Tillage Depth Detection and Control Based on Attitude Estimation and Online Calibration of Model Parameters
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn order to improve the detection accuracy and control stability of the tillage depth, a tillage depth detection and control method based on attitude estimation and online calibration of model parameters is proposed in this paper. The results of simulations and field tests confirm the effectiveness of the proposed method. But there are still some problems to be improved.
1. Some symbols in the Equation in the paper are not defined or explained, such as Equation (3) and Equation (4). Please provide additional explanations.
2. The titles and contents of Figure 6 and Figure 7 do not match. Please carefully check and modify.
3. What is the sampling frequency of the sensor? The calibration process in Section 4.2 of the paper is completed in about 2 seconds. Is the sampling data for the calibration process sufficient?
4. In the paper, the target value of the tillage depth control system is set as a target interval. Is the tillage depth error calculated by comparing the real-time tillage depth with the target value or with the upper and lower limits of the interval?
5. The parameters of the rotary encoder used in the parameter online calibration and field test are not given in the paper. Please add them in the paper.
Author Response
Thank you very much for your kindly suggestions, and the questions have been answered as follows:
Reply for reviewer1：
1: Some symbols in the Equation in the paper are not defined or explained, such as Equation (3) and Equation (4). Please provide additional explanations.
Reply: Thank you very much for your comment. We are sorry for our carelessness. We have explained and annotated the symbols that appear in equations but are not explained in the paper according to your suggestion. The modified parts have been highlighted in the manuscript. Thank you again for your comment.
2: The titles and contents of Figure 6 and Figure 7 do not match. Please carefully check and modify.
Reply: Thank you very much for your comment. We have revised the titles of Figure 6-7 and carefully checked all other figures in the manuscript. Thank you again for your comment.
3: What is the sampling frequency of the sensor? The calibration process in Section 4.2 of the paper is completed in about 2 seconds. Is the sampling data for the calibration process sufficient?
Reply: Thank you very much for your comment. The sampling frequency of the sensors is 40Hz. And the sampling data during the calibration process is sufficient to complete the parameter on-line calibration. Thank you again for your comment.
4: In the paper, the target value of the tillage depth control system is set as a target interval. Is the tillage depth error calculated by comparing the real-time tillage depth with the target value or with the upper and lower limits of the interval?
Reply: Thank you very much for your comment. The tillage depth detection and control system uses real-time detection of the tillage depth to compare it with the average value of the target interval (i.e., the target value) when calculating the error in tillage depth. Thank you again for your comment.
5: The parameters of the rotary encoder used in the parameter online calibration and field test are not given in the paper. Please add them in the paper.
Reply: Thank you very much for your comment. We have added the parameters of the rotary encoder used in the parameter online calibration and the field test in Section 4.4 of the paper. The modified parts have been highlighted in the manuscript. Thank you again for your comment.
Once again, we thank reviewers for their clear description of main concerns and constructive suggestions.
Reviewer 2 Report
Comments and Suggestions for AuthorsIn this article, a tillage depth detection and control method for tractor plowing operation based on attitude estimation and online calibration of model parameters is proposed. The effectiveness and feasibility of the tillage depth detection and control method have been demonstrated by the simulation and field experiments.
The theory of the proposed method in this paper is innovative. The experiments carried out in the paper and the analysis of the results of the experiments are adequate. But there are still some questions.
1. In Line 228 on Page 7, there is an error in the labeling of the equation. Please correct it.
2. What is the meaning of the symbol “αs” in Equation (32)? Please provide additional remark in the manuscript.
3. What is the difference between rotation angle and pitch angle in the calibration model in Section 2.3 of the paper?
4. In Section 4.4 of the paper, the performance parameters of the sensors used in the field test are not provided. Please supplement in the paper.
5. What are the detection frequency and control frequency of the tillage depth detection and control device in the field test?
