A Robust Electric Power-Steering-Angle Controller for Autonomous Vehicles with Disturbance Rejection

Round 1

Reviewer 1 Report

This paper discusses the adaptive sliding mode control for vehicle steering angle tracking. The comments are as follows:

1. In Section 2, the system uncertainty of the EPS is not clearly discussed.
2. In line 22, what is the value of n, w?
3. Is there any reference to support (4)?
4. In experiment, another comparison to conventional adaptive sliding mode controller is required.
5.  In Introduction, some new advances for active steering is missing, such as Active steering control for vehicle rollover risk reduction based on slip angle estimation.
6. The observer as well as the controller is recommended to be organized in a Theorem and its corresponding proof.
7. The main problem is that the design is simple which leads to limited contribution and improvement, compared to the similar research such as [10].

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Reviewer 2 Report

The authors present a robust electric power steering angle controller for autonomous vehicles with disturbance rejection. Below are some of the main concerns.

1. The contribution of this work is quite questionable to the reviewer. At the end, the EPS system is modeled as a quite simple 2^nd order system, almost linear. It is quite hard to be convinced that there are some major challenges for the control design of such a system. The authors should provide some discussion in Section 2 and maybe a problem formulation would be welcome to highlight related potential challenges.
2. There are some issues on the mathematical fonts in equations (4)-(6). Especially, the correction term s is not explicitly defined. And the remaining design technique is simply based on a standard LQR design.
3. How is it possible to have the form (13) since the disturbance is UNKNOWN! This is a major issue because it is crucial to get the sliding mode variable s in (14).
4. With the overall gain eta in (24), you need the time derivative of theta_p for the control law, which is not compatible with the observer part. Another major issue.
5. Moreover, I don’t see yet any mechanism that allow to effectively reduce the chattering effect since S depends on the time derivative of theta_p, which can be very noisy.
6. Some comparisons with existing methods should be necessary to show the interest of this work.
7. I believe that there is a lack of focus on the motivation for the work in Section 1. The authors talked about many challenges such as backslash, etc. that is not addressed in the paper. Moreover, I would recommend the authors to enrich the literature review with various control techniques for vehicle/EPS control, and not essentially stay with SMC. I would invite the authors to discuss the following works and recent references therein.

https://www.sciencedirect.com/science/article/pii/S0888327021003265

https://journals.sagepub.com/doi/full/10.1177/1748302620931312

Author Response

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Reviewer 3 Report

This paper presents a robust electric power steering angle controller for autonomous vehicles. Some comments are listed as follows.

1. Some symbols in equations are unclear, e.g., (4), (5), (6)…
2. SMC has been widely used to address the control of steering, I cannot find the contribution of this paper.
3. The comparative simulation between SMC and other control algorithm is suggested, e.g., robust control, MPC.
4. The simulation scenario and software are not clear. The steering control should be considered with the whole vehicle’s motion control, yielding a closed-loop control.

 

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Reviewer 4 Report

The paper is well structured and results are sound. Experimentation work is sufficient. A paper would benefit if comparison with alternative control approach is examined, to give a proper perspective.

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Round 2

Reviewer 1 Report

Thanks for the authors' response. The paper has been improved a lot. However, the comment is still not fully answered. In comment 1, the authors should clarify the definitions of n and w IN THE PAPER to avoid any possible confusing. In comment 3, although some revision is made, it is not supported by any reference such as 10.1049/iet-csr.2019.0030

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Reviewer 3 Report

Sorry, The response is not for my questions. 

1. Some symbols in equations are unclear, e.g., (4), (5), (6)…
2. SMC has been widely used to address the control of steering, I cannot find the contribution of this paper.
3. The comparative simulation between SMC and other control algorithm is suggested, e.g., robust control, MPC.
4. The simulation scenario and software are not clear. The steering control should be considered with the whole vehicle’s motion control, yielding a closed-loop control.

Author Response

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Round 3

Reviewer 3 Report

Thanks for the response. 

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