Soft Robot Design, Manufacturing, and Operation Challenges: A Review
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Comments for author File: 
Comments.pdf
Comments on the Quality of English Language
Moderate editing of English language required
Author Response
The authors provide an insightful and comprehensive overview of the challenges surrounding soft robot design, manufacturing, and operation. This holistic approach not only enhances the understanding of the complexities within soft robotics but also underscores the ongoing efforts to overcome these challenges.
Response:
Thank you for reviewing the manuscript.
However, there are still some issues could be improved.
1. Integration with existing systems is indeed a crucial aspect that presents significant challenges for the adoption of soft robotics in practical applications.
- a) Integration with Rigid Bodies
- b) Integration of Different Soft Materials
- c) Interface Mechanisms for Firm Attachment
The authors would better make some introduction or discussion about this part.
Response:
These are inarguably valid points. Hence, we added the following part to the Introduction section.
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- Perhaps, the application readiness level of soft robots is in infancy. Nonetheless, soft robots exhibit potential impacts on various industries including manufacturing [52, 53], medicine [15, 54-56], food [19, 20], etc. Although this literature survey focuses on soft robot design, manufacturing, and operation challenges, it is important to note that the precursors of these challenges are often defined by the applications of soft robots. An important aspect of soft robot applications is the integration of soft robots with existing platforms. Based on applications, a soft robot may need a certain mechanism or method for integration with existing platforms that may consist of either rigid or soft bodies. Such integration efforts need joining or assembling of dissimilar soft or rigid materials. Soft-rigid-material integration is still an open topic for future research. In general, a soft robot can be mounted on an existing soft or rigid platform through different bio-inspired attachment mechanisms, such as grasping or clinging [2, 56-60], magnetism [61], and/or adhesion [52, 62, 63].
2. The optimization of figures presents an opportunity for improvement. For instance, in Figure 5, centering the image and ensuring uniformity in caption size could enhance visual coherence. Additionally, expanding each figure to include more subfigures could enhance the depth and richness of the visual presentation. By subdividing the content of each figure into multiple subfigures, authors can provide a more detailed and nuanced depiction of their findings.
Response:
Agreed. The old figures are revised or replaced with new original figures along with explanations in the revised manuscript now.
3.The authors meticulously delineate the challenges within each section; nevertheless, the ultimate objective of soft robotic research is its practical application. While the authors delve into the intricacies of integration with existing systems, they could also provide a comprehensive discussion regarding the challenges inherent in the application of soft robotics. This discussion could include a profound analysis of the most critical issues that require immediate attention and resolution. By refining their discourse to encompass such considerations, the authors would not only enhance the depth of their exploration but also offer invaluable insights into the prioritization of research efforts aimed at advancing the practical implementation of soft robotics.
Response:
We added the following discussion parts to the Introduction section and the Summary section, respectively.
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- Perhaps, the application readiness level of soft robots is in infancy. Nonetheless, soft robots exhibit potential impacts on various industries including manufacturing [52, 53], medicine [15, 54-56], food [19, 20], etc. Although this literature survey focuses on soft robot design, manufacturing, and operation challenges, it is important to note that the precursors of these challenges are often defined by the applications of soft robots. An important aspect of soft robot applications is the integration of soft robots with existing platforms. Based on applications, a soft robot may need a certain mechanism or method for integration with existing platforms that may consist of either rigid or soft bodies. Such integration efforts need joining or assembling of dissimilar soft or rigid materials. Soft-rigid-material integration is still an open topic for future research. In general, a soft robot can be mounted on an existing soft or rigid platform through different bio-inspired attachment mechanisms, such as grasping or clinging [2, 56-60], magnetism [61], and/or adhesion [52, 62, 63].
- Although this literature survey focuses on soft robot design, manufacturing, and operation challenges, it is important to note that the precursors of these challenges are often defined by the applications of soft robots. An important aspect of soft robot applications is the integration of soft robots with existing platforms. Based on applications, a soft robot may need a certain mechanism or method for integration with existing platforms that may consist of either rigid or soft bodies. Such integration efforts need joining or assembling of dissimilar soft or rigid materials. Soft-rigid-material integration is still an open topic for future research.