Author Response
Thank you very much for your kindly suggestions, and the questions have been answered as follows:
Reply for reviewer1：
1: In Line 228 on Page 7, there is an error in the labeling of the equation. Please correct it.
Reply: Thank you very much for your comment. We are sorry for our carelessness. We have revised the equation number you mentioned and carefully checked the numbers of all other equations in the manuscript. Thank you again for your comment.
2: What is the meaning of the symbol “αs” in Equation (32)? Please provide additional remark in the manuscript.
Reply: Thank you very much for your comment. the symbol “αs” in Equation (32) the rotation angle of the lifting arm measured by the rotary encoder. We have added the explanation of the symbol meaning in the paper. The modified parts have been highlighted in the manuscript. Thank you again for your comment.
3: What is the difference between rotation angle and pitch angle in the calibration model in Section 2.3 of the paper?
Reply: Thank you very much for your comment. In the calibration model in Section 2.3 of the paper, the rotation angle refers to the angle of rotation of the lifting arm measured by the rotary encoder, the pitch angle is the pitch angle of the lower link and the plough measured by the IMU. The rotation angle represents the relative angular change between any two states of the carrier, while the pitch angle is the angle between the current angle of the carrier and the horizontal plane. Thank you again for your comment.
4: In Section 4.4 of the paper, the performance parameters of the sensors used in the field test are not provided. Please supplement in the paper.
Reply: Thank you very much for your comment. We have added the parameters of the sensors used in the field test in Section 4.4 of the paper. The modified parts have been highlighted in the manuscript. Thank you again for your comment.
5: What are the detection frequency and control frequency of the tillage depth detection and control device in the field test?
Reply: Thank you very much for your comment. The control frequency of the tillage depth detection and control system is 20 Hz. And the detection frequency of the tillage depth detection and control system is 40 Hz. Thank you again for your comment.
Once again, we thank reviewers for their clear description of main concerns and constructive suggestions.
Reviewer 3 Report
Comments and Suggestions for AuthorsSome clarifications should be made regarding how the tillage depth of the four plough bottoms of the share plough are used to obtain the final tillage depth. If there are different results for this 4 values how can the final obtained tillage depth be stable?
Please explain more in detail what do you mean by b-frame, geographic frame, earth-frame. These explanations should be linked with the aggregate tractor-plough technical description.
Please explain how the the electronically controlled hydraulic valve was inserted in the tractor's hydraulic circuit.
The experimental results could be improved by comparing with actual tillage depth measurements done in a conventional way. I presume figures 12 and 13 present the calculated tillage depth. To validate the results, these should be compared with actual tillage depth obtained after ploughing. If it's not the case, and in figures 12 and 13 are presented the actual tillage depth, then you should offer an explanation regarding the way in which these measurement were done.
Comments for author File: 
Comments.pdf
English language could be improved. Also the editing, since there are phrases with points instead of commas between. There are some identical labels for the presented pictures which should be corrected.
Author Response
Thank you very much for your kindly suggestions, and the questions have been answered as follows:
Reply for reviewer1：
1: Some clarifications should be made regarding how the tillage depth of the four plough bottoms of the share plough are used to obtain the final tillage depth. If there are different results for this 4 values how can the final obtained tillage depth be stable?
Reply: Thank you very much for your comment. Before conducting tillage tests, after the plough is mounted on the tractor, we adjust the length of the arms of the tractor's three-point hitch system to ensure that the plough remains as level as possible (close to 0 degrees) at the target tillage depth. This ensures that the tillage depths of the four plowshares are theoretically consistent. In this case, when measuring the initial pitch angle θp(0), only the first plowshare contacts the ground theoretically. Therefore, we can use the tillage depth of the first plowshare to represent the tillage depth for all four plowshares. In practical applications, the calculation result of the first plowshare is mostly used as the final tillage depth measurement.
