Recent Advances and Challenges in Agricultural Robotics, Unmanned Agricultural Machinery and Autonomous Farming Technologies

A special issue of Actuators (ISSN 2076-0825).

Deadline for manuscript submissions: closed (31 January 2022) | Viewed by 34314

Special Issue Editors

College of Science, Health, Engineering & Education, Murdoch University, Murdoch, WA 6150, Australia
Interests: sliding mode control and observation; robotics and mechatronics; autonomous vehicles and systems
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Guest Editor
College of Engineering, Anhui Agricultural University, Hefei 230036, China
Interests: intelligent agricultural machinery; precision agriculture
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Guest Editor
College of Engineering, China Agricultural University, Beijing, China
Interests: agricultural engineering; soil tillage equipment; straw cover; seeding equipment
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Guest Editor
College of Biological Systems and Food Science, Zhejiang University, Hangzhou 310030, China
Interests: agricultural intelligent equipment; agricultural robot; facility agricultural equipment; computer nondestructive testing technology

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Guest Editor
School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China
Interests: intelligent agricultural machinery equipment; intelligent control and adaptive control with application to agricultural machinery

Special Issue Information

Dear colleagues,

With the development of artificial intelligence (AI), agricultural Internet of Things (IoT) and big data technology, agricultural robotics (ARs), and unmanned agricultural machinery (UAM) as well as autonomous farming (AF) technologies have developed rapidly, such that traditional agricultural machinery has been gradually replaced in many agricultural areas. Robotics will play an essential role in improving productivity, increasing crop quality, and even enabling individualized weed and crop treatment. All these significant advancements will serve as the driving force for providing food to a growing worldwide population, expected to reach 9 billion by 2050, which requires agricultural production to double in order to meet such food demands. The increasing demand in food production should be achieved regardless of challenges such as climate change, limited supply of new arable land, and difficulties in sourcing skilled farm labor. Robotics and automation are considered to be a power option in meeting these challenges over the coming decades by helping to improve farm productivity.

However, considering the complex and changeable farmland operation environment, the operation performance of ARs and UAM is seriously disturbed by the external environment, such as soil and crops, which leads to the degradation and high failure frequency of operating unit components/systems. In the past few decades, with the development of advanced control and state monitoring theory, many new methods have exhibited strong potential to further improve the performance of actuator-based ARs (driving, walking and unit operation quality, etc.) and enhance their robustness and reliability. Additionally, the development of robust and accurate perception systems in future autonomous agricultural systems has consistently helped to perceive the agricultural environment, such as multi- and hyperspectral imaging, high-resolution cameras, radar, LiDAR, centimeter-precision GPS, etc.

In an effort to disseminate the current advances and challenges in AR, UAM, and AF technologies and to stimulate a discussion on future research directions in the field, we are pleased to announce a Special Issue on “Recent Advances and Challenges in Agricultural Robotics, Unmanned Agricultural Machines, and Autonomous Farming Technologies”. Researchers are invited to submit papers on the foundational, algorithmic, and experimental aspects of design, modeling, control, and validation of actuator-based AR, UAM, and AF technologies. We strongly encourage contributions that focus on agriculture, covering different fields of robotics, robotic vision, autonomous vehicles, manipulation, control, path planning, human–robot interaction, machine learning, etc. We particularly encourage papers with a thorough experimental evaluation. Review papers in these areas are also welcome.

This Special Issue will bring together original, high-quality articles through an international standard peer-review process, including (but not limited to) the following main topics:

  • Modeling, estimation, and control of actuator-based ARs/UAM;
  • Vision and action for ARs/UAM dealing with changes in appearance and geometry of the environment;
  • Sensors and vision systems and yield-estimation systems for agricultural ARs/UAM including passive and active methods;
  • Manipulators and platforms for harvesting, mowing, pruning, seeding, spraying, soil preparation, and crop protection and management;
  • Long-term autonomy and navigation in unstructured farming environments;
  • Automation of vertical farming, protected cropping systems, and phenotyping;
  • Theoretical and empirical data analytics and real-time decision making with robots-in-the-loop, such as machine learning, artificial intelligence, etc.;
  • User interfaces and human–robot interaction for end users;
  • Cooperative robots in agriculture;
  • New standardized benchmarks and long-term datasets in changing agricultural environments.

