Anti-Lock Braking System Performance Optimization Based on Fitted-Curve Road-Surface Recognition and Sliding-Mode Variable-Structure Control

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors are describing a novel ABS control algorithm for electronic hydraulic braking systems focusing on a road surface recognition and slip rate control. The paper is decent has some merits but it should be improved before being published.

My main concern is the lack of information of the so-called joint simulation model based on MATLAB/Simulink and CarSim. Please explain in detail how was this simulation environment constructed and its operating details. I presume the authors are using the CarSim from Mechanical Simulation. https://www.carsim.com/products/carsim/

Minor issues:

 - references should be cited in square brackets, e.g. [1], [2], [3], etc.

 - line 75: ω is the angular velocity of the wheel not vehicle, as it is written.

 - define m, as mass in equation (1)

 - use cursive (italic) letters in all equations

 - line 113. Missing full stop (period) punctuation at the end of section 2.3.

 - line 122 and line 221: instead of the "following" table/figure use the exact table/figure number, such as Table 1 and Figure 4.

 - equation (12) and (13), use math mode to write equations instead of text mode where multiplications are denoted as * instead of mid-line dot operator ⋅.

- equation (13), there's a problem with the brackets, i.e., the closing bracket should go in the middle of the second line to define the cosine argument.

 - equation (14) is identical to equation (3).

 - in figures 4, 5 and 6, instead of solid red and solid black please use solid and dashed lines to easily distinguish between the two even if printed grayscale.

Key missing references which the authors should cite and possibly compare to: A Model Predictive Control Approach With Slip Ratio Estimation for Electric Motor Antilock Braking of Battery Electric Vehicle - https://ieeexplore.ieee.org/document/9546632 from IEEE Transactions on Industrial Electronics

Author Response

 

 - references should be cited in square brackets, e.g. [1], [2], [3], etc.

A: Thanks for the correction, I corrected the reference citation.

 - line 75: ω is the angular velocity of the wheel not vehicle, as it is written.

A: I changed the vehicle to the angular velocity of the wheels

 - define m, as mass in equation (1)

A: I corrected the definition of m in the text.

 - use cursive (italic) letters in all equations

A: The equation font has been changed to italic, but the cursive font is not available in word.

 - line 113. Missing full stop (period) punctuation at the end of section 2.3.

A: Punctuation has been added.

 - line 122 and line 221: instead of the "following" table/figure use the exact table/figure number, such as Table 1 and Figure 4.

A: Exact tabular/numerical numbering has been used.

 - equation (12) and (13), use math mode to write equations instead of text mode where multiplications are denoted as * instead of mid-line dot operator ⋅.

A: Mathematical models have been used to write equations, with * denoting multiplication.

-equation (13), there's a problem with the brackets, i.e., the closing bracket should go in the middle of the second line to define the cosine argument.

A: The brackets have been removed and the equation is correctly expressed.

 - equation (14) is identical to equation (3).

A: One of the redundant equations has been removed.

 - in figures 4, 5 and 6, instead of solid red and solid black please use solid and dashed lines to easily distinguish between the two even if printed grayscale.

A: A distinction has been made between solid and dotted lines.

 

Reviewer 2 Report

Comments and Suggestions for Authors

This paper presents a road surface recognition algorithm utilizing fitted curves, along with a slip rate control strategy based on a sliding mode variable structure approach.

The following revisions are suggested:

1. The key findings and quantitative results of the proposed work should be emphasized in the abstract to provide a clear overview.
2. The road surface recognition algorithm, based on fitted curves, should be illustrated using a flowchart for better clarity.
3. Similarly, the slip rate control strategy, employing a sliding mode variable structure, should be depicted as a flowchart.
4. Given that the proposed algorithms are intended for real-time operation, an analysis of their computational complexity when executed on a practical on-board computer system should be conducted. The results should be presented and thoroughly discussed.
5. The limitations and weaknesses of both the road surface recognition and slip control algorithms should be addressed in the conclusion, along with suggestions for future improvements.
6. The quality of Figures 4, 5, and 6 should be enhanced to ensure the text is legible and the figures are clearer.

