Flight Test Results Research Articles

Thermal Centering Control for Autonomous Soaring; Stability Analysis and Flight Test Results

This paper addresses the challenge of using autonomous soaring gliders to search for and exploit thermal lift to extend the gliders’ endurance. For this purpose, a simple thermal centering controller is proposed. The paper includes theoretical analysis of stability and convergence properties of this controller. Using an exponentialGaussian function to represent the updraft field of a thermal, the Lyapunov type analysis shows the proposed controller to be asymptotically stable and determines its region of attraction. The size of the region of attraction is shown to be a function of the feedback gain that can be adjusted for any given strength and geometry of thermal. The paper additionally presents simulation and flight test results that verify the performance of the proposed controller. The results of the flight trials also confirm the feasibility and effectiveness of using autonomous thermal soaring to extend endurance for unmanned gliders.

Pilot-Involved-Oscillation Suppression Using Low-Order Antiwindup: Flight-Test Evaluation

This paper presents results from the Saturation Alleviation In-Flight Experiment flight-test campaign in which several antiwindup compensators, designed to reduce the adverse effects of rate saturation of the control surfaces, were tested on the Advanced Technologies Testing Aircraft System. The objectives of the tests were twofold: 1) to demonstrate the potential for rigorously designed low-order antiwindup compensators to reduce the pilot-involvedoscillation proneness and to improve the handling qualities of the aircraft and 2) to compare a variety of low-order antiwindup compensators to determine the importance of different design parameters. The antiwindup compensators were assessed based on pilot handling-quality ratings, pilot-involved-oscillation ratings and pilot comments. The flight-test results demonstrated that the low-order antiwindup compensators tested reduced the pilot-involved-oscillation proneness and improved the handling qualities of the aircraft.

Flight Test Results of a Thermoelectric Energy Harvester for Aircraft

The idea of thermoelectric energy harvesting for low-power wireless sensor systems in aircraft and its practical implementation was recently published. The concept of using a thermoelectric generator (TEG) attached to the aircraft inner hull and a thermal storage device to create an artificial temperature gradient at the TEG during take-off and landing from the temperature changes of the fuselage has passed initial tests and is now subject to flight testing. This work presents preflight test results, e.g., vibration and temperature testing of the harvesters, the practical installation of two harvesting devices inside a test plane, and the first test flight results. Several flight cycles with different flight profiles, flight lengths, and outside temperatures have been performed. Although the influence of different flight profiles on the energy output of the harvester can be clearly observed, the results are in good agreement with expectations from numerical simulations with boundary conditions evaluated from initial climate chamber experiments. In addition, the flight test demonstrates that reliable operation of thermoelectric energy harvesting in harsh aircraft environments seems to be feasible, therefore paving the way for realization of energy-autonomous, wireless sensor networks.

비행체 조종면에 작용하는 힌지 모멘트의 시험적 측정 방법 연구

본 논문에서는 비행체 날개의 조종면에 작용하는 힌지 모멘트 분석을 위한 시험적 방법 및 결과를 수록하였다. 비행 공력 하중에 의하여 조종면에 힌지 모멘트가 작용할 경우, 조종면 구동장치에서 측정된 각도와 실제 조종면의 각도 사이에 탄성 변형에 의한 차이가 발생하며, 이 차이를 측정하여 힌지 모멘트로 환산할 수 있다. 이를 위하여 지상에서 조종면 구동장치 시스템의 비틀림 강성을 측정하기 위한 정하중 시험 및 조종면 각도 센서 교정시험을 수행하였다. 이 결과를 이용하여 비행 중 작용하는 힌지 모멘트를 계산할 수 있으며, 또한 체결부위의 미끄러짐 및 백래시 등의 기계적 오차도 예측할 수 있다. 실제 비행시험 결과를 이용하여 조종면에 작용한 힌지 모멘트를 계산한 결과와 수치 해석 결과의 비교를 통하여, 제시된 하중 측정 방법의 타당성을 입증하였다. This paper contains the test method to obtain aerodynamic hinge moments acting on the control surface of air vehicle wing. During the flight, hinge moments make difference between actual control surface angle and control angle which is measured by sensor of actuator. The hinge moments can be obtained by using this difference. Static ground load test and calibration test were conducted to obtain torsional stiffness of control surface actuation system. This results are used to calculate hinge moments. In addition, the mechanical errors of actuation system such as slip angle of mounting point and backlash could be estimated. Using flight test results, this experimental measurement method of hinge moment acting on control surface is conducted. The results of this method are similar to those of numerical simulation method, and the validity of this method is proved.