Reviewer 2 Report
Comments and Suggestions for Authors
In this paper, the author reviews the design, manufacturing and operation of soft robots, and points out the technical challenges. It might be interested for readership of JMMP. However, there are also quite a few obvious flaws that should be improved in further revision.
1. At lines 42-43, the author mentioned that Figure 1 is similar to the graph in reference 7, so what is the difference between them? The soft materials and rigid materials in Figure 1 are not distinguished by color or any other representation, and it is not noticed that compared to rigid materials the Young’s Modulus of soft materials are closer to biomaterials. Thus, the reviewer did not see the significance of Figure 1.
2. This article should reflect the core difficulty and feasible breakthrough direction of the software robot technology in Design, Manufacture, and operation. For now, this article is more likely a review of progress.
3. As a review article, the information in Figure 5-8 is too little. Related advanced technologies are not shown in these figures, such as multi-material additive manufacturing, etc. These technologies can be easily found in the cited references.
Comments on the Quality of English Language
Nothing.
Author Response
In this paper, the author reviews the design, manufacturing and operation of soft robots, and points out the technical challenges. It might be interested for readership of JMMP. However, there are also quite a few obvious flaws that should be improved in further revision.
Response:
Thank you for reviewing the manuscript.
1. At lines 42-43, the author mentioned that Figure 1 is similar to the graph in reference 7, so what is the difference between them? The soft materials and rigid materials in Figure 1 are not distinguished by color or any other representation, and it is not noticed that compared to rigid materials the Young’s Modulus of soft materials are closer to biomaterials. Thus, the reviewer did not see the significance of Figure 1.
Response:
Agreed. We removed Figure 1.
2. This article should reflect the core difficulty and feasible breakthrough direction of the software robot technology in Design, Manufacture, and operation. For now, this article is more likely a review of progress.
Response:
We added new figures and more details to the revised manuscript to encompass the past, present, and future of soft robot design, manufacturing, and operation. We hope these additions improve the quality of the paper.
3. As a review article, the information in Figure 5-8 is too little. Related advanced technologies are not shown in these figures, such as multi-material additive manufacturing, etc. These technologies can be easily found in the cited references.
Response:
Agreed. The old figures are revised or replaced with new original figures in the revised manuscript now.
Reviewer 3 Report
Comments and Suggestions for Authors
Dear Authors,
this is a nice and comprehensive overview. However my impression is that it is covering too much. Design, Manufacturing and Operation for soft robotics are each a complex topic.
- At the moment each section is not providing too much insight into the individual topics.
- Although in the introduction you mention SMA, DEAs etc. in the review mostly pneumatic systems are adressed.
- If you want to stick to the current version of the review, I would suggest to highlight the interdependencies between operation, manufacturing and design. Right now many of the listed sources seem not to be connected. Maybe use tables, graphs etc. to discuss and compare in more detail.
- You mention that incorporating long fibers in additive manufacturing is difficult. That is true but with textile technology it is possible to construct complex shapes of reinforcement/actuator/sensor fibers and then cast the elastomer material ( https://doi.org/10.1002/aisy.202000221)
- I don't understand your text on page 12, l 481ff. What is the point of a soft robot if it cannot respond to external stimuli? At least you would want it to respond to your control signal in form of an electric stimuli or a conversion of the electric signal to temperatur etc.?
-Fig. 4: Dielectric (spelling) and most of the listed other elastomers like ecoflex are also dielectric elastomers. And mixing matrix material (Ecoflex, Dragon Skin) with sensing/conductive material (LM) and active materials (SMA) in one chart is confusing a offers little advantage. Also what is flexible resin? Resin usually refers to a material, which is not yet polymerized so Ecoflex A/B would also be flexible resins?
-Fig. 3 quality and source?
- Fig. 8 Pneumatic actuators mostly have non-linear pressure-deformation relations (one of their drawbacks), so I do not get why having two chambers makes it non-linear? Also image quality and axis label --> no square brackets, don't write axis as the label. The axis is what you are labeling not the quantity of what the axis is illustrating.
- Figures should be positioned after mentioning them in the text.
Author Response
Dear Authors,
this is a nice and comprehensive overview. However my impression is that it is covering too much. Design, Manufacturing and Operation for soft robotics are each a complex topic.
