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Accuracy assessment of real-time kinematics(RTK)measurements on unmanned aerial vehicles(uav)for direct geo-referencing

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Geo-Spatial Information Science 2020年第2期23卷 165-181页

作者： Desta Ekaso Francesco Nex Norman Kerle Department of Earth Systems Analysis ITC-Faculty of Geo-Information Science and Earth Observation of the University of TwenteEnschedeThe NetherlandsDepartment of Earth Systems AnalysisITC-Faculty of Geo-Information Science and Earth Observation of the University of TwenteEnschedeThe NetherlandsDepartment of Earth Systems AnalysisITC-Faculty of Geo-Information Science and Earth Observation of the University of TwenteEnschedeThe Netherlands

Geospatial information acquired with Unmanned Aerial Vehicles(uav)provides valuable decision-making support in many different domains,and technological advances coincide with a demand for ever more sophisticated data *** consequence is a research and development focus on more accurately referenced images and derivatives,which has long been a weakness especially of low to medium cost uav systems equipped with relatively inexpensive inertial measurement unit(IMU)and Global Navigation Satellite System(GNSS)*** research evaluates the positional accuracy of the real-time kinematics(RTK)GNSS on the DJI Matrice 600 Pro,one of the first available and widely used uavs with potentially surveying-grade *** a very high positional accuracy of the drone itself of 2 to 3 cm is claimed by DJI,the actual accuracy of the drone RTK for positioning the images and for using it for mapping purposes without additional ground control is not *** begin with,the actual GNSS RTK position of reference center(the physical point on the antenna)on the drone is not indicated,and uncertainty regarding this also exists among the professional user *** this study the reference center was determined through a set of experiments using the dual frequency static Leica GNSS with RTK *** RTK positioning data from the drone were then used for direct georeferencing,and its results were *** flights were carried out over a 70 x 70 m area with an altitude of 40 m above the ground,with a ground sampling distance of 1.3 *** against ground control points,the planimetric accuracy of direct georeferencing for the photogrammetric product ranged between 30 and 60 *** of direct georeferencing results showed a time delay of up to 0.28 seconds between the drone GNSS RTK and camera image acquisition affecting direct georeferencing results.

关键词： uav GNSS RTK direct georeferencing aerial triangulation lever arm offset

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Modelling operation parameters of uav on spray effects at different growth stages of corns

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International Journal of Agricultural and Biological Engineering 2017年第3期10卷 57-66页

作者： Zheng Yongjun Yang Shenghui Zhao Chunjiang Chen Liping Yubin Lan Tan Yu College of Engineering China Agricultural UniversityBeijing 100083China National Engineering Research Center of Information Technology in Agriculture(NERCITA) BeijingChina National Engineering Research Center of Intelligent Equipment for Agriculture(NERCIEA) BeijingChina College of Engineering South China Agricultural UniversityGuangzhou 510642China

Currently,unmanned aerial vehicles(uavs)were widely applied to spray for pest and disease ***,spray effect can be further improved by setting operation parameters more reasonably and ***,this study attempts to derive the relationship between operation parameters and spray *** growth stages were distinguished by various corn heights.A six-rotor uav was operated at different heights and velocities to test pesticides spray effects for corns at different growth *** plant canopy coverage rate and penetrating coefficients were obtained,according to which,the effects on droplet deposition rate caused by different uavs’operation parameters were *** penetrating coefficients were applied as indexes to evaluate and select uavs operation parameters for corns at different growth stages *** models of droplet penetrating coefficients with uavs operation parameters were established for corns at all growth *** determination coefficients(R2)of all models were greater than 0.90 and average relative errors were within 20%,which asserted high forecasting accuracy of droplet penetrating *** the help of the models,parameters like operating height away from the bottom of corns and uavs velocities were further analyzed,which guided the optimization of parameter settings and selection of spray methods for corns at different growth stages.

