Flight Mission Research Articles

DEVELOPMENT OF AN ENERGY SUPPLY SYSTEM BASED ON THE PROTOTYPE «KAZEOSAT – 2»

"This article discusses the development of a prototype power supply system «KAZEOSAT -2» for which two types of load behaviour are modeled and described. In the first approach, the analysis focused on using load duty cycles to simulate the average power consumption per orbit in order to study the behaviour of the subsystem for various orbit scenarios. The second approach consisted in modeling the load switching behaviour taking into account the event of the mission flight sequence. The article also analyses the state of the energy balance based on the events of the mission flight sequence, as well as predicts the effect of power peaks on battery discharge behaviour. Busbar regulation was implemented, the converter block and converter efficiency were modeled using resistive resistance in parallel to its input ports. It is noted that the fill factor of the converter was controlled using a PI controller and a comparator, which measure the load voltage and compare it with the reference value. Keywords: reliability, block diagram, modelling, block, subsystem"

QuickOSSE Research on the Impact of Airship-Borne Doppler Radar Radial Winds to Predict the Track and Intensity of a Tropical Cyclone

Different from the aircraft TC reconnaissance flight missions before, a tropical cyclone (TC) field campaign project with a Doppler radar equipped on an airship that could hang over on the top of a TC (about 20 km) has been recently carried out in China. To understand the impact of airship-borne radar radial wind observations in TC forecasting, this work conducted quick observation simulation system experiments (QuickOSSE) by assimilating simulated airship-borne Doppler radar radial winds with an Ensemble Kalman Filter (EnKF) algorithm. The results show that airship-borne radial winds assimilation reproduces the forecasted track and minimum sea level pressure of the nature run. The forecast of dynamic and thermodynamic TC structures, such as tangential wind, secondary circulation, and warm core, are also improved. In addition, two determining factors, the radar depression angle (D-ang) and the distance from the airship to the TC center (DIS), are found to primarily affect the forecast of the TC track and intensity, respectively. Benefiting from a larger horizontal coverage, observations under a smaller D-ang improved the track more significantly. Meanwhile, the intensity forecast error with a DIS around the radius of the maximum wind is the smallest among several sensitive experiments, which may because the peak-velocity winds representing the TC’s intensity could be observed by radar. The results are expected to help establish an observational strategy for upcoming airship flight missions in practice.

A Midcourse Guidance Method Combined with Trajectory Prediction for Antinear-Space-Gliding Vehicles

Near-space-gliding vehicles have variable maneuver modes and dramatic changes in their ballistic parameters, which lead to a need to accurately predict an intercept point based on predictions of their trajectories. First, a trajectory prediction method builds a set of time-varying maneuver models based on flight missions combined with an adaptive grid to infer maneuver modes. An interactive multiple-model method of variable structure is proposed to identify the characteristics of the maneuver mode by introducing a fading factor and the modified Markov probability transfer matrix and then predict the trajectory through numerical integration. In the midcourse guidance method, the prediction of the target trajectory is introduced, and the zero-control interception manifold with intersection angle constraints is designed as the midcourse guidance terminal constraint. For the calculation of the starting time of the boost phase, the optimization solution satisfying the remaining flight time constraint is realized based on the Newton-Raphson iterative method. The analytical expression of a guidance command based on zero-error-miss/zero-error-velocity is established on the basis of the optimal control theory to provide an optimal flight path guiding an NSGV fly toward a point of interception. The simulation results show that the trajectory-prediction method has high prediction accuracy and strong convergency for typical maneuver modes, and the proposed midcourse guidance algorithm meets the requirements of the zero-effort intercept manifold with the intersection angle constraints, which is of important theoretical significance and acts as a reference value for intercepting high-velocity maneuver targets.

Fine motor deficits exhibited in rat string-pulling behavior following exposure to sleep fragmentation and deep space radiation.

Deep space flight missions will expose astronauts to multiple stressors, including sleep fragmentation and space radiation. There is debate over whether sleep disruptions are an issue in deep space. While these stressors independently impair sensorimotor function, the combined effects on performance are currently unknown. String-pulling behavior involves highly organized bimanual reach-to-grasp and withdraw movements. This behavior was examined under rested wakeful conditions and immediately following one session of sleep fragmentation in Sham and irradiated rats 3months after exposure (10cGy 4Helium or 5-ion simulated Galactic Cosmic Radiation). Sleep fragmentation disrupted several aspects of string-pulling behavior, such that rats' ability to grasp the string was reduced, reach endpoint concentration was more variable, and distance traveled by the nose increased in the Y-range compared to rested wakeful performance. Overall, irradiated rats missed the string more than Sham rats 3months post-exposure. Irradiated rats also exhibited differential impairments at 3months, with additional deficits unveiled after sleep fragmentation. 4Helium-exposed rats took longer to approach the string after sleep fragmentation. Further, rats exposed to 4Helium traveled shorter withdraw distances 3months after irradiation, while this only emerged in the other irradiated group after sleep fragmentation. These findings identify sleep fragmentation as a risk for fine motor dysfunction in Sham and irradiated conditions, in addition to radiation exposure. There may be complex temporal alterations in performance that are stressor- and ion-dependent. Thus, it is critical to implement appropriate models of multi-flight stressors and performance assessments in preparation for future deep space flight missions.

