• Title/Summary/Keyword: Small UAVs

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Unmanned aerial vehicle routing algorithm using vehicular communication systems (차량 통신 시스템 기반 UAV 라우팅 알고리즘)

  • Kim, Ryul;Joo, Yang-Ick
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.7
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    • pp.622-628
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    • 2016
  • The prosperity of IT technologies and the removal of restrictions regarding Unmanned Aerial Vehicles (UAVs), also known as drones, have driven growth in their popularity. However, without a proper solution to the problem of accident avoidance for UAVs, this popularity increases the potential for collisions between UAVs and between UAV and terrain features. These collisions can occur because UAVs to date have flown using radio control or image recognition based autonomous navigation. Therefore, we propose efficient UAV routing schemes to tackle the collision problem using vehicular communication systems. Performance evaluation by computer simulation shows that the proposed methods effectively reduce the collision probability and improve the routing efficiency of the UAV. Furthermore, the proposed algorithms are compatible and can be directly applied with small overhead to the commercial vehicular communication system implementation.

Smart Anti-jamming Mobile Communication for Cloud and Edge-Aided UAV Network

  • Li, Zhiwei;Lu, Yu;Wang, Zengguang;Qiao, Wenxin;Zhao, Donghao
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.12
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    • pp.4682-4705
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    • 2020
  • The Unmanned Aerial Vehicles (UAV) networks consisting of low-cost UAVs are very vulnerable to smart jammers that can choose their jamming policies based on the ongoing communication policies accordingly. In this article, we propose a novel cloud and edge-aided mobile communication scheme for low-cost UAV network against smart jamming. The challenge of this problem is to design a communication scheme that not only meets the requirements of defending against smart jamming attack, but also can be deployed on low-cost UAV platforms. In addition, related studies neglect the problem of decision-making algorithm failure caused by intermittent ground-to-air communication. In this scheme, we use the policy network deployed on the cloud and edge servers to generate an emergency policy tables, and regularly update the generated policy table to the UAVs to solve the decision-making problem when communications are interrupted. In the operation of this communication scheme, UAVs need to offload massive computing tasks to the cloud or the edge servers. In order to prevent these computing tasks from being offloaded to a single computing resource, we deployed a lightweight game algorithm to ensure that the three types of computing resources, namely local, edge and cloud, can maximize their effectiveness. The simulation results show that our communication scheme has only a small decrease in the SINR of UAVs network in the case of momentary communication interruption, and the SINR performance of our algorithm is higher than that of the original Q-learning algorithm.

Region Defense Technique Using Multiple Satellite Navigation Spoofing Signals

  • Lee, Chi-Hun;Choi, Seungho;Lee, Young-Joong;Lee, Sang Jeong
    • Journal of Positioning, Navigation, and Timing
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    • v.11 no.3
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    • pp.173-179
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    • 2022
  • The satellite navigation deception technology disturbs the navigation solution of the receiver by generating a deceptive signal simulating the actual satellite for the satellite navigation receiver mounted on the unmanned aerial vehicle, which is the target of deception. A single spoofing technique that creates a single deceptive position and velocity can be divided into a synchronized spoofing signal that matches the code delay, Doppler frequency, and navigation message with the real satellite and an unsynchronized spoofing signal that does not match. In order to generate a signal synchronized with a satellite signal, a very sophisticated and high precision signal generation technology is required. In addition, the current position and speed of the UAV equipped with the receiver must be accurately detected in real time. Considering the detection accuracy of the current radar technology that detects small UAVs, it is difficult to detect UAVs with an accuracy of less than one chip. In this paper, we assume the asynchrony of a single spoofing signal and propose a region defense technique using multiple spoofing signals.

