摘要 :
Recent world events have highlighted that the proliferation of UAVs is bringing with it a new and rapidly increasing threat for national defense and security agencies. Whilst many of the reported UAV incidents seem to indicate tha...
展开
Recent world events have highlighted that the proliferation of UAVs is bringing with it a new and rapidly increasing threat for national defense and security agencies. Whilst many of the reported UAV incidents seem to indicate that there was no terrorist intent behind them, it is not unreasonable to assume that it may not be long before UAV platforms are regularly employed by terrorists or other criminal organizations. The flight characteristics of many of these mini- and micro-platforms present challenges for current systems which have been optimized over time to defend against the traditional air-breathing airborne platforms. A lot of programs to identify cost-effective measures for the detection, classification, tracking and neutralization have begun in the recent past. In this paper, ISL shows how the performance of a UAV detection and tracking concept based on acousto-optical technology can be powerfully increased through active imaging.
收起
摘要 :
Recent world events have highlighted that the proliferation of UAVs is bringing with it a new and rapidly increasing threat for national defense and security agencies. Whilst many of the reported UAV incidents seem to indicate tha...
展开
Recent world events have highlighted that the proliferation of UAVs is bringing with it a new and rapidly increasing threat for national defense and security agencies. Whilst many of the reported UAV incidents seem to indicate that there was no terrorist intent behind them, it is not unreasonable to assume that it may not be long before UAV platforms are regularly employed by terrorists or other criminal organizations. The flight characteristics of many of these mini- and micro-platforms present challenges for current systems which have been optimized over time to defend against the traditional air-breathing airborne platforms. A lot of programs to identify cost-effective measures for the detection, classification, tracking and neutralization have begun in the recent past. In this paper, ISL shows how the performance of a UAV detection and tracking concept based on acousto-optical technology can be powerfully increased through active imaging.
收起
摘要 :
Many state-of-the-art motion planning algorithms for UAVs rely on a simple kinematic model of aircraft dynamics, which is often referred to as Dubins vehicle model. On the other hand, Commercial Off-The Shelf (COTS) autopilots do ...
展开
Many state-of-the-art motion planning algorithms for UAVs rely on a simple kinematic model of aircraft dynamics, which is often referred to as Dubins vehicle model. On the other hand, Commercial Off-The Shelf (COTS) autopilots do not use such a model, and often only provide simpler capabilities such as waypoint navigation, or, altitude, speed, and turn rate hold. In this paper, in order to eliminate this gap, we describe an approach designed for implementation of controllers desgined for Dubins vehicles on a class of COTS autopilots. Given an open loop controller for a Dubins vehicle together with corresponding Dubins trajectory, we present an approach that uses output tracking to implement the open loop controller using the COTS autopilot closed-loop interface. The autopilots are modeled as black boxes accepting different sets of user inputs under different modes of operation. By choosing inputs to autopilots based on observed outputs, the autopilots track a pre-designed Dubins vehicle trajectory. Experimental results comparing the Dubins trajectory to the autopilot trajectory are presented. The approach provides an efficient way for systematic implementation of cooperative control algorithms on unmanned air vehicles without sacrificing their correctness or performance. The end result are the algorithms that work well in practice on UAVs using COTS autopilots and at the same time can be analyzed theoretically.
收起
摘要 :
This paper presents the design of the small-scale hand-launchable solar-powered AtlantikSolar UAV, summarizes flight results of a continuous 28-hour solar-powered flight that demonstrated AtlantikSolar's capability for energetical...
展开
This paper presents the design of the small-scale hand-launchable solar-powered AtlantikSolar UAV, summarizes flight results of a continuous 28-hour solar-powered flight that demonstrated AtlantikSolar's capability for energetically perpetual flight, and offers a model-based verification of flight performance and an outlook on the energetic margins that can be provided towards perpetual flight given today's solar-powered UAV technology. AtlantikSolar is a 5.6m-wingspan and 6.9kg mass low-altitude long-endurance UAV that was designed to provide perpetual endurance at a geographic latitude of 45N in a 4-month window centered around June 21st. A specific design emphasis is robust perpetual endurance with respect to local meteorological disturbances (e.g. clouds, winds, downdrafts). Providing the necessary energetic safety margins is a significant challenge on small-scale solar-powered UAVs. This paper thus describes the design optimizations undertaken on the AtlantikSolar UAV for maximum energetic safety margins. In addition, this paper presents the flight test results, analysis and performance verification of AtlantikSolar's first perpetual endurance continuous 28-hour flight. The flight results show a minimum state-of-charge of 40% or excess time of 7 hours during the night. In addition, the charge margin of 5.9 hours indicates sufficiently-fast battery charging during the day. Both margins exceed the performance of previously demonstrated solar-powered LALE UAVs. Another centerpiece of the paper is the verification of these flight results with the theoretical structural-, aerodynamics- and power-models that were developed and used to conceptually design the UAV. The solar-power income model is extended to take into account solar-panel temperature effects, the exact aircraft geometry and the current orientation and is compared against flight results. Finally, the paper provides an analysis and overview into under what conditions and with which energetic margins perpetual flight is possible with today's battery- and solar-cell technology. A perpetual endurance window of up to 6 months around June 21~(st) is predicted at northern latitudes for the AtlantikSolar UAV configuration without payload. A final outlook into first perpetual endurance applications shows that perpetual flight with miniaturized sensing payloads (small optical and infrared cameras) is possible with a perpetual flight window of 4-5 months.
收起
摘要 :
This study addresses an operation of unmanned aerial vehicles (UAVs) in a network environment where there is time-varying network delay. The network delay entails undesirable effects on the stability of the UAV control system due ...
展开
This study addresses an operation of unmanned aerial vehicles (UAVs) in a network environment where there is time-varying network delay. The network delay entails undesirable effects on the stability of the UAV control system due to delayed state feedback and outdated control input. Although several networked control algorithms have been proposed to deal with the network delay, most existing studies have assumed that the plant dynamics is known and simple, or the network delay is constant. These assumptions are improper to multirotor-type UAVs because of their nonlinearity and time-sensitive characteristics. To deal with these problems, we propose a networked control system using model predictive control (MPC) designed under the consideration of multirotor characteristics. We also apply a Gaussian process (GP) to learn an unknown nonlinear model, which increases the accuracy of path planning and state estimation. Flight experiments show that the proposed algorithm successfully compensates the network delay and Gaussian process learning improves the UAV's path tracking performance.
收起
摘要 :
Autonomous UAV cinematography is an active research field with exciting potential for the media industry. It bears the promise of greatly facilitating UAV shooting for various applications, while significantly reducing the costs c...
展开
Autonomous UAV cinematography is an active research field with exciting potential for the media industry. It bears the promise of greatly facilitating UAV shooting for various applications, while significantly reducing the costs compared to manual shooting. However, the general problem has not been clearly defined and the challenges arising from current legislation and technology restrictions have not been fully charted. A complete overview of issues related to autonomous UAV cinematography is needed, pertaining to the current situation in the field, so as to guide immediate-future research. The purpose of this paper is to lay exactly this groundwork, with the expectation of providing a global perspective to multiple domain-specific research communities. The outlined issues are partitioned into challenges deriving from ethical/legal/safety considerations and from operational/production requirements. A brief survey of current technological solutions, including their limitations, is also provided for each issue.
收起
摘要 :
We propose Nazr-CNN~1, a deep learning pipeline for object detection and fine-grained classification in images acquired from Unmanned Aerial Vehicles (UAVs) for damage assessment and monitoring. Nazr-CNN consists of two components...
展开
We propose Nazr-CNN~1, a deep learning pipeline for object detection and fine-grained classification in images acquired from Unmanned Aerial Vehicles (UAVs) for damage assessment and monitoring. Nazr-CNN consists of two components. The function of the first component is to localize objects (e.g. houses or infrastructure) in an image by carrying out a pixel-level classification. In the second component, a hidden layer of a Convolutional Neural Network (CNN) is used to encode Fisher Vectors (FV) of the segments generated from the first component in order to help discriminate between different levels of damage. To showcase our approach we use data from UAVs that were deployed to assess the level of damage in the aftermath of a devastating cyclone that hit the island of Vanuatu in 2015. The collected images were labeled by a crowdsourcing effort and the labeling categories consisted of fine-grained levels of damage to built structures. Since our data set is relatively small, a pretrained network for pixel-level classification and FV encoding was used. Nazr-CNN attains promising results both for object detection and damage assessment suggesting that the integrated pipeline is robust in the face of small data sets and labeling errors by annotators. While the focus of Nazr-CNN is on assessment of UAV images in a post-disaster scenario, our solution is general and can be applied in many diverse settings. We show one such case of transfer learning to assess the level of damage in aerial images collected after a typhoon in Philippines.
收起
摘要 :
In this paper we propose a novel numerical approach to the design of smooth trajectories for fixed-wing Unmanned Aerial Vehicles (UAVs) with applications to target tracking of marine vehicles. Given a desired geometric path with r...
展开
In this paper we propose a novel numerical approach to the design of smooth trajectories for fixed-wing Unmanned Aerial Vehicles (UAVs) with applications to target tracking of marine vehicles. Given a desired geometric path with respect to a possible moving target vehicle, we are interested in computing a feasible UAV trajectory that best approximates in L_2 sense the desired geometric moving path with a specified airspeed profile assigned on it. Due to communication range limitations (e.g., the UAV is operating as a wireless communication relay between a target vehicle and a ground station), the UAV trajectory needs to satisfy given path constraints. Space-varying wind is also taken into account. We address this problem by taking a Virtual Target Vehicle (VTV) perspective. We set up a suitable optimal control problem based on the error coordinates between the UAV and the VTV. We solve the optimal control problem numerically by using PRONTO, a very versatile control optimization tool enabling to deal with a wide variety of trajectory functionals and constraints. We provide and discuss numerical computations based on a practical scenario where an Autonomous Surface Vehicle (the target vehicle) transmits data to the UAV which sends them back to a ground station.
收起
摘要 :
Optical flows have great potential for navigation of small or micro unmanned aerial vehicles (UAVs) in GPS-degraded or GPS-denied environments, inspired by the study of the flight of several insects. This paper focuses on a compar...
展开
Optical flows have great potential for navigation of small or micro unmanned aerial vehicles (UAVs) in GPS-degraded or GPS-denied environments, inspired by the study of the flight of several insects. This paper focuses on a comparative study between optical flow and traditional navigation sensors with validation provided through UAV flight tests. More specifically, optical flow calculated from videos is compared side-by-side with the corresponding combination of GPS velocity, range, and IMU measurements. Scale invariant feature transform (SIFT) algorithm is used to convert camera videos into optical flows due to its stability and robustness for feature extraction purposes. Four basic motions are analyzed through ground tests including two rotational and two translational motions, with rotation axis parallel/orthogonal to optical axis. The UAV flight data are used for comparisons of more general motions. The flight results show that the measured optical flow has a mean error of 1.10/1.16 pixel per frame and a standard deviation of 1.05/1.18 pixel per frame in the longitudinal/lateral direction for a 33.4 millisecond interval (29.97 Hz), using the corresponding combination of GPS/INS/range data as the ground truth.
收起
摘要 :
To expand the operative area for surveillance UAV, we propose the use of a relay UAV. The relay UAV is used as an intermediary node in a communication network: the surveillance UAV transmits data to the relay UAV, which sends it b...
展开
To expand the operative area for surveillance UAV, we propose the use of a relay UAV. The relay UAV is used as an intermediary node in a communication network: the surveillance UAV transmits data to the relay UAV, which sends it back to a ground station. In this exploratory report, we calculate the route for a relay UAV, to ensure communication at certain time points, given the route of the surveillance UAV. The results presented here are preliminary and may be considered a first iteration of ideas and methods.
收起
原文获取