PONE-D-25-20009Adaptive Free-Will Arbitrary Time Sliding Mode Controller for Three-Phase Rectifier Used in Oil Palm Autonomous GrabberPLOS ONE

Dear Dr. Mahmood,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

It is suggested to please address all concerns and suggestions of the reviewers point-wise and also improve or expand the article where needed in order to justify the responses to the concerns. Therefore a major revision is proposed. 

Please submit your revised manuscript by Jul 11 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Akhtar Rasool, Ph.D.

Academic Editor

PLOS ONE

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4. Please amend the manuscript submission data (via Edit Submission) to include author Wan Zuha Wan Hasan.

5. Please amend your authorship list in your manuscript file to include author Wan Zuha Wan Hasan Wan Hasan.

6. Please remove your figures from within your manuscript file, leaving only the individual TIFF/EPS image files, uploaded separately. These will be automatically included in the reviewers’ PDF.

Additional Editor Comments :

It is suggested to please address all concerns and suggestions of the reviewers point-wise and also improve or expand the article where needed in order to justify the responses to the concerns. Therefore a major revision is proposed.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The authors have proposed “Adaptive free-will arbitrary time sliding mode controller for three-phase rectifier used in oil palm autonomous grabber”. In this the reviewer is pleased to inform that the paper is well written and documented. However, some corrections are required for the improvement of the quality of the paper. It is suggested to follow the suggestions as mentioned below and submit the revised version for further consideration. Overall decision by the reviewer is MAJOR REVISION.

Suggestions are as follows:

(1) The Abstract is quite elaborative. Abstract must be the summary of the entire paper in a concise and compact form. Thus, it is suggested to make the abstract compact by mainly focusing on the novelty of the proposed work.

(2) The Introduction is good and the literature reviews are well highlighted. However, the entire Introduction is written in a single paragraph. It is suggested to break it in small paragraphs. In the last paragraph, the contribution of the proposed work along with the organization of the rest parts the paper is to be included.

(3) In Figure 1, the images just above the blocks “Three Phase Rectifier” and “BMS” are absolutely blurred and nothing is visible. It is suggested to include HD images for those two pictures.

(4) In the sentence on page no. 3: “The phase rectifier can be represented in the below three equations [28]:”, there are four equations (1-4) not three. Correct.

(5) Below equation (13), replace r and e by r and e.

(6) Below equation (13), there is a long text. Break in paragraphs.

(7) Below equation 31, the sentence: “The advantages of using such an addition are It will provide a free-will convergence to the error of the DC-link voltage of the rectifier, which is the desired state (Vdc →V∗dc) within the arbitrary time (Tfadjusted) regardless of initial conditions or disturbances.” is ambiguous and not clear. Rewrite it. It is suggested to write all advantages either by using bullets or by numbering.

(8) Place equation 8 at the center of the page.

(9) The font size of Eqn. 10 is not same like other equations. Correct Eqn. 10. Also place the equation number 10 at right aligned position.

(10) Below Fig. 6, the authors have written “Figure 6 illustrates the iq ̶ iq harmonic current detection algorithm based on instantaneous reactive power theory.” However, the figure caption describes the block diagram. It is ambiguous.

(11) Fig 3 is blurred. Replace it by HD image.

(12) In step c:Error Threshold check of the Algorithm for the AFWATSMC for the sentence: “Next, the algorithm evaluate whether the error (edc) exceeds the predefined threshold set bt the algorithm” what “bt” means.

(13) On page 15 for the sentence: “Finally, the same 15 v as a reference voltage and loading conditions were applied to both systems.” 15 v will be replaced by 15 V.

(14) Explain Fig. 5 and Fig. 6 in more detail.

(15) Replace all figures of Fig. 7 with HD images and large font for axes indentations.

(16) Write all parameters in Table 2 in italics font.

(17) Change yellow color of all plots by some other deep colors like red or black. Also increase the depth of colors to understand the comparison plots between AFWATSMC and ASMC.