Fuzzy Model Based Control of Unmanned Aerial Vehicle

The design of fuzzy model based controller with a new analytical inversion method is presented and applied for attitude control problem of Unmanned Aerial Vehicle (UAV). The purpose of adaptive controller is to follow a certain pitch angle command under level flight condition which requires the roll stabilization controller. The Aerosonde simulation model has been chosen to apply the proposed analytical fuzzy model based controller. The simulation results show that both the roll rate and the pitch angles are tracked by the adaptive controller without significant transients. Flight test results for angle of attack control of a fixed wing platform which has been developed at UNSW@ADFA show that the controller is robust to operate in a real time environment.

Flight test results for UAVs using boid guidance algorithms

A critical technology for operating groups of Uninhabited Aerial Vehicles (UAVs) is distributed guidance. Distributed guidance allows an operator to command several vehicles at the same time, reduces operator workload, and adds redundancy to the system. Some of the leading software candidates for achieving distributed guidance are known as Boid Guidance Algorithms (BGAs), which are agent-based techniques relying on the interactions of simple behaviors. Flight tests are crucial to the advancement of flight technologies such as BGAs, and this was identified as an important area for development. This paper presents the results from the 2005 flight tests of BGAs at NASA Dryden Flight Research Center with two RnR Products’ APV-3 UAVs employing CloudCap Technology's Piccolo autopilot system. Major challenges in these flight tests include the use of a waypoint-following system, limited computation resources, and management of safety procedures. The conclusions of this work include the need for using a path-following platform and completion of a full system optimization. This work is an important step in the development of a deployable distributed guidance system.

A1 準軌道型宇宙輸送システムの飛行実験による回収システム実証と今後の開発計画(宇宙輸送・飛翔体)

The Space Systems Laboratoy of Kyushu Institute of Technology has been researched unmanned suborbital winged rockets as a research subject of future fully reusable suborbital space transportation system since 2005. This paper reports the flight test of a pre-winged rocket with a mission to demonstrate a recovery system. The recovery system is consist of drogue chute, main chute and three air bags. The rocket launch was successful and the rocket reached about an altitude of 764 m. Then the rocket succeeded in drogue and main chutes ejection, airbags deployment and soft touchdown. Therefore, flight test results show that the mission is completely achieved and the recovery system is validated.

Control of Aircraft for Inspection of Linear Infrastructure

Inspection aircraft equipped with cameras and other sensors are routinely used for asset location, inspection, monitoring, and hazard identification of oil-gas pipelines, roads, bridges, and power transmission grids. This paper is concerned with automated flight of fixed-wing inspection aircraft to track approximately linear infrastructure. We propose a guidance law approach that seeks to maintain aircraft trajectories with desirable position and orientation properties relative to the infrastructure under inspection. Furthermore, this paper also proposes the use of an adaptive maneuver selection approach, in which maneuver primitives are adaptively selected to improve the aircraft's attitude behavior. We employ an integrated design methodology particularly suited for an automated inspection aircraft. Simulation studies using full nonlinear semicoupled six degree-of-freedom equations of motion are used to illustrate the effectiveness of the proposed guidance and adaptive maneuver selection approaches in realistic flight conditions. Experimental flight test results are given to demonstrate the performance of the design.

