Improved Adaptive Feedforward Controller Based on Internal Model Principle with Disturbance Observer for Laser-Beam Steering Systems

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Recommended for publication after incorporating the following minor comments: 

1- Verify your model with mathematical equations

2- what will be the affect on adding multi-axis laser beam steering systems in the proposed model?

3- Any real world applications?

4- Is your work support scenarios with multiple simultaneous disturbances?

2- I didn't seen any comparison with other models. Suggest adding the comparison table with latest Ref such as

(i)Load frequency control of marine microgrid system integrated with renewable energy sources

(ii)Performance analysis of PID controller and fuzzy logic controller for DC-DC boost converter

3- what is the novelty? I have seen multiple paper with similar work.

Comments on the Quality of English Language

No

Author Response

Recommended for publication after incorporating the following minor comments:

1- Verify your model with mathematical equations

(Answer)

First of all. Thank you for your review comments Equation (1) is the expression for modeling a measured plant. As shown in Figure 1, the number of orders will be determined to fit the actual plant. In this paper, the expression is expressed in 6th order, resulting in a smaller font. Equation (1) has been deleted to avoid confusion.

2- what will be the affect on adding multi-axis laser beam steering systems in the proposed model?

(Answer)

It can also be used in multi-axis beam steering systems. After analyzing the periodic disturbances in each FSM system that can act on multi-beam steering, we believe that the proposed control algorithm can be applied.

3- Any real world applications?

(Answer)

We are currently in the process of developing and reviewing adaptation to the target platform.

4- Is your work support scenarios with multiple simultaneous disturbances?

(Answer)

In this paper, the periodic vibration generated by the rotation of the platform cooling fan is considered, and when the periodic vibration is applied to the platform, various mechanical vibration components can be generated. This periodic vibration component can cause the degradation of FSM control performance. Therefore, I proposed the algorithm mentioned in the paper.

2- I didn't seen any comparison with other models. Suggest adding the comparison table with latest Ref such as

(i)Load frequency control of marine microgrid system integrated with renewable energy sources

(ii)Performance analysis of PID controller and fuzzy logic controller for DC-DC boost converter

(Answer)

I think the comparison with other systems you suggested could be good, but the other systems you mentioned are different from optical systems that require high precision control, and unfortunately, I don't know anything about them, so I can't add anything related to the comparison.

3- what is the novelty? I have seen multiple paper with similar work.

(Answer)

In fact, it is a control algorithm that can be used in a variety of applications when periodic disturbances are applied. In particular, it is considered necessary in systems that require high control precision, such as this paper.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The author presents an effective control algorithm to improve the robustness of fast steering mirror-based laser beam steering systems against dynamic disturbances such as repetitive disturbances resulting from operating conditions. He describes an improved control method using an internal model principle-based non-linear controller with a disturbance observer for the fast steering mirror system.

The well-organized manuscript presents detailed, informative discussions for the future reader. The language of the manuscript is acceptable. I have only two minor suggestions. When the author introduces Eq. (1), he needs to provide proper reference and explanation of the expression. I also suggest enlarging the font of equations.

I recommend the acceptance of the manuscript.      

Author Response

The well-organized manuscript presents detailed, informative discussions for the future reader. The language of the manuscript is acceptable. I have only two minor suggestions. When the author introduces Eq. (1), he needs to provide proper reference and explanation of the expression. I also suggest enlarging the font of equations.

 

I recommend the acceptance of the manuscript.

 

(Answer)

Thank you for your review comments.

Equation (1) is the expression for modeling a measured plant. As shown in Figure 1, the number of orders will be determined to fit the actual plant. In this paper, the expression is expressed in 6th order, resulting in a smaller font. Equation (1) has been deleted to avoid confusion.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper presents a precise position control of steering mirror based laser beam steering systems. On that purpose is used the internal model principle and a disturbance observer. The paper do not bring any new theoretical results.

The plant model in Eq. 1 is critical because all other results are based on it. In Fig. 1, the fitted curve is not so “fitted”, especially at high frequencies.

The Bode characteristics of the open-loop transfer function of the PI controller designed for the FSM control system are not relevant. The transfer function of the PI controller is not given. I is not specified the design method of the PI controller

In Fig. 5 C(k) is not defined.

The transfer function of Q20 and Q30 is not given (pages 9-10, Fig. 10)

It seems that the experimental results presented in Fig. 16 are simulation results.

The steady-state error is more important than the transient time in this case. All the results are in the frequency domain. Anyway, it might be useful to see some results in time domain (step response in various cases).

Author Response

The paper presents a precise position control of steering mirror based laser beam steering systems. On that purpose is used the internal model principle and a disturbance observer. The paper do not bring any new theoretical results.

(Answer)

First of all. Thank you for your review comments. I agree with you about not getting new theoretical results, but I think the proposed control algorithm is necessary for optical systems that require high precision control performance.

 

The plant model in Eq. 1 is critical because all other results are based on it. In Fig. 1, the fitted curve is not so “fitted”, especially at high frequencies.

(Answer)

Equation (1) is the expression for modeling a measured plant. As shown in Figure 1, the number of orders will be determined to fit the actual plant. And, the nominal plant used for the DOB is written as an equation in the manuscript. However, Equation (1) has been deleted to avoid confusion.

 

The Bode characteristics of the open-loop transfer function of the PI controller designed for the FSM control system are not relevant. The transfer function of the PI controller is not given. I is not specified the design method of the PI controller

(Answer)

I agree with your comments. However, in this paper, the control gains should be set to balance stability and performance. Therefore, I manually adjust the feedback control gains (kp and ki) in the experiments.

 

In Fig. 5 C(k) is not defined.

(Answer)

I agree with your comments.  Therefore, I have modified the figure 5 and added expressions for C(s) and C(z) in the manuscript.

 

The transfer function of Q20 and Q30 is not given (pages 9-10, Fig. 10)

(Answer)

I agree with your comments.  Therefore, I have modified the figure 5 and added expressions for Q20 and Q30 in the manuscript.

 

It seems that the experimental results presented in Fig. 16 are simulation results.

(Answer)

Unfortunately, the data acquisition process resulted in a low sampling rate. Also, I made a mistake in the graph in Figure 16, so the figure has been corrected.

 

The steady-state error is more important than the transient time in this case. All the results are in the frequency domain. Anyway, it might be useful to see some results in time domain (step response in various cases).

(Answer)

I completely agree with your comments.

Only using DOB, it is possible to analyze the control performance with steady-state error.  However, the proposed controller could not be considered because the controller with high control gain at certain frequencies was used with DOB.

Steady-state errors can be reduced by internal disturbances (i.e., control inputs of a certain frequency).

Author Response File: Author Response.docx