(18) Fig. 9 is absolutely blurred. It can’t be accepted for the paper. All left hand side texts are blurred. Replace Fig. 9 by HD images. It is suggested to separate the images and place individually one after another with proper figure number.

(19) Write concluding remarks based on Table 4.

(20) Include a comparative table with some recently published works based on some common parameters to justify the novelty of the proposed work.

Reviewer #2: This manuscript proposes a novel Adaptive Free-Will Arbitrary Time Sliding Mode Controller (AFWATSMC) for a three-phase rectifier used in an oil palm autonomous grabber. The aim is to improve DC voltage regulation and reduce total harmonic distortion (THD) while addressing thermal issues due to excessive loading on the alternator in a robotic mobile platform. The paper includes an original control scheme with adaptive terms and modified convergence logic using MATLAB/Simulink modeling, genetic algorithms (GA), and particle swarm optimization (PSO) for parameter tuning. While the topic is timely and interesting, and the integration of FWAT with SMC is original, the manuscript requires significant revisions to improve readability, clarity, and alignment with standard engineering practices.

Major Comments

1. Structure and Flow:

• The manuscript is dense and lengthy, with long paragraphs and limited use of subheadings, making it difficult to navigate. Sections such as the introduction and methods should be broken down into clearly numbered subsections to improve organization and flow.

• The title is confusing and overly complex. Consider rephrasing to emphasize the application and novelty (e.g., "An Adaptive Sliding Mode Controller with Arbitrary-Time Convergence for Three-Phase Rectifiers in Autonomous Agricultural Vehicles").

2. Introduction:

• The introduction sets a solid context about the challenges in oil palm harvesting and the use of MBGs, but it lacks citations of recent work in control systems for autonomous agricultural machinery or rectifier control.

• While the motivation is clear, the novelty of the proposed controller should be stated explicitly. What differentiates this controller from other SMC variants or existing rectifier control strategies?

3. Novelty and Contribution:

• The key innovation lies in integrating free-will arbitrary convergence time with an adaptive SMC structure. However, this should be highlighted more clearly in the abstract and conclusion.

• The mathematical derivations are comprehensive, but the novelty gets buried in formula-heavy sections. A concise summary (e.g., bullet points or a table) comparing your approach to ASMC or other SMC methods would enhance clarity.

4. Figures and Tables:

• Many figures are not discussed adequately in the text. For example, Figures 5–16 are introduced with minimal analysis or interpretation.

• Captions are often too brief or generic. For example, “DC Output Voltage Behavior” doesn’t explain the scenario or what distinguishes the behavior shown.

• Table 1 on convergence lacks context—what does “yes” or “no” convergence mean practically?

• Consider adding a summary table of all tested conditions and system responses for clarity.

5. English Language and Style:

• The manuscript suffers from grammatical inconsistencies, awkward phrasing, and run-on sentences (e.g., the sentence starting with "The advantages of using such an addition are...").

• Please consider professional English language editing. Use consistent past tense for experimental descriptions and present tense for general truths.

• Terms like "free-will arbitrary time" are unconventional in engineering literature. You may want to explain this term clearly or use more standard terminology such as “user-defined convergence time.”

6. Validation and Discussion:

• While the controller is validated in simulation and parameter tuning is supported by GA and PSO, the physical implementation is not discussed. Is this purely simulated? If so, limitations should be explicitly stated.

• The paper would benefit from a quantitative comparison of key performance metrics (e.g., THD, convergence time, ripple factor) between AFWATSMC and conventional controllers.

• More insights should be provided into practical implementation issues: real-time feasibility, computational cost, and integration with embedded systems.

7. References:

• The literature review is broad but misses key studies on modern SMC applications in rectifiers, such as those using model predictive control, hybrid controllers, or grid-connected converters.

• The reference formatting is inconsistent; ensure all references follow PLOS ONE guidelines.

