Active Fault-Tolerant Control of a Four-Wheel Independent Steering System Based on the Multi-Agent Approach
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn the Table 1 I suggest that the Gravitational acceleration is given as 9.81m/s^2.
Comments on the Quality of English Language
Some fine tuning of the text could be conducted as for example in Abstract:
Instead of:
“In order to improve the handling stability and active safety of vehicle, this paper proposes an active fault-tolerant control based on multi-agent for four-wheel independent steering system actuator faults.”
It would be better to say:
“In this paper, we present an active fault-tolerant, vehicle motion control, based on the multi-agent approach for four-wheel independent steering system. This improves handling stability and active safety of the vehicle in the case of actuator’s faults”.
Instead of:
“Then, this paper establishes the topological structure of four-wheel independent steering subsystems based on graph theory.”
It would be better to say:
“Then, we established the topological structure of four-wheel independent steering subsystems based on graph theory”.
Instead of:
“The hardware in the loop experimental results validate the effectiveness of the proposed method in this paper”.
It would be better to say:
“The hardware in the loop experimental results validate the effectiveness of the proposed, novel method”.
In the Introduction, instead of:
“The four-wheel independent steering (4WIS) electric vehicles rely on a flexible control strategy of four wheels to ensure good power performance and handling performance in extreme environments”.
It would be better to say:
“The four-wheel independent steering (4WIS) electric vehicles rely on a flexible control strategy of four wheels to ensure good power and handling performances in extreme working conditions”.
Author Response
Dear reviewer,
Thank you very much for your suggestion. I have modified the corresponding sentence in the paper.Have a nice day !
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript is written clearly. The research content is valuable and worthy of publication. There are only minor comments to be addressed:
In the abstract, please rephrase this sentence: “the vehicle model is decomposed into four two degree of freedom single 12 input four wheel independent steering subsystems based on vector transformation” with like en dash. The current version is a little bit confusing.
It is recommended to provide some quantitative results in the abstract, alongside the qualitative ones, for a more comprehensive overview.
In the introduction, the authors mention both passive and active fault-tolerant controls. It is recommended to provide a brief overview of passive fault-tolerant control before delving into the details of the active fault-tolerant control.
It is recommended to articulate gaps in existing research and how these gaps limit the current technology or understanding before the last paragraph of the introduction. The innovation of this paper also needs to be emphasized.
In the experiment part, t would be helpful to describe how the faults are injected into the system.
Authors mention that fault-tolerant control improves vehicle safety and stability. It is recommended to expand on how significant these improvements are. For example, quantify the reduction in deviation from ideal values or the increase in system stability.
In the conclusion, it is recommended to briefly mention any limitations of this study, such as assumptions made, the scope of the simulation environments, or hardware constraints. Additionally, outlining potential areas for future research that could expand upon these findings is recommended.
Author Response
Dear reviewer,
1.This manuscript is written clearly. The research content is valuable and worthy of publication. There are only minor comments to be addressed:In the abstract, please rephrase this sentence: “the vehicle model is decomposed into four two degree of freedom single 12 input four wheel independent steering subsystems based on vector transformation” with like en dash. The current version is a little bit confusing.
Answer: Thank you very much for your suggestion. I have rephrased this sentence as follows: “Firstly, an eight degree of freedom four input vehicle model is established by using vector transformation method, which takes the four wheel angle as input and the yaw rate and the sideslip angle obtained by the lateral force of a single wheel as output. ”
2.It is recommended to provide some quantitative results in the abstract, alongside the qualitative ones, for a more comprehensive overview. In the introduction, the authors mention both passive and active fault-tolerant controls. It is recommended to provide a brief overview of passive fault-tolerant control before delving into the details of the active fault-tolerant control.
Answer: Thank you for your suggestion. In the simulation, the quantitative analysis of the deviation value between lateral displacement and ideal value has been added to the paper. In addition, we have added a description of passive fault-tolerant control in the paper, as follow “Passive fault-tolerant control designs control systems based on robust control concepts without changing the controller and system structure, making them insensitive to faults. However, its adaptive ability to fault tolerance is very limited.”
3.It is recommended to articulate gaps in existing research and how these gaps limit the current technology or understanding before the last paragraph of the introduction. The innovation of this paper also needs to be emphasized. In the experiment part, t would be helpful to describe how the faults are injected into the system.