 

Comments on the Quality of English Language

Additional Notes:

1. It would be preferable to consolidate the "Conclusion" section into a single paragraph for conciseness.
2. The abbreviation "ABS" in the title should be fully defined in the abstract.
3. In figure captions, ensure that only the first word starts with a capital letter.

 

Author Response

1.The key findings and quantitative results of the proposed work should be emphasized in the abstract to provide a clear overview.                         

A:Thank you for your suggestion, the main findings are that the pavement identification in this paper can effectively identify the pavement and the slip mode control can control the slip rate to the ideal slip rate, which has been written in the paper.

2.The road surface recognition algorithm, based on fitted curves, should be illustrated using a flowchart for better clarity.

A:A flowchart illustrating the use of the pavement identification algorithm has been put together.

3.Similarly, the slip rate control strategy, employing a sliding mode variable structure, should be depicted as a flowchart.

A:The slip rate control strategy for sliding mode control has been described as a flowchart.

4.Given that the proposed algorithms are intended for real-time operation, an analysis of their computational complexity when executed on a practical on-board computer system should be conducted. The results should be presented and thoroughly discussed.

A:The complexity of this algorithm in vehicles mainly depends on the time complexity of the sensor data acquisition phase and the space complexity of the data storage phase, this paper does not deal with the related research, I have listed the time complexity of this algorithm, the darker bar is the self-use time, the first figure shows the structural view of the model hierarchy and the second figure is the stack view, the total time of the model run is 10 seconds and in more than 3 seconds the vehicle stops. I think is can be used on real time vehicles.

5.The limitations and weaknesses of both the road surface recognition and slip control algorithms should be addressed in the conclusion, along with suggestions for future improvements.

A:Added to the conclusion section as you requested.

6.The quality of Figures 4, 5, and 6 should be enhanced to ensure the text is legible and the figures are clearer.

A:The clarity of the diagram has been changed.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have presented an interesting and novel combination of road surface recognition and sliding mode variable structure control (SMVSC) to optimize Anti-lock Braking System (ABS) performance, however, I have some concerns regarding the manuscripts as outlined below.

1.      Although the abstract captures more of the results, the introduction is very poorly written.

2.      Previous studies done in the field need to be discussed in the introduction as literature review of the present study. The novelty of the manuscript needs to be addressed in the introduction section, specifically at the last paragraph.

3.      There are several typos or grammatical mistakes in the manuscript, eg. Page 2 line 54. It requires that the entire manuscripts must be revised by a native English speaker

4.      Section “2 to 4” labelled “System Structure Modeling to Slip Rate Control Based on Sliding Mode Control” should be “Methodology” and properly presented.

5.      Figure 5 is wrongly plotted and Figures 4, 5, and 6 should be labeled a, b, c, d as well.

6.      The number of references is very small and old and MUST be increased to a minimum of 30 references. This can be done by working on the introduction section as recommended and discussing the results with existing related literature. The authors should focus on newer papers possibly from 2023 to data.

Author Response

1.Although the abstract captures more of the results, the introduction is very poorly written.

A: Thanks to your comment, I've revised the introductory section.

2.Previous studies done in the field need to be discussed in the introduction as literature review of the present study. The novelty of the manuscript needs to be addressed in the introduction section, specifically at the last paragraph.

A:The last paragraph of the introduction presents the innovations and contributions of the manuscript.

3.There are several typos or grammatical mistakes in the manuscript, eg. Page 2 line 54. It requires that the entire manuscripts must be revised by a native English speaker

A: Modified.

4.Section “2 to 4” labelled “System Structure Modeling to Slip Rate Control Based on Sliding Mode Control” should be “Methodology” and properly presented.

A: The serial numbers and structure of some chapters have been correctly corrected.

5.Figure 5 is wrongly plotted and Figures 4, 5, and 6 should be labeled a, b, c, d as well.

A: The diagram has been corrected and has been labelled separately.

6.The number of references is very small and old and MUST be increased to a minimum of 30 references. This can be done by working on the introduction section as recommended and discussing the results with existing related literature. The authors should focus on newer papers possibly from 2023 to data.

A: References have been added and added to the discussion in the introduction section.

Reviewer 4 Report

Comments and Suggestions for Authors

Dear Authors,

your work is covering quite interesting area but there are several details that need to be clarified:

In your introduction and abstract electronic hydraulic braking system is mentioned and described but in your modelling section you are describing permanent magnet synchronous motor model. What is the relation with the hydraulic braking? It is not explained and it is quite confusing.

