Sliding Mode Control of Electro-Hydraulic Position Servo System Based on Adaptive Reaching Law

Round 1

Reviewer 1 Report

This paper presents a SMC method based on adaptive reaching law. The proposed method is used to control the displacement and velocity of an electrohydraulic servo system. A comparative analysis of the results obtained using SMC controller with traditional exponential reaching law and adaptive reaching law is given. The presented results show that the proposed method can reduce the chattering of the piston displacement and velocity. Moreover, the convergence velocity of the adaptive reaching law is faster than that of the traditional exponential reaching law.

Authors discussed a very interesting topic. I believe this paper can be accepted after minor revisions. The article is well written and in the following some general objections are given.

1. The title matches the content of the paper.

2. The abstract is complete and self-reliant.

3. The text is well structured and technically correct.

4. The presented results are correct.

5. The motivation to conduct this study is clear and the methodology is understandable.

6. The content of this paper is interesting, and mathematical process is generally correct.

7. The authors claim in the abstract that the proposed method improves the robustness of the system. The authors should explain on the basis of which comparisons make such a claim. In the Simulation section, it seems that the authors did not deal with the robustness of the proposed method.

8.  The proposed SMC method is based on a linear model of the plant. In practice, electrohydraulic servo system (EHSS) is a highly nonlinear system and the authors should clarify whether they used the nonlinear or linear EHSS model in the system simulation, and why. Using a nonlinear model in the simulation would be more realistic.

9. Also, it is desirable to show the change of the control variable (for exponential and proposed adaptive reaching law and give some comments.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

1.    In Abstract, the terminology used to describe the state variable, i.e., “state quantity of the system”, “system state variable” and “system state”, should be unified.

2.    One section should be used to give an introduction of the design of the sliding mode controller based on the traditional exponential reaching law.

3.    A block diagram should be given to describe the co-simulation based on the AMESim and Simulink.

4.    The sampling period used in the simulation test should be given.

5.    All parameters selected for the proposed SMC algorithm and the SMC with traditional exponential reaching law must be summarized in a Table. Moreover, in order to show the fairness of the comparison, the authors should demonstrate that the selected parameters for the SMC with traditional exponential reaching law are optimal.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I have no further comments.