Active Composite Control of Disturbance Compensation for Vibration Isolation System with Uncertainty
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper considers an academic example with one vibration mode both from theoretical point of view and experimental point of view.
First remark: in practice there always more than one vibration mode
The paper consider uncertainties on the system as well as time varying unknown low frequencies disturbances.
Unfortunately the paper completely ignores the "internal model principle" for rejecting disturbances as well as the <Youla Kucera parametrization for implementing feedforward feedback adaptive active vibration isolation.
Papers on these topics have been published in Automatica, IEEE Trans. on Industrial electronics, IEEE Transations o Control System Technology, Journal and Sound and Vibration ( since 2011).
The author has to complete their reference reviews by integrating these approaches.
The adaptive control of systems with variable resonance modes have been considered in the control literature.
Author Response
Dear Professor,
We appreciate your valuable comments. We have studied your comments carefully and have made revisions which we hope meet with approval. Our replies to your comments are listed as follows:
Comment 1:
The paper considers an academic example with one vibration mode both from theoretical point of view and experimental point of view.
First remark: in practice there always more than one vibration mode
Response:
- Thank you for your comment. We agree that in practice there always more than one vibration mode. For instance, in order to ensure normal operation of the precision instrument, the vibration isolation of six-degrees-of-freedom modes of the precision instrument is required. However, in practical engineering, decoupling design of six-degree-of-freedom vibration isolation system is often carried out, which can be equivalent to vibration isolation of six-directional single-degree-of-freedom system. In this paper, a single-degree-of-freedom system is used as an academic example to verify the effectiveness of the proposed control algorithm. In fact, it can also be used for vibration isolation control in other degrees of freedom directions.
Comment 2:
The paper consider uncertainties on the system as well as time varying unknown low frequencies disturbances.
Unfortunately, the paper completely ignores the "internal model principle" for rejecting disturbances as well as the Youla-Kučera parametrization for implementing feedforward feedback adaptive active vibration isolation.
Papers on these topics have been published in Automatica, IEEE Trans. on Industrial electronics, IEEE Transations on Control System Technology, Journal and Sound and Vibration (since 2011).
The author has to complete their reference reviews by integrating these approaches.
The adaptive control of systems with variable resonance modes have been considered in the control literature.
Response:
- Thanks for your valuable comment. According your suggestions, these important papers [34-38] are cited in this revised manuscript in the second paragraph on Page 2, and we have added the following sentences: “Landau et al. [37] combined the internal model principle with adaptive control to realize time-varying narrow-band disturbance rejection. Airimitoaie et al. [38] took advantage of the Youla-Kučera parametrization to solve the instability problem caused by a strong coupling between adaptive feedback and adaptive feedforward.”
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Once again, thank you very much for your valuable comments.
With all best wishes!
Sincerely yours
Zhijun Zhu1,2, Yong Xiao 1,2, *, Minrui Zhou1,2, Yongqiang Li 1,2, Dianlong Yu1,2, *
1 College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China
2 Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, Changsha 410073, China
Reviewer 2 Report
Comments and Suggestions for AuthorsThis paper proposes an active composite control (ACC) strategy for vibration isolation systems with uncertainty by integrating feed forward control based on known systems and feedback control based on Kalman filter. Experimental verification confirms that the proposed ACC can effectively realize the low-frequency and wide-band vibration isolation for the system with uncertainty.
1. Fig. 4 shows the measurement error of acceleration at 10Hz is large. Is there any method to reduce the error?
2. Fig 11 shows the proposed ACC can isolate vibration within frequncy range of 30-65. Is it possible to extend the vibration isolation range to lower frenquncy and wider band?
Author Response
Dear Professor,
Thank you very much for your valuable comments. We have studied your comments carefully and have made revisions which we hope meet with approval. The following are our responses to your comments:
Comment 1:
This paper proposes an active composite control (ACC) strategy for vibration isolation systems with uncertainty by integrating feed forward control based on known systems and feedback control based on Kalman filter. Experimental verification confirms that the proposed ACC can effectively realize the low-frequency and wide-band vibration isolation for the system with uncertainty.
- Fig. 4 shows the measurement error of acceleration at 10Hz is large. Is there any method to reduce the error?
Response:
- Thanks for your comment. The measurement error of acceleration is caused by sensor noise. Due to the characteristics of the system, the vibration response of the load at low frequency is relatively small, and the measurement error of acceleration will be relatively large after superimposing noise. The magnitude of noise is related to the ambient noise and the performance of the sensor itself, so in addition to choosing a good test environment and excellent performance of the sensor, we currently have no good way to reduce the measurement error.
Comment 2:
- Fig 11 shows the proposed ACC can isolate vibration within frequency range of 30-65. Is it possible to extend the vibration isolation range to lower frequency and wider band?