We look forward to your valuable contributions.

Dr. Hai Wang
Prof. Dr. Liqing Chen
Prof. Dr. Jin He
Prof. Dr. Huanyu Jiang
Prof. Dr. Xiaoqiang Du
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Actuators is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Modeling, control, and estimation
  • Sensor and vision systems
  • Manipulators and platforms
  • Data analysis and real-time decision making
  • Machine learning and artificial intelligence
  • Cooperative robots

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Published Papers (8 papers)

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Research

16 pages, 5133 KiB  
Article
Simulation Optimization and Experimental Study of the Working Performance of a Vertical Rotary Tiller Based on the Discrete Element Method
by Shike Zhai, Yixin Shi, Junchi Zhou, Jianfei Liu, Defan Huang, Airu Zou and Ping Jiang
Actuators 2022, 11(12), 342; https://doi.org/10.3390/act11120342 - 23 Nov 2022
Cited by 9 | Viewed by 2976
Abstract
In order to investigate the mechanism of interaction between a vertical rotary tiller and the soil to obtain the best structural and operational parameters of the tool, improve the operational quality of the rotary tiller, achieve the effect of soil breaking and leveling [...] Read more.
In order to investigate the mechanism of interaction between a vertical rotary tiller and the soil to obtain the best structural and operational parameters of the tool, improve the operational quality of the rotary tiller, achieve the effect of soil breaking and leveling to meet the agronomic requirements of tillage, a series of simulation tests was conducted through the design of 3D models of rotary tillers with different structural forms and the building of discrete element models of the action between the rotary tiller and the soil. The virtual simulation of different operating parameters and structural parameters of vertical rotary tiller was carried out by EDEM, and the effects of operating parameters, tool bending angle, and cutter installation number on the operating effect were analyzed. The parameter combination with the best operating effect was obtained through orthogonal test analysis and verified by soil trough test. A soil tank test showed that, with the optimal combination of operating and structural parameters, the average soil breaking rate of the vertical rotary tiller was 81.3%, which meets the agronomic requirements of tillage operation, and the actual power consumption was 6% higher than the simulation value, which was sufficiently close to verify the validity of the simulation. This study can lay a foundation for optimization research on the vertical miniature rotary tiller. Full article
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15 pages, 2720 KiB  
Article
Research on Performance Evaluation Method of Rice Thresher Based on Neural Network
by Qiang Da, Dexin Li, Xiaolei Zhang, Weiling Guo, Dongyu He, Yanfei Huang and Gengchao He
Actuators 2022, 11(9), 257; https://doi.org/10.3390/act11090257 - 8 Sep 2022
Cited by 9 | Viewed by 2517
Abstract
Because the threshing device of a combine harvester determines the harvesting level and threshing separation performance of a combine harvester, the analysis and study of the threshing device of a combine harvester is key to improving its performance. Based on the threshing device [...] Read more.
Because the threshing device of a combine harvester determines the harvesting level and threshing separation performance of a combine harvester, the analysis and study of the threshing device of a combine harvester is key to improving its performance. Based on the threshing device of a half-feed combine harvester, the simulation model of a discrete element threshing device is established in this paper. With the threshing drum rotation speed, feed volume, and concave sieve vibration frequency as the variable factors, the BP neural network model and linear regression equation model established for the loss rate and impurity content for two kinds of threshing performance indicators, respectively, and through the discrete element threshing performance test, two kinds of methods of threshing performance prediction are analyzed. The results show that the neural network and linear regression can be used for the threshing performance indicators, however, the BP neural network prediction effect has a better prediction precision, better reliability, and the trained neural network can be used in the general case of the threshing performance indicators. This provides a new idea for improving the threshing performance of a combine harvester. Full article