A Fuel Cell Based Propulsion System for General Aviation Aircraft: The ENFICA-FC Experience

The hydrogen and fuel cell power based technologies that are rapidly emerging can be exploited to start a new generation of propulsion systems for light aircraft and small commuter aircraft. Different studies were undertaken in recent years on fuel cells in aeronautics. Boeing Research & Technology Centre (Madrid) successfully flew its converted Super Dimona in 2008 relying on a fuel cell based system. DLR flew in July 2009 with the motor-glider Antares powered by fuel cells. The goal of the ENFICA-FC project (ENvironmentally Friendly Inter City Aircraft powered by Fuel Cells -European Commission funded project coordinated by Prof.Giulio Romeo) was to develop and validate new concepts of fuel cell based power systems for more/all electric aircrafts belonging to a inter-city segment of the market. As a result of the project, a technology demonstrator was designed, manufactured and tested: a new proton exchange membrane (PEM) fuel cell based power system was installed in the Skyleader RAPID200 that had its demonstrative flights in 2010. One of the most critical, if not the most critical, aspect of the all-electric power system adopted for demonstrator is undoubtedly prediction of fuel cell behaviour, specifically in terms of temperature control since reduced volumes and low weights (needed for the aeronautical applications) are not beneficial from a heat-management point of view. Moreover temperature control of PEM fuel cell is extremely important for a correct employment of the cell itself and, since the fuel cell is the main power generating device on the aircraft (batteries are however present as emergency back-up), temperature control becomes a very important safety issue too. In particular, as the ionic conduction of the polymeric membrane is a function of its degree of humidification, the stack temperature has to be carefully controlled to avoid phenomena of water evaporation causing an increase of ohmic drop and a decrease of stack performances. The output power of the fuel cells system is affected considerably by the change of the stack temperature. The paper will report a description of the research activity that lead to the fuel cell based power system developed for the ENFICA-FC project: the main topics will regard the design phase, including numerical and theoretical modelling (validated by flight tests) of the fuel cell system and its cooling, the results of ground testing and installation and, finally, the results of flight testing

Non-linear Control of Heave for an Unmanned Helicopter Using a Neural Network

This paper describes a new non-linear control technique applied to the heave control of an unmanned rotorcraft. First a hybrid plant model consisting of exactly known dynamics is combined with a black-box representation of the unknown dynamics. Desired trajectories are calculated to smoothly achieve a sequence of random step changes in desired height according to certain optimal criterion and plant limitations. Control inputs are then determined using the MATLAB® optimisation toolbox to achieve those desired trajectories for the plant heave model. Finally, a neural network is trained to mimic the control inputs resulting from the optimisation process. The neural network controller produces trajectories closely resembling the results from the optimisation process but with a much reduced computation time. Flight test results of control of the heave dynamics of a helicopter confirm the neural network controller's ability to operate in high disturbance conditions and outperform a proportional-derivative (PD) controller.

Active rotor control for helicopters: motivation and survey on higher harmonic control

Since the early helicopter developments, these aircraft have made a tremendous progress in performance, handling qualities, comfort and efficiency. However, modern helicopters still suffer from many problems that hinder a further increase in their efficiency, acceptance and hence their market share. The high level of vibrations and the noise generated by the rotor are the most important reasons for this. While vibrations are a concern of pilot and passenger comfort, they also give rise to an increase in maintenance efforts and costs. The high noise level limits the acceptance of helicopters in the public, e.g. landing of helicopters on or close to hospitals during EMS missions. High noise levels also lead to an early aural detection during military missions. Further drawbacks of helicopters are the high fuel consumption in high speed forward flight due to the excessive power required, the limited speed of flight, the low range for the same reason, low lead-lag damping, etc. To alleviate these drawbacks of helicopters, active rotor control technologies have been investigated for a long time. Many different approaches have been investigated and most of them are not being followed any more. First investigations started with so-called Higher Harmonic Control (HHC) which has been replaced by Individual Blade Control (IBC). The paper gives a survey of the typical problems and explains the vibration and noise issues in more detail. Since active means have to compete with passive ones, such methods are also briefly addressed. Next, the paper gives a review on important HHC achievements. Due to space constraints, the paper mainly focuses on wind tunnel and flight test results. A second paper reviews IBC and gives an outlook on the idea of the swashplateless helicopter.

Dietary Effects on Cognition and Pilots' Flight Performance

The purpose of this study was to investigate the effects of diet on cognition and flight performance of 45 pilots. Based on a theory of self-care, this clinical study used a repeated-measure, counterbalanced crossover design. Pilots were randomly rotated through 4-day high-carbohydrate, high-protein, high-fat, and control diets. Cognitive flight performance was evaluated using a GAT-2 full-motion flight simulator. The Sternberg short-term memory test and Vandenberg's mental rotation test were used to validate cognitive flight test results. Pilots consuming a high-protein diet had significantly poorer (p < .05) overall flight performance scores than pilots consuming high-fat and high-carbohydrate diets.

계측레이더 추적 시뮬레이터 개발

Defense Systems Test Center in ADD supports increasingly various missile test requirements such as higher altitude event, multi target operation and low-altitude, high velocity target tracking. In this paper, we have proposed the development of instrumentation radar tracking status simulator based on virtual reality. This simulator can predict the tracking status and risk of failure using several modeling algorithms. It consists of target model, radar model, environment model and several algorithms includes the multipath interference effects. Simulation results show that the predict tracking status and signal are similar to the test results of the live flight test. This simulator predicts and analyze all of the status and critical parameters such as the optimal site location, servo response, optimal flight trajectory, LOS(Line of Sight). This simulator provides the mission plan with a powerful M&S tool to rehearse and analyze instrumentation tracking radar measurement plan for live flight test at DSTC(Defense Systems Test Center).

Orbital monitoring of the ionosphere and abnormal phenomena by the small Vulkan-Compass-2 satellite

Natural disasters, the processes of their origin and large-scale technogenic catastrophes are accompanied by anomalous physical phenomena in near-Earth space (NES). In order to reveal such phenomena, record and investigate them, complex NES monitoring is required with the use of specially designed research equipment onboard a low-orbiting spacecraft. This work presents the results of flight tests of the small Vulkan-Compass-2 satellite with research equipment specially designed for orbital monitoring of the ionosphere and search for abnormal phenomena caused by large-scale catastrophes of different nature.

Passive control of transition in three-dimensional boundary layers, with emphasis on discrete roughness elements

A brief review of laminar flow control techniques is given and a strategy for achieving laminarization for transonic transport aircraft is discussed. A review of some flight-test results on swept-wing transition is presented. It is also shown that polished leading edges can create large regions of laminar flow because the flight environment is relatively turbulence free and the surface finish reduces the initial amplitude of the stationary crossflow vortex.

Theory and Flight-Test Validation of a Concurrent-Learning Adaptive Controller

Theory and results of flight-test validation are presented for a novel adaptive law that concurrently uses current as well as recorded data for improving the performance of model reference adaptive control architectures. This novel adaptive law is termed concurrent learuing. This adaptive law restricts the weight updates based on stored data to the null-space of the weight updates based on current data for ensuring that learning on stored data does not affect responsiveness to current data. This adaptive law alleviates the rank-1 condition on weight updates in adaptive control, thereby improving weight convergence properties and improving tracking performance. Lyapunov-like analysis is used to show that the new adaptive law guarantees uniform ultimate boundedness of all system signals in the framework of model reference adaptive control. Flight-test results confirm expected improvements in performance.