关键词： multi-rotor unmanned aerial vehicle spraying parameter model growth stage corn

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Constrained docking control for shipborne uav SideArm recovery

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Chinese Journal of Aeronautics 2024年第5期37卷 39-59页

作者： Zikang SU Zhuolin XING Xuebing LI Chuntao LI Xinwei WANG Honglun WANG College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Engineering and Materials Science Queen Mary University of LondonLondon E14NSUK School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

In this work,we sought to investigate constrained docking control during shipborne SideArm recovery of an Unmanned Aerial Vehicle(uav)under preassigned safe docking constraints,rough ocean environments,and different initial *** aim was to solve the uav tracking-lag problem that manifests when attempting to dock with a rapidly moving SideArm and to improve the accuracy and rapidity of ***,together with the formulations of the shipborne SideArm system and environmental airflows,the affine nonlinear dynamics of the hook was established to reduce tracking ***,echo state network approximators with good approximation capacity and low computational consumption were designed to accurately approximate the uav’s unknown nonlinear *** feedforward compensation provided by these approximators,a nonlinear-mapping-based constrained docking control law was developed for shipborne SideArm recovery of *** approach to controlling the docking trajectory and the forward docking speed of the uav can achieve rapid and exact docking with a moving SideArm,without violating the preassigned safe docking-constraint *** under different docking scenarios were used to validate the effectiveness and advantages of the proposed docking-control algorithm.

关键词： SideArm recovery Unmanned aerial vehicle Docking control Nonlinear mapping Echo state network

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Droplet deposition and efficiency of fungicides sprayed with small uav against wheat powdery mildew

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International Journal of Agricultural and Biological Engineering 2018年第2期11卷 27-32页

作者： Weicai Qin Xinyu Xue Shaoming Zhang Wei Gu Baokun Wang Nanjing Research Institute for Agricultural Mechanization Ministry of AgricultureNanjing 210014China Jiangsu Province Plant Protective Station Nanjing 210036China

Small unmanned aerial vehicle(uav),a timely and effective pesticide sprayer,can be used to spray pesticide in a high efficiency without harming the crop,and is especially suitable for spraying for small farms and hills in Asian *** recent years,it has been chosen as a key and new technique for pesticide *** paper studied the impact of uav(uav N-3)spraying parameters(different working height and different spraying concentrations)on the deposition of droplets on the wheat canopy and the prevention of powdery *** sensitive paper was used as the sampler to collect the pesticide droplets and image processing software Deposit Scan was used to compute the coverage rate of droplets on the wheat top layer to acquire the proportional distribution of droplets on the wheat lower *** experimental results showed the impact of spraying height on the distribution of droplets on the wheat upper layer was quite significant,when the spraying height was 5.0 m and the spraying speed was 4 m/s,the coverage rate of droplets on the wheat lower layer was the largest,as it was 45.6%of that on the upper layer,the droplets distribution was the most uniform,and the coefficient of variation was 33.13%.450 g/hm^(2)(dosage registered)of triadimefon SC(44%)was sprayed by the uav,the control efficiency reached 55.1%after applying which was better than 20%and 40%of dosage decreased for each hectare,and the applying effect(35.6%)of 20%dosage decreased for each hectare had no significant difference from the applying effect(34.6%)applied by a knapsack-type electric *** 10 d after applying,the prevention effect realized by uav was lower than that realized by a knapsack-type electric sprayer,and it may be correlated to the meteorological condition and water amount in the pesticide ***,when uav spraying was chosen to prevent wheat powdery mildew under a serious disease situation,an auxiliary agent for spraying could be added to prolong the retention of p

关键词： unmanned aerial vehicle(uav) spraying pesticide parameters optimization fungicide deposition wheat powdery mildew control effect

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Estimation of Rice Aboveground Biomass by uav Imagery with Photosynthetic Accumulation Models

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Plant Phenomics 2023年第3期5卷 418-434页

作者： Kaili Yang Jiacai Mo Shanjun Luo Yi Peng Shenghui Fang Xianting Wu Renshan Zhu Yuanjin Li Ningge Yuan Cong Zhou Yan Gong School of Remote Sensing and Information Engineering Wuhan UniversityWuhanChina Lab for Remote Sensing of Crop Phenotyping Wuhan UniversityWuhanChina College of Life Sciences Wuhan UniversityWuhanChina

