Designing a Robotic Gripper Based on the Actuating Capacity of NiTi-Based Shape Memory Wires

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper presents the results of experimental characterization of the selected types of SMA and superelastic materials. Specifically, the scope of the work covers investigation of the force generation functionality observed for the above-mentioned materials. The two cases are considered: actuating capability (to provide active components) and generation of the restoring force, as for antagonistic mechanism providing means for achieving initial shape of the previously activated SMA wire. Both cases are interesting in terms of practical applications. Finally, with reference to the conducted experiments, the Authors propose a design of a robotic gripper.

In the reviewer’s opinion, the paper looks like a technical report (of high quality anyway) rather than a scientific work. There are presented interesting results, however, the question arises “What is a new contribution in the presented work?” Below, I would like to comment what could be the areas that may be addressed to highlight the claimed novelty of the scientific activity. I would recommend publication of the manuscript after a significant correction of the paper.

Please consider some of the following aspects to show the novelty. First of all, there is presented the application of the well-known antagonistic operation of two functional materials used as solid-state actuators to construct kinematic chains, robotic arms and grippers. The known applications also make also use of regular steel springs to activate the “cold shape” resetting. If some solution is new in the current research, please describe it in details.

Similar designs for the grips can be found the literature including the applications with a very complicated kinematic chains and various spatial configurations of the used SMA wires, also bioinspired, mimicking the operation of the tendons.

There is presented the reference to the known behavior for SMA, also including already reported investigations of subloops identified in the stress-strain-time coordinates, response time (delays) studies, etc. Neither the measurement technique (including DSC) is a new one. DSC is widely used to recognize the solid phase transitions. Moreover, no new numerical and analytical results are shown (which is found outside of the scope of the work). The tested materials are also known. Not new ideas are explicitly described to show the reader the novel contribution.

The section “Introduction” should be expanded to focus more on the context/background of the currently presented research to show its novelty. Now, it is hardly visible in the manuscript even though a number of interesting results are presented.

I have also some doubt regarding the way how the SMA wire specimens were fastened in the grips of the testing machine. I see that the Author prepare some specific dedicated clamping mechanism. However, for such specific materials (I mean with that visible specific phase-induced mechanical response – memory effects and superelasticity), a common installation approach is to use grips in which the specimen (fabric, rope, wire, etc.) passes around the load reduction roller and no jaw breaks are seen. Phase transition in SMA and superelastic materials is spontaneous and, hence, improper boundary conditions may significantly and disadvantageously influence the course of the mentioned physical phenomenon. The used solution must be commented and the explanation why it is applied and the results are reliable should be provided.

The section “Summary and Conclusions” only presents the results of the tests. There are no general conclusions. They must be added. More comprehensive discussion on the results will certainly lead to the that conclusions.

I would strongly recommend the Authors to have more effective scientific use of the conducted interesting tests, formulate some more general statements, not only showing the results of experiments. I recommend to focus on some of the above presented aspects and provide new views/ideas/directions for farther investigation.

To summarize, in the reviewer’s opinion the work should be subject to major revision. I see that the work has its interesting potential, but it must be improved to present a valuable novel contribution. I really appreciate the effort made by the Authors to prepare the manuscript, however, in my opinion it cannot be published in its present form.

Comments on the Quality of English Language

Language corrections and editorial issues:

The tile: “an robotic” -> “a robotic”

Abstract, in the sentence “By Differential Scanning Calorimetry (DSC) the reversible martensitic transformation to austenite, of all the three NiTi-based wires under study.” there is no verb.

Row 104 and for similar cases: I believe the circles at the temperature units should be located a bit higher.

Row 209: please add the unit to the value “0.4308”

Row 241: what is the reason to use the redundant expression “12 mm=0.012 m”?

Row 363: the location of the caption for Figure 11 should be corrected

Row 390: improper form of a capital delta

I would suggest to paraphrase some of the longest sentences to make them more readable.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This submission investigates actuating capacities of different types of NiTi-based SMAs, including NiTi, NiTiCu, NiTiFe. This study was well planned and validated. This can be considered for publication pending minor revision. Please find my comments below:

(1) Remove Fig. 1 as it just illustrates an equipment setup. 

(2) Important: Is your focus the development of a new claw gripper or replacing actuators of an existing design with the investigated wires? Either way, it is confusing because you present the final design only at the last part of the result sections.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I see now, the Authors improved the paper following my suggestion. Below there are provided just minor comments. After introducing them, I recommend publication of the work.

As regard, “Row 151: the term “technical report” was implemented.” That was my first impression that the document looks like a technical not a scientific work. Please, revert back the term “scientific work”. Now after some improving effort you may find the work to become the scientific work. Please consider also that pure technical reports should not be published in scientific journals.

 

Minor, language issue:

Row 63: “[19],.” -> “[19].”

Author Response

Please see the attachment

Author Response File: Author Response.pdf