Quasi-Passive Resistive Exosuit for Space Activities: Proof of Concept

Round 1

Reviewer 1 Report

The paper introduces a proof of concept of a novel exosuit for space operations.

 

The paper is very well structured and presented. In my opinion thereare just some minor revisions to be done to strenghten the soundness of the paper.

 

Some more introduction have to be done in order to introduce better biomechanical anlysis and problems. These paper can help and can be put in the referecenses to givve a better background:

 

Picerno, P., Cereatti, A., Cappozzo, A. Joint kinematics estimate using wearable inertial and magnetic sensing modules (2008) Gait and Posture, 28 (4), pp. 588-595. https://www.scopus.com/inward/record.uri?eid=2-s2.0-52049102652&doi=10.1016%2fj.gaitpost.2008.04.003&partnerID=40&md5=fbc22c073158c4536892c2b6923f50d1 DOI: 10.1016/j.gaitpost.2008.04.003

Cafolla, D., Marco, C. Design and simulation of humanoid Spine (2015) Mechanisms and Machine Science, 24, pp. 585-593. https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928231201&doi=10.1007%2f978-3-319-09411-3_62&partnerID=40&md5=ae9da363031b9439d4c0220c53c5353a DOI: 10.1007/978-3-319-09411-3_62
A little more enphasis should be put on the possible exercises in which the suit can help even if in the conclusion is mentioned that it will be part of future works.

AAfter these minor revision in my opinion the paper can be pubblished as it match the quality and focus of the journal.

Author Response

Au: We thank the reviewer for the comment, we included citation of Picerno et al. at line 323 and, we emphasized the exercises that we foresee to carry out with the suit.

In the text, the following changes are proposed at line 86:

The astronauts will train their limbs, as they would under normal gravity on earth,  without the need to dedicate long portions of their day to maintaining health/fitness. Previous studies have shown that a low-intensity resistance training with relatively tonic movement and a short rest period causes increases in muscular size and strength [107], and slow-speed resistance training has also shown to effectively cause an increase in muscular strength [108]. In conclusion, prolonged continuous low- to moderate-intensity endurance type exercise training is equally effective as continuous moderate- to high-intensity training in increasing whole body and skeletal muscle oxidative capacity (main responsible for the muscle regeneration process) [109].

Line 543:

Considering that, the final target is to use the exosuit at micro-gravity as muscle degradation countermeasure by modifying the training paradigm. These preliminary results start building evidence that continuous training could substitute concentrate training as micro-gravity countermeasure with potential equal benefits.

Reviewer 2 Report

I think the authors have sufficiently surveyed related research. However, it is difficult for reader to understand the authors' conclusions due to the distraction of the paper. An overall reorganization of the article is required.

Author Response

Au: We thank the reviewer for the comment; based on the comments of the other reviewers we don’t see the need to modify so much the structure. We would like to receive form the reviewer a more detailed and precise request instead.

Reviewer 3 Report

The author demonstrates a quasi-passive exosuit to provide muscle training using a small, portable, proprioceptive device. The author performed well the assessment of the resistive exosuit with QPA and specific sensors strategy during the walking tasks by analyzing the effects on gait kinematics, muscular activation and muscular fatigue well. Overall, this paper is well written, and I recommend publishing this manuscript.   

Author Response

Au: We thank the reviewer for the comment.

Reviewer 4 Report

The contribution presents research work on resistive exoskeleton with soft sensors and control system which could help astronauts overcomу fatigue in knees in Space. 
The manuscript is wright-organized, the introduction section presents proper background study and it is clear what are the development trends in the field. But the paper as a whole is written very unclearly and contains a lot of extra data.  It's really hard to read. 
The "Materials and methods" section gives an overview of the possible strategy to create a system that deals with an exoskeleton and gives an overview of the model used for the experiment. 
The "Experimental Evaluation" section seems adequate to me, but Fig.7 is unreadable. 
A huge part of the paper is occupied by the "Discussion & Limitations" section, but it seems like an attempt at data analysing.  I suggest rewriting it and present as a table form.
This paper could be interesting for a wide audience, not only from researchers from the space area and I suggest accepting the contribution after revision last part.

Author Response

Au: We thank the reviewer for the comment. We modify figure 7, now it is more readable. We have reviewed the discussion and limitation section adding the table as proposed by the reviewer.

Line 512:

The resistive exosuit presented and assessed in this work (results are summarized in Table 1) is able to increase the muscular activity of both extensor and flexor muscles of the knees

Table 1: Overall performance: comparison of modalities without the exoskeleton worn (NoExo)
and with the resistive exosuit (Exo).

Index	NoExo	Exo	difference
RoM PKF CI RMS of VL RMS of BF MF of VL MF of BF	54.6o 61.9o 6.3% 20.8%MVC 25.8%MVC 98.4% 90.9%	44.6o 48.6o 6.3% 55.2%MVC 32.1%MVC 79.8% 80.1%	-10o -13.3o 0.0 34.4%MVC 7.3%MVC -18.6% -10.8%

Round 2

Reviewer 2 Report

I think the authors did extensive surveys and experiments on exosuits. Unfortunately, I have no choice but to say that the content of the article is distracting. This article is considered a technical report rather than an academic paper. I will forward my opinion to the editor as well, so if you disagree with my opinion, please consult with the editor.

Reviewer 4 Report

 The manuscript could be accepted.