Muscle Fatigue Regulation through Muscle Activation Control in a Knee Hybrid Exoskeleton: Simulation Study

Round 1

Reviewer 1 Report

The work is good, and some questions are given as follows:

1. How to realize the model uncertainty of the model in simulation? And how to deal with the uncertainty problem.

2. How to deal with some nonlinear factors, such as time delay and friction.

3. How to design the control parameters?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This is an interesting paper. The authors proposed an innovative control structure that can regulate muscle fatigue by controlling muscle activation while keeping the joint angle at a desired position. Compared to many existing methods, such as NMPC and tube-MPC, the proposed methods show a lot of merits in terms of accuracy and fatigue control. The math is correct, and the result is convincing. 

Honestly, the English writing of this paper can be improved. Let's take the abstract as an example. You mentioned 'an innovative adaptive controller for FES is designed.' How about something like 'an innovative controller for FES with adaptive components is designed.'? 'A cooperative control structure is used to simultaneously use the electrical motor and FES' There are two 'use' in the same sentence. 'the ultimately uniformly boundedness of' does sound right. Maybe you need an adj. in the sentence. Maybe you can check your English again. By the way, I would recommend you put the negative sign in (29) to the top of the numerator K'. Otherwise, it gets mixed with the division sign and makes people think that result is diverging. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Dear Authors,

The manuscript presents a simulation study on the muscle fatigue regulation by muscle activation control. The manuscript presents a new method to control muscle activation and the knee joint angle.

Please find my comments below:

1. The paper needs undergo language edit. There are several issues in the current format of the text. Moderate editing of English language required.

2. Line 94-100: Please revise this paragraph. Also, add references and cite the previous works where applicable.

3. Line 100: "Considering these disadvantages, providing a method to regulate muscle fatigue is essential." Please elaborate on this statement.

4. L127-132: Text needs to be revised. 

5. Please improve the quality of Figure 2.

6. Please improve the quality of Figure 4.

7. Avoid using first person point of view in the main text. For example: "We add and subtract the expression..", "we can write (26) as (27)." , "We replace the expression..." etc.

8. Discussion section needs to be improved and the advantages of the proposed system needs to be highlighted in this section. Please use the obtained values (results) and compare them with the previous works to justify the proposed method and highlight its advantages (I suggest moving Table 9 to the discussion section or add a final table to compare/justify all the results).

9. L7.5-713: Please move the future works to the end of conclusions section. 

The manuscript needs undergo moderate editing of English language. There are issues in the current format of the text. Also, the readability of the manuscript needs to be improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Dear Authors,

Thank you for revising the manuscript and addressing the comments.

I have no further comments. 

Good luck.

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