Review Reports - A Cooperative Control Method for Excavation Support Robot with Desired Position/Posture

Round 1

Reviewer 1 Report

This paper introduces a control scheme of desired position/posture coordinated adjustment via real-time posture data and sliding position mode control method.

Numerical simulations and real experiment are used to demonstrate the effectiveness of the proposed method.

The paper may be technical correct, and the algorithm presented is a reasonable approach to the problem.

However, there are a couple of issues on paper.

1. The controller design needs to be introduced and explained in more detail.

2. The literature research is insufficient, and many important references are not summarized.

3. The main parameters of the controller are not given.

4. The innovation and contribution of this paper need further elaboration.

5. The writing and presentation of the paper need further improvement.

Author Response

September 6, 2022

Dear Editor

Editor-in-Chief

Dear Ms. Monja Milicevic

Section Managing Editor

Applied Sciences

We are very grateful for your help and suggestions in publishing the manuscript to the Applied Sciences, titled “A Cooperative Control Method for Excavation Support Robot with Desired Position/Posture.” The paper was coauthored by Xigui Wang, Jie Tang, Yongmei Wang, and Chen Li. We have checked the manuscript and revised it according to the comments. Overall, the comments have been fair, encouraging and constructive. We have learned much from it. We submit here the revised manuscript to meet the evaluation conditions and requirements of the reviewers.

Response to Reviewers' Comments:

Reviewer1:

On behalf of all members of our team, I would like to thank Reviewer 1 for approving and accepting this manuscript. This revised manuscript has again been thoroughly reviewed and refined by the authors, and the refined content is reflected in this article. In the long term, our research team will submit more excellent, high-quality articles to your journals.

Q1. The controller design needs to be introduced and explained in more detail.

Sincerely respond to Q1 raised by Reviewer 1:

The authors would like to thank Reviewer 1 for his reasonable suggestions and valuable comments on this manuscript. Based on the questions raised by Reviewer 1, the authors have introduced and explained the controller design in more detail as suggested by Reviewer 1, and a thorough and detailed inspection and necessary corrections are included in this manuscript. The authors have given a more detailed introduction and explanation of the controller design as described below.

Sliding mode controller design related explanation and more detailed introduction:

1) Toggle function selection

The switching function (sliding mode surface) characterizes the system characteristics, and the design goal is to ensure the stability of the system and satisfy the dynamic characteristics. When the system state slides to the sliding surface, it is represented by a switching function, and the coefficient of the switching function is generally positive. Different sliding mode surfaces are selected, and the characteristics are different. When designing the switching function, ensure that the sliding mode has good quality.

The selection of the switching function is mainly a reasonable selection coefficient. According to the requirements of the system, the switching function can ensure the stability and good dynamic quality of the system. In the design of the synovial control controller, it is very important to select the appropriate switching function.

2) Sliding mode control law design

The design of the sliding mode control law characterizes the arrival stage of the system, which ensures that the system can quickly enter the sliding mode no matter what position it is in, and keep it on the sliding mode surface. The switching function divides the state plane of the system into upper and lower parts, one part is and the other part is . The control law must be implemented to bring the motion of the system outside the sliding plane back onto the trajectory.

3) EHS system stability analysis

The Lyapunov stability theorem states that:

Assume the equation of state of the EHS system, where is the equilibrium state, if there is a positive definite function of continuous first-order partial derivatives that satisfies the following conditions:

(1) If is non-positive definite, then the system is consistent and stable at the origin

(2) The origin system is uniformly asymptotically stable if is at any and , and is not always 0 at , otherwise uniformly not asymptotically stable. Lyapunov is designed for the arrival phase of sliding mode control as described below.

Additional (1)

Where, the solution process of in the formula is as follows:

Additional (2)

The accessibility condition of the sliding mode is considered, which confirms that the sliding mode motion is stable, and thus the EHS system is reliable and feasible.

Q2. The literature research is insufficient, and many important references are not summarized.

Sincerely respond to Q2 raised by Reviewer 1:

The authors have accepted and thanked Reviewer 1 for their reasonable suggestion, and the authors have supplemented and briefly summarized the references in this manuscript. The authors have exemplified specific revisions to the relevant references in this manuscript.

The authors have added relevant references and have elaborated, with specific revisions as described below.