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15 pages, 4423 KiB  
Article
Evaluation Method of Soil Surface Roughness after Ditching Operation Based on Wavelet Transform
by Lichao Liu, Quanpeng Bi, Qianwei Zhang, Junjie Tang, Dawei Bi and Liqing Chen
Actuators 2022, 11(3), 87; https://doi.org/10.3390/act11030087 - 12 Mar 2022
Cited by 7 | Viewed by 3100
Abstract
Soil surface roughness (SSR) is an important parameter affecting surface hydrology, erosion, gas exchange and other processes. The surface roughness of the farmland environment is directly related to the tillage process. In order to accurately characterize the random roughness (RR) parameters of the [...] Read more.
Soil surface roughness (SSR) is an important parameter affecting surface hydrology, erosion, gas exchange and other processes. The surface roughness of the farmland environment is directly related to the tillage process. In order to accurately characterize the random roughness (RR) parameters of the surface after ditching, a three-dimensional (3D) digital model of the surface was obtained by laser scanning under the conditions of an indoor ditching test, and the influence of oriented roughness components formed by removing ridge characteristics on the RR of the surface was analyzed by introducing the wavelet processing method. For this reason, four groups of ditching depths and two types of surface conditions (whether the surface was agglomerated or not) were designed in this paper. By comparing the root mean squared height (RMSH) and correlation length (CL) data calculated before and after wavelet processing under each group of tests, it was concluded that the RMSH values of the four groups before and after wavelet processing all change more than 200%, the change amplitude reached 271.02% under the treatment of 12 cm ditching depth, meanwhile, the average CL value of five cross-sections under each group of ditching depths decreased by 1.43–2.28 times, which proves that the oriented roughness component formed by furrows and ridges has a significant influence on the calculation of RR. By further analyzing the roughness value differences of clods and pits in different directions and local areas before and after wavelet transform, it was shown that the wavelet transform can effectively remove the surface anisotropy characteristics formed in the tillage direction and provide a uniform treatment method for the evaluation of surface RR at different ditching depths. Full article
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15 pages, 5427 KiB  
Article
Lodged Sugarcane/Crop Dividers Interaction: Analysis of Robotic Sugarcane Harvester in Agriculture via a Rigid-Flexible Coupled Simulation Method
by Qingqing Wang, Qianwei Zhang, Yin Zhang, Guoan Zhou, Zhiqiang Li and Liqing Chen
Actuators 2022, 11(1), 23; https://doi.org/10.3390/act11010023 - 13 Jan 2022
Cited by 8 | Viewed by 4278
Abstract
As a critical component of the sugarcane harvester, the primary function of the crop dividers is to lift the lodged sugarcane (LS) and reduce the loss rate of the sugarcane harvest. In this study, a rigid-flexible coupling simulation method is proposed to improve [...] Read more.
As a critical component of the sugarcane harvester, the primary function of the crop dividers is to lift the lodged sugarcane (LS) and reduce the loss rate of the sugarcane harvest. In this study, a rigid-flexible coupling simulation method is proposed to improve the lifting efficiency of the crop dividers on severely LS and analyze the nature of interaction between the sugarcane stalk and the crop dividers. The model’s accuracy was verified using field experiments, and the operational performance of the crop dividers on sugarcane in different lodging postures was investigated. The results showed that the curve of the vertical height of the center (VHC) fluctuated more and slipped with highest frequency during the lifting process of side and forward LS. The speed of VHC was fastest during the lifting operation of side LS. The effect of side angle on the lifting effect of sugarcane was significant; the qualified values of the VHC of sugarcane being lifted in different lodged postures were: side and reverse lodged > side lodged > side and forward lodged. The coupling method and experimental results described in this paper can provide guidance for the optimal design and field operation of the crop dividers. Full article
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14 pages, 8913 KiB  
Article
