-->PONE-D-25-39430-->-->Real environment obstacle circular edge expansion desion robot path planning based on ant colony algorithm-->-->PLOS ONE

Dear Dr. Li,

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.

The main concerns relate to the limited scope of the experimental validation, insufficient quantitative analysis, and lack of methodological transparency. At present, the real-world experiments rely on a single tabletop scenario with one start–goal pair, which is not adequate to demonstrate robustness. The reported results are primarily qualitative, and critical numerical data such as medians, error distributions, runtime decompositions, and sensitivity analyses are missing. Furthermore, the evaluation relies exclusively on ACO as the planning method, without comparison to established baselines such as A*, D*, or RRT*, making it difficult to assess the true merit of the proposed approach.

In addition, several aspects of the methodology are insufficiently described or inconsistently presented, including the image binarization process, coordinate conventions, calibration of clearance thresholds, and the details of the control system used for trajectory execution. These omissions hinder both the interpretability and reproducibility of the study. The manuscript also requires significant improvements in language quality, figure presentation, and data availability, as the current form falls short of journal expectations for clarity and reproducibility.

Please submit your revised manuscript by Oct 29 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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Kind regards,

Francesco Visentin

Academic Editor

PLOS ONE

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Additional Editor Comments :

Reviewer #1:

1- The real-world evaluation appears to rely on a single tabletop layout (7 obstacles + 1 reference) captured by an overhead phone, with one chosen start–goal pair (codes 66 → 3538). This is not sufficient to establish robustness. Please repeat the full pipeline on multiple real environments (vary obstacle densities/shapes, start–goal pairs, and robot sizes) and report aggregate statistics (success rate, min-clearance, path length, tracking error, collisions). The current description shows one map being standardized (Fig. 13–14/16–18) and then used for the three comparative cases only.

2- Fig. 21/22 present x/y error and pose error “box diagrams,” but the manuscript reports only qualitative impressions (e.g., “median generally lower than 5°,” “y-error about 8”). Please tabulate the exact medians, IQRs, and RMS/MAE for x, y, and pose, and clarify how “abnormal points” (outliers) were identified/removed. Without explicit numbers and outlier policy, the comparison across the three maps is hard to interpret.

3- In the virtual-environment test, the authors note “17 dangerous points” along the planned pose before expansion; that’s useful, but please (i) state the exact δ used to classify danger per Eq. (19), (ii) report the count/min-clearance for all three maps in both virtual and real experiments, and (iii) provide distributions of point-to-obstacle distances along the final paths. A small summary table would make the improvement unambiguous.

4- You report “from original map to Fig. 18 used 23.075115 s.” Please decompose this into per-stage times (binarization, obstacle detection, circularization, edge expansion, gridding, ACO planning), list hardware/OS and software versions, and provide averages ± SD over ≥10 runs. Also report ACO convergence iterations/time for each of the three maps.

5- All comparisons hold the planner fixed (ACO) and vary map preprocessing (raw vs circular vs circular+expansion). For completeness, please add at least one classical baseline (e.g., A*, D*, RRT/RRT*) on the same three maps and report the same metrics (path length, min-clearance, collisions, planning time). This will show whether the claimed safety/robustness benefits persist beyond a single metaheuristic. (This request is motivated by the paper’s exclusive reliance on ACO in the current Results.

6- The “time coding graph” approach implies mostly open-loop pose execution; please detail the controller (kinematics of the four omni wheels, sampling period, speed limits, any odometry/IMU/vision feedback), the error computation method (in what frame? units on axes?), and how the time codes were generated from poses. These details are essential to interpret the tracking error plots in Fig. 21/22 and to reproduce the experiments. Also state whether wheel slip/friction was characterized.

7- BLC is computed from a 200 mm reference (REDMI 9A overhead capture), yielding BLC = 0.7425. Please report calibration uncertainty (lens distortion, perspective, height variation), how BLC propagates to path-length and clearance errors, and whether the min-clearance threshold δ includes a calibration safety margin. Without this, the mapping from pixels to millimeters in the Results remains uncertain.

Reviewer #2:

Thanks for sharing—there’s a very useful idea here. That said, in its current form it needs a major revision.

