Predefined-Time Nonsingular Attitude Control for Vertical-Takeoff Horizontal-Landing Reusable Launch Vehicle

Round 1

Reviewer 1 Report

Review paper for “Predefined-time Nonsingular Attitude Control for Vertical Takeoff Horizontal Landing Reusable Launch Vehicle”

The paper presents a novel predefined-time nonsingular attitude control system for the VTHL reusable launch vehicle (RLV) in the presence of model couplings, external disturbances and parameter uncertainties. In general, the topic of the paper is within the scope of the journal. However, there are some points that need to be addressed in detail to meet the quality of the publication. The comments and suggestions are given below:

1. Eq. (17), -2kx/Tf^2 è -2kx/Tf because x=t/Tf

2. Eq. (18) must be considered because EQ. (17)

Eq. (19) is also careful with the derivative of the right side

3. Line 353 needs to be re-write: From Figure.3-6? It also is in line 367.

4. Please discuss more details for results from Fig.3 to Fig. 6

Finally, a major revision is needed to rewrite the paper to reflect the contribution properly before the paper might be accepted for publication the above issues should be addressed.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The authors proposed a control method to vertical takeoff horizontal landing reusable launch vehicle. The paper is well written. The methodology and the theories are presented very clearly and are verified carefully. This is overall a solid work. I would recommend it for acceptance after minor corrections. For example, 1) fix citation format mistakes across the manuscript, such as line 36: Ming proposed --> Ming et. al [4] proposed; 2) lines 126-128, ||x|| does not appear anywhere, do you mean |x|? 3) lines 347-348, put brackets around the vectors. A thorough proofread may fix all possible small mistakes.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The authors proposed a novel predefined-time prescribed performance nonsingular sliding mode controller for attitude tracking control of a vertical takeoff horizontal landing (VTHL) reusable launch vehicle. The predefined performance methods have attracted increasing attention in recent years. This is an interesting work. My comments are listed as follows:

1. It is encouraged to add a figure of the launch vehicle.

2. In the introduction, when the references are cited, and if there are more than one or two authors, pls use et al. For example, in line 54, ‘Zhang presented a nonsingular SMC for RLV with a fixed-time terminal sliding mode surface [14]. Liang designed a  robust controller for RLV based on a fixed-time SMC [15].’

3. In section 3.1. Performance function design, line 201, where does y come from? Likewise, In Figure 1. The simulation results with different and Tf and k, pls compare the PTPPF and the first and second order derivative from equations 14 and 15.

4. In fig.3 and 4, pls distinguish the sub-figures as (a), (b), (c)

5. The authors need to compare the proposed and available models in Refs.[20-24] in the literature, and explain how the novel model is superior. Likewise, can the author’s method be applied to spacecraft and hypersonic flight vehicles, including different order dynamic systems?

 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The reviewer agrees with the revised version. Most contents satisfied the requirements.

The grammar of English needs to check carefully. Some words must be checked like Fig.10 to Fig. 10 with a space.