ATSUKF-Based Actuator Health Assessment Method for Quad-Copter Unmanned Aerial Vehicles

Round 1

Reviewer 1 Report

I agree with the authors claiming that the actuator, which generally consists of motors, electrical regulations, and propellers, is the key component of the quadrotor Unmanned Aerial Vehicle. Indeed, during the operation of the UAV, actuators are prone to degrade performance and even cause serious failure, which affects the service quality and flight safety of Unmanned Aerial Vehicles. From this point of view, the authors are dealing with a relevant topic that is also appropriate for MPDI. At th same time, the authors should be aware of recent work, some of them in MDPI, dealing with Unmanned Aerial Vehicles: Fault-tolerant control for quadrotor based on fixed-time ESO; The problem of reliable design of vector-field path following in the presence of uncertain course dynamics. The relevance of these suggestions is that, thanks to the use of "adaptive control" techniques, they can address the problem of actuator degradation and also deal with "reliability". In other words, these suggestions are relevant with respct to the following point (quoting this manuscript)

 

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Timely and accurate monitoring and evaluation of the health condition of actuators is of great significance to ensure the mission reliability of UAVs.

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Back to this manuscript, the methodology can be summarized as follows

 

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This paper proposes an Adaptive Two-stage Unscented Kalman Filter-based actuator health assessment method for Quadcopter Unmanned Aerial Vehicles. Firstly, a state space equation is established based on dynamic analysis to characterize the degradation mechanism of the actuator. Then, by modifying the Two-stage Unscented Kalman Filter algorithm, the Adaptive Two-stage Unscented Kalman Filter algorithm is constructed by combining the filter divergence criterion and the covariance matching technique to implement the health assessment of actuators. 

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The methodology is solid, taking into account that Unscented Kalman Filter is a solid methdology. In adition, I judge that the rganization and readability of the work is very high. In addition to the ones above, I would like to add a few more comments:

 

- The authors clain to use "an Adaptive Two-stage Unscented Kalman Filter". I suggest the authors to explain why a non-adaptive Unscented Kalman Filter would not be enough, and also to explain why a single-stage Unscented Kalman Filter would not be enough

 

- In order to increase repeatability of the results, I suggest the authors to collect all numerical values in a Table. Maybe this is partly done already in Table 1 and Table 2, but please make sure that all values are there.

 

- A question arises, how did the authors obtain the parameters in Table 1?

 

- According to Figure 1, it seems the authors are dealing with a quadrtor. A question arises if a similar methodology can be applied to fixed-wing Unmanned Aerial Vehicles as well, since these vehicles also may have similar problems of actuator degradation

 

- There is a typo in eq. (4), (14), (15)

 

- There is a typo in eq. (10), (45)

 

Experiments are carried out for different degradation scenarios to verify the effectiveness of the proposed method. I jdge the experiments convincing and also quite complete. Summarizing, I suggest acceptance of the work provided that the comments above are addressed.

 

 

 

Author Response

Dear reviewer,

The relevant modification description has been placed in the attachment.

If there are any questions or deficiencies, we are looking forward to your comments.

Your sincerely,

Zhenxin Zhang

Author Response File: Author Response.docx

Reviewer 2 Report

This article is written on the current topic of identifying defects of quadrotor Unmanned Aerial Vehicle actuators. Defects can cause the quadrotor Unmanned Aerial Vehicle to collapse, leading to the death of the people on whom it has fallen and damage to objects.

Comments:

It says "equa-tion" instead of "equation" on line 16.

Commas and dots after formulas are missing.

Equations 4, 14, 15, 45 use incomprehensible rectangle symbols.

Equations 16 and 17 are not related to equations 14 and 15.

Author Response

Dear reviewer

The relevant modification description has been placed in the attachment

If there are any questions or deficiencies, we are looking forward to your comments.

 

Your sincerely,

Zhenxin Zhang

Author Response File: Author Response.docx