Application Layer Software Design of Vehicle Comfort Braking Based on Brake-by-Wire System

Round 1

Reviewer 1 Report

The article contains interesting content related to vehicle braking systems and so-called control by-wire. Although the topics have been presented quite widely and with the use of experimental results, the manner of presentation and description needs to be reorganized and some issues need to be more fully explained:

1.       Abstract - the content of the abstract should correspond to the content that the article addresses. Referring to the results that are not presented is unjustified – e.g., the results confirming the improvement of the "nodding feeling" of the vehicle are not presented. In addition, the purpose of any braking system is to induce vehicle deceleration but reducing deceleration can flow out to increase stopping distances and reduce safety.

2.       The structure of the article should be organized to make it a logical whole:

a.       It would be worthwhile for the introduction to also include a clear description of the authors' contributions and the novelty of the approach used. It is also advisable to expand the literature review to include works by authors from other regions of the world on brake-by-wire issues as well as other concepts for building such systems. For example, some publications deal with braking systems that take into account braking with energy recuperation and the use of an electric motor/generator to slow the movement of the vehicle could be potentially beneficial.

b.       Conclusions section should contain conclusions on the results achieved instead of a brief description of the contributions.

c.       Authors should avoid formulating general expressions that are undefined (e.g., short period, at low speed, fluctuate greatly, fluctuate widely, speed is low, unit of time...) and to formulate conclusions unsupported by the research results presented in the article e.g., driving safety and passenger comfort are mostly considered as opposite criteria (in the manuscript an emergency braking vs. passengers comfort). The lack of definition of the metrics of the criteria and the results relating to them does not entitle to assess of the performance and impact of the proposed CST. It is all the more regrettable that the authors listed a number of sensors with which the actual vehicle was equipped and which allowed them to present the results in a form similar to Fig 2 e.g., pressure, vehicle deceleration, vehicle body tilt, braking distance, etc.

d.       Active or semi-active vehicle suspensions with variable damping characteristics can also be used to reduce passenger discomfort during braking. The response time of such systems can be less than 30-80 ms. What is the advantage of using CST over such systems?

e.       The safety criterion is often concerned with minimizing the change of the vertical  wheel force on the road surface and avoiding loss of longitudinal and lateral wheel traction. Have the authors considered and studied other cases of vehicle movement, e.g. braking on a curved road, on a road with a rough surface, etc.?

f.        It may be beneficial to discuss and present more extensively the sources and types of signals that are marked in Fig. 3. Although later they are somehow mentioned but there is no indication of their division into sources.

g.       The quantities and parameters used in Formula 1 should be precisely and unambiguously described in the absence of a drawing of the vehicle with markings of variables and parameters.

h.       In formulas 2 and 3, the authors refer to pressures in the "temporary parking state." What is this state? Are these pressures anyhow related to the operation of the CST, for example, shown in Figure 4? These pressures do not appear later in the article.

i.         The quantities used in Fig. 4 should be described. What are e.g. K1, err, pb_tar etc. Similarly in figure 9.

j.         Authors should add a reference to INCA software. In an English-language publication, if there is a possibility, screenshots of the software should also be in English.

k.       The data and names of vehicle parameters (e.g., quality wheelbase) in Table 1 should be revised. You may want to consider adding the parameter and size designations used at the beginning of the article (G, r1/2, d1/2,...).

l.         In Figure 11, drawings a) b) and c) d) appear to be identical. Shouldn't they illustrate the different pressures shown in Table 2?

m.     How do the K values change between high and low speed ranges (what speed ranges are these?) and in between (5-10 km/h?)?

n.       On the vertical axis in Figures 12 and 13, the units are probably incorrect, or a different quantity should be described.

o.       The beginning of section 5.3 mentions a pressure of 100 bar and a response time of 180 ms. The experimental studies in Figure 11 and Table 2 do not show such pressures.

p.       The authors should consider adding and discussing results related to the effect of using CST on the vehicle e.g., its deceleration, body vibration, braking distances showing the advantages of using the developed CST. It is worth considering comparing these results with the more traditional braking system without CST. Conclusions should be drawn from these results. A comparison of brake system pressures alone does not tell about body vibration during braking (which also depends on the vehicle's suspension parameters).

