Underwater Acoustically Guided Docking Method Based on Multi-Stage Planning

Round 1

Reviewer 1 Report

The authors present an acoustic based approach for guiding the docking maneuver of an underwater maneuvering vehicle. The paper is very interesting, the discussion is carried out with care and scientific rigor. The paper can be published on the journal. I have only a question to the authors: Is the control algorithm of the AUV based on a system based mathematical model that consider shallow waters and waves? Can such a kind of model, coupled for example with a Kalman filter, aid the improvement of the acoustic guidance do better counteracts the effects of the sea mentioned by the authors in the conclusions? 

Thank you

Author Response

Dear Reviewer:

Thank you very much for reviewing the manuscript, and providing the valuable comments to our work. We have uploaded the response to you as an attachment.

Best regards,
Hongli Xu

Author Response File: Author Response.docx

Reviewer 2 Report

The article describes an engineering problem aimed at acoustic docking of an underwater vehicle.  Although the authors mention the current state of knowledge in the literature, it is necessary to compare the obtained results with previous achievements.  It is recommended to include such a comparison in the article and directly demonstrate the authors' achievements.  A detailed description of the solution and tests is adequate, but it does not meet the requirements of the journal, which requires an element of scientific novelty.  The article is interesting, the information is given in a clear way and it seems that the authors are on their way to success.  They have achieved some progress compared to what was known before, but this is not clearly emphasized in the article

Specific comments:

1. It is expected that the results obtained will be compared with these achievements, e.g. control efficiency/guidance methods, docking correctness, and method of guiding the ARV to the docking station.

2. The article requires linguistic correction (punctuation, grammatical).

3. Spaces must be inserted between the measure numeric value and the unit.

1. Artykuł wymaga korekty językowej (interpunkcyjnej, gramatycznej).

Author Response

Dear Reviewer:

Thank you very much for reviewing the manuscript, and providing the valuable comments to our work. We have uploaded the response to you as an attachment.

Best regards,
Hongli Xu

Author Response File: Author Response.docx

Reviewer 3 Report

This paper is a well-written and description of an important topic, AUV docking. Importantly, it documents extensive trials that validate the claims being made and illustrations of examples of each type of control that has been attempted. The introduction and conclusions of the paper are clear, but there are some places where additional description and clarification could improve understanding.

The concepts are generally well described, but some further explanation would improve the readers' understanding:

- When the ARV navigates, what is a typical radius of its turning circle, and how long does it require to settle onto a course? How do these values relate to the choices of waypoint distances in the three stages of docking manoeuvre? It would be helpful if there is a paper that describes the vehicle and its control system.

- Can the ARV use its lateral thrusters to correct its course and orientation with respect to the docking station?

- How does the performance of the USBL affect the final approach stage? What is the standard deviation of the bearing estimates that it produces? How often can it send acoustic communications to the ARV and how long does each transmission take? Does the transmission time affect the control system?

- How does the docking station determine that the ARV has docked successfully? How does it measure the relative position of the ARV? What is the criterion it uses for success?

- In sections 3.1 and 3.2, how were control parameters like 5 m and 1 m chosen? The approach algorithm seems to be a variation of "pure pursuit" - have other variants been considered?

- In section 4.1, was the docking station present in the experiment, or was the experiment pure dead-reckoning with a simulated docking station?

- In sections 4.2.1, 4.2.2 and 4.2.3, what is the exact difference between the control methods? In each case, did the ARV control system have access to different information from the USBL? How did this change?

- In section 4.3, were all guidance methods operating? Was the ARV able to correct its orientation using its lateral thrusters?

- Finally, in section 5 and in the abstract, it would be more helpful to express the success ratio as a fraction than as a percentage, e.g., "9 out of 12" instead if "75%", because this gives the reader more information about the statistical properties.

This is an interesting paper to read, describing a very good set of experiments. Hopefully the authors will have further success in future.

Comments for author File: Comments.pdf

The quality of English is generally high, but there are some places where technical details are difficult to understand. The attached document attempts to provide clarifications in various places. Some grammatical corrections are also indicated.

Author Response

Dear Reviewer:

Thank you very much for reviewing the manuscript, and providing the valuable comments to our work. We have uploaded the response to you as an attachment.

Best regards,
Hongli Xu

Author Response File: Author Response.docx