Preliminary Analysis of a Lightweight and Deployable Soft Robot for Space Applications

Round 1

Reviewer 1 Report

The article describe a base system for an starting point of inflatable deployable robotic arm. The introduction fits the article in the new studies of soft robotics.

The chapter 2 describes the theoretical approach of the kinematics in the system and the possible theoretical solution of the axis change due to the different inflate pressures. 

In terms of chapter 3, a first approach of the system prototype is described. It only considered the different pressures and not any other parameters that will happen in the space like temperature or vacuum. Moreover, one arm is consider and not both proposed in the system. If two inflate volumes are consider there will be different freedom that are uncorrelated between each part of the arm.

Finally, I think that the authors mention that this is a first approach of the system so the point mention in the previous chapter should be part of a second paper of this topic.

Author Response

Dear reviewer,

thank you for your comments. We are working on models to evaluate the effect of other important parameters. In addition, we are developing the complete robot prototype with 3 motors and 2 links. Once the final prototype will be ready, we will be able to analyze, statically and dinamically, the behaviour of the robot considering both the two inflatable links.

As you said, we plan to examine these topics on a second paper.

Best regards

Reviewer 2 Report

Preliminary Analysis of a Lightweight and Deployable Soft 2 Robot for Space Applications

This article discusses the modeling and control approaches of an inflatable two-link robotic arm intended for use in space applications. The paper is well written and has the potential to be published in Applied Science journal.  I have few comments which I hope will be helpful.

1. The authors claimed that the robotic arm described in the paper is intended for use in space applications because of its lightweight design. However, robots that use pneumatic actuation require a bulky control board or air supply. I think this power requirement should be discussed in the paper. For example, in line 73 the authors said “a relatively small package”, which is ambiguous (relative to what?). I believe other than the weight, soft robotic arms are safe to interact with humans and they can adapt to the environment. In the introduction adding more discussion about other benefits will be useful.
2. The word “preliminary” in the title is weird. It is more like a report title. I think you should remove it from the title (also from line 78).
3. The definition of the Denavit-Hartenberg parameters should be added to the caption of Fig.1. Also, it will be nice to cite the paper  “Hartenberg, Richard Scheunemann; Denavit, Jacques (1965). Kinematic synthesis of linkages. McGraw-Hill series in mechanical engineering. New York: McGraw-Hill. p. 435”
4. It is also the same for the “pseudo-rigid body model”. Please cite Larry Howell, Compliant Mechanism book.
5. In Fig. 3, the links introduced by the virtual springs should be labeled. Also please show the rotation axis of the motors in the figure.
6. In experiments, the authors considered pressure values from 10 to 60 kPa and said that the change in the stiffness is not significant according to pressure. However, the k values given in Table 3 look different than each other. How many measurements did you perform for each case? Are the numbers given in Table 3 the mean of multiple experiments?  How did you choose the minimum and maximum pressure amount?
7. Does your model consider any disturbances? For example, if the arm doesn’t inflate properly, what happens? Could you comment on that in the paper?
8. Could you compare your experimental results with the simulation results given in Fig. 10?

 

Other comments:

1. “This dissertation” in line 76 should be “the paper”.
2. I think the caption of Fig. 2 should include “pseudo-rigid body model”.
3. The unit mbar in line 259 should be converted to an SI unit.
4. Is the number “-15” in line 246 correct?
5. M_w and M_max (in line 230) should be defined when they are first mentioned.
6. Are v in Table 1 and line 205 the same?
7. Is the symbol in Line 216 a divide symbol? If so, it should be replaced by “–“?

Author Response

Dear reviewer,
thank you for your comments and suggestions. We found them helpful. 
Please see the attachment. We have replied point-by-point to the comments.
We hope our explanations could be thorough.

Best Regards

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have improved the paper according to comments. I still think the figure captions can be more informative.