Pre-Compensation Strategy for Tracking Error and Contour Error by Using Friction and Cross-Coupled Control

Round 1

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

I ackoledge that the authors made some modifications to improve the paper. However, the identification of friction parameters is not satisfactory. The authors MUST calculate the standard deviatins of the estimates. Besides, the authors cite the LS method. Did they mean the nonlinear LS or the linear LS ? It is not clear. Without the calculation of the standard deviations of the estimatyes, it is impossible to evaluate their relevance.

The friction curve plotted in figure 4 is almost noise free. is it normal ? the "measurement" of the friction torque must be detailed. Are there dispertions or not ?

Figure 8 and Figure 9 show some improvement; around 15% - 20% I would say. The authors MUST show that we cannot achieve such improvement with other methods. Without comparisons, we are not convinced by your approach.

Author Response

Thank you for your valuable comments and the correction has been upoaded as attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (Previous Reviewer 3)

Comments and Suggestions for Authors

The paper is a better shape now. Most my technical points have been addressed. I have one major suggestion in terms of presentation. The authors are encouraged to use past verbs for any actions (including experiments and analysis) which was complete at the time of writing. There are many verbs with present tense in which their past tense should be used. 

Comments on the Quality of English Language

I have one major suggestion in terms of presentation. The authors are encouraged to use past verbs for any actions (including experiments and analysis) which was complete at the time of writing. There are many verbs with present tense in which their past tense should be used. 

Author Response

Thank you for your valuable comments and the correction has been upoaded as attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 1)

Comments and Suggestions for Authors

Although there is still room for improvement, the authors have tackled the points I have raised in the previous rounds.

I suggest polishing English and, perhaps, inserting the covariances calculation.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper deals with friction identification. Many works have treated this topic in the past.

Compared with these works, I do not believe this paper introduces a new concept. The material presented in this paper is, indeed, already known to the community.

Besides, the authors must improve the paper. Some symbols are not introduced and some figures are not easy to read. The authors did not fully explain or comment on the results they got. For instance, in Figure 10, the plus value is unclear and the authors should explain that. The authors should explain some experiments. For, in Table 1, they gave the estimates of friction parameters without the deviations. So, what is the quality of the estimates?

I suggest, therefore, major revisions before making a final decision.

Reviewer 2 Report

Comments and Suggestions for Authors

In the paper  it is studied the tracking accuracy for servo systems increasing  the contouring performance of precision machining by using the LuGre model.

The paper is well written and organized; nevertheless some comparisons with different approaches to the same problem must be added to improve the paper.

English needs improvements to avoid typos.

Comments on the Quality of English Language

Some typos should be removed.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper considers friction force as a disturbance in tracking a servo system. This disturbance is modelled with LuGre formula and compensated with a feedforward control strategy. Unknown parameters of LuGre formula parameters have been apparently identified with fly optimisation algorithm. In 2.1, some specific values were assumed for the parameters of LuGre formula, and they were identified with the proposed algorithm very close to the pre-assumed values. By the way, the authors do not explain how the experimental data were used for this purpose. Although, the content reflects considerable efforts; the paper is very hard to follow, lacks some critical information and includes lots of poorly relevant materials.

 

Here are some comments:

1-     I recommend to add a new short section after the introduction, entitled “Problem Statement and the Proposed Solution” (or something similar) to give a clear big picture of the problem and the proposed methodology before going into details.

2-     The parameters of LuGre formula for the experimental system must be listed in a table together with their accuracy (or range of modelling error, found from their mean value and the variance of test error). In section 3.2, it is not clear how experimental data were used to identify Eqs. 17 and 18.

3-     Five references have been cited to support a nearly evident statement in the second line of the introduction. A few of the references could serve the purpose, and the rest are recommended to be removed.

4-     There is no citation for Karnopp model.

5-     The statement in line 60 is incorrect; the listed methods are mainly used to develop multi-parameter models. This statement needs to be rewritten.

6-     Lines 62-68 seemingly do not belong to the introduction; these lines include no citations and apparently present the methodology of this work.

7-     “regarded as” in line 95 is quite vague and perhaps excessive. It is unclear that if U-type linear motors are a prevalent choice or the choice of this research.

8-     Lines 98-103 need references.

9-     Equation 1 needs a reference.

10-  W₀ in Eq.4 has not been defined.

11-  Lines 132-134 are quite loose.

12-  In term of identifying friction model parameters, the paper seems similar to “Parameter identification and sensitivity analysis of an improved LuGre friction model for magnetorheological elastomer base isolator”, Soft Mechatronics, Volume 50, pages 2691–2707, 2015. The authors are encouraged to consult with and cite this paper.

13-  It is not clear how “Substituting (16) into (1)” results in Eq. 17. Some variables have not been defined, and feed-rate has disappeared in Eq.17. Perhaps, it is fixed and multiplied by its parameter, in this case, modification of parameters and explanation are required.

14-  It is not necessary to know the dynamics of a disturbance force (e.g. through LuGre formula) to compensate it; this point should be mentioned in the paper not to misguide the readership. This paper is an example: “A New Active Anti-vibration System using a Magnetostrictive Bimetal Actuator”, Journal of Magnetism and Magnetic Materials, Volume 557, Article 169463, 2022. The authors are encouraged to consult with and cite this paper.

15-  The sentence in lines 256 and 257 needs a reference.

16-  Fig. 7 is unclear and apparently does not match with Fig.5..

 

Comments on the Quality of English Language

1-     “By using the control strategy” in line 62 is recommended to be replaced with “With a control strategy”.

2-     All equations need punctuations and need to be considered as a part of a sentence.

3-     Lines 259-261 seem both vague and excessive.

4-     In line 58, term “trained” is obvious and is recommended to be removed.