The effective and accurate aboveground biomass(AGB)estimation facilitates evaluating crop growth and site-specific crop *** that rice accumulates AGB mainly through green leaf photosynthesis,we proposed the photosynthetic accumulation model(PAM)and its simplified version and compared them for estimating *** methods estimate the AGB of various rice cultivars throughout the growing season by integrating vegetation index(Ⅵ)and canopy height based on images acquired by unmanned aerial vehicles(uav).The results indicated that the correlation of Ⅵ and AGB was weak for the whole growing season of rice and the accuracy of the height model was also limited for the whole growing *** comparison with the NDVI-based rice AGB estimation model in 2019 data(R^(2)=0.03,RMSE=603.33 g/m^(2))and canopy height(R^(2)=0.79,RMSE=283.33 g/m^(2)),the PAM calculated by NDVI and canopy height could provide a better estimate of AGB of rice(R^(2)=0.95,RMSE=136.81 g/m^(2)).Then,based on the time-series analysis of the accumulative model,a simplified photosynthetic accumulation model(SPAM)was proposed that only needs limited observations to achieve R^(2) above *** PAM and SPAM models built by using 2 years of samples successfully predicted the third year of samples and also demonstrated the robustness and generalization ability of the *** conclusion,these methods can be easily and efficiently applied to the uav estimation of rice AGB over the entire growing season,which has great potential to serve for large-scale field management and also for breeding.

关键词： Biomass cultivar season

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Distribution regularity of downwash airflow under rotors of agricultural uav for plant protection

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International Journal of Agricultural and Biological Engineering 2021年第3期14卷 46-57页

作者： Xin Liu Wei Zhang Haiba Fu Xiaoming Fu Liqiang Qi College of Engineering Heilongjiang Bayi Agricultural UniversityDaqing 163319China College of Information Technology Heilongjiang Bayi Agricultural UniversityDaqing 163319China

In the plant protection spray operation of uavs,the process of droplet from formation to sedimentation target is affected by airflow,easy to form uneven *** description of rotor downwash flow field,clarification of velocity vector distribution at different heights of the uav rotor flow field,simulation of the flow field with high precision,which are the prerequisites for accurately analyzing the droplet deposition distribution in rotor downwash flow *** on CFD method,the detail of rotor flow field was numerically *** LTH-100 single-rotor agricultural uav as the research object,the three-dimensional solid model of uav was established,the Reynolds average N-S equation was used as the control equation and the RNGκ-εas the turbulence model to simulate the flow field of uav in hover and lateral wind conditions,the wind velocity distribution at different altitudes of rotor downwash flow field was *** simulation results of the hover state showed that:In the flow field,the peak velocity appears in a circular distribution below the distal axis of the *** the decrease of height,the peak velocity distribution area showed a tendency to expand gradually after small shrinkage;When the distance from the rotor was not more than 1.5 m,the downwash flow field presented an axisymmetric distribution based on the rotor axis,and the variation rate of velocity in the peak velocity was basically the same,turbulence in downwash flow field made the flow field more complex when the distance from rotor was larger than 2.0 *** this basis,the optimal flight altitude of uav is 1.5 *** velocity test of the flow field was carried out on a rotor test bench,wind velocities at four altitudes of 0.5 m,1.0 m,1.5 m and 2.0 m were measured to verify the coincidence between the simulated and measured *** test results showed that:the relative error between the measured and simulated values at four measurement heights were between 0.382-0.524,

关键词： aviation plant protection downwash flow field distribution regularity numerical simulation single-rotor uav

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Research on key technologies of uav cluster cooperative system for Internet of Things applications

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Journal of Control and Decision 2024年第1期11卷 26-35页

作者： Xu Jing Xi’an International University Xi’anPeople’s Republic of China

The combat tasks faced by uavs are becoming more and more *** single uavs are limited by the constraints of platform load capacity,lightweight load,and insufficient lowpower equipment,so it is difficult to complete complex tasks *** at typical uav collaborative confrontation application scenarios,this paper constructs a multi-agentoriented cluster collaborative intelligent system architecture and establishes a swarm-oriented intelligent uav cluster collaborative control ***,this paper forms a simulation environment for uav cluster collaborative confrontation and completes the design and implementation of the uav cluster collaborative confrontation system based on swarm *** addition,this paper analyses the key technologies of the uav cluster collaborative system with the support of the Internet of Things technology and verifies the performance of the system after constructing the corresponding *** experimental results show that the system constructed in this paper is effective.