Guo Q., Yin J. M., Yu T., Jiang D. Coupled-disturbance-observer-based position tracking control for a cascade electro-hydraulic system, ISA Transactions, 2017, Vol. 68, p. 367-380.
Palli G., Strano S., Terzo M. Sliding-mode observers for state and disturbance estimation in electro-hydraulic systems, Control Engineering Practice, 2018, Vol. 74, p. 58-70.
Li X. D., Chen X., Zhou C. S. Combined Observer-Controller Synthesis for Electro-Hydraulic Servo System with Modeling Uncertainties and Partial State Feedback, Journal of the Franklin Institute, 2018, Vol. 355, Issue 13, p. 5893-5911.
Yao Z. K., Yao J. Y., Yao F. Y., Xu Q., Xu M. R., Deng Y. X. Model reference adaptive tracking control for hydraulic servo systems with nonlinear neural-networks, ISA Transactions, 2020, Vol. 100, p. 396-404.

The authors have succinctly summarized the themes of several key references. The revised summary discussion above has been exemplified.

Example 1, summary overview for reference 4:

In ref. 4, a new technique for adaptive gain selection for higher-order sliding mode observers is proposed. The state and disturbance estimation of hydraulic actuators are experimentally evaluated. Better convergence rates are obtained with larger estimation errors and noisy measurements, with performance comparable to or better than other gain selection methods.

Example 2, summary overview for reference 30:

In ref. 30, considering the different available measured values, parameter uncertainty and model nonlinearity, the sliding mode observer and higher-order sliding mode observer for hydraulic actuators are compared and analyzed, the frictional force acting on the hydraulic cylinder and the non-working area of the hydraulic valve are regarded as the uncertain interference items acting on the EHS system, is proposed.

Q3. The main parameters of the controller are not given.

Sincerely respond to Q3 raised by Reviewer 1:

The authors thank Reviewer 1 for sound suggestions and valuable comments on this manuscript. Based on the questions raised by Reviewer 1, the authors have refined and summarized the problems given by the main parameters of the controller based on the suggestions raised by Reviewer 1.

In this subject, considering that the servo valve and the hydraulic power mechanism are a series structure in the time domain, according to the control principle, the series mechanism in the time domain is a product relationship in the working domain, and the EHS system controller parameters are described in the Attached Table 1 below.

Attached Table 1 EHS system controller parameters

Symbol	Description	Values/Units
	Linearization gain factor
	Flow pressure coefficient
	Servo valve gain
	Hydraulic cylinder diameter	0.30m
	Hydraulic rod diameter	0.20m
	Hydraulic rod stroke	0.55m
	Hydraulic rod moving part	395kg
	Hydraulic chamber and piston damping
	leakage coefficient
	total leakage flow
	Effective modulus of elasticity of carbon steel	200GPa
	Hydraulic cylinder natural frequency	45Hz
	Solenoid valve natural frequency	100Hz
	Solenoid valve damping ratio	0.68

Q4. The innovation and contribution of this paper need further elaboration.

Sincerely respond to Q4 raised by Reviewer 1:

The authors have further elaborated on the innovations and contributions of this paper as suggested by Reviewer 1, and a revised concise summary section is reflected in this manuscript.

The innovations and contributions of this paper are briefly summarized as follows:

This study performs a critical impact on the efficiency of underground mining for a desired deviation of the position/posture of Excavation Support Robot (ESR). A control method of desired position/posture coordinated adjustment by real-time posture data and sliding position mode control algorithm, is proposed. In this topic, the action stroke of the non-longitudinal Adjustment Hydraulic Cylinder (AHC) is controlled by adaptively adjusting the opening and time of the Electro-Hydraulic Servo (EHS) valve, thereby adjusting the position offset and posture coordination of the ESR. The mathematical model of hydraulic system is deduced. Considering the kinematic characteristics of the ESR and the coupling relationship between the stroke and posture of the lateral AHC, a coupled kinematics model of the robot and the support body is derived.

Further, we believe that this paper will be of interest to the overall structure of the posture adjustment control system and the calculation method of the stroke adjustment amount of the AHC are presented, and the controller is further optimized. The simulation analysis model and test verification system of the desired posture adjustment control system are determined. These results show that the control method is effective and significant compared with the manual control system, which can meet the functional and precision requirements of position deviation and posture adjustment.

Q5. The writing and presentation of the paper need further improvement.

