- 标题
- 摘要
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- 实验方案
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Successive DSPE-based coherently distributed sources parameters estimation for unmanned aerial vehicle equipped with antennas array
摘要： In electronic countermeasures and reconnaissance, unmanned aerial vehicle (UAV) has played a more and more significant role. Usually when UAV conducts low altitude reconnaissance, due to the complicated environment, the reflected signals of the same source through different propagation paths will produce multipath signals. In this paper, we construct the received multipath signals of UAV with antennas array as coherently distributed (CD) sources model and propose a successive distributed signal parameter estimation (S-DSPE) algorithm to estimate its nominal direction of arrival (DOA) and angular spread. The proposed algorithm simplifies two-dimensional (2D) spectral peak searching within the conventional DSPE algorithm to one-dimensional spectral peak searching, which remarkably reduces the computational complexity of conventional DSPE algorithm. Furthermore, the parameters estimation performance of the proposed algorithm is close to the conventional DSPE algorithm, and outperforms the estimation of signal parameters via rotational invariance technique (ESPIRT) algorithm and propagator method(PM). The simulations results verify the usefulness of the proposed algorithm.
关键词： Distributed signal parameter estimation (DSPE),Nominal direction of arrival (DOA),Coherently distributed(CD),Unmanned aerial vehicle (UAV)
更新于2025-09-23 15:21:21
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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Null-filled Shaped Beam Horizontally Polarized Omnidirectional Antenna
摘要： In this paper, a compact, mechanically rugged, DC grounded Null-?lled horizontally polarized antenna having low gain ripple in the omnidirectional pattern is proposed for UAV Ground Command Station. The antenna is based on the coaxial cylinder structures, which consists of oversize coaxial cylinders, slots and their feeding assembly and a matching unit. The horizontal polarization property is realized by four vertical slots surrounding the axis of the coaxial cylinder in the outer conductor. The antenna is dc ground which eliminates the electrostatic discharge ESD problems. Simulation results show that the antenna bandwidth is 8.1% (2.56 GHz to 2.78 GHz respectively, gain variation in the horizontal plane is less than ±1 dB while the cross-polarization level is below 15 dB over the whole bandwidths.
关键词： DC grounded,UAV,horizontally polarized,Null-?lled,omnidirectional antenna
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Aerial Infrared Thermography of a CdTe Utility-Scale PV Power Plant
摘要： Aerial Infrared Thermography (aIRT) is a fast and flexible inspection method to monitor and assess utility-scale photovoltaic (PV) power plants. The literature is abundant on aIRT for crystalline silicon (c-Si) modules, but very little investigation has been carried out and reported thin-film PV. As Cadmium Telluride (CdTe) is currently the leading thin-film technology, and a good performer in warm and sunny climates, this paper aims to investigate the application of aIRT on CdTe PV plants in Brazil. Results demonstrate that aIRT is a reliable, cost-effective and fast method to detect faults on CdTe modules in large-scale PV plants.
关键词： Fault Inspection,Unmanned Aerial Vehicles (UAV),Photovoltaic Power Plants,Aerial Infrared Thermography (aIRT),Thin-Film,Cadmium Telluride (CdTe)
更新于2025-09-23 15:21:01
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Design of c-band telecontrol transmitter local oscillator for UAV data link
摘要： A C-band local oscillator of an Unmanned Aerial Vehicle (UAV) data link radio frequency (RF) transmitter unit with high-stability, high-precision and lightweight was designed in this paper. Based on the highly integrated broadband phase-locked loop (PLL) chip HMC834LP6GE, the system performed fractional-N control by internal modules programming to achieve low phase noise and small frequency resolution. The simulation and testing methods were combined to optimize and select the loop filter parameters to ensure the high precision and stability of the frequency synthesis output. The theoretical analysis and engineering prototype measurement results showed that the local oscillator had stable output frequency, accurate frequency step, high spurious suppression and low phase noise, and met the design requirements. The proposed design idea and research method have theoretical guiding significance for engineering practice.
