Fuelless On-Orbit Assembly of a Large Space Truss Structure Using Repulsion of the Service Spacecraft by Robotic Manipulators

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The content and organization of the manuscript are satisfactory, and I recommend accepting it after minor revisions towards the following suggestions:

1. At line 56, reference 23 is not cited validly. It is now displayed as [22?].

2. Several assumptions have been made in Section 5, by which the motion is fixed in the orbital plane Oxz. Would these assumptions be too strict? Please explain that this motion mode is common in practical or theoretical work.

3. Equation 18 is based on the viewpoint that a6 is much greater than z1 and a3 is much greater than x1. I have doubts about this since the specific calculation method of ai has been ignored. Providing general ranges for coefficients and coordinates may dispel these doubts.

4. In Fig. 15, the position error remains almost unchanged in approximately the 10th to 40th iterations but suddenly decreases again after the 45th iteration. Why does this phenomenon occur? How to set an appropriate catch zone to capture the final convergence and avoid premature termination?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Summary:

This is a manuscript on the issue of providing on-orbit assembly of large space truss estructure, addressing the limitation in size of launcher payloads. Authors propose a fuelless motion control approach for spacecrafts, equipped with robotic manipulators: their methodology is based on the use of repulsion forces generated by the manipulators to provide the servicing spacecraft with the robotic arms; by doing so, they can avoid the use of fuel/propulsion. Authors show the effectiveness of their proposal by using numerical simulations, describing the successful assembly of the structure of an antenna based on a truss.

 

Broad comments:

Strengths:

1. The research is focused on a hot topic in the space arena, and authors use a straightforward but apparently effective solution.
2. The text can be easily read by any reader.

Weaknesses:

1. To my humble opinion, the main weakness is related to.
2. I just can find some small improvements before publication (see list below).

 

Specific comments:

1. Major issues:
1. Please, consider creating a “Future Works” section, elaborating the ideas show in lines 550-552.
2. Please, consider creating a table with all magnitudes used in the text.
3. Please, provide a rationale for the sentences regarding algorithm 1 is faster than 2, but 1 is more sensitive (lines 437, 438)
4. Please, explain the limitation of 5 cm/s (line 283), and its relationship to the use case.
5. Please, explain why the “several meters” accuracy is unacceptable for repulsion velocity calculation, but acceptable for first guess for numerical search (lines 299-301)
6. Please, explain the rationale for the proposed barrier function in (22).

 

2. Minor issues:
1. Please, add a brief summary of your results in the abstract of the paper, for the simulation use case used.
2. Please avoid multi-citations, such as in [3-6] (line 31), or [14-19] (line 52): readers want to understand the different alternatives that have been already addressed, and why your research goes further.
3. Please, fix cite [22] (line 56)
4. I would avoid the specific acronyms in Figures’ captions (“…: (1) CC, (2) installing platform, (3) TS, (4) SS”, “…f SS with rod: (1, 2) two positions of SS with rod, (3) UB, (4) UB convex hul”, for instance). Altough they are previously defined in the text, the caption could benefit from clarity being stated complete (cargo container, servicing spacecraft, truss structure, …)
5. Please, consider including the rotation matrixes and Х as equations (lines 114 and 117)
6. Please, remove the comma after “]” in equation (3)
7. Please, include C₁ to C₆ as equations (line 145)
8. Please, include m_ex (line 151), J^k (157) and J^BRF (161) as equations.
9. Please, fix/clarify the references to “the problem”: in line 211, it cites the problem that has been introduced previously. But, in line 269, a “problem (16)” is introduced: what is this problem about? Then, in line 377, we have another problem (“problem (21)”).

 

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Just the small typos previously stated.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf