Flight Trials Research Articles

Design and Experimental Validation of a Robust Output Feedback Control for the Coupled Dynamics of a Micro Air Vehicle

This paper addresses the design and experimental validation of a linear robust static output feedback controller for a 150 mm span fixed wing micro air vehicle (MAV). Severe coupling between longitudinal and lateral dynamics of the MAV lead to the design of a multivariable controller for the combined dynamics. The control design problem is posed in the framework of static output feedback (SOF) due to the inexpensive computational requirements for implementation. The multiobjective control design problem including stability requirements, closed loop damping ratio requirements and H∞ norm minimization is solved using the hybrid technique of linear matrix inequalities (LMI) and genetic algorithm (GA). The design is carried out in the discrete time domain, facilitating in direct implementation of the multivariable controller in the onboard autopilot hardware. The robustness of the resulting closed loop system under parametric uncertainties is evaluated using structured singular value analysis. The effectiveness of the proposed controller is demonstrated through outdoor flight trial of the micro air vehicle with a customized lightweight autopilot hardware.

Raptor selection of captive reared and released Galliform birds

ABSTRACTCaptive rearing and release of birds in the order Galliformes remains a popular management tactic despite low survival rates. We investigated avian predator selection of captive‐reared northern bobwhites (Colinus virginianus) as a potential driver of their high mortality. We simulated avian predator hunts on a flushing pair of bobwhites during trials conducted from 6 February 2015 to 14 February 2015 in Texas, USA. When presented a choice of a captive‐reared bobwhite or wild bobwhite, a Harris's hawk (Parabuteo unicinctus) pursued a captive‐reared bobwhite in 8 of 10 flight trials. This selective rate, combined with observations from auxiliary research indicate avian predation may be a greater risk for captive‐reared birds than wild birds. The success of captive‐rearing and release efforts may benefit from a better understanding of how to more adequately prepare captive‐reared birds for release. © 2018 The Wildlife Society.

Trial protocol: a multicentre randomised trial of first-line treatment pathways for newly diagnosed immune thrombocytopenia: standard steroid treatment versus combined steroid and mycophenolate. The FLIGHT trial

IntroductionImmune thrombocytopenia (ITP) is an autoimmune condition that may cause thrombocytopenia-related bleeding. Current first-line ITP treatment is with high-dose corticosteroids but frequent side effects, heterogeneous responses and high relapse rates...

Reflector Localization for Geometrical Modeling the Air–Ground Channel

In the air–ground propagation channel, multipath propagation severely affects the performance of the communication, navigation, and surveillance systems used in civil aviation. To gain a deeper understanding of the air–ground channel, we are interested in the locations of objects causing multipath propagation. Therefore, in this paper we propose and experimentally validate an algorithm to localize reflectors causing multipath components based on channel sounding data collected using omnidirectional antennas. The algorithm relies on superresolution parameter estimation and tracking as well as on a localization algorithm. Using both simulations and channel sounding data collected from flight trials, we demonstrate the ability to reliably localize the reflectors causing multipath components.

Insect pollination as an agronomic input: Strategies for oilseed rape production

Abstract Ecological intensification involves the incorporation of biodiversity‐based ecosystem service management into farming systems in order to make crop production more sustainable and reduce reliance on anthropogenic inputs, including fertilizer and insecticides. The benefits of effectively managing ecosystem services such as pollination and pest regulation for improved yields have been demonstrated in a number of studies, however, recent evidence indicates that these benefits interact with conventional agronomic inputs such as fertilizer and irrigation. Despite the important contribution of biodiversity‐based ecosystem services to crop production their management is rarely considered in combination with more conventional agronomic inputs. This study combines a number of complementary approaches to evaluate the impact of insect pollination on yield parameters of Brassica napus and how this interacts with a key agronomic input, fertilizer. We incorporate data from a flight cage trial and multiple field studies to quantify the relationships between yield parameters to determine whether insufficient insect pollination may limit crop yield. We demonstrate that, by producing larger seeds and more pods, B. napus has the capacity to modulate investment across yield parameters and buffer sub‐optimal inputs of fertilizer or pollination. However, only when fertilizer is not limiting can the crop benefit from insect pollination, with yield increases due to insect pollination only seen under high fertilizer application. A nonlinear relationship between seed set per pod and yield per plant was found, with increases in seed set between 15 and 25 seeds per pod resulting in a consistent increase in crop yield. The capacity for the crop to compensate for lower seed set due to sub‐optimal pollination is therefore limited. Synthesis and applications. Oilseed rape has the capacity to compensate for sub‐optimal agronomic or ecosystem service inputs although this has limitations. Insect pollination can increase seed set and so there are production benefits to be gained through effective management of wild pollinators or by utilizing managed species. Our study demonstrates, however, that increased insect pollination cannot simply replace other inputs, and if resources such as fertilizer are limiting, then yield potential cannot be reached. We highlight the need to consider insect pollination as an agronomic input to be effectively managed in agricultural systems.

Modeling and Closed Loop Flight Testing of a Fixed Wing Micro Air Vehicle.

This paper presents the nonlinear six degrees of freedom dynamic modeling of a fixed wing micro air vehicle. The static derivatives of the micro air vehicle are obtained through the wind tunnel testing. The propeller effects on the lift, drag, pitching moment and side force are quantified through wind tunnel testing. The dynamic derivatives are obtained through empirical relations available in the literature. The trim conditions are computed for a straight and constant altitude flight condition. The linearized longitudinal and lateral state space models are obtained about trim conditions. The variations in short period mode, phugoid mode, Dutch roll mode, roll subsidence mode and spiral mode with respect to different trim operating conditions is presented. A stabilizing static output feedback controller is designed using the obtained model. Successful closed loop flight trials are conducted with the static output feedback controller.

Design of an Attachment Scheme of a Vehicle to a Typical Fighter Aircraft

Design of an attachment scheme of a flight vehicle to a fighter aircraft is a critical task. Here, flight vehicle is a cylindrical body and it is attached to fighter aircraft with the help of a component called launch lug. Loads experienced by the flight vehicle in captive condition have been estimated by using aircraft parameters obtained during previous missions of similar kind of vehicles. This paper provides state of the art design consideration of the attachment scheme (launch lug and shell assembly) of the flight vehicle to the fighter aircraft. The structural integrity of the flight vehicle and its attachments scheme to the fighter aircraft has been verified at various aircraft manoeuvring conditions in its flight envelope through analysis. Design is verified using laboratory testing and in field trials. Finally this flight vehicle with the attachment scheme was used in flight trials.

Automation of Combinatorial Interaction Test (CIT) Case Generation and Execution for Requirements based Testing (RBT) of Complex Avionics Systems

In the field of avionics, most of the software systems are either safety critical or mission critical. These systems are developed with high quality standards strictly following the relevant guidelines and procedures. Due to the high criticality of the systems, it is mandatory that the verification and validation of these systems are done with utmost importance and only then any system is cleared for flight trials. The verification and validation activities need to be very exhaustive and hence take a considerable amount of time in the software development lifecycle. This paper describes about the innovative approach towards automation of Combinatorial Interaction Test case generation and execution for Requirements Based Testing of complex avionics systems for achieving test adequacy in a highly time efficient and cost efficient manner.

A virtual engineering approach to the ship-helicopter dynamic interface – a decade of modelling and simulation research at the University of Liverpool

ABSTRACTThis paper reviews some of the research that has been carried out at the University of Liverpool where the Flight Science and Technology Research Group has developed its Heliflight-R full-motion research simulator to create a simulation environment for the launch and recovery of maritime helicopters to ships. HELIFLIGHT-R has been used to conduct flight trials to produce simulated Ship-Helicopter Operating Limits (SHOLs). This virtual engineering approach has led to a much greater understanding of how the dynamic interface between the ship and the helicopter contributes to the pilot's workload and the aircraft's handling qualities and will inform the conduct of future real-world SHOL trials. The paper also describes how modelling and simulation has been applied to the design of a ship's superstructure to improve the aerodynamic flow field in which the helicopter has to operate. The superstructure aerodynamics also affects the placement of the ship's anemometers and the dispersion of the ship's hot exhaust gases, both of which affect the operational envelope of the helicopter, and both of which can be investigated through simulation.

Maritime flight trials of the Southampton University laser sintered aircraft–Project Albatross

ABSTRACTAs part of the ongoing development of small unmanned air systems by the University of Southampton, an all laser sintered aircraft has been test flown from the Royal Navy's ice patrol ship HMS Protector to assist with navigating through the Antarctic. These flights were carried out with pre-planned autopilot control with oversight from Andrew Lock, acting as the pilot embarked on HMS Protector. This is the first time the Royal Navy has used unmanned aerial vehicles in this part of the world. In this paper, we set out the trial reports and lessons learnt from this series of test flights.