Sincerely respond to Q5 raised by Reviewer 1:

The authors thank Reviewer 1 for his reasonable suggestions, the authors have further improved the writing polish and presentation format of this paper, and have incorporated the revised refinements in the revisions to this submission as requested by Reviewer 1 in the manuscript.

The revised example is described below:

The subject is organized as follows: the multiple models of ESR including structure, hydraulic servo system and kinematic models in Section 2, are presented. Section 3 focuses on the description of the proposed controlled structure of the position/posture adjustment system, and proposes a coordinated adjustment strategy for ESR position deviation, posture bias, and optimized controller design. In Section 4, the numerical analysis of the coordinated position/posture adjustment is presented., The field experiments are verified in Section 5, where the results are discussed and the corresponding conclusions are drawn, thus validating the cooperative control method proposed in this study.

We are very hoped to publish this article in your journal, and I thank you on behalf of our group. We apologize for what we have not done well. We hope we will continue to submit better articles to you.

Thank you in advance for considering this revised submission.

Sincerely Yours

Corresponding author:

Xigui Wang Professor/Doctoral Supervisor

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

wyr20091207@126.com

Jie Tang

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

tjnefu1991@126.com

Yongmei Wang Professor/Master's Supervisor

School of Motorcar Engineering, Heilongjiang Institute of Technology, No. 999, Hongqidajie Road, Daowai District, Harbin, 150036, PRC

wyr20091207@163.com

Chen Li

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

lcnefu@163.com

Author Response File: Author Response.pdf

Reviewer 2 Report

The comments can be found in the uploaded file.

Comments for author File: Comments.pdf

Author Response

September 6, 2022

Dear Editor

Editor-in-Chief

Dear Ms. Monja Milicevic

Section Managing Editor

Applied Sciences

Response to Reviewers' Comments:

Reviewer: 2

The authors are very grateful to Reviewer 2 for sound suggestions and valuable comments on this manuscript. According to the questions raised by Reviewer 2 and the suggestions of Reviewer 2, the author has carried out a comprehensive and detailed inspection and correction of the full text, and explained and supplemented the questions raised by Reviewer 2 one by one.

Q1. The English level of this manuscript needs to be greatly improved. Please read the manuscript thoroughly to further polish the writing.

Sincerely respond to Q1 raised by Reviewer 2:

The authors thank Reviewer 2 for their reasonable comments, who have read through the manuscript and carefully proofread for writing deficiencies. The authors have asked professionals to further improve the English of this manuscript, in order to greatly improve the English level of this manuscript, thereby meeting the publication requirements of your journal.

Q2. In introduction, the descriptions of existing research need to be further summarized.

Sincerely respond to Q2 raised by Reviewer 2:

The authors have accepted and thanked reviewer 2 for their valuable suggestions, and the authors have further summarized and briefly described the current research situation, and here are detailed relevant explanations and necessary instructions.

At present, the tunneling equipment of the fully mechanized face is mainly tunneling equipment such as cantilever roadheaders and intelligent roadheading robot systems. The traditional excavation work method is operated by the excavation equipment driver, and the excavation equipment is adjusted by manually judging the mutual positional relationship between the excavation equipment and the roadway. Due to the influence of factors, the roadway is over-excavated or under-excavated, which ultimately affects the forming quality of the roadway and affects the mining efficiency. In addition, there are dangerous situations such as landslides and gas explosions in the fully mechanized excavation face, which pose a great threat to the personal safety of the excavation face workers. Therefore, the intelligent and unmanned driving equipment has a positive effect on improving the mining efficiency and reducing the occurrence of dangerous accidents. This subject takes the ESR system in the process of underground tunnel excavation as the research object, and focuses on the problem of accurate prediction of the position/posture adjustment of the ESR system.

Q3. The contributions of this article should be listed point by point to make it easier for readers to grasp the key points.

Sincerely respond to Q3 raised by Reviewer 2:

The authors fully accept and acknowledge the reasonable comments made by Reviewer 2, who have revised this manuscript as suggested by Reviewer 2 and have incorporated the revised main points.

Revisions in the contribution section of each co-author:

No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. We would like to declare on behalf of our co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed.

Author Contributions: Methodology, X.G. Wang, and J. Tang; Formal analysis, Y. M. Wang, C. Li, and X. G. Wang; Investigation and Resources, J. Tang, and Y. M. Wang. writing—original draft preparation, X.G. Wang, J. Tang, and C. Li. writing—review and editing and supervision: J. Tang and C. Li. All authors have read and agreed to the published version of the manuscript.