1.The author define J = floor(B/255) and then explain “<255→0, =255→1” (L158–L162). That basically treats only pure white as free space—too brittle. Use a real threshold (Otsu or EDT→threshold), report T and robustness.

2.The author first set origin at top-left, +x right, +y down (L147–L149, L172–L174), but later you switch to left→right & bottom→top (L191). Pick one convention and rewrite the encode/decode formulas accordingly.

3.The author state the rule Lij ≤ δ (unsafe) and Lij > δ (safe) (L269 & L273), and you expand obstacles with Rsi = (LCol + LCow)/2 + Ls (L305–L307), but there’s no calibration of δ / Ls (units, how chosen, sensitivity). Define δ = robot radius + sensing/pose error margin, implement via configuration-space dilation / EDT, and show a quick sensitivity check.

4.The author list ACO params only (K=100, M=100, α=1, β=30, ρ=0.2, Q=100) (≈L343–L351), claim 23.075115 s end-to-end (L427), but give no HW/SW context or manual/auto breakdown, no baselines (A*/D* Lite/RRT*), and later show a “Safety degree change graph” (L533) without a mathematical definition. Report path length, minimum clearance, runtime (mean±SD/CI), add baselines, define “safety” formally, and back the claim with stats.

Reviewer #3:

The contribution here is very incremental, obstacle expansion and ant colony optimization are not really new ideas. The experiments are small scale and very controlled, no replication or solid statistical robustness is shown. Also no comparisons with standard baselines (A*, D*, RRT etc) so it’s hard to judge if this method is actually effective. The claim of “100% safety” is overstated, not supported with strong evidence. The language quality is weak, lot of grammatical errors, awkward phrasing, even typos. Figures feel repetitive and captions don’t explain clearly. Data availability is also not enough for reproducibility, no raw trajectories, code or scripts provided. Overall, the presentation falls short of journal standards.

[Note: HTML markup is below. Please do not edit.]

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: Yes

Reviewer #3: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

-->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: Yes

Reviewer #3: Yes

**********

-->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: Yes

Reviewer #3: No

**********

-->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: 1- The real-world evaluation appears to rely on a single tabletop layout (7 obstacles + 1 reference) captured by an overhead phone, with one chosen start–goal pair (codes 66 → 3538). This is not sufficient to establish robustness. Please repeat the full pipeline on multiple real environments (vary obstacle densities/shapes, start–goal pairs, and robot sizes) and report aggregate statistics (success rate, min-clearance, path length, tracking error, collisions). The current description shows one map being standardized (Fig. 13–14/16–18) and then used for the three comparative cases only.

2- Fig. 21/22 present x/y error and pose error “box diagrams,” but the manuscript reports only qualitative impressions (e.g., “median generally lower than 5°,” “y-error about 8”). Please tabulate the exact medians, IQRs, and RMS/MAE for x, y, and pose, and clarify how “abnormal points” (outliers) were identified/removed. Without explicit numbers and outlier policy, the comparison across the three maps is hard to interpret.

3- In the virtual-environment test, the authors note “17 dangerous points” along the planned pose before expansion; that’s useful, but please (i) state the exact δ used to classify danger per Eq. (19), (ii) report the count/min-clearance for all three maps in both virtual and real experiments, and (iii) provide distributions of point-to-obstacle distances along the final paths. A small summary table would make the improvement unambiguous.

4- You report “from original map to Fig. 18 used 23.075115 s.” Please decompose this into per-stage times (binarization, obstacle detection, circularization, edge expansion, gridding, ACO planning), list hardware/OS and software versions, and provide averages ± SD over ≥10 runs. Also report ACO convergence iterations/time for each of the three maps.

5- All comparisons hold the planner fixed (ACO) and vary map preprocessing (raw vs circular vs circular+expansion). For completeness, please add at least one classical baseline (e.g., A*, D*, RRT/RRT*) on the same three maps and report the same metrics (path length, min-clearance, collisions, planning time). This will show whether the claimed safety/robustness benefits persist beyond a single metaheuristic. (This request is motivated by the paper’s exclusive reliance on ACO in the current Results.

6- The “time coding graph” approach implies mostly open-loop pose execution; please detail the controller (kinematics of the four omni wheels, sampling period, speed limits, any odometry/IMU/vision feedback), the error computation method (in what frame? units on axes?), and how the time codes were generated from poses. These details are essential to interpret the tracking error plots in Fig. 21/22 and to reproduce the experiments. Also state whether wheel slip/friction was characterized.

