Screw Dynamics of a Multibody System by a Schoenflies Manipulator

Round 1

Reviewer 1 Report

Title: Screw dynamics of multibody systems for a Schoenflies parallel manipulator

Authors: Jing-Shan Zhao, Han-Lin Sun, Hao-yang Li, and Dong-Jie Zhao

 The dynamics analysis of multi-rigid-body systems with Schoenflies-motion is a complex task of modern robotics. The proposed momentum screw method makes it possible to significantly reduce the number of unknowns, which leads to low computation cost. One of the strengths of the manuscript is a carefully conducted comparison of the proposed method with the traditional Newton-Euler method. In my opinion, this well-done paper can be recommended for publication with a few clarifications.

 A few points should be addressed:

1   1. The number of degrees of freedom of the mechanism taking into account over constraints and passive degree of freedom is not specified in the paper.

2   2. Has the angular acceleration vector of the moving platform been defined? The screw theory allows us to do this quite accurately. 

3   3. It is necessary to carefully check the references to the equations (page 4, lines 121, 123, 138, 140; page 8, lines 248, 257; page 9, line 275; page 10, lines 286, 287).

Author Response

Please see the attached response. Thank you so much.

Author Response File: Author Response.docx

Reviewer 2 Report

Document attached

Comments for author File: Comments.pdf

Moderate editing of English language required

Author Response

Please see the attached response. Thank you so much.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper presents a momentum screw method to study the dynamics of multi rigid body systems. An example of an unsymmetrical parallel manipulator was reported also. 

The paper is well written and presented while its theoretical foundation has a moderate novelty. The methods, equations and the simulations were well presented.

There some specific corrections needed :

-at page 4, there are some errors regarding the references at rows 121,123,138 and 140.

Similar at pages 8, 9, 10.

Please check the paper for similar errors.

 

Author Response

Please see the attached response. Thank you so much.

Author Response File: Author Response.docx

Reviewer 4 Report

In my opinion, the following issues must be clarified/corrected:

 

#1) The side of variables included in the main text is different than the size of the text. Please unify all. See for instance page 2 line 89 and 91. Do it hereafter in the manuscript.

#2) Page 1. Line 16. For the sake of clarity, please be more rigorous, do not use terms such as “far more efficient”

#3) Page 1. Line 19. Please be more precise, do not use terms such as "the calculation is less than…”

#4) Page 1. Line 20. Please do not use qualitative terms such as “complicated”.

#5) Page 1. Line 30. For the sake of clarity, please give examples of “special manipulation”.

#6) Page 1. Line 35. Please do not terms such as “tough” or “complicated”

#7) Page 2. Lines 48-49. Please do not use “first kind” of “second kind”. Please use “type” instead.

#8) Page 2. Line 90. Please be clearer “the differential moment of momentum of the differential mass………………”

#9)Page 3. Line 96. In my opinion, Figure 1 is not necessary for readers of scientific journal such as applied sciences.

#10) Page 4. Line 116. Please do not the dollar symbol for a variable.

#11) Page 4. Line 123. A reference is missed here. Hereafter references are missed.

#12) Page 4. Lines 145-146. Please use italics for “U”, “P” and “S” included in the main text.

#13)  Page 5. Line 158. The use of “realize” seems to be not adequate. Please revise it. Do the same in page 11 line 308.

#14) Page 8. Line 237 and 252. Please use italics for subsections.

#15) Page 10. Line 281. Please do not include matrices in the main text.

#16) Page 11. Section 4. Simulation and discussion. In my opinion this section must be revised and modified including descriptions in-detail of the simulation and properly discussing results. The calculation of the Newton-Euler must be also included and discussed. More cases of study are needed and more results must be included and discussed.

#17) Page 11. Table 2. In my opinion is necessary to describe how values are obtained (Table 1) and how results are obtained. In addition, do not use description of variables in the y-axis label, please just use a variable with units.  

#18)  Page 11. Line 310. Please justify why this trajectory is selected and show it. Include an explanation about why the parameters amplitude and frequency are selected. In addition, include an analysis for a straight-line trajectory.

#19) Page 12. Line 320. Do not use two-lines paragraphs.

#20) Page 12. Line 327. For the sake of clarity, please include the equations of the Newton-Euler  method of this manipulator including schemes. See also Line 348.

#21) Page 12. Line 330. Please, include a numerical value of the relative error instead of “…are very close”.

#22) Page 12. Line 331. Please discuss this properly. “….there are 6000 periodic nodes”.

#23) Page 13. Line 345 and Table 2. The difference in computing tine is just a 17% between the proposed method and the Newton-Euler Method. This is a key point since according to conclusions “Compared with the traditional methods, this algorithm has lower cost of computation.”. Is this difference significative?. For both cases it is less than 1s. Please discuss this.

#24)  Page 13-14, Lines 348-375. In my opinion authors should revise the discussion of results. Results in Fig. 7 and 8 are not properly described and discussed only a mention about the error is included.

#25) Reference section. Some references include the full journal name and other the abbreviated. Please use the last one.  

 Extensive editing of English language required

Author Response

Please see the attached response. Thank you so much.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors of the article "Screw dynamics of multibody systems for a Schoenflies parallel manipulator" have thoroughly addressed all the requests made by the reviewers. The revision was clear and precise, resulting in a substantial improvement of the article. They have provided a more detailed calculation comparison between the Newton-Euler method and the momentum screw method, which clarifies and highlights the prospects of their methodology. In my opinion, the article is ready for publication in its current form.

Reviewer 4 Report