关键词： local oscillator,UAV,HMC834LP6GE,C-band,data link,PLL
更新于2025-09-23 15:21:01
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[American Society of Agricultural and Biological Engineers 2018 Detroit, Michigan July 29 - August 1, 2018 - ()] 2018 Detroit, Michigan July 29 - August 1, 2018 - <i>Cotton Yield Estimation based on Plant Height From UAV-based Imagery Data </i>
摘要： Accurate estimation of crop yield before harvest, especially in early growth stages, is important for farmers and researchers to optimize field management and evaluate crop performance. However, conventional methods of using ground sensing to estimate crop yield are not efficient. The goal of this research was to evaluate the potential of using a UAV-based remote sensing system with a low-cost RGB camera to estimate yield of cotton within season. The UAV system took images at 50 m above ground level over a cotton field at the growth stage of first flower. Waypoints and flight speed were selected to allow > 70% image overlap in both forward and side directions. Images were processed to develop a geo-referenced orthomosaic image and a digital elevation model (DEM) of the field, which was then used to map plant height by calculating the difference in elevation between the crop canopy and the bare soil surface. Twelve ground control points (calibration objects) with known GPS coordinates and height were deployed in the field and were used as check points for geo-referencing and height calibration. Geo-referenced yield data were registered with the plant height map row-by-row. Correlation analysis between yield and plant height was conducted row-by-row with row registration and without row registration respectively. Pearson correlation coefficients between yield and plant height for all individual rows were in the range of 66% to 96%, higher than those without row registration (54% to 95%). A non-parametric regression used for building a yield estimation model based on image-derived plant height was able to estimate yield with less than 10% error (root mean square error of 360.4 kg ha-1 and mean absolute error of 180.9 kg ha-1). The results indicated that the UAV-based remote sensing system equipped with a low-cost digital camera was able to estimate cotton yield with acceptable errors.
关键词： yield estimation,UAV-based remote sensing,geo-registration,plant height,Cotton
更新于2025-09-23 15:21:01
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Cache-enabled physical-layer secure game against smart uAV-assisted attacks in b5G NOMA networks
摘要： This paper investigates cache-enabled physical-layer secure communication in a no-orthogonal multiple access (NOMA) network with two users, where an intelligent unmanned aerial vehicle (UAV) is equipped with attack module which can perform as multiple attack modes. We present a power allocation strategy to enhance the transmission security. To this end, we propose an algorithm which can adaptively control the power allocation factor for the source station in NOMA network based on reinforcement learning. The interaction between the source station and UAV is regarded as a dynamic game. In the process of the game, the source station adjusts the power allocation factor appropriately according to the current work mode of the attack module on UAV. To maximize the benefit value, the source station keeps exploring the changing radio environment until the Nash equilibrium (NE) is reached. Moreover, the proof of the NE is given to verify the strategy we proposed is optimal. Simulation results prove the effectiveness of the strategy.
关键词： UAV,Cache,B5G,Reinforcement learning,Physical-layer security,NOMA
更新于2025-09-23 15:19:57
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Under-canopy UAV laser scanning for accurate forest field measurements
摘要： Surveying and robotic technologies are converging, offering great potential for robotic-assisted data collection and support for labour intensive surveying activities. From a forest monitoring perspective, there are several technological and operational aspects to address concerning under-canopy flying unmanned airborne vehicles (UAV). To demonstrate this emerging technology, we investigated tree detection and stem curve estimation using laser scanning data obtained with an under-canopy flying UAV. To this end, we mounted a Kaarta Stencil-1 laser scanner with an integrated simultaneous localization and mapping (SLAM) system on board an UAV that was manually piloted with the help of video goggles receiving a live video feed from the onboard camera of the UAV. Using the under-canopy flying UAV, we collected SLAM-corrected point cloud data in a boreal forest on two 32 m 32 m test sites that were characterized as sparse ( = 42 trees) and obstructed ( = 43 trees), respectively. Novel data processing algorithms were applied for the point clouds in order to detect the stems of individual trees and to extract their stem curves and diameters at breast height (DBH). The estimated tree attributes were compared against highly accurate field reference data that was acquired semi-manually with a multi-scan terrestrial laser scanner (TLS). The proposed method succeeded in detecting 93% of the stems in the sparse plot and 84% of the stems in the obstructed plot. In the sparse plot, the DBH and stem curve estimates had a root-mean-squared error (RMSE) of 0.60 cm (2.2%) and 1.2 cm (5.0%), respectively, whereas the corresponding values for the obstructed plot were 0.92 cm (3.1%) and 1.4 cm (5.2%). By combining the stem curves extracted from the under-canopy UAV laser scanning data with tree heights derived from above-canopy UAV laser scanning data, we computed stem volumes for the detected trees with a relative RMSE of 10.1% in both plots. Thus, the combination of under-canopy and above-canopy UAV laser scanning allowed us to extract the stem volumes with an accuracy comparable to the past best studies based on TLS in boreal forest conditions. Since the stems of several spruces located on the test sites suffered from severe occlusion and could not be detected with the stem-based method, we developed a separate work flow capable of detecting trees with occluded stems. The proposed work flow enabled us to detect 98% of trees in the sparse plot and 93% of the trees in the obstructed plot with a 100% correction level in both plots. A key benefit provided by the under-canopy UAV laser scanner is the short period of time required for data collection, currently demonstrated to be much faster than the time required for field measurements and TLS. The quality of the measurements acquired with the under-canopy flying UAV combined with the demonstrated efficiency indicates operational potential for supporting fast and accurate forest resource inventories.
