuable comments on our paper, and we have carefully modified our paper according to your suggestions. Attached please find our responses to your comments, thank you once again! 

Best,

Yu Zhang 

Author Response File: Author Response.docx

Reviewer 2 Report

This paper presents an interesting Control of a Flexible Net Robot. The paper is well written, but it does not really present anything new to the state of the art. That said, the article is still a very interesting report to read. Below are some improvement suggestions:

1. Please explain the novelty and advantages of your method in the Abstract and Introduction.
2. Please add some new references around 2021-2022
3. Explain in more detail the novelty of the proposed method, it seems that this paper only discusses the existing methods. Please provide a block diagram or pseudo-code.
4. Since it's talking about a robot, give an illustration of the shape of the robot used. Explain the relationship between the variables in the equation with the robot part.
5. I found several papers discussing the same thing, please add a discussion about previous papers and explain the difference with the proposed method 

Author Response

Dear reviewer,

Thank you for your valuable comments on our paper, and we have carefully modified our paper according to your suggestions. Attached please find our responses to your comments, thank you once again! 

Best,

Yu Zhang 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Ok, you fully answered to the requested comments.

Author Response

Dear reviewer, thank you for your attention to our paper.

Reviewer 2 Report

1) In my previous comment no. 4, I think I said it very clearly. I ask for a figure or illustration. But the author didn't answer it.

2) And I asked the author to provide the variables used in the equation in the robot/actuator image.

3) Add the used equation (if any), for each block in the flowchart Fig. 1.

4) Add a discussion by comparing the results of the proposed method with the previous methods. Can be explained with a table or chart.

Author Response

Dear reviewer,

Thank you for your attention to our paper. We have revised our manuscript according to the comments, and all the comments have been carefully addressed. The modifications are marked red in our updated manuscript. Please check it. 

Best

Yu Zhang

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

The author has reviewed the paper well. My suggestion, the author can add related works to clarify the comparison with the previous methods.

Author Response

Dear reviewer,

Thank you for your attention to our paper. We have revised our manuscript according to the comment, and the comment has been carefully addressed. The modifications are marked red in our updated manuscript.

Best,

Yu Zhang

Author Response File: Author Response.docx