Path Tracking Control of an Autonomous Tractor Using Improved Stanley Controller Optimized with Multiple-Population Genetic Algorithm
by Liang Wang, Zhiqiang Zhai, Zhongxiang Zhu and Enrong Mao
Actuators 2022, 11(1), 22; https://doi.org/10.3390/act11010022 - 11 Jan 2022
Cited by 20 | Viewed by 5267
Abstract
To improve the path tracking accuracy of autonomous tractors in operation, an improved Stanley controller (IMP-ST) is proposed in this paper. The controller was applied to a two-wheel tractor dynamics model. The parameters of the IMP-ST were optimized by multiple-population genetic algorithm (MPGA) [...] Read more.
To improve the path tracking accuracy of autonomous tractors in operation, an improved Stanley controller (IMP-ST) is proposed in this paper. The controller was applied to a two-wheel tractor dynamics model. The parameters of the IMP-ST were optimized by multiple-population genetic algorithm (MPGA) to obtain better tracking performance. The main purpose of this paper is to implement path tracking control on an autonomous tractor. Thus, it is significant to study this field because of smart agricultural development. According to the turning strategy of tractors in field operations, five working routes for tractors were designed, including straight, U, Ω, acute-angle and obtuse-angle routes. Simulation tests were conducted to verify the effectiveness of the proposed IMP-ST in tractor path tracking for all routes. The lateral root-mean-square (RMS) error of the IMP-ST was reduced by up to 36.84% and 48.61% compared to the extended Stanley controller and the original Stanley controller, respectively. The simulation results indicate that the IMP-ST performed well in guiding the tractor to follow all planned working routes. In particular, for the U and Ω routes, the two most common turning methods in tractor field operations, the path tracking performance of the IMP-ST was improved by 41.72% and 48.61% compared to the ST, respectively. Comparing and analyzing the e-Ψ and β-γ phase plane of the three controllers, the results indicate that the IMP-ST has the best control stability. Full article
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19 pages, 6356 KiB  
Article
Wheel Deflection Control of Agricultural Vehicles with Four-Wheel Independent Omnidirectional Steering
by Qimeng Xu, Hongwen Li, Quanyu Wang and Chunlei Wang
Actuators 2021, 10(12), 334; https://doi.org/10.3390/act10120334 - 16 Dec 2021
Cited by 12 | Viewed by 6655
Abstract
Due to the harsh working environment of wheeled agricultural vehicles in the field, it is difficult to ensure that all wheels make contact with the ground at the same time, which is easy to unequally distribute the yaw moments of each independent wheel. [...] Read more.
Due to the harsh working environment of wheeled agricultural vehicles in the field, it is difficult to ensure that all wheels make contact with the ground at the same time, which is easy to unequally distribute the yaw moments of each independent wheel. The commonly used vehicle lateral control methods are mostly controlled by coordinating the individual torque between different wheels. Obviously, this control method is not suitable for agricultural four-wheeled vehicles. The goal of this study was to provide a wheel steering angle control method that uses electric push rods as actuators that can cope with this problem. The design of a four-wheel steering controller generally adopts the linear PID control method, but the research object of this paper is difficult to establish an accurate and linear mathematical model due to the complex working environment. Therefore, fuzzy adjustment is added on the basis of PID control, which can meet the requirements of model difficulty and control accuracy at the same time. In order to verify the feasibility and rationality of the designed wheel steering mechanism, the model dynamics simulation based on ADAMS software and the response analysis of the electric linear actuator thrust were completed. Based on the kinematics model of the controlled object, the rotation angle of the actuator motor is used as the control target, the lateral deviation e and deviation variation ec are taken as input variables and the parameters KP, KI and KD are taken as output variables, thereby establishing a fuzzy PID controller. Then, this controller is constructed in the Matlab/ Simulink simulation environment to analyze the lateral deviation and response stability during the process of vehicle path tracking. From the verification results of the linear path walking test under the fuzzy PID control method, the maximum lateral deviation of vehicle chassis is 2.7 cm when the driving speed is set as 1 m/s, and the deviation adjustment stable time of the system is 0.15 s. It can be seen that the proposed steering control strategy has good response performance and effectively increases the steering stability. Full article