- Thanks for your comment. The results of Fig.11 show that the proposed ACC in the frequency range of 30-65Hz has a significantly improved vibration isolation performance than the model-based ACC. The main reason that low frequency and wide band vibration isolation can be achieved is that feedforward controller is employed. However, the proposed ACC used the same feedforward controller as the model-based ACC in this paper, so it is difficult to achieve lower frequency and wider band control than the model-based ACC. We will further improve the feedforward control part to achieve lower frequency and wider band vibration isolation in our future work.
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Once again, thank you very much for your valuable comments.
With all best wishes!
Sincerely yours
Zhijun Zhu1,2, Yong Xiao 1,2, *, Minrui Zhou1,2, Yongqiang Li 1,2, Dianlong Yu1,2, *
1 College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China
2 Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, Changsha 410073, China
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this nex version, the reference list has been completed with adequate references and these references are discussed in the text.
Unnfortunately, no any justification is given in the paper for the approach proposed in the paper with respect to existing litterature.
The authors should answer the following questions:
What is the drawback of solutions proposed in the literature with respect to the objective of the paper?
The opinion od the recieiwer is that the existing methods can solve the problem raised in the paper with less efforts.
Are any relationship between the solution proposed in the paper and the potential solutions proposed in the literature?
Is the "internal model principle "hidden" somewhere in the procedure proposed in the paper?
I am not asking to implement an existing approach and do a comparison, but at least, a justification for the approach used in the paper should be done
Comments on the Quality of English LanguageNo
Author Response
Dear Professor,
We appreciate your valuable comments. We have studied your comments carefully and have made revisions which we hope meet with approval. Our replies to your comments are listed as follows:
Comment 1:
In this next version, the reference list has been completed with adequate references and these references are discussed in the text.
Unfortunately, no any justification is given in the paper for the approach proposed in the paper with respect to existing literature.
The authors should answer the following questions:
What is the drawback of solutions proposed in the literature with respect to the objective of the paper?
The opinion od the receiver is that the existing methods can solve the problem raised in the paper with less efforts.
Response:
- Thanks for your valuable comment. Following your suggestions, we have further refined the introduction of the paper in the revised version. The drawbacks of solutions proposed in the literature have been further concluded in first paragraph on page 3 as: “To sum up, for the uncertainty problem of the system, the control algorithms commonly used at present (robust control, adaptive control and so on) mainly have problems such as high control cost, too conservative or poor stability.” And we have added the following descriptions in the third paragraph on page 3: “Thus, good vibration isolation performance can be achieved for the uncertain system with lower control cost and better stability compared with existing methods.”
Comment 2:
Are any relationship between the solution proposed in the paper and the potential solutions proposed in the literature?
Response:
- Yes, there are relationship between our solution proposed in the paper and the potential solutions proposed in the literature. The control strategy combining feedforward control and feedback control is an important method often used to realize active low-frequency and wide-band vibration isolation in existing literature. Therefore, the basic framework of the proposed ACC in this paper is a combination of feedforward and feedback. However, for the problem of uncertain systems, the existing literature mainly uses some adaptive algorithms or perturbation observers to obtain more accurate system models for controller design, which may result in high control cost and poor stability. This paper presents a simpler and more efficient control method, which can achieve good control capability without knowing the system model exactly.
Comment 3:
Is the "internal model principle "hidden" somewhere in the procedure proposed in the paper?
I am not asking to implement an existing approach and do a comparison, but at least, a justification for the approach used in the paper should be done.
Response:
- The feedforward controller is designed by using the known partial model and perturbation. And the feedback controller is also designed based on a system model that takes uncertainty into account. Following your comment, we further summarized the advantages and disadvantages of the existing methods, and then proposed and described the structure of the proposed ACC in detail on Page 3: “Nevertheless, part of the system information and disturbance can be accurately obtained by means of theory or experiments. In view of such characteristics, this paper employs an active composite control (ACC) strategy to improve the vibration isolation performance of the system. Based on the known disturbance and known system model information, the feedforward controller is designed to achieve two goals: on the one hand, low broadband vibration isolation of the system is realized; On the other hand, the system stability is in-creased by reducing the burden of feedback controller. The feedback control is a combination of Kalman filter and LQR algorithm (based on internal model considering uncertainty). Kalman filter is used to deal with the uncertainty of the system to obtain accurate system state variables (load displacement, load velocity), and then LQR algorithm is used to optimize the state feedback gains.”
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Once again, thank you very much for your valuable comments.
With all best wishes!
Sincerely yours
Zhijun Zhu1,2, Yong Xiao 1,2, *, Minrui Zhou1,2, Yongqiang Li 1,2, Dianlong Yu1,2, *
1 College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China
2 National Key Laboratory of Equipment State Sensing and Smart Support, Changsha 410073
