A UAV Formation Control Method Based on Sliding-Mode Control under Communication Constraints
Round 1
Reviewer 1 Report
why fixed wings uav is selected, authors should justify
Authors should leave space "estimation delay.The contributions of this"
Authors missing more recent and related work such as Collaboration of Drone and Internet of Public Safety Things in Smart Cities: An Overview of QoS and Network Performance Optimization, Computing in the sky: A survey on intelligent ubiquitous computing for uav-assisted 6g networks and industry 4.0/5.0, UAV computing-assisted search and rescue mission framework for disaster and harsh environment mitigation
paper structure is missing
explain fig 2 with more details
verify eq. 24
fig.4 and 9 are not good quality
ref.16 is written in Chinese , i dont know it is ok or not
Author Response
Thank you for reviewing our paper and suggesting revisions. Please see the attachment for the specific revised response.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this paper, a global stable sliding mode control algorithm is proposed for formation control of fixed-wing UAVs using relative information between aircraft. Under the assumption that there is no communication link between UAV formation, the stability of UAV formation under the delay of state transfer is proved, which provides a new idea and method for UAV formation control. However, the following problems still exist in the experimental process:
1. In chapter 2.1 Equation of motion for single machine, the author introduces three coordinate frames I, Vi , and Li as the inertial coordinate frame, the follower velocity frame of the UAV i, and the line of sight frame. However, these three coordinate systems are not commonly used in UAV control, especially the line of sight frame. It's better to describe the purpose of setting up these three frames.
2. It can be seen from Figure 3 that the position state of the Leader UAV is input into the controller as the state expected value of the Follower UAV. However, it is also mentioned in lines 100-101 that there is no communication link between the formation of UAVs. How does the state of the Leader UAV be fed back to the Follower UAV?
3. (line 160) The position state and velocity state of the leader UAV are estimated, but there is no feedback on the velocity state in Figure 3. Meanwhile, the speed state of the leader UAV is also used in the calculation error of the state in line 211 of this paper, so the logical contradiction of this method needs to be modified.
4. In 4 Simulation and Test Results, does the simulation establish the dynamics model of the UAV? How to obtain the position, speed, altitude, and other real-time states of UAV in a simulation? How does the expectation of controller output in simulation translate into the actual form of UAV?
5. In 4.1 case1, the author simulated the case of four UAVs in formation in a simple curve environment, but this simple route is not described in the article. Although Figure 4 shows the effect after the flight, it cannot be seen what the input mission route is, nor can the specific route information be seen from the UAV input in Figure 5. The same problem appears in 4.2 and 4.3.
In summary, it is recommended that you modify the manuscript according to the above suggestions.
Author Response
Thank you for your review of our paper and your proposed revisions. Please see the attachment for the specific revision responses.
Author Response File: Author Response.pdf
Reviewer 3 Report
This paper studies the sliding-mode control-based UAV formation control method under communication constraints. The idea of the paper is interesting and obtained results are valuable and verified using a numerical example. The authors will address the following issues before acceptance of this paper
Comments:
1. What computational issues appear when the number of UAV’s is sufficiently large?
2. The authors could provide a remark to discuss the advantages of the proposed work.
3. The authors could provide more discussion in the simulation example.
4. The motivation and highlights of the paper need to be further strengthened.
5. The authors could enhance the introduction with some recent related works such as Nonfragile control design for consensus of semi‐Markov jumping multiagent systems with disturbances, Observer-based memory consensus for nonlinear multi-agent systems with output quantization and Markov switching topologies.
Author Response
Thank you for your review of our paper and your proposed revisions. Please see the attachment for the specific revision responses.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors addressed my comments very well
Reviewer 3 Report
The paper can be accepted.
