High-Transparency Linear Actuator Using an Electromagnetic Brake for Damping Modulation in Physical Human–Robot Interaction

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a novel approach to enhancing the transparency of high-force robotic systems through a macro–mini linear actuator incorporating an electromagnetic (EM) brake. However, several sections of the paper lack clarity in technical descriptions, particularly regarding the implementation and operation of the actuator system. The discussion surrounding the integration of the EM brake with the macro–mini linear actuator requires more detailed explanation. For instance, the precise mechanism by which the EM brake modulates damping under different load conditions is not thoroughly elucidated. A deeper exploration into the design rationale and the specific engineering choices made during the development of the actuator system would greatly enhance the reader's understanding and the overall technical robustness of the paper.

 

The paper fails to adequately compare the proposed system with existing works in the field. The authors should consider discussing the work in the context of existing literature more thoroughly, particularly those dealing with distributed real-time control architectures for electro-hydraulic humanoid robots and data-driven learning for H∞ control of adaptive cruise control systems, as these areas might share relevant challenges and solutions. For instance, the work "Distributed Real-Time Control Architecture for Electro-Hydraulic Humanoid Robots" could provide insights into how distributed architectures can be leveraged to improve system performance, while "Data-Driven Learning for H∞ Control of Adaptive Cruise Control Systems" might offer perspectives on optimizing control systems through data-driven methodologies. Incorporating these discussion and discussing their relevance to the proposed system would strengthen the paper's contribution to the field and provide a clearer context for the proposed innovations.

 

3. The paper primarily focuses on the empirical validation of the proposed actuator system, but the theoretical underpinnings are underdeveloped. The authors should include a more rigorous theoretical analysis to support their empirical findings. This could involve a more detailed modeling of the actuator dynamics, including the interaction between the macro and mini components and the effect of varying impedance on system stability. Furthermore, the impact of the EM brake on the overall system performance should be analyzed in greater depth, with particular attention to how the system handles sudden changes in load or environmental conditions.

 

4. The methodology section lacks clarity in some key areas. The description of the experimental setup, particularly the configuration of the load cell and its interaction with the EM brake, is somewhat confusing. The authors need to provide a more detailed schematic or diagram that clearly illustrates the experimental setup. Additionally, the rationale behind the chosen parameters for the vibration tests and constant speed tests should be explained in greater detail. For instance, the choice of damping coefficients and their relevance to real-world applications should be justified more explicitly.

 

5. The practical implications of the proposed system, particularly in the context of rehabilitation robotics, are not fully explored. The authors briefly mention the potential applications in body weight support systems, but this discussion is too superficial. A more detailed exploration of how the proposed actuator system could be integrated into existing rehabilitation frameworks, and the potential benefits and limitations of such integration, would greatly enhance the paper's impact. Additionally, the authors should consider discussing the potential challenges in scaling up the system for broader applications and any future work needed to address these challenges.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper describes problems for improving the efficiency of a linear actuator applied to the rehabilitation of people with neurological disabilities. The article examines interesting and important questions related to medicine and some related engineering challenges. The manuscript submitted for review contains all the necessary structural elements and is written in a reasonably good scholarly style.

I have the following remarks and questions for the authors:

1. In the title of the article and then in the exposition, the term "Transparency" is used. The most common use of this tremin concerns visibility or more precisely the quality of allowing light to pass through so that objects behind can be distinctly seen. I did not notice any optical issues being worked on in this manuscript, so I am asking the authors to address this issue.

2. In the abstract (line 11) it is mentioned that the mechanism works near people. Is the proposed mechanism used next to people or directly on people?

3. Figure 2 clearly gives an idea of ​​the structure and principle of operation of the mechanism. A force F acts on the end effector. To make it clearer to the reader, is it possible to schematically show the same figure and which organ of the human body is driven. If necessary, add another projection for the interaction of the human body with the mechanism.

4. The article uses the term impedance and more precisely mechanical impedance. In my opinion, this term is more characteristic of acoustic mechanical systems. My request to the authors is, if possible, to provide more information about this term. What units is it measured in? What characterizes in this system.

5. The theoretical part is presented very simply. A deeper look at the dynamics and control of the electromechanical system would give a clearer picture of the system's capabilities.

6. The article would be clearer, in my opinion, if some basic mechanical characteristics, material properties and management parameters were presented, for example, in a table.

 

Based on all these remarks and questions, I will propose that the article be accepted after a major revision.

Comments on the Quality of English Language

My remarks on the language are terminological. For example, the use of Transparency and Impedance are controversial and hardly the most appropriate for this type of scientific publication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper well reports the advasnced aspects of the proposed actuator.

The system could have suitable applications in more fields also in industrial area of position control.

The authors are invited to remark this aspect.

Moreover as the authors underline the aspect respect the human- machine interface involve the peculiar items of the systems, therefore recent literature in the subject must be included.

THe suggestion is the following paper:

Scibilia, A., Pedrocchi, N., & Fortuna, L. (2022). Human control model estimation in physical human–machine interaction: A survey. Sensors, 22(5), 1732.

The paper is well written and both the title and the abstract clearly explain the research.

In my opinion the paper is timely and it is appropriate for the journal

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The current version can be accepted. 

Author Response

Authors appreciate reviewer for valuable suggestions to improve the quality of this paper.
Thank you very much.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have taken into account my remarks and they have made changes to the article that improve its content and understanding. This gives me reason to recommend to the esteemed editorial board to accept for publication the article in its revised form.

Author Response

Authors appreciate reviewer for valuable suggestions to improve the quality of this paper.
Thank you very much.