Line 35 / line 36 In one case references is written as superscript and in other like normal letter. Please check and correct.

Line 85 – In all formulas, below formula should be an explanation of physical quantities (variables).

Line 89 – Please check the formula since it is stated Fxr-Tb but in the picture force Fx and momentum Tb have the same direction.

Line 90 – It is written that I is moment of inertia oh the tire. Is it only the tire or is it of the complete wheel ? Please explain.

Line 104 – In formula (3) should lambda be defied with the subscript I denoting tyre location since in the formula wheel speed for some tyre is used?

Line 115 – Please reference from where the Burchardt tire model is used?

Line 125 – in section 3.2 formulas are given without any explanation. For example, front and rear loads formula are given without any explanation where in the paper values of front and rear loads rear wheel load are used.

Line 213 – In your results section it is stated that CarSim is used but in the results it is not shown or explained

Also, all the given results are not supported by results from other literature or by any experimental research.

Author Response

1.In your introduction and abstract electronic hydraulic braking system is mentioned and described but in your modelling section you are describing permanent magnet synchronous motor model. What is the relation with the hydraulic braking? It is not explained and it is quite confusing.

A: Thanks for your comment, I have removed the redundant permanent magnet synchronous motor model, which acts as the power source for the electro-hydraulic braking system and is defaulted to the ideal motor model in the text.

2.Line 35 / line 36 In one case references is written as superscript and in other like normal letter. Please check and correct.

A: Checked and corrected.

3.Line 85 – In all formulas, below formula should be an explanation of physical quantities (variables).

A: An explanation of physical quantities has been added.

4.Line 89 – Please check the formula since it is stated Fxr-Tb but in the picture force Fx and momentum Tb have the same direction.

A: This has been corrected by changing the direction of the force Fx in the diagram.

5.Line 90 – It is written that I is moment of inertia oh the tire. Is it only the tire or is it of the complete wheel ? Please explain.

A: Forgive the misrepresentation, it has been corrected and here are the full wheels.

6.Line 104 – In formula (3) should lambda be defied with the subscript I denoting tyre location since in the formula wheel speed for some tyre is used?

A: Changed to use subscripts to represent the wheel speed for a particular tyre.

7.Line 115 – Please reference from where the Burchardt tire model is used?

A: The Burchaedt tyre model appears to be from the literature and has been labelled as such.

8.Line 125 – in section 3.2 formulas are given without any explanation. For example, front and rear loads formula are given without any explanation where in the paper values of front and rear loads rear wheel load are used.

A: The front and rear load formulas are used because the front and rear vertical loads change during emergency braking when the vehicle is moving in a straight line, and the rear wheels will lock up first, so I'm looking at the front tyres here, which I've corrected in the article.

9.Line 213 – In your results section it is stated that CarSim is used but in the results it is not shown or explained

A: I have added an explanation for the co-simulation of CarSim and simulink, thanks for the correction.

10.Also, all the given results are not supported by results from other literature or by any experimental research.

A:All the given results were obtained by co-simulation of CarSim and simulink, due to insufficient conditions to do real car experiments, sorry.

Reviewer 5 Report

Comments and Suggestions for Authors

The article needs to be significantly improved. It currently contains many formatting errors. The article would be more interesting to the reader if it also contained experimental studies. In general, the following are the suggestions:

1) [Line 32/40/44/50]: References to literature are not added correctly. This problem has been observed throughout the work.

2) It would be desirable to make the literature review more extensive. It is too short for a journal of this level.

3) [Methodology]: This section is missing from the article. Please add it with a detailed description.

4) [Line 122/113]: There is no visible space between the table and the paragraph.

5) [Line 126]: Table numbering is in Roman letters.

6) [Line 150/151]: There is no visible space between the table and the paragraph.

7) [Line 217/218]: There is no visible space between the table and the paragraph.

8) [Table 3]: The table needs to be adjusted to accommodate all units of measurement.

9) [Figure 4]: The font is too small for the reader to understand the information in the graphs. Corrections are recommended. It is desirable to number the graphs in Figures 4, 5 and 6, for example, a, b, c, d. This will make it easier for the reader to understand the analysis of the figures in the description.

