Output Feedback Tracking Control with Collision Avoidance for Dynamic Positioning Vessel under Input Constraint

Round 1

Reviewer 1 Report

Title: Output Feedback Tracking Control with collision avoidance for surface vessel under input constraint

This paper presents the modified artificial potential function for vessel navigate using back stepping technique, extended disturbance state observer, input constraint and active surface for collision avoidance control strategy. Some proves are showed in Lyapunov. In general, this topic is very interesting and many meaning in the marine environment. However, there are some points that need to be addressed in detail to meet the quality of the publication. The comments and suggestions are given below:

1. Some typos in manuscript like effects[2], problem[14], control strategy [10], [11], [12] and [13], given in [0m,0m,0,rad], engine power,the input signals.

2. A little confusing in eq. (21) for differentiating V­₀. It should be collected to previous part and equation. And add some explanation to collect all paragraphs.

3. For controller design, please add a diagram to show overall the system and explain in details before discuss the steps of designing.

4. The reason why the virtual input is selected in eq. (25). It must be explained to clearly with reader. What is the meaning and how does it effects to the system?

5. Please collecting eq. (31) to eq. (23) to make a logic and easier to follow the contents.

6. In Fig. 6, please explain in detail that why the control input range is from -2.5 to 2.5 [N] (maybe because it is not explained and show clearly). And add some cases with different range if it does not have equation related to accuracy of result.

 Finally, a major revision is needed to rewrite, reorganization the paper to reflect the contribution properly before the paper might be accepted for publication the above issues should be addressed.

Author Response

Please check the attachment.+

Author Response File: Author Response.pdf

Reviewer 2 Report

I highly appreciate the scientific nature of the manuscript:

-          Even though the analyzed references are less than 20 entries, the literature review is solid and places very well the subject of the manuscript and the objectives, and it discusses clearly what are the shortcomings of existing solutions that the authors set out to solve or, at least, tackle. Here, I recommend the authors to increase the entries to at least 25;

-          The mathematic model is sound, it’s easy to follow and is of great support for tracking how the authors deal with identified problems from the literature review.

On the other hand, even if the essence of the manuscript is of high scientific value, there are a some important aspects that need to be solved:

-          English language, grammar and text editing is very poor and significantly reduces the value of the manuscript;

-          The text needs definite refining, such that it has more of a fluency (if it weren’t for the mathematical model, it would have been extremely difficult to follow what the authors set out to do);

-          The conclusions section is very scarce, surely the authors can draw other conclusions from their work that are supported by the obtained results. This section must be extended significantly.

Finally, I recommend the authors to also address the following minor oversights:

-          Line 24: PID controller – the first-time use of an acronym implies explanation in brackets;

-          Line 53: the following construction is used: “existing achievements often use path planning algorithm”, but only one reference is indicated;

-          Line 91: “the mathematic model of surface vessel” – improper phrasing, of the surface vessel’s what? trajectory? velocity? orientation?;

-          Lines 102, 112 instead of “assumption” please use “hypothesis”;

-          All the figures should be bigger, the font size of the figures should match the font size of the text, so they can be easily observed;

-          Figures 11 and 12 are between references, their position in the manuscript needs to be revised and they should be placed accordingly;

-          The numbering of sections shouldn’t start from “0”, but from “1”.

Author Response

Please see attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All issues were solved in the revised manuscript. Suggest to accept this manuscript.

Reviewer 2 Report

The authors addressed the concerns indicated by myself in the previous revision round.

I congratulate them for their work!