Answer: Thank you for your suggestion. We have added the analysis of the drawbacks of existing methods, as follows: “Through the above analysis, it is found that current research on 4WIS steering fault-tolerant control is more focused on hardware redundancy design and complex fault-tolerant control method design. These methods will increase manufacturing costs and real-time computing burden in practical applications.” In addition, this paper added a description of the fault time of the actuator in the hardware in the loop simulation experiment.
4.Authors mention that fault-tolerant control improves vehicle safety and stability. It is recommended to expand on how significant these improvements are.
Answer: Thank you for your suggestion. I have added the necessity of fault-tolerant control for stable steering of 4WIS in the paper, as follow “The actuator of 4WIS needs to be started frequently to cope with the time-varying driving conditions, and because the mechanical coupling between the subsystems is relatively weak, the actuator fault is more hidden. Therefore, the design of fault tolerant control mechanism for 4WIS has important practical significance to improve the driving safety of the vehicle. Multi-agent control allows each agent to be independently. When an actuator fails, other agents can ensure the stable steering of the vehicle through information exchange. In addition, sliding mode control has unique robustness and complete adaptability to matching uncertainty and external disturbances.”
5.In the conclusion, it is recommended to briefly mention any limitations of this study, such as assumptions made, the scope of the simulation environments, or hardware constraints. Additionally, outlining potential areas for future research that could expand upon these findings is recommended.
Answer:Thank you for your suggestion. In the conclusion, we have added limitations of this paper, as follow “The proposed method only considers that the lateral acceleration is less than 0.4g and the tire side stiffness is in the linear range. In addition, only the gain change fault, constant deviation fault and stuck fault of the actuator are considered in this paper. Next, research on fault-tolerant control methods for actuator faults in four-wheel independent steering systems under all working condition and actual vehicle verification will be carried out.”
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper proposes an active fault-tolerant control system for a four-wheel independent steering system based on multi-agent technology, aiming to improve vehicle handling stability and active safety. The system decomposes the vehicle model into four two-degree-of-freedom single input four-wheel independent steering subsystems and establishes their topological structure using graph theory. For known fault conditions, an adaptive sliding mode active fault-tolerant control method is proposed, while for unknown fault conditions, an active fault-tolerant control method based on a state observer is proposed. The effectiveness of the proposed methods is validated through hardware-in-the-loop experimental results.
1. The paper does not explicitly mention the limitations of the proposed active fault-tolerant control system for the four-wheel independent steering system based on multi-agent technology
Author Response
The paper does not explicitly mention the limitations of the proposed active fault-tolerant control system for the four-wheel independent steering system based on multi-agent technology.
Answer: Thank you for your suggestion. In the conclusion, we have added limitations of this paper, as follow “The proposed method only considers that the lateral acceleration is less than 0.4g and the tire side stiffness is in the linear range. In addition, only the gain change fault, constant deviation fault and stuck fault of the actuator are considered in this paper. Next, research on fault-tolerant control methods for actuator faults in four-wheel independent steering systems under all working condition and actual vehicle verification will be carried out.”
Reviewer 4 Report
Comments and Suggestions for AuthorsIn this paper, the authors propose a fault-tolerant active control system applied to a four-wheel independent vehicle steering system actuator. The proposed active control considers adaptive sliding mode control. Additionally, the authors include a state observer in the control proposal.
The paper presents interesting and relevant results, is well written and well discussed, and recent references are considered. However, the paper needs some considerations before being accepted for publication.
The problem considered is well known and investigated, and the results presented in the current literature consider a more classic control such as PID. I recommend that authors include in the results a comparison of the proposed control and the PID control, and include a comparison of the results obtained with results already published in current literature.
Author Response
However, the paper needs some considerations before being accepted for publication. The problem considered is well known and investigated, and the results presented in the current literature consider a more classic control such as PID. I recommend that authors include in the results a comparison of the proposed control and the PID control, and include a comparison of the results obtained with results already published in current literature.
Answer: Thank you very much for your suggestion. In the hardware in the loop simulation experiment, the comparison between the proposed method and PID control is added, the content can be seen in the sixth part of the paper.
Author Response File: Author Response.pdf
Round 2
Reviewer 4 Report
Comments and Suggestions for AuthorsThe current version contains the requested corrections and clarifications and can be accepted for publication.
