Review of Industrial Robot Stiffness Identification and Modelling

Round 1

Reviewer 1 Report

I believe that the subject of the work is very important. The work has been organized and presented very well. The summarization of results are impressive. Before final decision some comments have to be revised

1. Need to cite recent published papers in the literature section.
2. Conclusion section should be added separately after discussion part.

Author Response

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Reviewer 2 Report

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

Please see my comments in the attached PDF file.

Comments for author File: Comments.pdf

Author Response

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Reviewer 4 Report

In this paper, a review of recent research in the area of identification of stiffness parameters of industrial robots is presented. The paper describes in detail the three methods FEA, MSA, VJM which are discussed in terms of their principle, applicability and limitations. The authors draw knowledge from 121 references, which is sufficient for this type of paper. To increase the interest of the readers in the subject, I recommend changing the title of the paper to "A review on the investigation of industrial robot stiffness identification and modelling". I have no reservations about the content of the paper. I do not dare to evaluate the grammar, as I am not a native speaker. However, I find the text comprehensible.

I find the formality of the paper lacking. The mathematical expressions and symbols used in the text do not respect the conventional rules of their writing.

1) Units are written in normal font.

2) Scalar quantities are written in italics.

3) Matrices and vectors are written in bold regular font.

4) Mathematical functions and operators are written in normal font.

5) All symbols in the text must have the same formatting (style and font) as the symbols in the equations.

There are many such errors that need to be corrected.

Other comments:

Figures 9, 15, 16, 17 are missing references to the source documents.

Equation (1) occurs twice.

Figure 4 divides a paragraph of text. It should be placed on line 186. The sentence on line 176 ("where K is the....") should be aligned to the left margin.

In the context of the finite element method, I recommend replacing the term "grid" with "mesh". (Line 146, 164, etc.)

Instead of "grid element nodes", just "nodes" or "mesh nodes". (Line 169)

Author Response

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Reviewer 5 Report

The review proposed by the authors could be of interest for the research community. However, the topic is very vast and many aspects regarding stiffness/compliance control and optimization are not fully covered. I suggest the Authors to deeply elaborate on the availeble literature for a more comprehensive review. The following are only some works, from the group of Siciliano, De Luca, Dario and others, that are fundamental for the topic and are not be considered in the current form of the paper.

[1] L. Zollo, B. Siciliano, A. De Luca, E. Guglielmelli, and P. Dario. Compliance
control for an anthropomorphic robot with elastic joints: Theory and experiments. Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME, 127(3):321–328, 2005.

[2] A. De Luca, B. Siciliano, and L. Zollo. Pd control with on-line gravity compensation for robots with elastic joints: Theory and experiments. Automatica, 41(10):1809–1819, 2005.

[3] F. Flacco, A. De Luca, I. Sardellitti, and N.G. Tsagarakis. On-line estimation
of variable stiffness in flexible robot joints. International Journal of Robotics
Research, 31(13):1556–1577, 2012.

[4] N.P. Belfiore, M. Verotti, P. Di Giamberardino, and I.J. Rudas. Active joint
stiffness regulation to achieve isotropic compliance in the euclidean space. Journal of Mechanisms and Robotics, 4(4), 2012.

[5] H. Wang, F. Patota, G. Buondonno, M. Haendl, A. De Luca, and K. Kosuge.
Stability and variable admittance control in the physical interaction with a
mobile robot. International Journal of Advanced Robotic Systems, 12(12), 2015.

[6] F. Flacco, T. Kroeger, A. De Luca, and O. Khatib. A depth space approach
for evaluating distance to objects: with application to human-robot collision
avoidance. Journal of Intelligent and Robotic Systems: Theory and Applications,
80:7–22, 2015.

[7] M. Verotti, P. Masarati, M. Morandini, and N.P. Belfiore. Isotropic compliance
in the special euclidean group se(3). Mechanism and Machine Theory, 98:263–
281, 2016.

[8] G. Buondonno and A. De Luca. Efficient computation of inverse dynamics and feedback linearization for vsa-based robots. IEEE Robotics and Automation
Letters, 1(2):908–915, 2016.

[9] S. Haddadin, A. De Luca, and A. Albu-Sch¨affer. Robot collisions: A survey
on detection, isolation, and identification. IEEE Transactions on Robotics,
33(6):1292–1312, 2017.

[10] L. Meli, C. Pacchierotti, G. Salvietti, F. Chinello, M. Maisto, A. De Luca, and
D. Prattichizzo. Combining wearable finger haptics and augmented reality:
User evaluation using an external camera and the microsoft hololens. IEEE
Robotics and Automation Letters, 3(4):4297–4304, 2018.

[11] M. Verotti, P. Masarati, M. Morandini, and N.P. Belfiore. Active isotropic
compliance in redundant manipulators. Multibody System Dynamics, 49(4):421–445, 2020.

[12] A. Palleschi, R. Mengacci, F. Angelini, D. Caporale, L. Pallottino, A. De Luca,
and M. Garabini. Time-optimal trajectory planning for flexible joint robots.
IEEE Robotics and Automation Letters, 5(2):938–945, 2020.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 5 Report

Even if some Reviewers suggested many investigations to be considered in the paper, the Authors declined to modify the manuscript. As a consequence, this investigation can not be considered acceptable as review paper, not including very relevant works on the subject.

Author Response

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Author Response File: Author Response.docx