Path Tracking Control of a Tractor on a Sloping Road with Steering Compensation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

Taking into account the difficulty of accurately tracking a reference route when traveling on a slope, this paper proposes a method of compensating the lateral force on an agricultural machine using a steering angle by analyzing the forces of the tractor when traveling on a slope.

 

The study has research value, and the findings are contributory. The paper is also well-written and structured. There is flow in the writing and it is well-cited. The depth of analysis and discussion on findings appear to be defendable. Section 3 titled "Model predictive control for path tracking of a tractor" is one of the paper's biggest flaws. It appears to be a copy of a book chapter, and it is impossible to determine whether it is the author's wonderful work or a copy from a book chapter. The presentation appears clunky, and inexperienced readers may not be interested in delving more into this.  Despite various limitations, such as control environment modeling using simulink and carsim, the main strength is the experimental testing on the use of proposed steering angle compensation.  

 

A few specific comments are below that need to be addressed.

 

Sticking experimental outcomes in number and a few contributions should be included in the abstract.

Should elaborate the abbreviated forms at first time e.g., PID, MPC

The work is strongly supported by relevant references. The research background is properly described and includes adequate references.

The research contributions are specific and noteworthy.

 

Basic Principles of Steering Angle Compensators: The working procedure and mathematical representation are thoroughly described. However, it is quite elaborative and written in simple language. It is preferable to separate into groupings under specific subheadings. References are missing.

 

“The results show that this method can effectively reduce adverse effects of tractors traveling on slopes”. It's unclear, nevertheless, how to measure effectiveness.  Additionally, there is no evaluation of the effectiveness's relevance.  Therefore, the overall efficacy of the suggested strategy to modify the steering compensation coefficient is questionable from a statistical perspective.  

The conclusion should add the research applications, limitations, and future research directions.

 

 

Comments on the Quality of English Language

Well written, need minor correction. 

Author Response

Please see the attachment，thank you!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript Title: Path tracking control of a tractor on a sloping road with steering compensation

Strengths:

·         The problem is important.

·         The experiments are convincing.

 Weaknesses:

·         The authors need to better explain the context of this research, including why the research problem is important.

·         The introduction should clearly explain the key limitations of prior work that are relevant to this paper.

·         The authors should add a clear and detailed problem definition.

·         Authors should give a clear formal definition of the problem.

·         The authors should add an example to illustrate the problem definition.

·         The problem definition is not formal enough.

·         Some improvements are needed in the description of the method.

·         The paper has several typos. Authors need to proofread the paper to eliminate all of them.

·         Some sentences are too long. Generally, it is better to write short sentences with one idea per sentence.

·         The text of some figures is too small. Authors should make sure that the text can be read if printed on paper.

·         Some figures are blur. Authors should either use a higher resolution figure(s) or redo them as vector graphics.

·         There are many irrelevant references. Authors should remove them to keep those that are closely related to the topic of the paper.

·         The reference format is inconsistent. Please check the format carefully and ensure it is consistent for all references. Also check the last reference, which is not in English language.

·         Please add a table that summarize all the notations used in the paper.

·         The authors should first give an overview of their solution before explaining the details.

·         Experimental evaluation must be improved.

·         It is important to clearly explain what is new and what is not in the proposed solution. If some parts are identical, they should be appropriately cited and differences should be highlighted.

·  Some text must be added to discuss the future work or research opportunities.

Comments on the Quality of English Language

English language needs extensive proof reading by the experts.

Author Response

Please see the attachment, thank you!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper proposes a control system to adjust the steering compensation coefficient for a tractor to achieve a better path-following capability on a sloping road. Several comments need to be addressed before proper publication, as follows:

1.      Please provide a description of the tractor considered in this study.

2.      Is the tractor operated on highways or off-road in this study?

3.      When does the tractor experience a sloping road? During turning? What is the typical range of road sloping percentage?

4.      Section 5 should be labeled Simulation Results instead of Experimental Results, as this study does not perform lab or field tests.

5.      Does the tractor typically haul a trailer?

6.      In Figures 5 and 6, and their corresponding paragraphs, it is unclear about the road sloping conditions that the simulation study considers.

 

7.      Why was 10km/s selected in this study? This should be discussed in the paper.

Author Response

Please see the attachment，thank you！

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The present paper proposes a system to compensate steering opersation, in an automatically adjusted way.

Experimental part is poorly described. It is not clear how the path has been designed and how many experiments have been carried out. In order to really verify the reported theory it would be important to repeat experiments under the same conditions (to verify repeatability of results) but also different conditions in terms of path curvatures and lengths, vehicles dimensions, slopes, ....

Multiple experiments in different tractors would be recommendable. 

Figures 7 and 8 are unreadable and ununderstandable.  

Authors should find a way to better quantify the performance of the applied approach. 

The approach can be applied to isodiametric tractors having 4 steering wheels?

I am not sure I properly understand the approach in a practical way: the approach can be applied to compensate at the same time anglòe and speed of the wheels?

In figure 6a it is evident how the feedback is causing a sinusoidal deviation of the compensated route from the reference route. The authors should better discuss how and when such deviations can be expected and reduced.  

Table 2 is very difficult to read and to understand.

Reference 33 is unreadable: is it possible to translate in English?

English language needs some revision

Comments on the Quality of English Language

Poor experimental part. 

If experiments are not going to be improved the paper should be rejected. 

Author Response

Please see the attachment, thank you!

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Recheck the Figure 13-15. They look blur. Rest of the article is well improved after the suggested changes.

Author Response

First of all, thank you very much for the reminder. We reviewed the case of Figures 13-15 in the text, and we found that these figures are clear enough in the word document (DPI=1200), but not so clear when in normal reading mode, probably because it shows the corresponding thumbnails. When the text is enlarged, we find that the pictures are clear enough.

Reviewer 4 Report

Comments and Suggestions for Authors

The paper has been clearly improved following the comments of the referees. 

Please reduce the dimensions of figures from 5 to 16, which are excessively large. 

Comments on the Quality of English Language

English is fine

Author Response

Thank you very much for the reminder, we have resized Figure 5-16 accordingly to make the article layout more logical.