Cooperative Navigation for Low-Cost UAV Swarm Based on Sigma Point Belief Propagation
Round 1
Reviewer 1 Report
This paper presents a strategy for cooperative navigation of a UAV swarm based on a sigma point belief propagation that can integrate self-measurement and inter-uav data to improve the position performance when, for example, the GNSS is not available. In my view, the paper is very interesting, the results seem correct, and it has a good quality in the presentation. Moreover, the approach is experimentally validated. The article has good motivation, and the literature review is enough to justify the contribution.
Some comments to improve the paper.
* Line 47... what is an "observation fault"? Does it refer to a sensor fault? Please include a reference, e.g., A review of convex approaches for control, observation, and safety of linear parameter varying and Takagi-Sugeno systems, Processes.
* Line 79-87. It would be advisable to add a sentence where the difference with previous work is explicitly stated.
* Line 129. It starts with "Figure 1"; however, it is not part of the sentence. Please correct it.
* All acronyms and variables must be defined in the first use, e.g., GNSS, UWB. Please check the manuscript thoroughly.
* Please ensure all the variables are in a math environment (not in italics, but in a math environment). Some variables are in text format, e.g., m and k in line 138. Please check the manuscript thoroughly.
* Lines 176, 225 ... use the correct reference format for [15], [27].
* In Algorithm 1, state the inputs and outputs.
* Why did you select refs [19,35,36] for comparisons? They are a bit old.
* Figure 7... It is hard to distinguish the difference between plots in the legend.
Author Response
Dear Reviewer,
Thank you very much for your time involved in reviewing the manuscript and your very encouraging comments on the merits.
We also appreciate your clear and detailed feedback and hope that the explanation has fully addressed all of your concerns. In the attachment, we discuss each of your comments individually along with our corresponding responses.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript proposed a sigma point belief propagation method to improve the positioning performance of UAV swarm, the paper is well organized. Comments as:
- What kind ranging information can be acquired by UWB? and how to build a wireless communication network between UAVs should be discussed.
- What about the network topology of the UAV swarm in the simulation and field test, can be introduced and analyzed.
Author Response
Dear Reviewer,
Thank you very much for your time involved in reviewing the manuscript and your very encouraging comments on the merits.
We also appreciate your clear and detailed feedback and hope that the explanation has fully addressed all of your concerns. In the attachment, we discuss each of your comments individually along with our corresponding responses.
Author Response File: Author Response.pdf
Reviewer 3 Report
Module text and language are well set. Globally the work doesn't need of review or modify.
The only request is to improve the state of art about the different approach to use UAV in outdoor urban space. I would know the values obtained from other research. In this paper there is only an idea of output provided here. This is too limited on research field.
Author Response
Dear Reviewer,
Thank you very much for your time involved in reviewing the manuscript and your very encouraging comments on the merits.
We also appreciate your clear feedback and hope that the explanation has fully addressed your concerns. In the attachment, we discuss your comments along with our corresponding responses.
Author Response File: Author Response.pdf
Reviewer 4 Report
The paper is interesting, although there are several issues to be addressed before the publication. See the attachment for more details
Comments for author File: Comments.pdf
Author Response
Dear Reviewer,
Thank you very much for your time involved in reviewing the manuscript and your very encouraging comments on the merits.
We also appreciate your clear and detailed feedback and hope that the explanation has fully addressed all of your concerns. In the attachment, we discuss each of your comments individually along with our corresponding responses.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I am happy with the revisions. I have no further comments.
Reviewer 4 Report
Everything's fine now, all my comments are mostly answered. The only comment to be dealt with is the inertial forces -- authors have added Coriolis force, but forgot the centrifugal force, which is
-m ω x [ω x r],
where ω is the earth angular velocity, r -- UAV with respect to the Earth Centered Earth fixed frame.