According to your comment, we added the steps of the actual measurement process to the manuscript to make the presentation more rigorous. The modified parts have been highlighted in the manuscript. Thank you again for your comment.
2: Please explain more in detail what do you mean by b-frame, geographic frame, earth-frame. These explanations should be linked with the aggregate tractor-plough technical description.
Reply: Thank you very much for your comment. The definitions of each coordinate system used in this article are provided as follows:
(1) b-frame: SINS body frame, IMU-centered orthogonal reference frame aligned with Right-Forth-Up (RFU) axes. In this paper, the IMU is placed above the share plough. Therefore, the origin of the b-frame is the IMU, and the directions of the b-frame are rightward, forward, and upward of the tractor-plough, respectively.
(2) n-frame: navigation frame, equivalent to geographic frame, carrier-centered orthogonal reference frame aligned with East-North-Up (ENU) geodetic axes. In this paper, the origin of the n-frame is the IMU, and the directions of the n-frame are eastward, northward, and upward of the tractor-plough, respectively.
(3) e-frame: earth frame, Earth-centered Earth-fixed (ECEF) orthogonal reference frame. In this paper, the origin of the e-frame is the geocenter. The x-axis of the e-frame points to the intersection of the tractor-plough's meridian and the equator. The z-axis points to the North Pole. The y-axis, along with the x-axis and z-axis, forms a right-handed coordinate system.
(4) b0-frame: inertially non-rotating frame aligned with the b-frame at t0.
(5) n0-frame: inertially non-rotating frame aligned with the n-frame at t0.
(6) e0-frame: inertially non-rotating frame aligned with the e-frame at t0.
The above coordinate system definitions have been added to the manuscript. The added parts have been highlighted in the manuscript. Thank you again for your comment.
3: Please explain how the electronically controlled hydraulic valve was inserted in the tractor's hydraulic circuit.
Reply: Thank you very much for your comment. In the tractor tillage depth regulation system, we focus on solving the detection model and method, control idea and system design scheme. We invited professionals in hydraulics to install the electronically controlled hydraulic valve. The modification of the electronically controlled hydraulic valve is not the focus of this study, we just use the electronically controlled hydraulic valve to facilitate the stable control of tillage depth. We apologize that we are unable to provide detailed installation procedures for electronically controlled hydraulic valve. As far as I know, the professionals insert the electronically controlled hydraulic valve in parallel into the tractor hydraulic system. Thank you again for your comment.
4: The experimental results could be improved by comparing with actual tillage depth measurements done in a conventional way. I presume figures 12 and 13 present the calculated tillage depth. To validate the results, these should be compared with actual tillage depth obtained after ploughing. If it's not the case, and in figures 12 and 13 are presented the actual tillage depth, then you should offer an explanation regarding the way in which these measurement were done.
Reply: Thank you very much for your comment. You are right that the results of tillage depth control given in Figures 12 and 13 are based on our proposed method of real-time detection of tillage depth. However, in the actual field environment, the rice stubble in our experimental plots is between 20 and 30 cm in height. This results in signal attenuation for the distance-based tillage depth detection method. And the wheels of the feeler wheels-based tillage depth detection method are unable to make full contact with the ground. Due to these factors, both methods are unable to effectively measure the tillage depth. Therefore, we performed manual measurements using a tillage depth gauge, and the average measurement error was within 0.8 cm.
On the one hand, the manual measurement method is unable to measure in real time and has a limited amount of sample data. On the other hand, the manual measurement results show that the tillage depth detection scheme proposed in this study has good accuracy. In our subsequent research program, we will try to find a more accurate reference true value of tillage depth that can be detected in real time. Thank you again for your comment.
5: English language could be improved. Also the editing, since there are phrases with points instead of commas between. There are some identical labels for the presented pictures which should be corrected.
Reply: Thank you very much for your comment. We have modified our article carefully. The grammatical mistakes have been revised and highlighted. And the article has been revised by the professional English editing of Sensors. And we have also carefully modified the Figure in the manuscript. If there are still some inappropriate parts, we will continue to modify according to your suggestions. Thank you again for your comment.
