Multi-Objective ADRC-Based Aircraft Gust Load Control

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article employs the ADRC approach to estimate perturbations and mitigate gust loads on flexible aircraft. The numerical simulations demonstrate that the aircraft exhibits improved performance when implementing the ADRC. The authors must address the following issues to improve the clarity and presentation of the article.

 

1. Does the aircraft model SE2A or SE^2A?
2. Figure 1 does not present any information about the aircraft.
3. Explain Figure 3. Why is \ddot{\eta} equal to zero? What does LAD mean?
4. When giving an equation, define all the variables. For example, in equation 1, what is A_z, V, \dot{gamma}? In equation 2, which is the pitch angle, the angle of attack, and the flight path angle?
5. Why can theta be approximated to q? What is q?
6. What is Z_delta, delta?
7. How is the disturbance term (6) obtained?
8. Explain how (6) is obtained from (5).
9. Function fal depends on the value of delta; however, delta has been defined as a vector. What is the relation between the alpha of equation 2 and alpha1 and alpha2 of the function fal?
10. Equation 10 is the control strategy. What is Azc? What is kp? Furthermore, there is a singularity when V=0 or Z_delta_flap=0. How do the authors avoid that singularity? What is the meaning of V=0 or Z_delta_flap=0?
11. In equation 12, what is wg?
12. The perturbation term can be mistaken with the one defined in (6).
13. The model given in equation (16) is a second-order model; therefore, the ESO given in (8) can not be applied. How is control defined for system (16)?
14. Why is the 1-cosine discrete gust considered a relatively dangerous scenario?
15. Please give all the numerical parameters that the authors used to perform the simulation.
16. In Figure 5b, a peak is observed when the ADRC is used. Why?
17. In Figure 6, it is evident that as the delay increases, the peaks are attenuated. What is the largest delay the system can withstand?
18. There are spelling and grammatical errors throughout the document. For example, missing spaces between words, and capitalizing a word after a semicolon. A native speaker must review the article before resubmitting it.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The author has presented an approach to mitigate the effects of gust disturbances by implementing control decoupling. The study offers valuable insights and is well-structured. However, the manuscript requires the following revisions:

1. The author has presented detailed simulation work under varying parameter conditions. The results demonstrate the effectiveness of the proposed approach in terms of reduced wing-root bending moments, lower peak normal load factors, decreased RMS fluctuations in structural loads, improved attitude stability, and an extension in structural fatigue life. However, a significant concern remains: the absence of experimental validation. It is strongly recommended that experimental studies be conducted to verify the effectiveness of the proposed method.
2. Some of the compound nouns used in the paper may be difficult to interpret clearly. It is kindly suggested that the manuscript be reviewed by a native English speaker to enhance clarity and overall readability.
3. The introduction section should be organized in a manner that enables the reader to:
4. Grasp the overall context and significance of the topic.
5. Identify the existing research gap.
6. Understand how this study aims to address and contribute to filling that gap.
7. Rewrite conclusions. Wrap up your ideas and leave the reader with a strong final impression. Please restate the problem statement addressed in the paper, summarise your overall arguments or findings, and suggest the key takeaways from your paper. Please include a list of symbols, abbreviations, and nomenclature.
8. The author has presented the Extended State Observer (ESO) in Equation (8), but its derivation has not been explained. If the formulation is taken from previously published literature, please provide the appropriate reference.
9. In the paper, the author assumes that “during flight, the variation of aerodynamic parameters is continuous and bounded; the effectiveness coefficient of the elevator also varies continuously and remains bounded with deflection; and gust excitations are modeled as external disturbances with finite energy, so their amplitudes are also bounded.” Could the author clarify whether these assumptions are practically achievable in real-time flight applications?

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The concepts Wing Root Bending Moment and Modal frequencies of critical symmetric modes are not clarified. Section 2.3.1 does not clearly indicate the notations used in the formulas. In conclusion, the authors indicate that the simulation was made for combined adverse conditions, but this is not described in point 3, describing the simulation. The authors did not indicate why they chose no GAL and ADRC for comparison, and did not compare their method with another similar one. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have done a great job answering my doubts. Nevertheless, some issues should be addressed.

 

1. Update Figure 3. Instead of az, it should be a_z.
2. Use mathematical mode in the paragraphs.
3. Variable q has not been defined.
4. In equation 9, what happens if the airspeed V is equal to zero?
5. Lines 293-305, another type of letter is used.

Author Response

Comments 1:[Update Figure 3. Instead of az, it should be a_z.]

Response 1:Thank you for your careful review. The notation has been corrected from az to a_z in Figure 3 as suggested.

Comments 2:[Use mathematical mode in the paragraphs.]

Response 2:Thank you for the suggestion. The mathematical formatting has been carefully checked.

Comments 3:[Variable q has not been defined.]

Response 3:Thank you for pointing this out. The variable q, representing the pitch rate of the aircraft, has been defined in the Nomenclature section at the end of the manuscript.

Comments 4:[In equation 9, what happens if the airspeed V is equal to zero?]

Response 4:Thank you for the valuable comment. In practical scenarios, the aircraft operates under non-zero airspeed conditions, and Equation (9) assumes V>0. In our simulation implementation, to avoid numerical singularities and ensure stability, we set a lower bound for airspeed as Vmin=0.1 m/s. This threshold avoids division-by-zero issues while preserving the physical consistency of the model. 

Comments 5:[Lines 293-305, another type of letter is used.]

Response 5:Thank you for pointing this out. The font inconsistency in Lines 293–305 has been corrected.

Reviewer 2 Report

Comments and Suggestions for Authors

I have reviewed the revised version of the manuscript. The author has addressed the majority of my comments satisfactorily and revised the manuscript accordingly. I am satisfied with the revisions and the responses provided to my concerns.

Author Response

我们衷心感谢审稿人的积极评价和宝贵建议。