10) [Figure 5]: The font is too small for the reader to understand the information in the graphs.

11) [Figure 6]: The font is too small for the reader to understand the information in the graphs.

12) Please provide a novelty in your article so that it is easier for the reader to understand your contribution to the specific field.

13) It is also desirable to compare your research results with other similar studies to expand on the results and discussion section.

Comments on the Quality of English Language

Extensive English language improvements are needed.

Author Response

1) [Line 32/40/44/50]: References to literature are not added correctly. This problem has been observed throughout the work.

A:I have added the literature correctly, thank you for your comment!

2) It would be desirable to make the literature review more extensive. It is too short for a journal of this level.

A: I have restructured the introduction and added some new literature.

3) [Methodology]: This section is missing from the article. Please add it with a detailed description.

A: Thank you for your comment, I have restructured it in the article.

4) [Line 122/113]: There is no visible space between the table and the paragraph.

A: I have corrected the formatting.

5) [Line 126]: Table numbering is in Roman letters.

A: The form numbers have been changed.

6) [Line 150/151]: There is no visible space between the table and the paragraph.

A: I have corrected the formatting.

7) [Line 217/218]: There is no visible space between the table and the paragraph.

A: I have corrected the formatting.

8) [Table 3]: The table needs to be adjusted to accommodate all units of measurement.

A:Tables have been adjusted

9) [Figure 4]: The font is too small for the reader to understand the information in the graphs. Corrections are recommended. It is desirable to number the graphs in Figures 4, 5 and 6, for example, a, b, c, d. This will make it easier for the reader to understand the analysis of the figures in the description.

A:I have adjusted the information in the chart and numbered it.

10) [Figure 5]: The font is too small for the reader to understand the information in the graphs.

A:I have adjusted the information in the chart and numbered it.

11) [Figure 6]: The font is too small for the reader to understand the information in the graphs.

A; I have adjusted the information in the chart .

12) Please provide a novelty in your article so that it is easier for the reader to understand your contribution to the specific field.

A: The end of the introduction contains novelty.

13) It is also desirable to compare your research results with other similar studies to expand on the results and discussion section.

A: Added a discussion section with the limitations of this paper and future research directions.

Reviewer 6 Report

Comments and Suggestions for Authors

Please see the attachment

Comments for author File: Comments.pdf

Author Response

1.The manuscript introduces traditional ABS control techniques such as PID controllers and Neural network-based control. However, the study does not compare the results with the ABS control techniques. 

A: Sorry, PID control is prone to violent fluctuations at the end of the braking process, which tends to affect the visibility of the graphs out of this paper, so I did not put it on, and because PID control is not the same as the value of the regulation in different cases, and not as simple as the algorithm proposed in this paper, so I did not put it on.

2.The abstract gives good technical information but lacks the novelty and significance of the study in general terms. Please include. 

A: It has been written in the last paragraph of the introduction.

3.Line 24: ±5% relative to what baseline? 

A: Based on the actual optimal slip rate, the slip rate of the sliding mode control is controlled at about 5% of the optimal slip rate.

4.Why was a vehicle mass of 1412 kg used, and how did it represent real-world conditions? 

A: Since I am using the Classic C in CarSim, I have added information about co-simulation in the text.

5.Expand ABS in the title. 

A: It has been changed.

6.Line 37: The citations do not follow the journal format. 

A: This has been corrected.

7.Line 57: Add a paragraph explaining fitted curves and slip rate control before the study goal.

A: It has been added in  the article.

8.Line 58-59: Need an explanation of theoretical analysis and simulation research using examples from previous research studies.

A: Previous research methods have been incorporated.

9.In the introduction, before defining the study goal, there needs to be a clear explanation of all the terms used in the goal so that the readers can understand the study objectives.

A: An explanation of the terminology has been added.

10.Line 71: Can you include a reference for adopting a single wheel model? and why this model is chosen?

A: References to single-wheel models have been provided.According to the needs of the research, the single-wheel model can be easily extended and improved by adding more physical factors and constraints to make it closer to the operation of real vehicles.

11. Line 99: "and" is missing

A: It has been added.

12.Line 116-117: Add the reference for Burckhardt tire model and the reason for using this model.

