Inverse Kinematics Data Adaptation to Non-Standard Modular Robotic Arm Consisting of Unique Rotational Modules
, Michal Šašala 1, Zdenko Bobovský 2, Tomáš Stejskal 1, Jozef Dobránsky 3, Peter Demeč 1 and Lukáš Hrivniak 1Round 1
Reviewer 1 Report
The originality of the work is not high, the inverse kinematics of serial arms (modular or non-modular) is deeply investigated in the scientific literature; however, this paper can be useful for researchers from a practical point of view because it compares different modelling tools. Since the paper is about a modular robotic system, the state-of-the-art about this topic must be extended in the introduction section, which now is focussed mainly on inverse kinematic analysis. Some works about libraries of components for composing modular robots are the following:
Yim, M., Duff, D.G. and Roufas, K.D. (2000), “PolyBot: a modular reconfigurable robot”, Proceedings ICRA ’00, IEEE International Conference on Robotics and Automation, San Francisco, CA, 24-28 April, Vol. 1, pp. 514-20.
Yim, M., Roufas, K., Duff, D., Zhang, Y., Eldershaw, C. and Homans, S. (2003), “Modular reconfigurable robots in space applications”, Autonomous Robots, Vol. 14 Nos 2/3, pp. 225-37.
Xi, F., Xu, Y. and Xiong, G. (2006), “Design and analysis of a re-configurable parallel robot”, Mechanism and Machine Theory, Vol. 41 No. 2, pp. 191-211.
Acaccia, G., Bruzzone, L. and Razzoli, R. (2008), “A modular robotic system for industrial applications”, Assembly Automation, Vol. 28 No. 2, pp. 151–162.
Xu, W., Han, L., Wang, X. and Yuan, H. (2021), “A wireless reconfigurable modular manipulator and its control system”, Mechatronics, Vol. 73, Article number 102470.
English should be carefully checked, and the language style should be adequate to a scientific paper; in particular the use of articles should be refined, and the use of the past tense should be limited.
Some examples of sentences to be modified (no t exhaustive list):
page 1, line 18: “…our own robotic arm...”: not scientific language
page 1, line 21: “It has been constructed…”--> “it has been modelled”
page 1, line 35: “modular structures” --> “modular robots”
page 1, line 41: “availability of its own power source and its modularity”: not scientific language
page 2, line 45: “principal implementation rules within the Total Productive Maintenance in the industry”: not scientific language
page 2, line 62: “Rather the…”
page 5, line 121 “were to be obtained in the sampling period T_sp each 0.005 s” --> “are obtained using a sampling period of…”
page 6, line 146: “takes the shape…”
page 6, line 159: “disintegration” is not a scientific term (computational instability)
The titles 2.1 and 2.2 should be changed.
Table 1: the number of decimals in the dimensions in mm is not reasonable (10^-8 mm is not significant in robotics); 3 decimals are more than sufficient.
The quality of the Matlab graphs of Fig. 9, 10, 12 should be improved using in the legends subscripts and Greek letters.
Author Response
Reviewer 1:
The authors thank the reviewer for their precise comments. These contribute to the improvement of the article. The authors analyzed all comments in detail and incorporated them all into the new version of the article. Specific changes are marked in yellow directly in the new revision of the article.
Reviewer's comment:
The originality of the work is not high, the inverse kinematics of serial arms (modular or non-modular) is deeply investigated in the scientific literature; however, this paper can be useful for researchers from a practical point of view because it compares different modelling tools. Since the paper is about a modular robotic system, the state-of-the-art about this topic must be extended in the introduction section, which now is focussed mainly on inverse kinematic analysis. Some works about libraries of components for composing modular robots are the following:
Yim, M., Duff, D.G. and Roufas, K.D. (2000), “PolyBot: a modular reconfigurable robot”, Proceedings ICRA ’00, IEEE International Conference on Robotics and Automation, San Francisco, CA, 24-28 April, Vol. 1, pp. 514-20.
Yim, M., Roufas, K., Duff, D., Zhang, Y., Eldershaw, C. and Homans, S. (2003), “Modular reconfigurable robots in space applications”, Autonomous Robots, Vol. 14 Nos 2/3, pp. 225-37.
Xi, F., Xu, Y. and Xiong, G. (2006), “Design and analysis of a re-configurable parallel robot”, Mechanism and Machine Theory, Vol. 41 No. 2, pp. 191-211.
Acaccia, G., Bruzzone, L. and Razzoli, R. (2008), “A modular robotic system for industrial applications”, Assembly Automation, Vol. 28 No. 2, pp. 151–162.