关键词： Stem volume,Under-canopy flight,SLAM,Airborne laser scanning,Stem curve,UAV
更新于2025-09-23 15:19:57
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Estimation of Forest Growing Stock Volume with UAV Laser Scanning Data: Can It Be Done without Field Data?
摘要： Laser scanning data from unmanned aerial vehicles (UAV-LS) offer new opportunities to estimate forest growing stock volume (V) exclusively based on the UAV-LS data. We propose a method to measure tree attributes and using these measurements to estimate V without the use of field data for calibration. The method consists of five steps: i) Using UAV-LS data, tree crowns are automatically identified and segmented wall-to-wall. ii) From all detected tree crowns, a sample is taken where diameter at breast height (DBH) can be recorded reliably as determined by visual assessment in the UAV-LS data. iii) Another sample of crowns is taken where tree species were identifiable from UAV image data. iv) DBH and tree species models are fit using the samples and applied to all detected tree crowns. v) Single tree volumes are predicted with existing allometric models using predicted species and DBH, and height directly obtained from UAV-LS. The method was applied to a Riegl-VUX data set with an average density of 1130 points m?2 and 3 cm orthomosaic acquired over an 8.8 ha managed boreal forest. The volumes of the identified trees were aggregated to estimate plot-, stand-, and forest-level volumes which were validated using 58 independently measured field plots. The root-mean-square deviance (RMSD%) decreased when increasing the spatial scale from the plot (32.2%) to stand (27.1%) and forest level (3.5%). The accuracy of the UAV-LS estimates varied given forest structure and was highest in open pine stands and lowest in dense birch or spruce stands. On the forest level, the estimates based on UAV-LS data were well within the 95% confidence interval of the intense field survey estimate, and both estimates had a similar precision. While the results are encouraging for further use of UAV-LS in the context of fully airborne forest inventories, future studies should confirm our findings in a variety of forest types and conditions.
关键词： in-situ data,Riegl-VUX,UAV-LS,drone,forest inventory
更新于2025-09-23 15:19:57
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Application of unmanned aerial vehicle (UAV) to photogrammetric developments
摘要： The article presents the possibility of using unmanned aerial vehicle to perform selected photogrammetric studies. The first part shows the mathematical basis of aerotriangulation based on a series of images. Next, a photogrammetric system consisting of an unmanned aerial vehicle (UAV) equipped with a camera and specialized software for recording and processing images was presented. The main part shows the stages of the photogrammetric processing from the images i.e. mission plan of the incursion, creation of a thick cloud of points and a three-dimensional model. It also shows the analysis of the quality of the developed orthophotomap and a numerical model of the surface area, including photopoints by comparing them to orthographic images that are shared on Google. The final part contains generalized conclusions derived from the conducted research.
关键词： orthophotomap,NMPT,3D model,UAV,Pix4D
更新于2025-09-23 15:19:57
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Error Budget for Geolocation of Spectroradiometer Point Observations from an Unmanned Aircraft System
摘要： We investigate footprint geolocation uncertainties of a spectroradiometer mounted on an unmanned aircraft system (UAS). Two microelectromechanical systems-based inertial measurement units (IMUs) and global navigation satellite system (GNSS) receivers were used to determine the footprint location and extent of the spectroradiometer. Errors originating from the on-board GNSS/IMU sensors were propagated through an aerial data georeferencing model, taking into account a range of values for the spectroradiometer field of view (FOV), integration time, UAS flight speed, above ground level (AGL) flying height, and IMU grade. The spectroradiometer under nominal operating conditions (8° FOV, 10 m AGL height, 0.6 s integration time, and 3 m/s flying speed) resulted in footprint extent of 140 cm across-track and 320 cm along-track, and a geolocation uncertainty of 11 cm. Flying height and orientation measurement accuracy had the largest influence on the geolocation uncertainty, whereas the FOV, integration time, and flying speed had the biggest impact on the size of the footprint. Furthermore, with an increase in flying height, the rate of increase in geolocation uncertainty was found highest for a low-grade IMU. To increase the footprint geolocation accuracy, we recommend reducing flying height while increasing the FOV which compensates the footprint area loss and increases the signal strength. The disadvantage of a lower flying height and a larger FOV is a higher sensitivity of the footprint size to changing distance from the target. To assist in matching the footprint size to uncertainty ratio with an appropriate spatial scale, we list the expected ratio for a range of IMU grades, FOVs and AGL heights.
关键词： geolocation,error propagation,UAV,spectroradiometer,footprint,UAS,aerial spectroscopy
更新于2025-09-19 17:15:36