A: References and reasons have been added.

13.The fitted curve equation (12 & 13) is used without explaining why this particular model was chosen over other possible curve-fitting techniques. Have you taken any statistical measurements to ensure the fitting accuracy?

A: Explanation has been given in the text.

14.The Fourier equation is introduced without justification.

A: Explanations have been given in the text.

15.Line 204-205: No explanation for why this Lyapunov function is chosen

A:Explanations have been given in the text.

16.Why the vehicle speed unit is different in line 224 and figure 4?

A:Have united the units.

17. Can assumptions 1 to 4 be considered integrated in future research?

A: Thank you for your suggestion, we will consider integrating it in the future.

18. The conclusion lacks clarity on how the method improves over existing algorithms.

A: It has been added to the conclusions section.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have addressed almost all the issues they could. On a minor side, references should not be cited in superscript, but as in normal text inside square brackets. Please correct all the citations throughout the paper.

For example, instead of (lines 43-44):

"Due to its low complexity and high integration, the EHB system has become the mainstream trend in current vehicle braking system development⁴."

it should write:

Due to its low complexity and high integration, the EHB system has become the mainstream trend in current vehicle braking system development [4].

 

Author Response

Comment 1:The authors have addressed almost all the issues they could. On a minor side, references should not be cited in superscript, but as in normal text inside square brackets. Please correct all the citations throughout the paper.For example, instead of (lines 43-44):"Due to its low complexity and high integration, the EHB system has become the mainstream trend in current vehicle braking system development⁴."it should write:Due to its low complexity and high integration, the EHB system has become the mainstream trend in current vehicle braking system development [4].

Response 1:Thank you for the correction, the reference citation format has been corrected.

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for addressing most of my comments in the revised manuscript.

Author Response

Comment:Thanks for addressing most of my comments in the revised manuscript.

Response:Thank you for your comments on my manuscript.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed comments raised and have significanly improved the quality of the manuscript and may be accepted.

Author Response

Comment:The authors have addressed comments raised and have significanly improved the quality of the manuscript and may be accepted.

Response:Thank you for your comments on my manuscript.

 

Reviewer 4 Report

Comments and Suggestions for Authors

Line 40, 44. 47  – reference made without parentheses

Line 69 – references are written one after other without space

Line 184 - Translated with www.DeepL.com/Translator (free version)? Please check

Line 190 – Table 2 is written, actually is table 1

Line 194 – Please check sentence. Iti s stated table 3 (missing in the text) and formula 5 which doesn’t seem correct.

Line 200 – It is quite unclear why is mentioned “braking force generated by the permanent magnet synchronous motor” since in the Introduction part complete braking system is described for hydraulic braking. It is unclear which type of braking system is used in the paper. Please explain more in detail.

Line 206 – In formula there are physical quantity symbols without explanation: L

Line 212 – In formulas there are physical quantity symbols without explanation: l, la, lb

Line 217 – It is stated in formula (5), but probably it shoud be formula (4)

Line 221 – stated Table 4, but it’s actually table 2.

Line 222 – stated Table 5, but it’s actually table 2.

Line 236 – Please check the formula. For lambda values between 0 and 0.01 adhesion coefficient is negative which does not make sense. Please explain.

Line 251 – Figure 3. For lambda value 0 adhesion coefficient value is 0, please explain value given in Fig 3. For adhesion coefficient value 0.

Line 295 – Figure 4. Slide mold controller – is mold correct?

Line 312 – stated table VI is actually table 3.

Line 313 – stated table VII is actually table 3.

Line 319 – In Fig 6. It is not clear what x values from 0 to 8 represent. Please clarify

Since this is scientific paper it would be beneficial that the given results are supported by results from other literature since there is no experimental research. Your results are calculated in the simulation and to confirm that simulation is making correct calculation, results should be confirmed or compared with similar research from other literature.

Author Response

1.Line 40, 44. 47  – reference made without parentheses

Response：Thank you for your comment, I have corrected the references cited.

2.Line 69 – references are written one after other without space

Response：I have adjusted the references.

3.Line 184 - Translated with www.DeepL.com/Translator (free version)? Please check

Response：Okay, the redundancy has been removed.