편대 유도 법칙 및 초소형 비행체의 자동 편대 비행 구현

본 논문에서는 초소형 비행체의 자동 편대 비행을 위한 유도 법칙과 비행 시험 결과를 기술하였다. 초소형 비행체는 탑재 중량과 비행시간 등의 제한으로 인해 짧은 시간 안에 복수의 비행체가 임무를 분담하거나 협력하여 동시에 수행하는 것이 효율적이며 편대 비행은 이러한 임무 하중을 효과적으로 감소시킬 수 있다. 제안된 편대 유도 법칙은 Leader-Follower 편대 비행의 기하학적 관계 기반으로 비선형 모델 역변환 기법을 이용하여 설계하였다. 편대 유도 법칙에 필요한 비행체의 상태 정보는 비행체 간 고속의 데이터 통신 시스템을 구성하고 지상국을 통해 송수신하도록 하였다. 본 연구에서 제안된 비행체간 통신 기반의 편대 유도 기법은 센서의 측정 잡음에 대한 강건한 성능을 확인하기 위해 실제 비행 데이터 기반 시뮬레이션을 수행하였고 다수의 초소형 비행체를 이용한 편대 비행 시험을 통해 유도 법칙의 타당성을 검증하고 확인하였다. This paper presents an autonomous formation flight algorithm for micro aerial vehicles (MAVs) and its flight test results. Since MAVs have severe limits on the payload and flight time, formation of MAVs can help alleviate the mission load of each MAV by sharing the tasks or coverage areas. The proposed formation guidance law is designed using nonlinear dynamic inversion method based on 'Leader-Follower' formation geometric relationship. The sensing of other vehicles in a formation is achieved by sharing the vehicles' states using a high-speed radio data link. the designed formation law was simulated with flight data of MAV to verify its robustness against sensor noises. A series of test flights were performed to validate the proposed formation guidance law. The test result shows that the proposed formation flight algorithm with inter-communication is feasible and yields satisfactory results.

Helicopter Modeling and Autopilot Design

AbstractA full autopilot system was designed for a small electrical helicopter. It contains two Web cameras as sensors that are connected to the standard PC through USB port. A model of aerodynamic forces and moments was written in the complex form. The system parameters were identified by results of flight tests. An onboard sensor with three micromechanical gyroscopes and three accelerometers was istalled on the helicopter. It produces essentially new information about rotation velocity. The autopilot system was studied in detail and finally, the helicopter was stabilized in a three dimensional point.

Improvements in Small-scale Helicopter Rotor Modeling for the Real-time Simulation of Hovering Flight

The traditional flight mechanics for scale helicopters uses a counter-clockwise, reduced-order rotor model that does not account for off-axis responses. The present paper deals with an improved rotor model that can set different directions of rotation and also reflects the off-axis responses of the rotor. In addition, the iterative method, which is used for rotor thrust calculations, is replaced with the dynamic inflow model. The nonlinear simulation results correlate well with the flight test results.

Wind Estimation and Airspeed Calibration using a UAV with a Single-Antenna GPS Receiver and Pitot Tube

This paper proposes a method that uses an aircraft with a single-antenna GPS receiver and Pitot tube to estimate wind speed and direction and to calibrate the airspeed. This sensor combination alone does not determine the true attitude of the aircraft, so the wind parameters cannot be obtained directly from the measurements. However, if the aircraft flies at different headings, such as in banking turns or circle maneuvers, the wind magnitude and direction can be estimated from the geometrical relation between the wind and the measurements. An extended Kalman filter (EKF) is applied to estimate wind parameters. The EKF can also estimate the scaling factor used to convert dynamic pressure to airspeed. This is useful for the operation of small unmanned aerial vehicles (UAVs) because of difficulty in determining the airspeed scaling factor of a low-cost UAV. Simulations are performed for a constant 2-D wind. To test the effectiveness of the proposed method, flight tests of a small UAV are conducted. Simulations and flight test results show that the proposed method is effective.