关键词： Internet of Things uav cluster collaborative control key technology

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Coactive design of explainable agent-based task planning and deep reinforcement learning for human-uavs teamwork

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Chinese Journal of Aeronautics 2020年第11期33卷 2930-2945页

作者： Chang WANG Lizhen WU Chao YAN Zhichao WANG Han LONG Chao YU College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China College of Liberal Arts National University of Defense TechnologyChangsha 410073China School of Data and Computer Science Sun Yat-sen UniversityGuangzhou 510275China

Unmanned Aerial Vehicles(uavs)are useful in dangerous and dynamic tasks such as search-and-rescue,forest surveillance,and anti-terrorist *** tasks can be solved better through the collaboration of multiple uavs under human ***,it is still difficult for human to monitor,understand,predict and control the behaviors of the uavs due to the task complexity as well as the black-box machine learning and planning algorithms being *** this paper,the coactive design method is adopted to analyze the cognitive capabilities required for the tasks and design the interdependencies among the heterogeneous teammates of uavs or human for coherent ***,an agent-based task planner is proposed to automatically decompose a complex task into a sequence of explainable subtasks under constrains of resources,execution time,social rules and ***,a deep reinforcement learning approach is designed for the uavs to learn optimal policies of a flocking behavior and a path planner that are easy for the human operator to understand and ***,a mixed-initiative action selection mechanism is used to evaluate the learned policies as well as the human’s *** results demonstrate the effectiveness of the proposed methods.

关键词： Coactive design Deep reinforcement learning Human-robot teamwork Mixed-initiative Multi-agent system Task planning uav

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Contributions to data transmission at critical moments on unmanned aerial vehicles

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Chinese Journal of Aeronautics 2023年第8期36卷 247-257页

作者： Jose Enrique RODRIGUEZ David SEGURADO Manuel SANCHEZ Jose Javier MARTINEZ Rafael GONZALEZ National Institute of Aerospace Technology Madrid 28850Spain Department of Computer Science University of AlcalaAlcala de HenaresMadrid 28054Spain

As for unmanned aircraft, the knowledge of the aircraft performance is directly related with the navigation, guidance, and control system programming. Therefore, the measured data in each phase of the flight must be sufficiently precise to obtain a good characterization of *** article proposes new methods of sending information to ground, which make it possible to know the aircraft behavior accurately, and for this purpose, four contributions have been made for ALO(Avión Ligero de Observación, Spanish acronym for Light Observation Aircraft). Currently, the characterization is based on data obtained at ten samples per second, insufficient to acquire detailed knowledge of what happened during the whole flight of an aircraft. As a result of these contributions, many more samples per second of accelerations and angular velocities are obtained at the most critical moments of the flight, such as takeoff or landing. Among the improvements included are data compression techniques, providing references to locate the measured data in time and identifying labels of each parameter.

关键词： Critical moments Data transmission Datacompression tech-niques Radio-modem Recommended Standard 232(RS-232) Unmannedaerial vehicle

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Vision-based adaptive variable rate spraying approach for unmanned aerial vehicles

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International Journal of Agricultural and Biological Engineering 2019年第3期12卷 18-26页

作者： Linhui Wang Yubin Lan Xuejun Yue Kangjie Ling Zhenzhao Cen Ziyao Cheng Yongxin Liu Jian Wang International Laboratory of Agricultural Aviation Pesticide Spraying Technology(ILAAPST) Guangzhou 510642China College of Electronic Engineering South China Agricultural UniversityGuangzhou 510642China College of Engineering South China Agricultural UniversityGuangzhou 510642China School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510640China

The rapid developments of unmanned aerial vehicles(uav)and vision sensor are contributing a great reformation in precision *** can fly their uav spraying pesticides around their crop fields while staying at their remote control room or any place that is separated from their farm ***,there is a common phenomenon in rice planting management stage that some empty areas are randomly located in ***,a critical problem is that the waste of pesticides that occurs when spraying pesticides over rice fields with empty areas by using the common uav,because it is difficult to control the flow accuracy based on the empty areas *** tackle this problem,a novel vision-based spraying system was proposed that can identify empty areas automatically while spraying a precise amount of pesticides on the target *** this approach,the image was preprocessed with the Lucy-Richardson algorithm,then the target area was split from the background with k-means and the feature parameters were extracted,finally the feature parameters were filtered out with a positive contribution which would serve as the input parameters of the support vector machine(SVM)to identify the target *** a fuzzy control model was analyzed and exerted to compensate the nonlinearity and hysteresis of the variable rate spraying *** results proved that the approach was applicable to reducing the amount of pesticides during uav spraying,which can provide a reference for precision agriculture aviation in the future.

关键词： vision sensor uav adaptive spray variable rate spraying fuzzy control empty area precision agriculture aviation

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