4.Line 190 – Table 2 is written, actually is table 1

Response：Sorry, the table numbers were messed up due to cross-referencing in the title note, which has been corrected.

5.Line 194 – Please check sentence. Iti s stated table 3 (missing in the text) and formula 5 which doesn’t seem correct.

Response：Due to confusion over the title note, this has now been corrected.

6.Line 200 – It is quite unclear why is mentioned “braking force generated by the permanent magnet synchronous motor” since in the Introduction part complete braking system is described for hydraulic braking. It is unclear which type of braking system is used in the paper. Please explain more in detail.

Response：Well, this paper uses an electro-hydraulic braking system that moves and drives a brake master cylinder actuator through a permanent magnet synchronous motor, which in turn causes brake fluid to flow into the four wheel cylinders.

7.Line 206 – In formula there are physical quantity symbols without explanation: L

Response：L is the axle length of the vehicle.

8.Line 212 – In formulas there are physical quantity symbols without explanation: l, la, lb

Response：la is the length from the front axis to the center of gravity and lb is the length from the rear axis to the center of gravity

9.Line 217 – It is stated in formula (5), but probably it shoud be formula (4)

Response：Corrected.

10.Line 221 – stated Table 4, but it’s actually table 2.

Response：The title note has been correctly cited.

11.Line 222 – stated Table 5, but it’s actually table 2.

Response：The title note has been correctly cited.

12.Line 236 – Please check the formula. For lambda values between 0 and 0.01 adhesion coefficient is negative which does not make sense. Please explain.

Response：Sorry for the re-specification of the quoted range, as the lowest lambda in the table is 0.032, and due to an oversight on my part, the lowest value was set to 0.

13.Line 251 – Figure 3. For lambda value 0 adhesion coefficient value is 0, please explain value given in Fig 3. For adhesion coefficient value 0.

Response：Updated the scope of the diagram.

14.Line 295 – Figure 4. Slide mold controller – is mold correct?

Response：It has been corrected.

15.Line 312 – stated table VI is actually table 3.

Response：The title note has been corrected.

16.Line 313 – stated table VII is actually table 3.

Response：The title note has been corrected.

17.Line 319 – In Fig 6. It is not clear what x values from 0 to 8 represent. Please clarify

Response：The horizontal coordinate is the time, 0-8s, which I have added on.

18.Since this is scientific paper it would be beneficial that the given results are supported by results from other literature since there is no experimental research. Your results are calculated in the simulation and to confirm that simulation is making correct calculation, results should be confirmed or compared with similar research from other literature.

Response：I have added the bench test section, thanks for your comment.

Reviewer 5 Report

Comments and Suggestions for Authors

All corrections have been taken into account, except for the numbering of tables. Check the numbering of tables in the text and also the tables themselves - there is no appropriate numbering.

Author Response

Comment:All corrections have been taken into account, except for the numbering of tables. Check the numbering of tables in the text and also the tables themselves - there is no appropriate numbering.

Response:The form numbering has been changed and the forms adjusted. Thank you for your correction.

Round 3

Reviewer 4 Report

Comments and Suggestions for Authors

Dear author, it seems that some comments was not corrected, please check.

Line 40, 44, 47, 50, 52, 55 – brackets are missing

Line 69 – references are numbered but not separated with brackets

References do not appear in numbered order one after other, and some are missing:

Line 124 – Reference 9 appears for the first time after the references with higher number.

Reference 20 is missing

Line 134 Reference 31 appears for the first time before the references with higher number.

Line 317, line 319 – Please check table number.

Author Response

Line 40, 44, 47, 50, 52, 55 – brackets are missing

Response:Sorry, it may be a file formatting issue, I've added the brackets.

Line 69 – references are numbered but not separated with brackets

References do not appear in numbered order one after other, and some are missing:

Response:Thank you for your comment, I have adjusted the reference order and the missing ones have been cited in the text.

Line 124 – Reference 9 appears for the first time after the references with higher number.

Response:I have adjusted the formatting in order of precedence.

Reference 20 is missing

Response:Reference 20 added.

Line 134 Reference 31 appears for the first time before the references with higher number.

Response:The references have been reordered.

Line 317, line 319 – Please check table number.

Response:There may have been a problem with the display, in my case it was table 3, which has been corrected, thanks for your comment.