電離圏異常環境でのGNSSデータ取得飛行実験について( GPS/GNSS研究会)

電離圏異常環境でのGNSSデータ取得飛行実験について( GPS/GNSS研究会)

Dispersion sensitivity analysis & consistency improvement of APFSDS

Abstract The purpose of this study is to investigate and quantify some possible sources of dispersion of 120 mm APFSDS tank ammunition both experimentally and numerically. This paper aims to point out the most influential source during In-Bore Balloting Motion phase as well as in External Ballistics phase of the ammunition and quantifies its effect on dispersion. Data obtained from flight trials is critically analysed and parameters affecting dispersion such as initial yaw/pitch rates, yaw/pitch dampening, plane start angle, launch spin, clearance, centre of gravity shift, dynamic imbalance angle, cross wind, etc. are observed and, later on, studied in detail by extensive External Ballistics Monte Carlo (EBMC) simulation and Six Degree of Freedom (6-DOF) trajectory analysis. In Bore Balloting Motion simulation shows that reduction in residual spin by about 5% results in drastic 56% reduction in first maximum yaw. A correlation between first maximum yaw and residual spin is observed. Results of data analysis are used in design modification for existing ammunition. Number of designs are evaluated numerically before freezing five designs for further soundings. These designs are critically assessed in terms of their comparative performance during In-bore travel & external ballistics phase. Results are validated by free flight trials for the finalised design.

Flight Capacity of the Walnut Twig Beetle (Coleoptera: Scolytidae) on a Laboratory Flight Mill.

The walnut twig beetle, Pityophthorus juglandis Blackman, and associated fungus Geosmithia morbida Kolařík, Freeland, Utley, & Tisserat constitute the insect-fungal complex that causes thousand cankers disease in walnut, Juglans spp., and wingnut, Pterocarya spp. Thousand cankers disease is responsible for the decline of Juglans species throughout the western United States and more recently, the eastern United States and northern Italy. We examined the flight capacity of P. juglandis over 24-h trials on a flight mill in the laboratory. The maximum total flight distance observed was ∼3.6 km in 24 h; however, the mean and median distances flown by beetles that initiated flight were ∼372 m and ∼158 m, respectively. Beetles flew for 34 min on average within a 24-h flight trial. Male and female flight capacities were similar, even though males were larger than females (0.64 vs. 0.57 mm pronotal width). Age postemergence had no effect on flight distance, flight time, or mean flight velocity. The propensity to fly, however, decreased with age. We integrated results of flight distance with propensity to fly as beetles aged in a Monte Carlo simulation to estimate the maximum dispersal capacity over 5 d, assuming no mortality. Only 1% of the insects would be expected to fly >2 km, whereas one-third of the insects were estimated to fly <100 m. These results suggest that nascent establishments remain relatively localized without anthropogenic transport or wind-aided dispersal, which has implications for management and sampling of this hardwood pest.

Quadcopter applications for wildlife monitoring

Recently, Unmanned Aerial Vehicle (UAV) had been use as an instrument for wildlife research. Most of that, using an airplane type which need space for runaway. Copter is UAV type that can fly at canopy space and do not need runaway. The research aims are to examine quadcopter application for wildlife monitoring, measure the accuracy of data generated and determine effective, efficient and appropriate technical recommendation in accordance with the ethics of wildlife photography. Flight trials with a camera 12 - 24 MP at altitude ranges from 50-200 m above ground level (agl), producing aerial photographs with spatial resolution of 0.85 – 4.79 cm/pixel. Aerial photos quality depends on the type and setting of camera, vibration damper system, flight altitude and punctuality of the shooting. For wildlife monitoring the copter is recommended to take off at least 300 m from the target, and flies at 50 - 100 m agl with flight speed of 5 - 7 m/sec on fine weather. Quadcopter presence with a distance more than 30 m from White-bellied Sea Eagles (Haliaeetus leucogaster) nest and Proboscis Monkey (Nasalis larvatus) did not cause negative response. Quadcopter application should pay attention to the behaviour and characteristic of wildlife.

Behavioral evidence for a magnetic sense in the oriental armyworm, Mythimna separata.

ABSTRACTProgress has been made in understanding the mechanisms underlying directional navigation in migratory insects, yet the magnetic compass involved has not been fully elucidated. Here we developed a flight simulation system to study the flight directionality of the migratory armyworm Mythimna separata in response to magnetic fields. Armyworm moths were exposed to either a 500 nT extreme weak magnetic field, 1.8 T strong magnetic field, or a deflecting magnetic field and subjected to tethered flight trials indoors in the dark. The moths were disoriented in the extreme weak magnetic field, with flight vectors that were more dispersed (variance=0.60) than in the geomagnetic field (variance=0.32). After exposure to a 1.8 T strong magnetic field, the mean flight vectors were shifted by about 105° in comparison with those in the geomagnetic field. In the deflecting magnetic field, the flight directions varied with the direction of the magnetic field, and also pointed to the same direction of the magnetic field. In the south-north magnetic field and the east-west field, the flight angles were determined to be 98.9° and 166.3°, respectively, and formed the included angles of 12.66° or 6.19° to the corresponding magnetic direction. The armyworm moths responded to the change of the intensity and direction of magnetic fields. Such results provide initial indications of the moth reliance on a magnetic compass. The findings support the hypothesis of a magnetic sense used for flight orientation in the armyworm Mythimna separata.