Xu, W., Han, L., Wang, X. and Yuan, H. (2021), “A wireless reconfigurable modular manipulator and its control system”, Mechatronics, Vol. 73, Article number 102470.
Authors comment:
- The authors thank the reviewer for proposing to expand the references. After careful study, 4 of the 5 proposed [8-11] were added to the references. Text in lines 45-53 has been added to the text.
Reviewer's comment:
English should be carefully checked, and the language style should be adequate to a scientific paper; in particular the use of articles should be refined, and the use of the past tense should be limited.
Some examples of sentences to be modified (no t exhaustive list):
page 1, line 18: “…our own robotic arm...”: not scientific language
- Corrected, line 18
page 1, line 21: “It has been constructed…”--> “it has been modelled”
- Corrected, line 22
page 1, line 35: “modular structures” --> “modular robots”
- Corrected, line 36
page 1, line 41: “availability of its own power source and its modularity”: not scientific language
- Corrected, line 42
page 2, line 45: “principal implementation rules within the Total Productive Maintenance in the industry”: not scientific language
- Corrected, line 54
page 2, line 62: “Rather the…”
- Corrected, line 71
page 5, line 121 “were to be obtained in the sampling period T_sp each 0.005 s” --> “are obtained using a sampling period of…”
- Corrected, line 129
page 6, line 146: “takes the shape…”
- Corrected, line 155
page 6, line 159: “disintegration” is not a scientific term (computational instability)
- Corrected, line 168
The titles 2.1 and 2.2 should be changed.
- Corrected, lines 124 and 136. In addition, an error was found in the numbering of subchapters. It has been fixed as well.
Table 1: the number of decimals in the dimensions in mm is not reasonable (10^-8 mm is not significant in robotics); 3 decimals are more than sufficient.
- An additional error was found and fixed for a1
The quality of the Matlab graphs of Fig. 9, 10, 12 should be improved using in the legends subscripts and Greek letters.
- Corrected: Fig. 9 (a), 12 (a)
- 10 we could not insert "greek letters" in the Simulink environment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper describes a kinematic design of a serial robot. The robot is modeled in 3 different environments (CoppeliaSim, Matlab and SolidWorks). Coppelia Sim Edu is used to identify the joint variables according to a description of the spatial trajectory with a predefined deviation. Using Matlab and Solidworks, the deviation between the real trajectory and the calculated trajectory is calculated and illustrated.
- Enclosed are some remarks:
A picture illustrating the mechanism of how the passive joints are connected to URM and how the passive joints rotate, would be beneficial (fig. 4). - The presented solution to calculate the Euler angles is problematic at a33= 0. At this point a mathematical singularity exists. An alternative solution would be to use quaternions (lines 109-112).
- The language of the contribution can still be checked. Attached is the list of small errors:
- 23: measurements, structural changes measurements and structural changes
- 54: Jacobian Jacobian
- Equations: often X is used for multiplication. This leads to confusion with cross product
Author Response
Reviewer 2:
The authors thank the reviewer for their precise comments. These contribute to the improvement of the article. The authors analyzed all comments in detail and incorporated them all into the new version of the article. Specific changes are marked in yellow directly in the new revision of the article.
Reviewer's comment:
A picture illustrating the mechanism of how the passive joints are connected to URM and how the passive joints rotate, would be beneficial (fig. 4).
- The authors thank the reviewer for suggesting improvements. Fig. 1 shows the function of the passive joint. It is a fixed, constant static rotation of an angle ϑiin the plane zi xi. In Fig.4 it is the part which is composed of ri - ai - bi & ai+1 except for the last part, because it is composed of r6- a6- b6 & r7. For the sake of clarity, (b) has been added to Fig.4: (b) Detail URM with passive joint.
Reviewer's comment:
The presented solution to calculate the Euler angles is problematic at a33= 0. At this point a mathematical singularity exists. An alternative solution would be to use quaternions (lines 109-112).
- The description by rotation matrices we met in the literature as the standard. We have no experience with quaternions. The results of the different solutions we compared are identical. For the problem of geometric singularity, we enter, for example: a33=0.000000001.
Reviewer's comment:
The language of the contribution can still be checked. Attached is the list of small errors:
23: measurements, structural changes measurements and structural changes
- Fixed, line 23
54: Jacobian Jacobian
- Fixed, line 63
Reviewer's comment:
Equations: often X is used for multiplication. This leads to confusion with cross product
- We use "x" in the equations because it is a cross multiplication. For a scalar product, we would use "."
Author Response File: Author Response.pdf
