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Drones
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Unconventional Drone-Based Surveying
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Unconventional Drone-Based Surveying

A special issue of Drones (ISSN 2504-446X).

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 40109

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Arianna Pesci

E-Mail Website
Guest Editor
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Viale Berti Pichat, 6/2 Creti 12, I-40127 Bologna, Italy
Interests: terrestrial laser scanner; remote sensing; structure from motion photogrammetry; crustal deformation; geodesy ground deformation; time series; volcanology
Special Issues, Collections and Topics in MDPI journals
Dr. Giordano Teza

E-Mail Website
Guest Editor
Department of Physics and Astronomy, Alma Mater Studiorum, University of Bologna, Viale Berti Pichat, 6/2 Creti 12, I-40127 Bologna, Italy
Interests: remote sensing (terrestrial laser scanning and structure-from-motion) and application to landslide monitoring; cultural heritage; preservation and medical imaging; 3D modeling; image processing; thermal imaging; GNSS and applications to crustal kinematics; deep learning and applications to time series analysis and medical imaging
Special Issues, Collections and Topics in MDPI journals
Dr. Massimo Fabris

E-Mail Website
Guest Editor
Department of Civil, Environmental and Architectural Engineering-ICEA, University of Padova, 35122 Padova, Italy
Interests: geomatics; digital aerial photogrammetry; digital surface models; deformations monitoring; 3D surveys; land subsidence
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We are pleased to invite you to submit manuscripts to the MDPI Drones Special Issue on “Unconventional Drone-based Surveying.” Unconventional contributions are requested in this Special Issue.

Structure-from-Motion photogrammetry (SfM) allows the detection of physical surfaces of interest in an extremely fast and simple way. There is a wide range of applications based on the use of drones for photogrammetric purposes, leading to the creation of dense and accurate point clouds representing the objects of interest. Typically, surface variations and change detections are based on the comparison of multi-temporal models or on the morphological analysis of the present state of the object checking for differences with respect to a known supposed regularity.

This Special Issue is supposed to collect and revise papers to face any problems encountered and solved in the use of SfM also outside a classical approach: 1) providing new methods for data analysis, highlighting their strengths and weaknesses; 2) studying possible unexpected systematic errors from data analysis due to digital camera specifications and/or the image distribution on the covered areas; 3) conceiving methods for error mitigations and their applications; 4) analyzing the impact of scale factor corrections on results in terms of surface variation reliability; 5) verifying the role of real ground sampling distance (GSD) in digital models resolution; 6) other original miscellaneous approaches. Generally, only papers concerning a successful application of a methodology in its final version are published. However, even papers devoted to problem analysis will be welcome in this Special Issue if they are of interest to researchers and practicioners.

In particular, the contributions describing new methods for fast and low-cost observation and monitoring are particularly encouraged.

Any type of application of interest for research and practice is welcome under the condition that it is carried out in an unconventinal way. The areas of interest for the applications can vary from architecture to environmental, volcanic, geological, seismological, civil engineering and agricultural fields, including, for example, the monitoring of the spatio-temporal evolution of unstable slopes or of the piezometric levels in aquifers to the use of drones in archeology, civil engineering, and agriculture.  Laboratory experiments are also accepted if they fit the points listed above.

Dr. Arianna Pesci
Dr. Giordano Teza
Prof. Dr. Massimo Fabris
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Drones 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 2600 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

  • Structure-from-Motion
  • unconventional applications
  • errors
  • calibration
  • analysis methods
  • point clouds repeatability
  • GSD
  • scale factor
  • experiments

Published Papers (12 papers)

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Editorial

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7 pages, 234 KiB  
Editorial
Editorial of Special Issue “Unconventional Drone-Based Surveying”
by Arianna Pesci, Giordano Teza and Massimo Fabris
Drones 2023, 7(3), 175; https://doi.org/10.3390/drones7030175 - 03 Mar 2023
Cited by 2 | Viewed by 913
Abstract
Nowadays, Unmanned Aerial Vehicles (UAVs), as well as Unmanned Surface Vehicles (USVs) or also Unmanned Underwater Vehicles (UUVs), later on simply called drones, have reached a sufficient degree of maturity to allow their use for various purposes [...] Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)

Research

Jump to: Editorial

21 pages, 17628 KiB  
Article
Expeditious Low-Cost SfM Photogrammetry and a TLS Survey for the Structural Analysis of Illasi Castle (Italy)
by Massimo Fabris, Pietro Fontana Granotto and Michele Monego
Drones 2023, 7(2), 101; https://doi.org/10.3390/drones7020101 - 01 Feb 2023
Cited by 7 | Viewed by 1923
Abstract
The structural analysis of degraded historical buildings requires an adequate 3D model of the object. Structure from motion (SfM) photogrammetry and laser scanning geomatics techniques can satisfy this request by providing geometrically affordable data. The accuracy and resolution depend on the instruments and [...] Read more.
The structural analysis of degraded historical buildings requires an adequate 3D model of the object. Structure from motion (SfM) photogrammetry and laser scanning geomatics techniques can satisfy this request by providing geometrically affordable data. The accuracy and resolution depend on the instruments and procedures used to extract the 3D models. This work focused on a 3D survey of Illasi Castle, a strongly degraded historical building located in northern Italy, aimed at structural analysis in the prevision of a static recovery. A low-cost drone, a single-lens reflex (SLR) camera, and a smartphone were used in the survey. From each acquired dataset, using the integration between the images acquired by the drone and the SLR camera, a 3D model of the building was extracted by means of the SfM technique. The data were compared with high-precision and high-resolution terrestrial laser scanning (TLS) acquisitions to evaluate the accuracy and performance of the fast and low-cost SfM approach. The results showed a standard deviation value for the point cloud comparisons in the order of 2–3 cm for the best solution (integrating drone and SLR images) and 4–7 cm using smartphone images. Finally, the integration of the best SfM model of the external walls and the TLS model of the internal portion of the building was used in finite element (FE) analysis to provide a safety assessment of the structure. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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15 pages, 3211 KiB  
Article
Accuracy Assessment of Direct Georeferencing for Photogrammetric Applications Based on UAS-GNSS for High Andean Urban Environments
by Rolando Salas López, Renzo E. Terrones Murga, Jhonsy O. Silva-López, Nilton B. Rojas-Briceño, Darwin Gómez Fernández, Manuel Oliva-Cruz and Yuri Taddia
Drones 2022, 6(12), 388; https://doi.org/10.3390/drones6120388 - 30 Nov 2022
Cited by 8 | Viewed by 2669
Abstract
Unmanned Aircraft Systems (UAS) are used in a variety of applications with the aim of mapping detailed surfaces from the air. Despite the high level of map automation achieved today, there are still challenges in the accuracy of georeferencing that can limit both [...] Read more.
Unmanned Aircraft Systems (UAS) are used in a variety of applications with the aim of mapping detailed surfaces from the air. Despite the high level of map automation achieved today, there are still challenges in the accuracy of georeferencing that can limit both the speed and the efficiency in mapping urban areas. However, the integration of topographic grade Global Navigation Satellite System (GNSS) receivers on UAS has improved this phase, leading to a reach of up to a centimeter-level accuracy. It is therefore necessary to adopt direct georeferencing (DG), real-time kinematic positioning (RTK)/post-processed kinematic (PPK) approaches in order to largely automate the photogrammetric flow. This work analyses the positional accuracy using Ground Control Points (GCP) and the repeatability and reproducibility of photogrammetric products (Digital Surface Model and ortho-mosaic) of a commercial multi-rotor system equipped with a GNSS receiver in an urban environment with a DG approach. It was demonstrated that DG is a viable solution for mapping urban areas. Indeed, PPK with at least 1 GCP considerably improves the RMSE (x: 0.039 m, y: 0.012 m, and z: 0.034 m), allowing for a reliable 1:500 scale urban mapping in less time when compared to conventional topographic surveys. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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19 pages, 3834 KiB  
Article
The Bathy-Drone: An Autonomous Uncrewed Drone-Tethered Sonar System
by Antonio L. Diaz, Andrew E. Ortega, Henry Tingle, Andres Pulido, Orlando Cordero, Marisa Nelson, Nicholas E. Cocoves, Jaejeong Shin, Raymond R. Carthy, Benjamin E. Wilkinson and Peter G. Ifju
Drones 2022, 6(10), 294; https://doi.org/10.3390/drones6100294 - 10 Oct 2022
Cited by 6 | Viewed by 4292
Abstract
A unique drone-based system for underwater mapping (bathymetry) was developed at the University of Florida. The system, called the “Bathy-drone”, comprises a drone that drags, via a tether, a small vessel on the water surface in a raster pattern. The vessel is equipped [...] Read more.
A unique drone-based system for underwater mapping (bathymetry) was developed at the University of Florida. The system, called the “Bathy-drone”, comprises a drone that drags, via a tether, a small vessel on the water surface in a raster pattern. The vessel is equipped with a recreational commercial off-the-shelf (COTS) sonar unit that has down-scan, side-scan, and chirp capabilities and logs GPS-referenced sonar data onboard or transmitted in real time with a telemetry link. Data can then be retrieved post mission and plotted in various ways. The system provides both isobaths and contours of bottom hardness. Extensive testing of the system was conducted on a 5 acre pond located at the University of Florida Plant Science and Education Unit in Citra, FL. Prior to performing scans of the pond, ground-truth data were acquired with an RTK GNSS unit on a pole to precisely measure the location of the bottom at over 300 locations. An assessment of the accuracy and resolution of the system was performed by comparison to the ground-truth data. The pond ground truth had an average depth of 2.30 m while the Bathy-drone measured an average 21.6 cm deeper than the ground truth, repeatable to within 2.6 cm. The results justify integration of RTK and IMU corrections. During testing, it was found that there are numerous advantages of the Bathy-drone system compared to conventional methods including ease of implementation and the ability to initiate surveys from the land by flying the system to the water or placing the platform in the water. The system is also inexpensive, lightweight, and low-volume, thus making transport convenient. The Bathy-drone can collect data at speeds of 0–24 km/h (0–15 mph) and, thus, can be used in waters with swift currents. Additionally, there are no propellers or control surfaces underwater; hence, the vessel does not tend to snag on floating vegetation and can be dragged over sandbars. An area of more than 10 acres was surveyed using the Bathy-drone in one battery charge and in less than 25 min. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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23 pages, 18751 KiB  
Article
Structure-from-Motion 3D Reconstruction of the Historical Overpass Ponte della Cerra: A Comparison between MicMac® Open Source Software and Metashape®
by Matteo Cutugno, Umberto Robustelli and Giovanni Pugliano
Drones 2022, 6(9), 242; https://doi.org/10.3390/drones6090242 - 06 Sep 2022
Cited by 13 | Viewed by 3050
Abstract
In recent years, the performance of free-and-open-source software (FOSS) for image processing has significantly increased. This trend, as well as technological advancements in the unmanned aerial vehicle (UAV) industry, have opened blue skies for both researchers and surveyors. In this study, we aimed [...] Read more.
In recent years, the performance of free-and-open-source software (FOSS) for image processing has significantly increased. This trend, as well as technological advancements in the unmanned aerial vehicle (UAV) industry, have opened blue skies for both researchers and surveyors. In this study, we aimed to assess the quality of the sparse point cloud obtained with a consumer UAV and a FOSS. To achieve this goal, we also process the same image dataset with a commercial software package using its results as a term of comparison. Various analyses were conducted, such as the image residuals analysis, the statistical analysis of GCPs and CPs errors, the relative accuracy assessment, and the Cloud-to-Cloud distance comparison. A support survey was conducted to measure 16 markers identified on the object. In particular, 12 of these were used as ground control points to scale the 3D model, while the remaining 4 were used as check points to assess the quality of the scaling procedure by examining the residuals. Results indicate that the sparse clouds obtained are comparable. MicMac® has mean image residuals equal to 0.770 pixels while for Metashape® is 0.735 pixels. In addition, the 3D errors on control points are similar: the mean 3D error for MicMac® is equal to 0.037 m with a standard deviation of 0.017 m, whereas for Metashape®, it is 0.031 m with a standard deviation equal to 0.015 m. The present work represents a preliminary study: a comparison between software packages is something hard to achieve, given the secrecy of the commercial software and the theoretical differences between the approaches. This case study analyzes an object with extremely complex geometry; it is placed in an urban canyon where the GNSS support can not be exploited. In addition, the scenario changes continuously due to the vehicular traffic. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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26 pages, 1987 KiB  
Article
A Time-Efficient Method to Avoid Collisions for Collision Cones: An Implementation for UAVs Navigating in Dynamic Environments
by Manaram Gnanasekera and Jay Katupitiya
Drones 2022, 6(5), 106; https://doi.org/10.3390/drones6050106 - 25 Apr 2022
Cited by 4 | Viewed by 2307
Abstract
This paper presents a methodology that can be used to avoid collisions of aerial drones. Even though there are many collision avoidance methods available in literature, collision cone is a proven method that can be used to predict a collision beforehand. In this [...] Read more.
This paper presents a methodology that can be used to avoid collisions of aerial drones. Even though there are many collision avoidance methods available in literature, collision cone is a proven method that can be used to predict a collision beforehand. In this research, we propose an algorithm to avoid a collision in a time-efficient manner for collision cone based aerial collision avoidance approaches. Furthermore, the paper has considered all possible scenarios including heading change, speed change and combined heading and speed change, to avoid a collision. The heading-based method was mathematically proven to be the most time-efficient method out of the three. The proposed heading-based method was compared with other work presented in the literature and validated with both simulations and experiments. A Matrice 600 Pro hexacopter is used for the collision avoidance experiments. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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19 pages, 9348 KiB  
Article
An Experimental Apparatus for Icing Tests of Low Altitude Hovering Drones
by Eric Villeneuve, Abdallah Samad, Christophe Volat, Mathieu Béland and Maxime Lapalme
Drones 2022, 6(3), 68; https://doi.org/10.3390/drones6030068 - 06 Mar 2022
Cited by 6 | Viewed by 3321
Abstract
The icing facilities of the Anti-Icing Materials International Laboratory AMIL have been adapted to reproduce icing conditions on a Bell APT70 drone rotor, typical of small-to-medium UAV models. As part of an extensive icing test campaign, this paper presents the design and preliminary [...] Read more.
The icing facilities of the Anti-Icing Materials International Laboratory AMIL have been adapted to reproduce icing conditions on a Bell APT70 drone rotor, typical of small-to-medium UAV models. As part of an extensive icing test campaign, this paper presents the design and preliminary testing of the experimental setup and representative icing conditions calibration in the laboratory’s cold chamber. The drone rotor used has four blades with a diameter of 0.66 m and a maximum tip speed of 208 m/s. For the icing conditions, freezing rain and freezing drizzle were selected. A Liquid Water Content (LWC) calculation methodology for a rotor in hover was developed, and procedures to determine experimental LWC in the facility are presented in this paper. For the test setup, the cold chamber test section was adapted to fit the rotor and to control its ground clearance. Testing was aimed at studying the effect of rotor height h on aerodynamic performance, both with and without icing conditions. Results show no significant effect on the ground effect between h = 2 m and h = 4 m in dry runs, while the icing behavior can be largely influenced for certain conditions by the proximity of the precipitation source, which depend on the height of the rotor in these experiments. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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23 pages, 1066 KiB  
Article
Multi-Camera Networks for Coverage Control of Drones
by Sunan Huang, Rodney Swee Huat Teo and William Wai Lun Leong
Drones 2022, 6(3), 67; https://doi.org/10.3390/drones6030067 - 03 Mar 2022
Cited by 6 | Viewed by 2503
Abstract
Multiple unmanned multirotor (MUM) systems are becoming a reality. They have a wide range of applications such as for surveillance, search and rescue, monitoring operations in hazardous environments and providing communication coverage services. Currently, an important issue in MUM is coverage control. In [...] Read more.
Multiple unmanned multirotor (MUM) systems are becoming a reality. They have a wide range of applications such as for surveillance, search and rescue, monitoring operations in hazardous environments and providing communication coverage services. Currently, an important issue in MUM is coverage control. In this paper, an existing coverage control algorithm has been extended to incorporate a new sensor model, which is downward facing and allows pan-tilt-zoom (PTZ). Two new constraints, namely view angle and collision avoidance, have also been included. Mobile network coverage among the MUMs is studied. Finally, the proposed scheme is tested in computer simulations. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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22 pages, 8344 KiB  
Article
Low-Altitude Sensing of Urban Atmospheric Turbulence with UAV
by Alexander Shelekhov, Alexey Afanasiev, Evgeniya Shelekhova, Alexey Kobzev, Alexey Tel’minov, Alexander Molchunov and Olga Poplevina
Drones 2022, 6(3), 61; https://doi.org/10.3390/drones6030061 - 27 Feb 2022
Cited by 10 | Viewed by 3333
Abstract
The capabilities of a quadcopter in the hover mode for low-altitude sensing of atmospheric turbulence with high spatial resolution in urban areas characterized by complex orography are investigated. The studies were carried out in different seasons (winter, spring, summer, and fall), and the [...] Read more.
The capabilities of a quadcopter in the hover mode for low-altitude sensing of atmospheric turbulence with high spatial resolution in urban areas characterized by complex orography are investigated. The studies were carried out in different seasons (winter, spring, summer, and fall), and the quadcopter hovered in the immediate vicinity of ultrasonic weather stations. The DJI Phantom 4 Pro quadcopter and AMK-03 ultrasonic weather stations installed in different places of the studied territory were used in the experiment. The smoothing procedure was used to study the behavior of the longitudinal and lateral spectra of turbulence in the inertial and energy production ranges. The longitudinal and lateral turbulence scales were estimated by the least-square fit method with the von Karman model as a regression curve. It is shown that the turbulence spectra obtained with DJI Phantom 4 Pro and AMK-03 generally coincide, with minor differences observed in the high-frequency region of the spectrum. In the inertial range, the behavior of the turbulence spectra shows that they obey the Kolmogorov–Obukhov “5/3” law. In the energy production range, the longitudinal and lateral turbulence scales and their ratio measured by DJI Phantom 4 Pro and AMK-03 agree to a good accuracy. Discrepancies in the data obtained with the quadcopter and the ultrasonic weather stations at the territory with complex orography are explained by the partial correlation of the wind velocity series at different measurement points and the influence of the inhomogeneous surface. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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15 pages, 14861 KiB  
Article
Accuracy Assessment of a UAV Direct Georeferencing Method and Impact of the Configuration of Ground Control Points
by Xiaoyu Liu, Xugang Lian, Wenfu Yang, Fan Wang, Yu Han and Yafei Zhang
Drones 2022, 6(2), 30; https://doi.org/10.3390/drones6020030 - 20 Jan 2022
Cited by 32 | Viewed by 5664
Abstract
Unmanned aerial vehicles (UAVs) can obtain high-resolution topography data flexibly and efficiently at low cost. However, the georeferencing process involves the use of ground control points (GCPs), which limits time and cost effectiveness. Direct georeferencing, using onboard positioning sensors, can significantly improve work [...] Read more.
Unmanned aerial vehicles (UAVs) can obtain high-resolution topography data flexibly and efficiently at low cost. However, the georeferencing process involves the use of ground control points (GCPs), which limits time and cost effectiveness. Direct georeferencing, using onboard positioning sensors, can significantly improve work efficiency. The purpose of this study was to evaluate the accuracy of the Global Navigation Satellite System (GNSS)-assisted UAV direct georeferencing method and the influence of the number and distribution of GCPs. A FEIMA D2000 UAV was used to collect data, and several photogrammetric projects were established. Among them, the number and distribution of GCPs used in the bundle adjustment (BA) process were varied. Two parameters were considered when evaluating the different projects: the ground-measured checkpoints (CPs) root mean square error (RMSE) and the Multiscale Model to Model Cloud Comparison (M3C2) distance. The results show that the vertical and horizontal RMSE of the direct georeferencing were 0.087 and 0.041 m, respectively. As the number of GCPs increased, the RMSE gradually decreased until a specific GCP density was reached. GCPs should be uniformly distributed in the study area and contain at least one GCP near the center of the domain. Additionally, as the distance to the nearest GCP increased, the local accuracy of the DSM decreased. In general, UAV direct georeferencing has an acceptable positional accuracy level. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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22 pages, 1483 KiB  
Article
Optimal Navigation of an Unmanned Surface Vehicle and an Autonomous Underwater Vehicle Collaborating for Reliable Acoustic Communication with Collision Avoidance
by Andrey V. Savkin, Satish Chandra Verma and Stuart Anstee
Drones 2022, 6(1), 27; https://doi.org/10.3390/drones6010027 - 17 Jan 2022
Cited by 8 | Viewed by 3647
Abstract
This paper focuses on safe navigation of an unmanned surface vehicle in proximity to a submerged autonomous underwater vehicle so as to maximise short-range, through-water data transmission while minimising the probability that the two vehicles will accidentally collide. A sliding mode navigation law [...] Read more.
This paper focuses on safe navigation of an unmanned surface vehicle in proximity to a submerged autonomous underwater vehicle so as to maximise short-range, through-water data transmission while minimising the probability that the two vehicles will accidentally collide. A sliding mode navigation law is developed, and a rigorous proof of optimality of the proposed navigation law is presented. The developed navigation algorithm is relatively computationally simple and easily implementable in real time. Illustrative examples with extensive computer simulations demonstrate the effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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18 pages, 7408 KiB  
Article
An Acoustic Source Localization Method Using a Drone-Mounted Phased Microphone Array
by Yeong-Ju Go and Jong-Soo Choi
Drones 2021, 5(3), 75; https://doi.org/10.3390/drones5030075 - 06 Aug 2021
Cited by 10 | Viewed by 4344
Abstract
Currently, the detection of targets using drone-mounted imaging equipment is a very useful technique and is being utilized in many areas. In this study, we focus on acoustic signal detection with a drone detecting targets where sounds occur, unlike image-based detection. We implement [...] Read more.
Currently, the detection of targets using drone-mounted imaging equipment is a very useful technique and is being utilized in many areas. In this study, we focus on acoustic signal detection with a drone detecting targets where sounds occur, unlike image-based detection. We implement a system in which a drone detects acoustic sources above the ground by applying a phase difference microphone array technique. Localization methods of acoustic sources are based on beamforming methods. The background and self-induced noise that is generated when a drone flies reduces the signal-to-noise ratio for detecting acoustic signals of interest, making it difficult to analyze signal characteristics. Furthermore, the strongly correlated noise, generated when a propeller rotates, acts as a factor that degrades the noise source direction of arrival estimation performance of the beamforming method. Spectral reduction methods have been effective in reducing noise by adjusting to specific frequencies in acoustically very harsh situations where drones are always exposed to their own noise. Since the direction of arrival of acoustic sources estimated from the beamforming method is based on the drone’s body frame coordinate system, we implement a method to estimate acoustic sources above the ground by fusing flight information output from the drone’s flight navigation system. The proposed method for estimating acoustic sources above the ground is experimentally validated by a drone equipped with a 32-channel time-synchronized MEMS microphone array. Additionally, the verification of the sound source location detection method was limited to the explosion sound generated from the fireworks. We confirm that the acoustic source location can be detected with an error performance of approximately 10 degrees of azimuth and elevation at the ground distance of about 150 m between the drone and the explosion location. Full article
(This article belongs to the Special Issue Unconventional Drone-Based Surveying)
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