Analysis of Bifurcation Vibrations of an Industrial Robot Arm System with Joints Compliance

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper, the authors analyse the non-linear low-frequency vibration in the arm system

of an industrial robot by analytical and numerical methods. The introduction is well described. Starting to read the paper, Figure 1 is not referenced in the text, nor is the meaning of the variables explained. It is not clear what is represented. What is the difference between the full line arms and the dashed line arms? What is the meaning of ||xn? How many arms does the robot have? In equation (1), beta is an angular variable. After equation (3), beta is a vector of coordinates representing the robot/arm position? The same problem with alpha.

Section 2 should be completely reformulated. Also, the passage to Lagrangian formalism should be better explained.

Figure 3 is not in English.

Section 3 has a set of statements where the connection with the equations of motion is ambiguous.

Therefore I do not recommend publishing this paper in its current form.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Title of the peer-reviewed manuscript: “Analysis of bifurcation vibrations of an industrial robot arm 2 system with joints compliance”.

The manuscript consists of an Abstract, Keywords, an Introduction section, four main parts, list of References from 30 titles, 15 of which were published during the last 5 years. The manuscript contains 5 Figures and 1 Table.

In this manuscript, the authors set themselves the task of providing readers with the results of their theoretical analysis of the influence of bifurcation parameters on the vibrations of the robot arm.

The studies were carried out by the analytical and simulation method. The manuscript presents the mathematical model of the robot arm with two degrees of freedom, using which the authors conducted their theoretical research.

Questions and recommendations:

1. The manuscript is positioned by the authors as a theoretical study. However, the mathematical dependencies presented in section 2 are well known. Please explain what is the scientific novelty of the research presented in your manuscript?

2. The manuscript does not provide any information about the verification of the results obtained. Have the authors conducted experimental studies on a real robot arm  under real conditions? If not, what is the basis for the authors’ confidence in the adequacy of the results of their research?

3. Also, the authors do not explain the practical significance of their research. I think the manuscript needs to add information about possible specific practical applications of the research results.

4. In Figure 2 there are inscriptions in Polish. This must be corrected.

In general, the presented studies may be of interest to scientists, researchers and specialists in the field of robotics. I believe that the manuscript can be recommended for publication only after major revision.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

 

Analyses of non-linear vibration phenomena in the planar industrial robotic arm with compliant joints are presented in this manuscript. Vibration isolation is an interesting research topic, especially for low frequency vibrations. This paper can be considered for publication before addressing following issues.

1, In practical applications, the flexible joint takes advantage of a rigid joint due to it can avoid assembly errors, although it may cause vibrations. Low frequency vibrations also can be isolated by compliant based mechanisms using quasi-zero stiffness. Thus, authors should pay attention to this sentence “Low frequency vibrations are related to the compliance of joints” in line 69.

2, In introduction section, authors said that “In robotic mechanical processing, low-frequency vibrations result in low dimensional and shape accuracy of the processed workpieces.” The reviewer agreed with that and suggested that low frequency vibrations using compliance joints reference should be included “Modular quasi-zero-stiffness isolator based on compliant constant-force mechanisms for low frequency vibration isolation”.

3, What are the purposes of analyzing bifurcation vibrations of a robot arm with flexible joints? For compliant robot design or low frequency vibration isolation. The reviewer thinks that motivations for this research should be presented in a clearer way.

4, It better to revise the “Discussion” of the Section 5 as “Conclusions and Discussions”.

5, In Section 5, authors pointed their further research direction (polishing or grinding) about flexible robot arm since flexible joints with compliance received widely attention in the field of precision polishing as discussed in “Design of a spatial constant-force end-effector for polishing/deburring operations”. The reviewer thinks including some experimental studies for future studies is essential.

6, Fig. 3 appears some non-English characteristics. It may cause confuse to international readers.

Comments on the Quality of English Language

Good

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised version is better.

Reviewer 3 Report

Comments and Suggestions for Authors

Authors well addressed my concerns. This manuscript can be considered for publication in current form.