Ground Test and Performance Evaluation of Miniaturized AHRS for Small-Scale UAV (소형무인항공기를 위한 소형 경량 AHRS의 지상시험 및 성능 평가)

  • Roh, Min-Shik;Song, Jun-Beom;Song, Woo-Jin;Kang, Beom-Soo
    • Journal of Advanced Navigation Technology
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    • v.15 no.2
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    • pp.181-188
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    • 2011
  • A small UAVs(Unmaned Aerial Vehicles) have limited by the payload capacity which requires miniaturization of a navigation system. In this paper, the performance of the lightweight and small sized AHRS(Attitude Heading Reference System), which is self-developed, is evaluated at low acceleration environment. The designed AHRS adopts the commercial low-cost MEMS sensors. A quaternion-based attitude calculation method, which eliminates singularity with relatively simple algebra, is used. In an attitude correction algorithm, the Kalman filter is used with accelerometers and magnetometers combined. The fabricated AHRS is also evaluated with reference to a COTS(Commercial Off-The-Shelf) AHRS which reports a number of successful applications to a small UAVs. The test results show that the measurements from the fabricated AHRS provide proper attitude output data with acceptable amount of differences(horizontal axis 0.5$^{\circ}$, vertical axis 1.5$^{\circ}$) in test environment.

A Sizing Method for Solar Power Long Endurance UAVs (태양에너지 기반 장기체공 무인기 주요 치수 결정 방법론)

  • Lee, Ju-Ho;Lee, Chang-Gwan;Lim, Se-Sil;Kim, Keum-Seong;Han, Jae-Hung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.8
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    • pp.758-766
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    • 2010
  • The design procedure of Solar Power UAVs is complicated because the configuration and required power for flight must be considered simultaneously as the supplied power is influenced by the wing area. In order to minimize trial and error for the Solar Power UAVs design, a systematic sizing method is proposed which can be used to determine whether a Solar Power UAV is feasible for a given mission, and to derive preliminary dimensional specification of it. The sizing procedure begins with initially assumed wing area because the power, lift, and drag of the wing are directly proportional to it. The assumed wing area and mission requirements are then used to determine step by step the airfoil specifications including lift coefficient and drag coefficient, weight, required power, and wing area. This procedure is iterated for each newly assumed wing area until the error between the assumed wing area and calculated wing area becomes significantly small enough. This sizing methodology was applied to previously developed Solar Power UAVs for validation purposes, resulting in good agreement. The methodology was also applied to determine the dimensions and specifications of the Solar Power High-Altitude Long-Endurance UAV.

Utilization of UAV Remote Sensing in Small-scale Field Experiment : Case Study in Evaluation of Plat-based LAI for Sweetcorn Production

  • Hyunjin Jung;Rongling Ye;Yang Yi;Naoyuki Hashimoto;Shuhei Yamamoto;Koki Homma
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2022.10a
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    • pp.75-75
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    • 2022
  • Traditional agriculture mostly focused on activity in the field, but current agriculture faces problems such as reduction of agricultural inputs, labor shortage and so on. Accordingly, traditional agricultural experiments generally considered the simple treatment effects, but current agricultural experiments need to consider the several and complicate treatment effects. To analyze such several and complicate treatment effects, data collection has the first priority. Remote sensing is a quite effective tool to collect information in agriculture, and recent easier availability of UAVs (Unmanned Aerial Vehicles) enhances the effectiveness. LAI (Leaf Area Index) is one of the most important information for evaluating the condition of crop growth. In this study, we utilized UAV with multispectral camera to evaluate plant-based LAI of sweetcorn in a small-scale field experiment and discussed the feasibility of a new experimental design to analyze the several and complicate treatment effects. The plant-based SR measured by UAV showed the highest correlation coefficient with LAI measured by a canopy analyzer in 2018 and 2019. Application of linear mix model showed that plant-based SR data had higher detection power due to its huge number of data although SR was inferior to evaluate LAI than the canopy analyzer. The distribution of plant-based data also statistically revealed the border effect in treatment plots in the traditional experimental design. These results suggest that remote sensing with UAVs has the advantage even in a small-scale experimental plot and has a possibility to provide a new experimental design if combined with various analytical applications such as plant size, shape, and color.

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Tracking of Walking Human Based on Position Uncertainty of Dynamic Vision Sensor of Quadcopter UAV (UAV기반 동적영상센서의 위치불확실성을 통한 보행자 추정)

  • Lee, Junghyun;Jin, Taeseok
    • Journal of Institute of Control, Robotics and Systems
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    • v.22 no.1
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    • pp.24-30
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    • 2016
  • The accuracy of small and low-cost CCD cameras is insufficient to provide data for precisely tracking unmanned aerial vehicles (UAVs). This study shows how a quad rotor UAV can hover on a human targeted tracking object by using data from a CCD camera rather than imprecise GPS data. To realize this, quadcopter UAVs need to recognize their position and posture in known environments as well as unknown environments. Moreover, it is necessary for their localization to occur naturally. It is desirable for UAVs to estimate their position by solving uncertainty for quadcopter UAV hovering, as this is one of the most important problems. In this paper, we describe a method for determining the altitude of a quadcopter UAV using image information of a moving object like a walking human. This method combines the observed position from GPS sensors and the estimated position from images captured by a fixed camera to localize a UAV. Using the a priori known path of a quadcopter UAV in the world coordinates and a perspective camera model, we derive the geometric constraint equations that represent the relation between image frame coordinates for a moving object and the estimated quadcopter UAV's altitude. Since the equations are based on the geometric constraint equation, measurement error may exist all the time. The proposed method utilizes the error between the observed and estimated image coordinates to localize the quadcopter UAV. The Kalman filter scheme is applied for this method. Its performance is verified by a computer simulation and experiments.

A Study on the Safe Separation of En-route Airway under altitude of 500 ft for the Flight Safety of Small UAVs (소형무인기 저고도 안전 비행을 위한 순항 경로 분리 간격 고찰)

  • Bae, Jung-Won;Lee, Sang-Jeong
    • 한국항공운항학회:학술대회논문집
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    • 2016.05a
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    • pp.39-47
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    • 2016
  • 150미터(500피트) 이하의 공역에서 무인기 택배 등의 활용을 목적으로 고속 비행이 요구되는 소형무인기(드론)의 순항을 가정하여 안전 분리 간격을 고려한 고속 비행 공역을 제안하고, 해당 경로에서 무인기간의 충돌방지를 위한 항법시스템의 성능요구조건과 안전한 분리 간격에 대한 선행 연구 분석과 고찰 결과를 제시한다.

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Development of AR.Drone's Controller for the Indoor Swarm Flight (실내 군집비행을 위한 AR.Drone의 제어기 개발)

  • Cho, Dong-Hyu;Moon, SungTae;Rew, DongYoung
    • Aerospace Engineering and Technology
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    • v.13 no.1
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    • pp.153-165
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    • 2014
  • Multi-rotor UAVs are utilized in various fields because of the advantages such that a hovering capability such as helicopters, a simple structure and a relatively high thrust. Recently, AR.Drone manufactured by Parrot is easily operated by beginner due to its internal stabilization loop in the on-board computer and it can be easily applied on various researches for the multi-rotor UAVs by providing an SDK(Software Development Kit). Further this platform can be suitably used for application to swarm flight since it is low cost and relatively small. Therefore, in this paper, we introduce the development process of the controller for indoor swarm flight by using the AR.Drone.

Design of Decentralized Guidance Algorithm for Swarm Flight of Fixed-Wing Unmanned Aerial Vehicles (고정익 소형무인기 군집비행을 위한 분산형 유도 알고리듬 설계)

  • Jeong, Junho;Myung, Hyunsam;Kim, Dowan;Lim, Heungsik
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.12
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    • pp.981-988
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    • 2021
  • This paper presents a decentralized guidance algorithm for swarm flight of fixed-wing UAVs (Unmanned Aerial Vehicles). Considering swarm flight missions, we assume four representative swarm tasks: gathering, loitering, waypoint/path following, and individual task. Those tasks require several distinct maneuvers such as path following, flocking, and collision avoidance. In order to deal with the required maneuvers, this paper proposes an integrated guidance algorithm based on vector field, augmented Cucker-Smale model, and potential field methods. Integrated guidance command is synthesized with heuristic weights designed for each guidance method. The proposed algorithm is verified through flight tests using up to 19 small fixed-wing UAVs.