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22 pages, 3874 KiB  
Article
A Tillage Depth Monitoring and Control System for the Independent Adjustment of Each Subsoiling Shovel
by Shangyi Lou, Jin He, Caiyun Lu, Peng Liu, Hui Li and Zhenguo Zhang
Actuators 2021, 10(10), 250; https://doi.org/10.3390/act10100250 - 28 Sep 2021
Cited by 8 | Viewed by 3151
Abstract
Subsoiling can break the compacted hardpan without turning or mixing soil layers. It has significant advantages in improving soil structure, promoting rainwater infiltration, and increasing air permeability of soil. The soil compacted hardpan will not be completely broken and more power consumption will [...] Read more.
Subsoiling can break the compacted hardpan without turning or mixing soil layers. It has significant advantages in improving soil structure, promoting rainwater infiltration, and increasing air permeability of soil. The soil compacted hardpan will not be completely broken and more power consumption will be generated unless the desired tillage depth is obtained. However, due to uneven surface between and within each row of subsoiling shovel in the field, the existing adjustment methods, adjusting via the lifting device of the whole machine or a group of tillage components, cannot ensure each subsoiling shovel avoiding undesired tillage depth. Therefore, a tillage depth monitoring and control system for the independent adjustment of each subsoiling shovel was developed, and the methods of detecting, adjusting, displaying, and recording tillage depth were described. Field experiments were conducted to evaluate detecting accuracy, stability of tillage depth, transient response time, and advantages. The results showed that the value obtained by sensor differed from manual measurement at the speed of 3 km/h, 4 km/h, and 5 km/h averagely by 8.28%. The mean value of the coefficient of the tillage depth stability at three speeds were all greater than 94%. The mean transient response time was 0.6 s. The standard deviation of tillage depth obtained under system control was 38.31, which was less than the 51.52 obtained by only adjusting on the three-point suspension. The subsoiler equipped with this system was capable of obtaining a desired tillage depth of each subsoiling shovel in every second. Full article
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19 pages, 8959 KiB  
Article
Development and Performance Evaluation of a Precise Application System for Liquid Starter Fertilizer while Sowing Maize
by Changchang Yu, Qingjie Wang, Xinpeng Cao, Xiuhong Wang, Shan Jiang and Shaojun Gong
Actuators 2021, 10(9), 221; https://doi.org/10.3390/act10090221 - 3 Sep 2021
Cited by 2 | Viewed by 3631
Abstract
At present, liquid starter fertilizer (LSF) application technologies experience problems with low fertilizer utilization efficiency. In this study, we adopted a method of precise application of LSF near the seeds on seed bed in point form during sowing. A precise application system that [...] Read more.
At present, liquid starter fertilizer (LSF) application technologies experience problems with low fertilizer utilization efficiency. In this study, we adopted a method of precise application of LSF near the seeds on seed bed in point form during sowing. A precise application system that can detect seed information in real time and control the solenoid valve to open automatically was developed for this method. The LSF supply system and detection control system were studied in detail. Field experiments were conducted to evaluate the performance of the precise application system in terms of operation quality (qualified index of the length of the LSF, QIL; the amount of the LSF, FA; and qualified index of the distance between the seeds and the LSF, QID) at forward speeds of 4, 6, and 8 km/h and pressures of 0.10, 0.15, 0.20, 0.25, and 0.30 MPa. The results indicated that QIL was 96.4%, the range of FA was 1.34 to 13.86 mL, and QID was 82.6%, which signifies the developed system meets the demands of precise LSF application. This method achieves the target of improving fertilizer use efficiency and provides a reference for developing fertilization devices for precisely applying LSF. Full article
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