RADI's Airborne X-SAR with High Resolution: Performance, Characterization and Verification

X-SAR is an airborne multi-mode synthetic aperture radar (SAR) system with high- resolution, interferometer and full-polarization, developed by the Institute of Remote Sensing and Digital Earth (RADI), Chinese Academy of Sciences (CAS), funded by the CAS Large Research Infrastructures. Since 2009, the first developed stage of X-SAR system was successfully implemented to an operational SAR with high resolution (up to 0.5 meter). In May 2013, the imaging verification on flights test was carried out. The data calibration on the laboratory measurements were completed at the end of 2015. Many valuable results of imaging verification and data calibration have emphasized the quantitative microwave measurement capabilities. This paper presents the results of X-SAR system performance, characterization, optimization, and verification as carried out during the flight trials and laboratory measurement. The system performance and calibration parameters are presented such as transmitter amplitude accuracy, phase noise, system gain change with temperature variation, long-term radiometric stability. The imaging verification of the key performance parameters is discussed, including target-response function, target pairs discrimination, image noise and radiometric resolution. The example imagery of radiometric enhanced products for intensity change detection is also described.

Measurement of the l-band air-to-ground channel for positioning applications

In the paper, we present results from flight trials conducted to investigate the characteristics of the L-band air-to-ground radio channel for positioning applications. We discuss the employed hardware setup, synchronization concept, calibration procedures, and investigated flight patterns. It is shown that the setup is suitable for investigating both multipath structure and absolute propagation time of the radio signals. The power delay and Doppler power profiles, as well as the time-of-arrival estimation accuracy, are presented. Manuscript

Flight Test Assessments of Pilot Workload, System Usability, and Situation Awareness of Tasar

Traffic Aware Strategic Aircrew Requests (TASAR) is a NASA-developed on-board automation concept intended to identify trajectory improvement opportunities clear of known traffic, weather, and airspace restrictions prior to the aircrew initiating a trajectory-change request to Air Traffic Control (ATC). The software implementation of the TASAR concept is the Traffic Aware Planner (TAP). A flight trial was conducted with commercial airline pilots flying in a Piaggio Avanti flight test aircraft, with the TAP software installed onboard. This paper focuses on the results of the subjective assessments of pilots collected during this flight trial, specifically, pilot workload, situation awareness, and system usability. These data were subjected to statistical analyses, and the results generally indicate the following: there were no statistical differences for any measure as a function of pilot position in the aircraft; pilot cognitive workload was reported as low; and system usability ratings were reported as high. Generally, ratings of comprehensibility, usefulness, and usability of TAP’s human machine interface (HMI) and features were high. These results will be used to further refine and improve the capabilities and features of the TAP HMI in preparation for operational use with NASA partner airlines.

Demonstration of the Traffic Aware Planner

NASA has been developing and testing the Traffic Aware Strategic Aircrew Requests (TASAR) concept for aircraft operations featuring a NASA-developed cockpit automation tool, the Traffic Aware Planner (TAP), which computes traffic/hazard-compatible route changes to improve flight efficiency. The TAP technology is anticipated to save fuel and flight time and thereby provide immediate and pervasive benefits to the aircraft operator, as well as improving flight schedule compliance, passenger comfort, and pilot and controller work-load. Previous work has indicated the potential for significant benefits for TASAR-equipped aircraft, and a flight trial of the TAP software application in the National Airspace System has demonstrated its technical viability. As part of ongoing software research, development, and testing of the TAP software, we developed the capability to run the current build of the TAP software using the NASA Airspace and Traffic Operations Simulator (ATOS) with preloaded flight scenarios. Our demonstration is fully interactive and will allow participants to operate the TAP software on an iPad Air themselves, or observe the demonstrators operating it. The purpose of developing this capability is not only to assist with testing during software development, but also to acquaint researchers and potential stakeholders with the TAP human machine interface and the functionality and capabilities of the software itself.

Vibration detection with 100 Hz GPS PVAT during a dynamic flight

This investigation gives insights into real 100Hz GPS velocity and acceleration estimates from a position, velocity, acceleration and time (PVAT) extended Kalman filter (EKF) during a highly dynamic flight trial with a Dornier Do 128-6 aircraft. We investigated the accelerations during take-off, landing and wing shaking manoeuvres in order to compare the vibration behaviour of the given aircraft determined by means of GPS against an onboard IMU. We found that 100Hz GPS acceleration is useful for characterising vibrations and giving valuable insights during highly dynamic flights. Potential latency of 0.12s and amplitude misestimation of up to 80% w.r.t. the reference amplitude occur that should be determined beforehand in order to correctly interpret the results.