Airborne forward pointing UV Rayleigh lidar for remote clear air turbulence (CAT) detection: system design and performance

A high-performance airborne UV Rayleigh lidar system was developed within the European project DELICAT. With its forward-pointing architecture it aims at demonstrating a novel detection scheme for clear air turbulence (CAT) for an aeronautics safety application. Due to its occurrence in clear and clean air at high altitudes (aviation cruise flight level), this type of turbulence evades microwave radar techniques and in most cases coherent Doppler lidar techniques. The present lidar detection technique relies on air density fluctuations measurement and is thus independent of backscatter from hydrometeors and aerosol particles. The subtle air density fluctuations caused by the turbulent air flow demand exceptionally high stability of the setup and in particular of the detection system. This paper describes an airborne test system for the purpose of demonstrating this technology and turbulence detection method: a high-power UV Rayleigh lidar system is installed on a research aircraft in a forward-looking configuration for use in cruise flight altitudes. Flight test measurements demonstrate this unique lidar system being able to resolve air density fluctuations occurring in light-to-moderate CAT at 5 km or moderate CAT at 10 km distance. A scaling of the determined stability and noise characteristics shows that such performance is adequate for an application in commercial air transport.Comment: 17 pages, 19 figures. Pre-publish to Applied Optics (OSA

Localization in Unstructured Environments: Towards Autonomous Robots in Forests with Delaunay Triangulation

Autonomous harvesting and transportation is a long-term goal of the forest industry. One of the main challenges is the accurate localization of both vehicles and trees in a forest. Forests are unstructured environments where it is difficult to find a group of significant landmarks for current fast feature-based place recognition algorithms. This paper proposes a novel approach where local observations are matched to a general tree map using the Delaunay triangularization as the representation format. Instead of point cloud based matching methods, we utilize a topology-based method. First, tree trunk positions are registered at a prior run done by a forest harvester. Second, the resulting map is Delaunay triangularized. Third, a local submap of the autonomous robot is registered, triangularized and matched using triangular similarity maximization to estimate the position of the robot. We test our method on a dataset accumulated from a forestry site at Lieksa, Finland. A total length of 2100\,m of harvester path was recorded by an industrial harvester with a 3D laser scanner and a geolocation unit fixed to the frame. Our experiments show a 12\,cm s.t.d. in the location accuracy and with real-time data processing for speeds not exceeding 0.5\,m/s. The accuracy and speed limit is realistic during forest operations

Real-Time Digital Simulators: A Comprehensive Study on System Overview, Application, and Importance

The multifarious improvements in computational and simulation tools have brought tremendous progress in the field of designing, testing and analyzing technologies. In this paper, the technological aspects and the concept of modern real-time digital simulators are presented. The real-time simulator functions in real time, thus it produces continuous output that realistically represents the conditions of a real system. Also, in a real-time simulator the user can test physical devices. Therefore, it is of great importance to understand the features and roles of the advanced simulator technologies. Also, User-friendly system interface, easy application in system design and testing, and most importantly cost effectiveness are the most desire features for implying these simulator into a research. Therefore, this paper summarizes all significant features by considering the above-mentioned facts of some most popular, globally, and commercially available simulator technologies. Real Time Digital Simulators (RTDS), OPAL-RT, Network Torsion Machine Control (NETOMAC), dSPACE, Real-Time solution by MathWorks (xPC target, Real-Time Windows target), Power_system Online_simulation Unveil Your Analysis (POUYA) Simulator and Typhoon HIL Simulator are discussed in this review paper based on the accessibility of information. A summarization of these simulators’ background, hardware, software and communication protocols are presented. Applications of these above-mentioned simulators are also added to understand the potentials of these simulators

Fast Ground Filtering of Airborne LiDAR Data Based on Iterative Scan-Line Spline Interpolation

Over the last two decades, a wide range of applications have been developed from Light Detection and Ranging (LiDAR) point clouds. Most LiDAR-derived products require the distinction between ground and non-ground points. Because of this, ground filtering its being one of the most studied topics in the literature and robust methods are nowadays available. However, these methods have been designed to work with offline data and they are generally not well suited for real-time scenarios. Aiming to address this issue, this paper proposes an efficient method for ground filtering of airborne LiDAR data based on scan-line processing. In our proposal, an iterative 1-D spline interpolation is performed in each scan line sequentially. The final spline knots of a scan line are taken into account for the next scan line, so that valuable 2-D information is also considered without compromising computational efficiency. Points are labelled into ground and non-ground by analysing their residuals to the final spline. When tested against synthetic ground truth, the method yields a mean kappa value of 88.59% and a mean total error of 0.50%. Experiments with real data also show satisfactory results under visual inspection. Performance tests on a workstation show that the method can process up to 1 million points per second. The original implementation was ported into a low-cost development board to demonstrate its feasibility to run in embedded systems, where throughput was improved by using programmable logic hardware acceleration. Analysis shows that real-time filtering is possible in a high-end board prototype, as it can process the amount of points per second that current lightweight scanners acquire with low-energy consumptionThis work was supported by the Ministry of Education, Culture, and Sport, Government of Spain (Grant Number TIN2016-76373-P), the Consellería de Cultura, Educación e Ordenación Universitaria (accreditation 2016–2019, ED431G/08, and ED431C 2018/2019), and the European Union (European Regional Development Fund—ERDF)S

Low Cost and Flexible UAV Deployment of Sensors

This paper presents a platform for airborne sensor applications using low-cost, open-source components carried by an easy-to-fly unmanned aircraft vehicle (UAV). The system, available in open-source , is designed for researchers, students and makers for a broad range of exploration and data-collection needs. The main contribution is the extensible architecture for modularized airborne sensor deployment and real-time data visualisation. Our open-source Android application provides data collection, flight path definition and map tools. Total cost of the system is below 800 dollars. The flexibility of the system is illustrated by mapping the location of Bluetooth beacons (iBeacons) on a ground field and by measuring water temperature in a lake

The AMMA mulid network for aerosol characterization in West Africa

Three ground based portable low power consumption microlidars (MULID) have been built and deployed at three remote sites in Banizoumbou (Niger), Cinzana (Mali) and M'Bour (Senegal) in the framework of the African Monsoon Multidisciplinary Analyses (AMMA) project for the characterization of aerosols optical properties. A description of the instrument and a discussion of the data inversion method, including a careful analysis of measurement uncertainties (systematic and statistical errors) are presented. Some case studies of typical lidar profiles observed over the Banizoumbou site during 2006 are shown and discussed with respect to the AERONET 7-day back-trajectories and the biomass burning emissions from the Combustion Emission database for the AMMA campaign

development of a software to optimize and plan the acquisitions from uav and a first application in a post seismic environment

AbstractAn Unmanned Aerial Vehicle (UAV) is an aircraft without a human pilot on board. UAVs allow close-range photogrammetric acquisitions potentially useful for building large-scale cartography and acquisitions of building geometry. This is particularly useful in emergency situations where major accessibility problems limit the possibility of using conventional surveys. Presently, however, flights of this class of UAV are planned based only on the pilot's experience and they often acquire three or more times the number of images needed. This is clearly a time-consuming and autonomy-reducing procedure, which is certainly detrimental when extensive surveys are needed. For this reason new software, to plan the UAV's survey will be illustrated

From Simulation to Runtime Verification and Back: Connecting Single-Run Verification Techniques

Modern safety-critical systems, such as aircraft and spacecraft, crucially depend on rigorous verification, from design time to runtime. Simulation is a highly-developed, time-honored design-time verification technique, whereas runtime verification is a much younger outgrowth from modern complex systems that both enable embedding analysis on-board and require mission-time verification, e.g., for flight certification. While the attributes of simulation are well-defined, the vocabulary of runtime verification is still being formed; both are active research areas needed to ensure safety and security. This invited paper explores the connections and differences between simulation and runtime verification and poses open research questions regarding how each might be used to advance past bottlenecks in the other. We unify their vocabulary, list their commonalities and contrasts, and examine how their artifacts may be connected to push the state of the art of what we can (safely) fly