Proposal of an Equal-Stiffness and Equal-Stroke 2D Micro-Positioning Platform Driven by Piezoelectric Actuators
Round 1
Reviewer 1 Report
It's an interesting work with interesting approaches.
More explanations for the working principles, set-up description, chosen materials and more exprimental results are on my opinion needed.
Besides, I also have the following suggestions and questions:
Line 37: It would be helpful to specify what the single driving method and main differences to the two driving stage are.
Line 54: I think the stroke amplitudes and mechanical coupling factors are as same important as the stiffness.
Line 61 to 63: Please reorganize the sentence.
Line 64: Short stroke and large size sound rather disadvantageous.
Line 64: The sentence is not completed.
Line 70-71: Please reorganize the sentence.
Line 83: Outer substrate or outer frame?
Line 87: Where is the nested structure?
Line 91: Even though the authors claim for equal-stiffness, due to the slightly asymmetric structures for x and y axes, I think the effect needs evidences to confirm or hints referring to the later text.
Line 100: The working principle is not really clear to see for the readers. Try 3D visualization?
Line 103: In which direction PZT deforms will be effected by the layer properties. Please give more information about which PZT is used (ceramic PZT or thin-film PZT and deposition condition?), how is the driving signal applied and which modus is used here d33 or d31?
Line 112-116: A cross-sectional description will help to understand the layer composition.
Figure 4: It’s not really clear how the bump works.
Equation 8: So the displacement amplification y to x is only depending on l and thickness E? What if the hinges and bumps are made from another material? Is it not more complete, when material properties are also taken into account?
Figure 7: What are the explanations for the turning point?
Figure 13: In total please mark the figures are they measurement results or simulation results and so on.
Line 267: Please give the definition for the coupling factor in this work.
Conclusion:
- Please give some application sceneries so that the reader can have reference to evaluate the achieved results.
- Since the equal-stroke is the important result for this work, more results about repeatability tests should be provided.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In the following text is presented a list with some minor mistakes that have been detected and other improvements that should be implemented before the publication of this work.
In introduction section should be implemented a comparison with some commercial micro-positioning stage. For example from Thorlabs?
- Line 114 and 115: Not everyone knows about what it is a 7075Al and EDM-LS. Please explain it…
- Figure 3: It is necessary to introduce some details about the PZT actuator presented in Figure 3.
- Line 123: A better explanation of the mechanism could help the reader.
- Figure 6. At least in my figure it is not clear the symbol α. It seems like “a” (equal for figure 5)
- Line 146: correct: “the”
- Line 156 and 157: better explanation
- Line 170: why 1 mm? It is not clear?
- Line 177: By comprehensive consideration?
- Eq 14: correct: “k2y”
- Line 202 Correct: “into Equations (11-14)”
- Table 1: Same theoretical values for axis X and Y???. If It is the same could be resume in one column…
- Line 207: Reference for ANSYS
- Line 240: Rp150/7*7/42 piezoelectric actuator? Please introduce some reference.
- Line 242: Reference for dSPACE1104 controller
- Line 247: it should maximum output displacement of 500µm?
- Line 263. “in X and Y directions. Take a step…” there is no cohesion with the previous phrase.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
See the attachment.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
This paper presents the design for a piezoelectric actuated micro-positioning platform that can be used in a number of applications. The main contribution of the work is the proposal of the so-called “hourglass” displacement amplification mechanism. The performance of the actuation platform was investigated through theoretical modelling, numerical simulation, and experimental verification. The paper is generally well written, and the proposed design can be useful for a number of disciplines. However, the authors should address the below points to improve clarity and rigour of their presented work:
- Line 11: the word “so on” should be avoided as this is not a typical scientific word.
- Lines 35-36: It is an unusual practice to have a paragraph made of one sentence. Please consider merging with other paragraphs.
- Lines 64-66: please revise the English language. This is arguably the most important sentence of the introduction, and yet is very distracted.
- The introduction section does a relatively acceptable job in presenting the problem; however, I strongly recommend to further extend it to address several other studies. For example, the study “Development of a novel two-DOF pointing mechanism using a bending-bending hybrid piezoelectric IEEE Transactions on Industrial Electronics, 66(10), 7861-7872, 2018.” is relevant and should be discussed. Additionally, I suggest that the authors include a paragraph on the general recent advances in piezoelectric actuation and not just limit the discussion to those related to the topic of the current work. This should include discussion on different actuator configurations as stack actuators and bending actuators. I recall, for example, the study on characterising the dynamic performance and efficiency of piezoelectric bending actuators: Dynamic electromechanical coupling of piezoelectric bending actuators. Micromachines, 7(1), 12, 2016. As such, I suggest to widen the scope of discussion on piezoelectric actuation and discuss my suggested paper together with other papers (suggested by the authors) within the introduction.