Q4. The established system model should clearly list the references cited, because it is not the first time that the authors put forward it.

Sincerely respond to Q4 raised by Reviewer 2:

The authors have fully accepted and are very grateful for the reasonable suggestion made by Reviewer 2, who have clearly listed the cited references for the established system model in the revised manuscript. The specific revisions have been reflected in this forthcoming revised manuscript.

The authors have added relevant references and have elaborated, with specific revisions as described below.

Guo Q., Yin J. M., Yu T., Jiang D. Coupled-disturbance-observer-based position tracking control for a cascade electro-hydraulic system, ISA Transactions, 2017, Vol. 68, p. 367-380.
Palli G., Strano S., Terzo M. Sliding-mode observers for state and disturbance estimation in electro-hydraulic systems, Control Engineering Practice, 2018, Vol. 74, p. 58-70.
Li X. D., Chen X., Zhou C. S. Combined Observer-Controller Synthesis for Electro-Hydraulic Servo System with Modeling Uncertainties and Partial State Feedback, Journal of the Franklin Institute, 2018, Vol. 355, Issue 13, p. 5893-5911.
Yao Z. K., Yao J. Y., Yao F. Y., Xu Q., Xu M. R., Deng Y. X. Model reference adaptive tracking control for hydraulic servo systems with nonlinear neural-networks, ISA Transactions, 2020, Vol. 100, p. 396-404.

Q5. The authors had better add a control schematic diagram to make the reader more aware of the designed control structure.

Sincerely respond to Q5 raised by Reviewer 2:

The authors are very grateful and accept the valuable suggestions of Reviewer 2. Based on the comments made by Reviewer 2, the authors have attached the control schematic diagram to give readers a better understanding of the designed control structure and give a detailed necessary relevant explanations and clarifications.

Feedback linearization generally lacks an accurate nonlinear system model. For this reason, a mathematical model of servo valve control symmetrical cylinder is established considering the existence of external load interference and system pressure modeling error. Aiming at the above problems, the control algorithm in this paper is proposed, which can ensure the feedback The robustness of the linearized system to parameter uncertainty and external disturbance can also improve the tracking performance of the EHS system.

The block diagram of the control principle of the EHS system proposed in this paper is as follows:

Additional Figure 1. Block diagram of the control principle of the EHS system proposed in this paper

Q6. The research background needs to be further strengthened. I would suggest that authors would look into meta-heuristic learning algorithms, which are widely utilized these days to solve several real-world problems including the described issues: neuroadaptive control of saturated nonlinear systems with disturbance compensation, neuroadaptive learning algorithm for constrained nonlinear systems with disturbance rejection.

Sincerely respond to Q6 raised by Reviewer 2:

The authors are extremely grateful to Reviewer 2 for his valuable suggestions on metaheuristic learning algorithms that are widely used today to solve multiple real-world problems, including the described problem: Neural Adaptive Control of Disturbance Compensated Saturated Nonlinear Systems, Neural Adaptive Learning Algorithms for Constrained Nonlinear Systems Disturbance Suppression. This pair will get help and hints in our future research and study, and take the time to study these algorithms mentioned by Reviewer 2 in depth.

The authors have the following ideas for the future research prospects:

ESR works under different pavement medium conditions. In order to improve the tracking performance of the electro-hydraulic servo system due to the load disturbance and system modeling error of the EHS system, it is necessary to suppress the disturbance and use the controller to compensate the disturbance. Under the condition of variable stiffness, the interference suppression is carried out for the problems existing in the system, and the IMC-PID (In-Timal Control (IMC)- Proportional Integral Derivative (PID)) controller is also designed for the load disturbance and modeling error. The IMC-PID control plays a certain role in the interference suppression of the system, but the effect is still It is not very ideal. This chapter conducts disturbance observation for the nonlinear model established in Chapter 2 considering the external load disturbance and the system modeling error. The disturbance is predicted by the synovial observer, and the predicted disturbance is fed back to the synovial controller. Interference compensation, improve the tracking accuracy of the system, determine the stability through Lyapunov, and conduct simulation analysis through Simulink to verify the robustness of the controller.

Q7. The authors should further discuss how to tune the controller parameters.

Sincerely respond to Q7 raised by Reviewer 2:

The authors would like to thank Reviewer 2 for their suggestion, which has been accepted and has been discussed further with regard to adjusting controller parameters.