7- BLC is computed from a 200 mm reference (REDMI 9A overhead capture), yielding BLC = 0.7425. Please report calibration uncertainty (lens distortion, perspective, height variation), how BLC propagates to path-length and clearance errors, and whether the min-clearance threshold δ includes a calibration safety margin. Without this, the mapping from pixels to millimeters in the Results remains uncertain.

Reviewer #2: Thanks for sharing—there’s a very useful idea here. That said, in its current form it needs a major revision.

1.The author define J = floor(B/255) and then explain “<255→0, =255→1” (L158–L162). That basically treats only pure white as free space—too brittle. Use a real threshold (Otsu or EDT→threshold), report T and robustness.

2.The author first set origin at top-left, +x right, +y down (L147–L149, L172–L174), but later you switch to left→right & bottom→top (L191). Pick one convention and rewrite the encode/decode formulas accordingly.

3.The author state the rule Lij ≤ δ (unsafe) and Lij > δ (safe) (L269 & L273), and you expand obstacles with Rsi = (LCol + LCow)/2 + Ls (L305–L307), but there’s no calibration of δ / Ls (units, how chosen, sensitivity). Define δ = robot radius + sensing/pose error margin, implement via configuration-space dilation / EDT, and show a quick sensitivity check.

4.The author list ACO params only (K=100, M=100, α=1, β=30, ρ=0.2, Q=100) (≈L343–L351), claim 23.075115 s end-to-end (L427), but give no HW/SW context or manual/auto breakdown, no baselines (A*/D* Lite/RRT*), and later show a “Safety degree change graph” (L533) without a mathematical definition. Report path length, minimum clearance, runtime (mean±SD/CI), add baselines, define “safety” formally, and back the claim with stats.

Reviewer #3: The contribution here is very incremental, obstacle expansion and ant colony optimization are not really new ideas. The experiments are small scale and very controlled, no replication or solid statistical robustness is shown. Also no comparisons with standard baselines (A*, D*, RRT etc) so it’s hard to judge if this method is actually effective. The claim of “100% safety” is overstated, not supported with strong evidence. The language quality is weak, lot of grammatical errors, awkward phrasing, even typos. Figures feel repetitive and captions don’t explain clearly. Data availability is also not enough for reproducibility, no raw trajectories, code or scripts provided. Overall, the presentation falls short of journal standards.

**********

-->6. 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: No

Reviewer #2: No

Reviewer #3: No

**********

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Real environment obstacle circular edge expansion design robot path planning based on ant colony algorithm

PONE-D-25-39430R1

Dear Dr. Li,

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.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Francesco Visentin

Academic Editor

PLOS One

Additional Editor Comments (optional):

After consideration of the revised manuscript, the authors’ rebuttal, and the current reviewer reports, I find that the manuscript has improved substantially relative to the previous round. In particular, the revised version includes additional experiments, timing breakdowns, results across multiple environments, and comparisons with alternative planning algorithms, which help clarify the practical scope of the proposed workflow and address several of the earlier concerns.

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: (No Response)

Reviewer #3: (No Response)

**********

-->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: (No Response)

Reviewer #3: Yes

**********

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

Reviewer #1: (No Response)

Reviewer #3: Yes

**********

-->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: (No Response)

Reviewer #3: No

**********

-->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: (No Response)

Reviewer #3: Yes

**********

-->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: Upon reviewing the authors' responses and the revised manuscript, the paper has been significantly improved.

Reviewer #3: Most comments have been addressed to some extent, and the added figures and tables help. But in several places, the response is just “this is not the focus,” which is fair, but it leaves some gaps in how to interpret and trust the results.

They do mention some of these points here and there, but it’s scattered. It would help to clearly state these as limitations in one place, so the scope of the work is obvious.

Maybe make minor changes -

Add simple numbers where comparisons are made, not just figures

Clearly define terms like safety, and avoid strong claims like “100% safety” without context

Briefly describe the experimental setup assumptions where needed

Keep baseline comparisons consistent, even if not very detailed

Be upfront about what is not reproducible (code, data) and why

**********

-->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: No

Reviewer #3: No

**********