 

The authors should revise the English language of the manuscript, grammar, read and verify the clarity of wording, description of the quantities and parameters used, and improve the editing side of the article.

 

Author Response

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Reviewer 2 Report

This paper designed an algorithm that could realize the vehicle CST and conducted the verification. Some comments and suggestions are listed in bellows:

(1)  In abstract or even the full text, the theoretical or methodology contribution of this study is not highlighted. The study work is simply described, however, what is the difference between this study and other research work?

(2) The writing is not prepared: ‘(100-200ms’ in line 30, duplicate definition of the CST in line 76, case problem for ‘Angle’ in line 77, format problem for the equation in line 107, symbol problem for ‘G’ and ‘R’ which is different with those in Eq. (1) in line 109, description in line 127-128, ‘7.  0001 W Z ,Liu Y ,0001 P G .’ in line 334, and so on.

(3) Almost all the figures are given without the corresponding description or discussion. So we do not understand the meaning or intension. For example, we could not get the algorithm given by Fig.4 as there is no explanation. And the Fig.10(b) is meaningless.

(4) The discussion for the results is insufficient. In addition, the vehicle performance is not emphatically discussed in the results.

(5) Literature review need to be enriched. More latest publications on brake-by-wire should be acknowledged and discussed. Some relevant research is listed for reference: 1. Active Safety Control of X-by-Wire Electric Vehicles: A Survey; 2. Hardware-in-the-Loop Testing of a Hybrid Brake-by-Wire System for Electric Vehicles; 3. Brake-by-Wire System Redundancy Concept for the Double Point of Failure Scenario.

Writting should be improved.

Author Response

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Reviewer 3 Report

The paper proposes a study to design an algorithm capable of realizing the Vehicle Comfort Stop Technology (CST) in the functioning of the Brake-by-Wire system.

The topic can be considered quite interesting and the results could provide a contribution to improve the feeling during autonomous braking.

In the paper there are many spelling errors and inaccuracies in the text: the paper should be carefully revised to eliminate errors in form and language.

The figures should also be carefully reviewed to improve the quality.

By way of example, some inaccuracies are reported below. The inaccuracies of the other chapters are not cited, but all the work (including References) needs careful revision.

Remark n.1 (line 30) – one parenthesis is missing.

Observation n.2 (Fig. 1) – the connecting lines need to be reviewed.

Observation n.3 (Fig. 2) – a nomenclature table is needed.

Observation n.4 (line 107 and following) – format errors of the lines.

Etc.

General comments:

Verification of the real vehicle requires a more in-depth analysis:

The authors should better explain the meaning of Fig. 11 - Pressure response of each stag. 

The real tests are conducted on an electric vehicle with regenerative braking. A diagram describing the flow of power would be useful to understand the intervention of the brake-by-wire system.

Are there differences using different electric-powered vehicles?

Author Response

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Reviewer 4 Report

References to literature should not be footnotes Figures should be signed Figure 1 and also in the text. In accordance with the guidelines of the magazine. Figure 9, 10 not legible on the printout. There is no reference in the text to formulas 2-4. The reference to formula 1 in the text is correct. An article with research and a scientific aspect, which translates into the results obtained. The structure of the document is very good and smoothly guides the reader to the final result.

Author Response

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Round 2

Reviewer 1 Report

Although the moanuscript has been noticeably improved, the summary, introduction and conclusion are still not strong points. Potentially they could be improved - although they could be accepted. In my opinion, still inovation, contribution and impact is not emphasized strongly enough in relation to the current state of knowledge. This is what the article loses because the rest of the manuscript is already concentrated only on the description of the research and the algorithm.

The reference to safety and comfort although now indirectly addressed but the authors wrote in the manuscript that they performed a reading of vehicle acceleration from the CAN bus. It is a pity that this signal was not also shownin the figure with a comparison of the speed of the car with and without CST. It would also have been worthwhile to indicate by how much the braking distance differed - by about 10-20?

Author Response

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Reviewer 2 Report

The literature review still need to be enriched. More latest publications on brake-by-wire should be acknowledged and discussed. Please refer to corresponding review comment in the previous version.  At least 30+ references are highly recommended for a quality journal paper to be published.

It could be improved.

Author Response

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Reviewer 3 Report

I have no further comments. 

Author Response

Thanks again for your review! I have revised the paper.