Signal Processing for a Laser Based Air Data System in Commercial Aircrafts (original) (raw)
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Airborne laser sensors and integrated systems
The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the development of such requirements, useful guide lines are provided for test and evaluation of airborne laser systems including laboratory, ground and flight test activities.
Review of Lidar-Based Applications for Aviation Weather
Pure and Applied Geophysics, 2018
Measurements collected by Leosphere Doppler lidars were reviewed to study meteorological processes such as wind shear, wind profiles, gust fronts, and wake vortices over airports. First, the basic concepts of lidar are discussed, then its use for wind environments with respect to high-impact weather events is presented. Issues related to previous definitions of wind-related algorithms and criteria are summarized to validate the use of Doppler lidar for clear-air environmental conditions. Based on International Civil Aviation Organization (ICAO) criteria that use a 500-m height threshold in the vertical for wind warning conditions, this work suggests that use of Doppler lidars can significantly improve the safety of flight environments along landing and takeoff corridors at airports by providing warnings to pilots and ground crew and optimizing air-traffic management. The wind measurements from the lidars are found to be accurate to 0.1 m s-1 , and use of Doppler lidars can increase the probability of detection of wind-related severe weather conditions by up to 50% beyond the 500 m of the atmospheric boundary layer (ABL).
A simulation tool for a laser based air traffic management system
2009
Abstract:-Laser detection and tracking of aircrafts based systems (LIDARs, LIgth Detection And Ranging systems) are emerging as a critical design trend in development of new generation ATM (Air Traffic Management) paradigms, of which they are the main innovations. A novel laser tracking technology (SKY-Scanner System) capable to detect and track of aircrafts up to at least 6 nautical miles from the Aerodrome Traffic Zone (ATZ) has been proposed.
ABLE: Development of an Airborne Lidar
Journal of Atmospheric and Oceanic Technology, 1999
The acronym ABLE (Airborne Lidar Experiment) identifies a project to develop and fly an optical radar on a stratospheric platform for studies related to atmospheric radiation and composition. The prototype, ABLE 1, has been successfully flown on board the M55 Geophysica aircraft in the Arctic campaign of December 1996-January 1997 to observe stratospheric clouds and aerosol. The lidar, which runs automatically, has been installed in the unpressurized bay of the aircraft where the temperature approaches the low values of external air. The lidar transmitter is based on a Nd:YAG laser, with second and third harmonic outputs. The receiver consists of a 0.3-m Cassegrain telescope and several detection channels to look at different wavelengths and polarizations. A fluid circulation unit connected to the aircraft provides heating control. The instrument can point to the zenith or to the nadir. In the past campaign only ϭ 532 nm was utilized: observations were carried out at two polarizations, pointing to the zenith. The present status of the device and foreseeable developments are described.
Atmospheric Measurement Techniques, 2014
A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s −1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents) that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 • C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.
Advanced concept for air data system using EBF and Lidar
We describe here two innovative in-flight measurement techniques for onboard operation on atmospheric re-entry demonstrator vehicles like EXPERT or pre-X actually in study in Europe. The first one is the Electron Beam Fluorescence (EBF) technique which aims at characterising shock layer chemistry through measurements of density, rotational and vibrational temperatures of N 2 and NO in low density hypersonic flows. These data are of great importance for the validation of the modelling tools commonly used for aerothermodynamics simulations, since they include a variety of thermo-chemical models yet to be fully validated with relevant flight data. The second measurement technique is a short range Rayleigh Lidar for measurements of upstream total density which is a primary variable in many aerodynamic key features like forces or heat flux.
Modern photogrammetry and remote sensing have found small Unmanned Aerial Vehicles (UAVs) to be a valuable source of data in various branches of science and industry (e.g., agriculture, cultural heritage). Recently, the growing role of laser scanning in the application of UAVs has also been observed. Laser scanners dedicated to UAVs consist of four basic components: a laser scanner (LiDAR), an Inertial Measurement Unit (IMU), a Global Navigation Satellite System (GNSS) receiver and an on-board computer. The producers of the system provide users with detailed descriptions of the accuracies separately for each component. However, the final measurement accuracy is not given. This paper reviews state-of-the-art of laser scanners developed specifically for use on a UAV, presenting an overview of several constructions that are available nowadays. The second part of the paper is focussed on analysing the influence of the sensor accuracies on the final measurement accuracy. Mathematical models developed for Airborne Laser Scanning (ALS) accuracy analyses are used to estimate the theoretical accuracies of different scanners with conditions typical for UAV missions. Finally, the theoretical results derived from the mathematical simulations are compared with an experimental use case.