8. Suggested References (for Authors to Consider Including):

• Here are five relevant references that the authors might cite to strengthen the novelty and relevance of the harmonic mitigation and control methodology (especially for high-performance rectifier systems). These references would enhance the relevance of your harmonic mitigation discussion and modernize your bibliography:

1) Al-Barashi, M., Zou, A., Wang, Y., Luo, W., Shao, N., Tang, Z., & Lu, B. (2025). Magnetic Integrated Multi-Trap Filters Using Mutual Inductance to Mitigate Current Harmonics in Grid-Connected Power Electronics Converters. Energies, 18(2), 423. https://doi.org/10.3390/en18020423.

2) Al-Barashi M, Wang Y, Bhutta MS (2024) High-frequency harmonics suppression in high-speed railway through magnetic integrated LLCL filter. PLOS ONE 19(6): e0304464. https://doi.org/10.1371/journal.pone.0304464.

3) Al-Barashi, M., Wang, Y., Lan, B. et al. Magnetic integrated double-trap filter utilizing the mutual inductance for reducing current harmonics in high-speed railway traction inverters. Sci Rep 14, 10058 (2024). https://doi.org/10.1038/s41598-024-60877-y.

4) Al-Barashi, M., Meng, X., Liu, Z., Saeed, M.S.R., Tasiu, I.A., Wu, S.: Enhancing power quality of high-speed railway traction converters by fully integrated T-LCL filter. IET Power Electron. 16, 699–714 (2023). https://doi.org/10.1049/pel2.12415.

5) Al-Barashi, M., Wu, S., Liu, Z., Meng, X., Tasiu, I.A.: Magnetic integrated LLCL filter with resonant frequency above Nyquist frequency. IET Power Electron. 15, 1409–1428 (2022). https://doi.org/10.1049/pel2.12313.

Summary and Recommendation

• This manuscript presents a potentially impactful control strategy for improving power quality in robotic agricultural platforms. However, in its current form, the manuscript suffers from lack of clarity, verbosity, and insufficient comparative discussion.

Recommendation: Major Revision

• The paper has potential, but it requires significant reorganization, improved English usage, a stronger literature review, and clearer highlighting of contributions before being suitable for publication.

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Reviewer #1: Yes: DR. TARUN KUMAR DAS

Reviewer #2: No

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Attachments

Attachment

Submitted filename: PONE-D-25-20009_reviewer Comments.docx

PONE-D-25-20009R1An Adaptive Sliding Mode Controller with Free-Will Arbitrary Time Convergence for Three-Phase Rectifiers in Autonomous Agricultural VehiclesPLOS ONE

Dear Dr. Mahmood,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Aug 27 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Akhtar Rasool, Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise. 

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

I congratulate the authors that the reviewers have acknowledged the improvements in the article and they are also satisfied with the responses submitted. However, they have raised a couple of points which we feel will be very important to raise the quality of your manuscript and as well as its presentation. So, we are advising a minor revision and expect to receive the final corrected version at the earliest. Thanks

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Now, the paper is ready for publication except for a small issue: it is suggested to include one more row at the end of Table 7 mentioning "This Work" and then write the supporting results in subsequent columns. It will help the reader to understand the novelty of the proposed work at a glance. Congratulations on such a wonderful work. I request to extend such work in the future with some other methodologies.

Reviewer #2: First of all, I appreciate the authors for the perfect responses and improvements. I am delighted to inform you that this manuscript is very strong now, and I believe that this paper will gain a high number of citations in the future. The authors made a major correction from the previous round. The revised manuscript can be accepted for publication. I only have a minor notice, which can be considered in the final version. The paper is not required to be sent again to the reviewer. You just consider this note before publishing the paper. Kindly find the following note for further improvements:

1. In technical writing, it is not true to write “we, I, our, etc.” There are still some places that were not corrected, or some places in the new content were not written considering this comment.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: DR. TARUN KUMAR DAS

Reviewer #2: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

An Adaptive Sliding Mode Controller with Free-Will Arbitrary Time Convergence for Three-Phase Rectifiers in Autonomous Agricultural Vehicles

PONE-D-25-20009R2

Dear Dr. Mahmood,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Akhtar Rasool, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Congratulations

Reviewers' comments: