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https://www.readbyqxmd.com/read/29047778/low-cost-dynamic-real-time-foveated-imager
#1
Yajun Niu, Jun Chang, Fengxiang Lv, Benlan Shen, Weilin Chen
Foveated imaging systems have the ability to capture local high-resolution or high-magnification images with wide field of view (FOV); thus, they have great potential for applications in the field of monitoring and remote sensing of unmanned aerial vehicles. Hence, foveated optical systems are in strong demand. However, the existing foveated imaging systems either are equipped with expensive modulators or require fixing the local high resolution imaging field, which is not suitable for mass production or object tracking in industrial applications...
October 1, 2017: Applied Optics
https://www.readbyqxmd.com/read/29047746/building-texture-acquisition-and-processing-based-on-an-unmanned-airship-low-altitude-aerial-survey-system
#2
Feifei Xie, Zongjian Lin, Guozhong Su
The traditional oblique cameras cannot self-calibrate to complete the three-dimensional (3D) modeling to meet high mapping accuracy requirements. We propose an oblique combined camera system, called a texture camera, aboard an unmanned airship that can simultaneously obtain a single vertical image and four oblique images of an object. The images acquired by this self-calibrating camera system can be used to produce traditional products on a large scale. Additionally, they can be used to accurately determine the orientation elements of each individual camera, which are essential for 3D modeling...
September 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29043046/among-tree-variability-and-feedback-effects-result-in-different-growth-responses-to-climate-change-at-the-upper-treeline-in-the-swiss-alps
#3
Matthias Jochner, Harald Bugmann, Magdalena Nötzli, Christof Bigler
Upper treeline ecotones are important life form boundaries and particularly sensitive to a warming climate. Changes in growth conditions at these ecotones have wide-ranging implications for the provision of ecosystem services in densely populated mountain regions like the European Alps. We quantify climate effects on short- and long-term tree growth responses, focusing on among-tree variability and potential feedback effects. Although among-tree variability is thought to be substantial, it has not been considered systematically yet in studies on growth-climate relationships...
October 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/29039755/comparing-riegl-ricopter-uav-lidar-derived-canopy-height-and-dbh-with-terrestrial-lidar
#4
Benjamin Brede, Alvaro Lau, Harm M Bartholomeus, Lammert Kooistra
In recent years, LIght Detection And Ranging (LiDAR) and especially Terrestrial Laser Scanning (TLS) systems have shown the potential to revolutionise forest structural characterisation by providing unprecedented 3D data. However, manned Airborne Laser Scanning (ALS) requires costly campaigns and produces relatively low point density, while TLS is labour intense and time demanding. Unmanned Aerial Vehicle (UAV)-borne laser scanning can be the way in between. In this study, we present first results and experiences with the RIEGL RiCOPTER with VUX ® -1UAV ALS system and compare it with the well tested RIEGL VZ-400 TLS system...
October 17, 2017: Sensors
https://www.readbyqxmd.com/read/29023504/the-potential-of-small-unmanned-aircraft-systems-for-the-rapid-detection-of-threatened-unimproved-grassland-communities-using-an-enhanced-normalized-difference-vegetation-index
#5
Conor J Strong, Niall G Burnside, Dan Llewellyn
The loss of unimproved grassland has led to species decline in a wide range of taxonomic groups. Agricultural intensification has resulted in fragmented patches of remnant grassland habitat both across Europe and internationally. The monitoring of remnant patches of this habitat is critically important, however, traditional surveying of large, remote landscapes is a notoriously costly and difficult task. The emergence of small-Unmanned Aircraft Systems (sUAS) equipped with low-cost multi-spectral cameras offer an alternative to traditional grassland survey methods, and have the potential to progress and innovate the monitoring and future conservation of this habitat globally...
2017: PloS One
https://www.readbyqxmd.com/read/28961219/a-novel-online-data-driven-algorithm-for-detecting-uav-navigation-sensor-faults
#6
Rui Sun, Qi Cheng, Guanyu Wang, Washington Yotto Ochieng
The use of Unmanned Aerial Vehicles (UAVs) has increased significantly in recent years. On-board integrated navigation sensors are a key component of UAVs' flight control systems and are essential for flight safety. In order to ensure flight safety, timely and effective navigation sensor fault detection capability is required. In this paper, a novel data-driven Adaptive Neuron Fuzzy Inference System (ANFIS)-based approach is presented for the detection of on-board navigation sensor faults in UAVs. Contrary to the classic UAV sensor fault detection algorithms, based on predefined or modelled faults, the proposed algorithm combines an online data training mechanism with the ANFIS-based decision system...
September 29, 2017: Sensors
https://www.readbyqxmd.com/read/28956839/adaptation-of-dubins-paths-for-uav-ground-obstacle-avoidance-when-using-a-low-cost-on-board-gnss-sensor
#7
Ramūnas Kikutis, Jonas Stankūnas, Darius Rudinskas, Tadas Masiulionis
Current research on Unmanned Aerial Vehicles (UAVs) shows a lot of interest in autonomous UAV navigation. This interest is mainly driven by the necessity to meet the rules and restrictions for small UAV flights that are issued by various international and national legal organizations. In order to lower these restrictions, new levels of automation and flight safety must be reached. In this paper, a new method for ground obstacle avoidance derived by using UAV navigation based on the Dubins paths algorithm is presented...
September 28, 2017: Sensors
https://www.readbyqxmd.com/read/28946659/secure-utilization-of-beacons-and-uavs-in-emergency-response-systems-for-building-fire-hazard
#8
Seung-Hyun Seo, Jung-In Choi, Jinseok Song
An intelligent emergency system for hazard monitoring and building evacuation is a very important application area in Internet of Things (IoT) technology. Through the use of smart sensors, such a system can provide more vital and reliable information to first-responders and also reduce the incidents of false alarms. Several smart monitoring and warning systems do already exist, though they exhibit key weaknesses such as a limited monitoring coverage and security, which have not yet been sufficiently addressed...
September 25, 2017: Sensors
https://www.readbyqxmd.com/read/28941951/on-decentralized-adaptive-full-order-sliding-mode-control-of-multiple-uavs
#9
Xianbo Xiang, Chao Liu, Housheng Su, Qin Zhang
In this study, a novel decentralized adaptive full-order sliding mode control framework is proposed for the robust synchronized formation motion of multiple unmanned aerial vehicles (UAVs) subject to system uncertainty. First, a full-order sliding mode surface in a decentralized manner is designed to incorporate both the individual position tracking error and the synchronized formation error while the UAV group is engaged in building a certain desired geometric pattern in three dimensional space. Second, a decentralized virtual plant controller is constructed which allows the embedded low-pass filter to attain the chattering free property of the sliding mode controller...
September 20, 2017: ISA Transactions
https://www.readbyqxmd.com/read/28925947/a-dynamic-multi-projection-contour-approximating-framework-for-the-3d-reconstruction-of-buildings-by-super-generalized-optical-stereo-pairs
#10
Yiming Yan, Nan Su, Chunhui Zhao, Liguo Wang
In this paper, a novel framework of the 3D reconstruction of buildings is proposed, focusing on remote sensing super-generalized stereo-pairs (SGSPs). As we all know, 3D reconstruction cannot be well performed using nonstandard stereo pairs, since reliable stereo matching could not be achieved when the image-pairs are collected at a great difference of views, and we always failed to obtain dense 3D points for regions of buildings, and cannot do further 3D shape reconstruction. We defined SGSPs as two or more optical images collected in less constrained views but covering the same buildings...
September 19, 2017: Sensors
https://www.readbyqxmd.com/read/28906428/spatial-scale-gap-filling-using-an-unmanned-aerial-system-a-statistical-downscaling-method-for-applications-in-precision-agriculture
#11
Leila Hassan-Esfahani, Ardeshir M Ebtehaj, Alfonso Torres-Rua, Mac McKee
Applications of satellite-borne observations in precision agriculture (PA) are often limited due to the coarse spatial resolution of satellite imagery. This paper uses high-resolution airborne observations to increase the spatial resolution of satellite data for related applications in PA. A new variational downscaling scheme is presented that uses coincident aerial imagery products from "AggieAir", an unmanned aerial system, to increase the spatial resolution of Landsat satellite data. This approach is primarily tested for downscaling individual band Landsat images that can be used to derive normalized difference vegetation index (NDVI) and surface soil moisture (SSM)...
September 14, 2017: Sensors
https://www.readbyqxmd.com/read/28891985/cross-correlation-based-structural-system-identification-using-unmanned-aerial-vehicles
#12
Hyungchul Yoon, Vedhus Hoskere, Jong-Woong Park, Billie F Spencer
Computer vision techniques have been employed to characterize dynamic properties of structures, as well as to capture structural motion for system identification purposes. All of these methods leverage image-processing techniques using a stationary camera. This requirement makes finding an effective location for camera installation difficult, because civil infrastructure (i.e., bridges, buildings, etc.) are often difficult to access, being constructed over rivers, roads, or other obstacles. This paper seeks to use video from Unmanned Aerial Vehicles (UAVs) to address this problem...
September 11, 2017: Sensors
https://www.readbyqxmd.com/read/28885547/a-stereo-dual-channel-dynamic-programming-algorithm-for-uav-image-stitching
#13
Ming Li, Ruizhi Chen, Weilong Zhang, Deren Li, Xuan Liao, Lei Wang, Yuanjin Pan, Peng Zhang
Dislocation is one of the major challenges in unmanned aerial vehicle (UAV) image stitching. In this paper, we propose a new algorithm for seamlessly stitching UAV images based on a dynamic programming approach. Our solution consists of two steps: Firstly, an image matching algorithm is used to correct the images so that they are in the same coordinate system. Secondly, a new dynamic programming algorithm is developed based on the concept of a stereo dual-channel energy accumulation. A new energy aggregation and traversal strategy is adopted in our solution, which can find a more optimal seam line for image stitching...
September 8, 2017: Sensors
https://www.readbyqxmd.com/read/28880254/concrete-crack-identification-using-a-uav-incorporating-hybrid-image-processing
#14
Hyunjun Kim, Junhwa Lee, Eunjong Ahn, Soojin Cho, Myoungsu Shin, Sung-Han Sim
Crack assessment is an essential process in the maintenance of concrete structures. In general, concrete cracks are inspected by manual visual observation of the surface, which is intrinsically subjective as it depends on the experience of inspectors. Further, it is time-consuming, expensive, and often unsafe when inaccessible structural members are to be assessed. Unmanned aerial vehicle (UAV) technologies combined with digital image processing have recently been applied to crack assessment to overcome the drawbacks of manual visual inspection...
September 7, 2017: Sensors
https://www.readbyqxmd.com/read/28867775/remote-marker-based-tracking-for-uav-landing-using-visible-light-camera-sensor
#15
Phong Ha Nguyen, Ki Wan Kim, Young Won Lee, Kang Ryoung Park
Unmanned aerial vehicles (UAVs), which are commonly known as drones, have proved to be useful not only on the battlefields where manned flight is considered too risky or difficult, but also in everyday life purposes such as surveillance, monitoring, rescue, unmanned cargo, aerial video, and photography. More advanced drones make use of global positioning system (GPS) receivers during the navigation and control loop which allows for smart GPS features of drone navigation. However, there are problems if the drones operate in heterogeneous areas with no GPS signal, so it is important to perform research into the development of UAVs with autonomous navigation and landing guidance using computer vision...
August 30, 2017: Sensors
https://www.readbyqxmd.com/read/28853176/optimal-mission-abort-policy-for-systems-operating-in-a-random-environment
#16
Gregory Levitin, Maxim Finkelstein
Many real-world critical systems, e.g., aircrafts, manned space flight systems, and submarines, utilize mission aborts to enhance their survivability. Specifically, a mission can be aborted when a certain malfunction condition is met and a rescue or recovery procedure is then initiated. For systems exposed to external impacts, the malfunctions are often caused by the consequences of these impacts. Traditional system reliability models typically cannot address a possibility of mission aborts. Therefore, in this article, we first develop the corresponding methodology for modeling and evaluation of the mission success probability and survivability of systems experiencing both internal failures and external shocks...
August 29, 2017: Risk Analysis: An Official Publication of the Society for Risk Analysis
https://www.readbyqxmd.com/read/28811888/performance-test-and-verification-of-an-off-the-shelf-automated-avian-radar-tracking-system
#17
Roel May, Yngve Steinheim, Pål Kvaløy, Roald Vang, Frank Hanssen
Microwave radar is an important tool for observation of birds in flight and represents a tremendous increase in observation capability in terms of amount of surveillance space that can be covered at relatively low cost. Based on off-the-shelf radar hardware, automated radar tracking systems have been developed for monitoring avian movements. However, radar used as an observation instrument in biological research has its limitations that are important to be aware of when analyzing recorded radar data. This article describes a method for exploring the detection capabilities of a dedicated short-range avian radar system used inside the operational Smøla wind-power plant...
August 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28805689/visual-servoing-for-an-autonomous-hexarotor-using-a-neural-network-based-pid-controller
#18
Carlos Lopez-Franco, Javier Gomez-Avila, Alma Y Alanis, Nancy Arana-Daniel, Carlos Villaseñor
In recent years, unmanned aerial vehicles (UAVs) have gained significant attention. However, we face two major drawbacks when working with UAVs: high nonlinearities and unknown position in 3D space since it is not provided with on-board sensors that can measure its position with respect to a global coordinate system. In this paper, we present a real-time implementation of a servo control, integrating vision sensors, with a neural proportional integral derivative (PID), in order to develop an hexarotor image based visual servo control (IBVS) that knows the position of the robot by using a velocity vector as a reference to control the hexarotor position...
August 12, 2017: Sensors
https://www.readbyqxmd.com/read/28796184/a-heterogeneous-sensing-system-based-method-for-unmanned-aerial-vehicle-indoor-positioning
#19
Can Wang, Kang Li, Guoyuan Liang, Haoyao Chen, Sheng Huang, Xinyu Wu
The indoor environment has brought new challenges for micro Unmanned Aerial Vehicles (UAVs) in terms of their being able to execute tasks with high positioning accuracy. Conventional positioning methods based on GPS are unreliable, although certain circumstances of limited space make it possible to apply new technologies. In this paper, we propose a novel indoor self-positioning system of UAV based on a heterogeneous sensing system, which integrates data from a structured light scanner, ultra-wideband (UWB), and an inertial navigation system (INS)...
August 10, 2017: Sensors
https://www.readbyqxmd.com/read/28789685/remote-monitoring-of-cardiorespiratory-signals-from-a-hovering-unmanned-aerial-vehicle
#20
Ali Al-Naji, Asanka G Perera, Javaan Chahl
BACKGROUND: Remote physiological measurement might be very useful for biomedical diagnostics and monitoring. This study presents an efficient method for remotely measuring heart rate and respiratory rate from video captured by a hovering unmanned aerial vehicle (UVA). The proposed method estimates heart rate and respiratory rate based on the acquired signals obtained from video-photoplethysmography that are synchronous with cardiorespiratory activity. METHODS: Since the PPG signal is highly affected by the noise variations (illumination variations, subject's motions and camera movement), we have used advanced signal processing techniques, including complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and canonical correlation analysis (CCA) to remove noise under these assumptions...
August 8, 2017: Biomedical Engineering Online
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