Sliding Mode Control of Spool Position for a Lead-Type Electro-Hydraulic Proportional Multi-Way Valve Based on Disturbance Observation
, Chao Ai 1 and Lizhong Wei 4
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Research topic is timely and valuable for improving electro-hydraulic control performance. The structure of the paper is generally sound, with clear segmentation of modeling, control law design, simulation, and experiment. However, several major issues must be addressed.
Please provide more specific information on sensor models and accuracy, real-time control hardware (e.g., controller type, sampling frequency), data acquisition method and filtering strategies, and Environmental conditions (fluid temperature, etc.). A schematic with labeled signal flow, not just mechanical components, would improve clarity.
The current literature review emphasizes Chinese studies, missing broader international contributions from recent years, looks like no other researchers work on this problematic, but in the same time these studies for example 10.3390/app13010458 ; 10.1177/10775463231215103 and 10.3390/axioms12010008 provide complementary insights into modeling, control, and optimization of hydraulic valve behavior, which would strengthen your research context.
Several key equations (e.g., Equations (1), (7), and (24)) lack detailed derivation steps and clarity on assumptions. Please explain the rationale for parameter selection in the SMC and LESO (e.g., gain tuning strategy).
You compare LESO-SMC only with PID, which is outdated as a benchmark for complex nonlinear hydraulic systems. Include at least one state-of-the-art comparison, e.g., adaptive fuzzy control, model predictive control, or neural-network-based SMC.
What types of disturbances were modeled in simulation (friction, pressure ripple, external load)?
Some minnor suggestions:
Several figures (especially simulation graphs) lack axis labels in English and clear legends. Please revise figure captions to describe the significance of the results, not just what is plotted.
Use consistent terminology: e.g., “spool valve” vs. “valve spool.”
Ensure all symbols in equations are clearly defined.
Improve grammar in some areas; e.g., Abstract lines 27–31 can be more concise.
Clarify abbreviations like LESO the first time they appear in the main text (not only in the abstract).
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authors
The modeling and simulation of EH multi-way directional valve with load sensing is very important. Your work in the paper is of significance. But the structure of the current paper is not clear, the important descriptions on the constitution and working principle should be increased. The detail comments are as follows:
(1) Title is OK, but I suggest cancelling "Research on".
(2) Abstract, the expression quality needs to be improved, for example, what is the meaning of "hard-assembly control of the valve core position"?
(3) Introduction section, to simplify existing references focused on modeling interference observation and load sensitive electro-hydraulic proportional valves.
(4) Introduction section, line 131, the word "improve" should be corrected to "realize".
(5) In this paper, "Electro-hydraulic proportion relief valve" shoud be "Electro-hydraulic proportion reducing pressure valve" or "Electro-hydraulic proportion pressure valve".
(6) The hydraulic schematic and modeling analysis diagram corresponding to Figure 1 should be provided.
(7) Electric circuit digram corresponding to the analysis in section 2.1-1, block diagram corresponding to the analysis in section 2.1-2, should be provided.
(8) Please check (3) and (4), in multi-way direction valve, EH piloted pressure valve uses coil current to control the pressure at both sides of the main valve, and the dynamic relationship between the pressure difference at both ends of the main valve and the displacement of the main valve is a second-order link.
(9) Because of the error in the main valve tranfer function, the state equation and design of the disturbance observer need to be revised.
References: to thoroughly check the citation contents of [4] and [5], and [11]-[23].
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors After careful evaluation of provided revision, paper is recommend current submissions for acceptation and publication. Well performed research report paper.
Reviewer 2 Report
Comments and Suggestions for Authors
No
