Research on the Torque Control Strategy of a Distributed 4WD Electric Vehicle Based on Economy and Stability Control

Round 1

Reviewer 1 Report

Dear authors,

after reviewing the proposed paper, here are some of my comments and suggestions.

The proposal is to study the distribution of torque between electric motors in a bus, specifically by applying a Golden section search and Fuzzy logic system. The proposal is interesting and the problem certainly is in the state of the art of the sector.

The models used in the control system design are simple, but sufficiently accurate to capture the main behavior of the system (as far as no big non-linearity is included). The authors could highlight more clearly the limitations and conditions in which the proposed model is not valid/precise.

I miss some mentions to other papers dealing with Torque Vectoring in Electric Vehicles. Some literature, particularly when talking about All-wheel drive and In-wheel motors could help giving a stronger background to the article. Furthermore, it could be explored in the bibliography the alternative control strategies (such as PID, SMC, etc..) applied to the Torque Vectoring, as well as control strategies for fuel efficiency (like dynamic programming).

The system is validated with a HiL approach, essential to this kind of study. However, no mention is made regarding the response of the driver (for example a experimental validation of Driver in the loop test). Some interesting literature on driving simulators applied to Direct yaw control could be included, even as future developments or possible improvements.

How does the authors propose a practical implementation of the controller, given that the side-slip angle is used as input but, in practice, it is hardly direct measured?

The overall paper is good, just some minor changes must be done.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents a torque control strategy of distributed four-wheel-drive using fuzzy yaw moment control.

The paper is written in adequate English, however, sentences, definitions and reasonings are difficult to follow throughout the article. The structure of the paper is average - related literature is mentioned in the paper, but very little background is given to the novel scientific contribution of the work.   This work applies a basic fuzzy control strategy to a well-defined problem in the literature (distributed torque control), and uses a common minimum search algorithm to provide the value of the torque distribution coefficient.  Since the equations representing the efficiency of the control are given in the literature, the contribution of the paper is restricted to the substitution of the existing formula to a common fuzzy membership function set. The solution is not really unique, authors shall compare and assess their alternative to the stat of the art. See and refer to e.g.,     DOI: 10.12700/APH.15.7.2018.7.8   The paper highlights that the method improves the 'economy' (efficiency?) of the drive and increases yaw stability. However, the paper does not define these terms fully, therefore the quantitative justification of the results (mostly in terms of stability) are not complete. Authors should also compare their solution to other approaches presented in the literature, e.g., see http://acta.uni-obuda.hu/AlAmyal_Hamouda_Szamel_114.pdf    Overall, the paper is adequately structured and delivers the application of fuzzy control on a basic linear control problem, demonstrated in a SiL environment. However, neither the controller design, nor the optimization method represent the level of scientific contribution that is necessary for the acceptance of the work into publishing.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

1) The title of this manuscript is too general and does not reveal the essence of the work done. The purpose of a work cannot be only research;

2) The abstract of this work is too general. In my opinion, it is necessary to briefly describe the work done and the results achieved with the necessary facts, which can then be found in the exposition;

3) How are the number of fuzzy logic rules determined?

4) Figures 5, 6, 8, etc. are too illegible and need to be changed;

5) The authors have to describe in more detail the experimental study conducted. What is the reason for the differences with the simulation results - some figures are illegible, especially the numbers on the axes.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors managed to largely satisfy the points of the reviewer, however, the research could still be better nested in the fuzzy control domain, given the vast literature relevant to this topic. Authors should correct minor typos and grammar issues across the paper.