- Figures 2, 4, and 5: Please indicate in the caption which colour indicate the initial state, and which indicate the deformed status.
- Lines 114-115: Can you please elaborate in the paper on the material used in terms of its characteristics and how it was resourced as well as elaborate on the EDM-LS. Can you also provide the characteristics for the used piezoelectric actuator and if it was modelled at all?
- Lines 134-135: Maybe I have missed something, but can you please elaborate on how the hinge could be represented as a cantilever beam – This is not clear at the moment.
- The whole paper must be revised to ensure that symbols that appear within text and within figures are consistent in terms of using the same font size, font type, and appearance, for example some “alpha”s appear as “a”s. In general symbols are generally very poor within the paper and should be all produced using the same equation editor.
- Line 146: please check language “he”!
- Line 174: I really can’t see the gentle growth as the length exceeds 25 mm. First, no variation is shown beyond 25 mm. Second, gentle growth may be deemed for high tilt angles but not for low ones. As such please consider re-wording your argument here to be more representative to the demonstrated trend.
- Lines 177-178: I can’t understand the logic behind the authors’ decision to select these values. First, more amplifications could be achieved using other combinations. Second, the length value used is not even shown in Figure 7. This selection needs to be better explained as it currently invites lots of questions.
- Line 205: Can you please clearly indicate in the paper what each symbol stands for and why these values were specifically selected?
- Lines 216-219: Can you please explain in the paper why different stiffness values are obtained from different forcing? I understand that the difference is small, but why is there a difference at all? Also, why is there a difference between X and Y values in table 2 whilst this was not the case for table 1?
- Please discuss the numerical simulation set-up and how the aspects of the simulation were decided. Is it a 2D or 3D simulation? Is it a FEM based simulation? How are the BCs implemented and was grid convergence considered? What were the solved equations by the numerical solver etc. Please provide a detailed explanation.
- Table 3: please include the percentage difference between theory and simulation results and comment on the significance of this difference.
- Line 225: The claim that the results are “basically consistent” needs to be further quantified. How do you judge consistency?
- Line 240: Can you please add full details of the actuator used including manufacturer, part number, main characteristics etc. This is important to ensure the repeatability of the experiment.
- Figure 12 needs to be enlarged; it is really hard to see the set-up in a clear fashion. Moreover, the developed platform deserves a clear picture on its own to be able to see how it was realised.
- Figure 13: please include simulation results for the whole voltage range for better comparison between experiment and simulation.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Line 61: determines-> determine
Line 66-68: Some commercial micro-positioning platforms, such as Thorlabs®, have done very well in the stroke and accuracy of the micro positioning platforms, but have not seen any haven’t reported on the micro-positioning platform of equalstiffness and equal-stroke. [References needed]
Line 73: Under the condition of achieving more degrees of freedom, the number of driving elements required is reduced [21]. -> Why can number of driving elements be reduced, while achieving more degrees of freedom?
Line 84: Aiming at the problems of
Line 90: In abstract the word “adopt” were used twice. Also here it is indicated, that the hourglass design of this paper was inspired by an existing design. Please give the reference.
Line 101-102: It is not a sentence. Please check the grammar.
Line 120: How about the most important material of PZT? Please give more information about it. In total the information on the structures is missing (how thick is the Al layer and how thick is PZT layer?) How have the authors formed the Al structure and bring the PZT layer onto it?
Question in total:
The authors simulated the displacement by different driving forces. It would be interesting to compare driving signal of forces or voltages on the actuators. It’s also important to give information about where the force is applied and on the direction of the force, since force is a vector.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
The authors have addressed most of my suggestions from the previous review. There are still some comments that need to be better addressed:
- The explanation provided by the authors in response to point 7 of the previous review is not entirely clear for me. Please simplify the discussion and provide better explanation within the paper.
- In relation to figure 7, the authors should explain in the paper (not just in the response document) why they selected alpha=3.5 degs rather than a lower alpha value (1 deg.) that would allow better amplification.
- The response to point 14 of my previous review was not convincing. First, this discussion must appear in the paper so that readers are aware how the simulation is set-up and they can then repeat it if they wish. Details of the software, type of simulation, BCs, and mesh used should all appear in the paper. Second, it is strange that no consideration is given to grid convergence, so how can you be satisfied that the used grid is appropriate and leads to correct results? Please comment in the paper.
- Figure 12: the authors included a better figure, but I also suggested adding a separate figure for the micro-positioning platform that show full details of the manufactured platform.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