Once again, we thank reviewers for their clear description of main concerns and constructive suggestions.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe paper basically deals with the development of a precise method for detecting and estimating the position of the plowing depth using the raw data of the plow slope sensor. In addition, this thesis developed a plowing depth measurement and control system and conducted field tests to validate the developed plowing depth detection and control model.
In view of the content of the study, the criteria of the journal "Agriculture" are met.
The technical terminology used in the article corresponds to the field of agriculture, i.e. the field of agricultural techniques.
In the introductory part, a literature review was prepared describing previous research on the topic of the article.
In the article, the method for determining the position and the model for recognizing the tillage depth are clearly explained and supported by a detailed mathematical analysis
NOTES:
11. In Figures 6, 7, 8, 9, 12 and 13, it would be more correct to write the units of measurement e.g. in the form Pitch Angle Error, [°] and not as in the paper Pitch Angle Error/ °.
22. In Table 1, a space must be placed between the numerical value and the unit of measurement in the "Value" column, e.g. 8.5 °/h, not 8.5°/h as written in the paper.
33. If any type of numerical data with a unit of measurement is given in the text, there must be a space between the number and the unit of measurement. This applies in particular to line 341 (200 s), line 435 (20 ~ 24 cm), line 455 (1 cm) and line 466 (1 cm).
44. To improve the quality of the article in chapter 4.4 "Field test", it would not be a bad idea to compare the results obtained with your method with some previous studies (some other methods) after the test results given. I am referring here primarily to the method for determining the processing depth based on the measurement position.
Author Response
Thank you very much for your kindly suggestions, and the questions have been answered as follows:
Reply for reviewer1：
1: In Figures 6, 7, 8, 9, 12 and 13, it would be more correct to write the units of measurement e.g. in the form Pitch Angle Error, [°] and not as in the paper Pitch Angle Error/ °.
Reply: Thank you very much for your comment. We have modified the units of measurement in Figures 6, 7, 8, 9, 12, 13 according to your suggestion. The modified Figures have been highlighted in the manuscript. Thank you again for your comment.
2: In Table 1, a space must be placed between the numerical value and the unit of measurement in the "Value" column, e.g. 8.5 °/h, not 8.5°/h as written in the paper.
Reply: Thank you very much for your comment. We have revised all similar issues in the paper according to your suggestions. Thank you again for your comment.
3: If any type of numerical data with a unit of measurement is given in the text, there must be a space between the number and the unit of measurement. This applies in particular to line 341 (200 s), line 435 (20 ~ 24 cm), line 455 (1 cm) and line 466 (1 cm).
Reply: Thank you very much for your comment. We have revised all similar issues in the paper according to your suggestions. Thank you again for your comment.
4: To improve the quality of the article in chapter 4.4 "Field test", it would not be a bad idea to compare the results obtained with your method with some previous studies (some other methods) after the test results given. I am referring here primarily to the method for determining the processing depth based on the measurement position.
Reply: Thank you very much for your comment. Your analysis is very accurate, and I fully agree with your point of view. However, in the actual field environment, the rice stubble in our experimental plots is between 20 and 30 cm in height. This results in signal attenuation for the distance-based tillage depth detection method. And the wheels of the feeler wheels-based tillage depth detection method are unable to make full contact with the ground. Due to these factors, both methods are unable to effectively measure the tillage depth. Given the limitations of the actual environment and experimental conditions, we did not conduct a comprehensive comparative test of the tillage depth detection methods. However, we performed manual measurements using a tillage depth gauge, and the average measurement error was within 0.8 cm. The manual measurement results show that the tillage depth detection scheme proposed in this study has good accuracy. Thank you again for your comment.
Once again, we thank reviewers for their clear description of main concerns and constructive suggestions.