The designed controller proposed in this paper is compared with the synovial controller and the PID controller, and the simulation analysis proves that the proposed controller is more effective than the above two controllers. As shown in the Additional Figures 2-3, the synovial film control and PID control have a certain anti-disturbance, which can suppress a certain degree of disturbance, but cannot completely eliminate it. The control strategy proposed in this paper can well compensate for the disturbance of the system.

In the Additional Figure 2, it is considered that under the condition of oscillation, the maximum error of PID control is below 0.4 and the minimum error is above -0.4, the maximum error of synovial control is between 0.05 and 0.1, and the minimum error is between -0.2 and -0.1. The maximum control error is below 0.05, and the minimum error is -0.2 to -0.1. It can be concluded that the synovial control has a certain anti-interference ability to external disturbances, but the anti-interference effect is not optimal. In order to further improve the system's anti-interference ability, it is necessary to Compensation, through the control proposed in this paper, the disturbance of the system can be well suppressed and the system output tends to be more stable.

Additional Figure 2. Errors under system oscillation condition

Additional Figure 3. Errors under the condition that the system has anti-interference ability

In the Additional Figure 3, the maximum error of PID control is 0.05～0.1, and the minimum control error is -0.1～0.5. The maximum error of synovial film control is also 0.05~0.1, and the minimum control error is -0.1~0.5, which is smaller than the error of IMC-PID control, and the error band is narrower. The maximum error of the control proposed in this paper is between 0 and 0.03, and the minimum error is between -0.03 and 0. No matter what kind of stiffness conditions, the control proposed in this paper reflects a certain degree of anti-disturbance ability, which further improves the rapidity and tracking of the system, which ensures the robustness of the system.

The conclusions should be further condensed. And future research directions need to be included in the conclusion part.

Sincerely respond to Q8 raised by Reviewer 2:

The authors fully accept and thank Reviewer 2 for their valuable suggestions, and the authors have further condensed the conclusions in this manuscript based on Reviewer 2's comments, including future research directions.

In this paper, only external load disturbance and system modeling error are considered in mathematical modeling, and other factors such as leakage, friction, damping, etc. are not considered. There are certain deviations in system simulation analysis and experimental verification, and more external factors will be considered in the future.

Refined conclusion part:

(1) The desired expected position/posture coordinated adjustment control method of ESR is effective, and the proposed ESR control system is adapted to the performance requirements of field applications.

(2) The minimum error of the declination angle in the simulation calculation results is less than 0.2°, and the error is limited to within ±0.5°. The minimum error of the roll angle in the results does not exceed 0.1°, and the error is controlled within ±0.5°. The minimum error of the simulated sidewall distance is not more than 0.01m, and the error range is within ±0.03m of the desired expected value.

(3) The minimum error of the declination angle in the experimental test results of the field verification link is controlled within 0.2°, and the error does not exceed ±0.5°. The minimum error of the scroll angle in the test results is less than 0.2°, and the error is limited to within ±0.5°. The minimum error of the margin in the test results is not more than 0.01m, and its error range is within the desired expected value of ±0.03m.

(4) The main reason for ESR position deviation/support posture inclination is the combined influence of the unaccounted instantaneous fluctuation of the excavation floor and the ESR transient push-pull effect in the space environment. The position stroke of each lateral adjustment hydraulic cylinder is adjusted to coordinate the deviation state of the ESR support posture, which verifies the effectiveness and feasibility of the proposed adjustment strategy and cooperative control process.

The format of references needs to be further standardized.

Sincerely respond to Q9 raised by Reviewer 2:

The authors would like to thank Reviewer 2 for their reasonable suggestion, which led to a further careful revision of the reference format of this manuscript in accordance with the specifications of this journal.

Thank you in advance for considering this revised submission.

Sincerely Yours

Corresponding author:

Xigui Wang Professor/Doctoral Supervisor

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

wyr20091207@126.com

Jie Tang

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

tjnefu1991@126.com

Yongmei Wang Professor/Master's Supervisor

School of Motorcar Engineering, Heilongjiang Institute of Technology, No. 999, Hongqidajie Road, Daowai District, Harbin, 150036, PRC

wyr20091207@163.com

Chen Li

School of Engineering Technology, Northeast Forestry University, No. 26, Hexing Road, Xiangfang District, Harbin, 150040, PRC

lcnefu@163.com

Author Response File: Author Response.pdf