Response:
Thank you for reviewing the manuscript.
- At the moment each section is not providing too much insight into the individual topics.
Response:
Each section has new figures with corresponding texts to provide more clarity and insights into each individual topic.
- Although in the introduction you mention SMA, DEAs etc. in the review mostly pneumatic systems are adressed.
Response:
For clarity, the key aspects of Section 4 and Section 5 are italicized in the revised manuscript to emphasize the diversity of methods and systems.
- If you want to stick to the current version of the review, I would suggest to highlight the interdependencies between operation, manufacturing and design. Right now many of the listed sources seem not to be connected. Maybe use tables, graphs etc. to discuss and compare in more detail.
Response:
The revised manuscript has updated Figure 1, Figure 3, and Figure 5 and corresponding texts that intend to highlight the relationships between different topics and sources.
- You mention that incorporating long fibers in additive manufacturing is difficult. That is true but with textile technology it is possible to construct complex shapes of reinforcement/actuator/sensor fibers and then cast the elastomer material ( https://doi.org/10.1002/aisy.202000221)
Response:
We included the suggested reference, which is [122], in Section 4 as shown below.
-
- Moreover, in the areas of additively manufactured functional elements, the process of embedding long fibers is time consuming, laborious, and prone to errors. To facilitate the fiber embedding process, an automated fiber embedding mechanism [102] as well as a textile-based method [122] have been proposed.
- I don't understand your text on page 12, l 481ff. What is the point of a soft robot if it cannot respond to external stimuli? At least you would want it to respond to your control signal in form of an electric stimuli or a conversion of the electric signal to temperatur etc.?
Response:
Thank you for noticing it. We revised the sentence as shown below.
-
- Recently, an innovative breakthrough has been achieved in the field of soft sensing and actuation, so that soft robots can be actuated without the need for any external energy sources.
-Fig. 4: Dielectric (spelling) and most of the listed other elastomers like ecoflex are also dielectric elastomers. And mixing matrix material (Ecoflex, Dragon Skin) with sensing/conductive material (LM) and active materials (SMA) in one chart is confusing a offers little advantage. Also what is flexible resin? Resin usually refers to a material, which is not yet polymerized so Ecoflex A/B would also be flexible resins?
Response:
Agreed. We made necessary changes to the figure, which is Figure 3 now.
-Fig. 3 quality and source?
Response:
Figure 3, which is Figure 2 now, is our own original figure that has not been published yet. The figure quality is improved now.
- Fig. 8 Pneumatic actuators mostly have non-linear pressure-deformation relations (one of their drawbacks), so I do not get why having two chambers makes it non-linear? Also image quality and axis label --> no square brackets, don't write axis as the label. The axis is what you are labeling not the quantity of what the axis is illustrating.
Response:
Figure 8, which is Figure 6 now, is our own original figure. We made improvements as suggested.
- Figures should be positioned after mentioning them in the text.
Response:
Agreed. We made sure that all figures follow their respective first citations in the text.
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
Based on the revisions made, I endorse the publication of this manuscript in JMMP.
Author Response
Thank you for reviewing the revised manuscript.
Reviewer 3 Report
Comments and Suggestions for Authors
Dear Authors,
thank you for updating your manuscript according to the suggestions.
I have to requests where I am not agreeing with your updates:
- Figure 3: The issue of mixing different aspects in one pie chart remains: One publication can use Ecoflex, SMA and Liquid Metals. Having all amount to 100% does not make sense imho. So I suggest to divide between matrix material and actuating mechanism.
- Recently, an innovative breakthrough has been achieved in the field of soft sensing and actuation, so that soft robots can be actuated without the need for any external energy sources. --> This seems a bit misleading. The robot still requires an external energy source. In this case a temperature increase, which is a transfer of energy from the environment to the robot. It is not possible to perform work without some sort of energy supply.
Author Response
Thank you for reviewing the revised manuscript.
In the new revision of the manuscript, we replaced the pie chart with Table 1 that contains more details. We also revised the misleading statement with the following statement:
- Recently, an innovative breakthrough has been achieved in the field of soft robotics, so that a soft robot can be actuated using strain energy stored in a structural member.
All new changes are highlighted in red.