Integrated Communication and Measurement System with BOC-Assisted OFDM

For unmanned aerial vehicles (UAVs), high-precision measurement and high-speed communication are necessary to realize flight and operational missions. In this paper, we propose an integrated communication and measurement system in a Doppler frequency offset environment. The system combines orthogonal frequency division multiplexing (OFDM) modulation with binary offset carrier (BOC) modulation to formulate an OFDM+BOC composite signal through power control. High-precision measurement is achieved through BOC modulation, and high data transmission is achieved through OFDM modulation. Furthermore, the high-precision Doppler frequency offset tracked by the BOC signal is adopted to assist in the demodulation of the OFDM signal. This substantially decreases the impact of the Doppler frequency offset on the OFDM signal. Moreover, the ranging error is within 10−2, and the maximum Doppler frequency error is within 2 Hz.

Guidance Law for Autonomous Takeoff and Landing of Unmanned Helicopter on Mobile Platform Based on Asymmetric Tracking Differentiator

For some flight missions, such as autonomous landing on mobile platforms, the demands on indicators such as target-tracking accuracy and so on are relatively high. To achieve this, a guidance system with excellent precision is necessary. An asymmetric tracking differentiator based on a tracking differentiator is proposed to establish the guidance system. On the basis of the proposed asymmetric tracking differentiator, an altitudinal and horizontal helicopter guidance system structure is designed. In this paper, a guidance law is designed in order to meet the accuracy and precision requirements in the autonomous landing and transition process. Apart from that, a plane-motion-guidance law is also designed to realize static and dynamic point tracking, linear route tracking and circular route tracking to improve the trajectory smoothness and accuracy. Finally, simulations of the autonomous landing process on moving platforms, including three stages, namely approaching, tracking and landing, are completed. The application effects and precision of the autonomous landing guidance algorithm under different wave heights and period conditions are analyzed through the obtained simulation curves.

A Fast Aerodynamic Model for Aircraft Multidisciplinary Design and Optimization Process

A multidisciplinary design analysis and optimization process is developed at ONERA for the design of tube and wing and blended wing–body aircraft configurations. This process is composed of different disciplinary modules (geometry, propulsion, aerodynamics, structure, handling qualities and flight mission), and the overall process considers different fidelity levels for these modules at each step of the design process. This article describes the low-fidelity aerodynamic module used during the preliminary design optimization process. Analytical formulations retained for lift and drag components are presented in the first part. Then, the performances estimated by the aerodynamic module on some reference configurations are compared with both numerical and experimental data, showing a quite good agreement for both tube and wing and blended wing–body configurations not only for global performance but also for individual drag components.

Pengendalian Sudut Pitch dan Roll Pesawat Flying Wing

The development of the aviation world in recent years has increased, one of which is the field of unmanned aerial vehicles. This development is in line with the increasing use of UAVs in various fields, including for military missions, natural disaster monitoring missions, and aerial photography missions. Many types of aircraft that can be used to complete these missions, one type of aircraft that is widely used is the flying wing type aircraft. This type of aircraft is triangular in shape and does not have a tail. This aircraft controller uses elevons on the right and left sides of its wings, and its form is relatively small, so this aircraft is susceptible to environmental disturbances and causes flight mission failures. To overcome this problem, a control system is needed that is able to make the aircraft maintain flight stability. In this study, the Linear Quadratic Regulator control method was applied to overcome this. The LQR control method is used to control the pitch and roll angles of the aircraft. Based on the test results, the interference given can be handled well by the aircraft. It was proven that when given a disturbance, the aircraft experienced an overshoot of 4.24º at the pitch angle and 4.26º at the roll angle, but could quickly return to the setpoint within 1.2 seconds at the pitch angle, and 1.3 seconds at the roll angle. Thus the aircraft is able to maintain flight stability.

Detecting structural anomalies of quadcopter UAVs based on LSTM autoencoder

Detecting a structural anomaly, such as a damaged propeller or motor, is crucial for mission-critical operation of unmanned aerial vehicles (UAVs). The existing solutions often fail to detect structural anomalies because the pre-defined parameters required for the solution are limited in reflecting the flight pattern or the external environment, such as wind conditions. In this paper, we propose a method for detecting structural anomalies in quadcopter UAVs, using only regular data and specifically considering flight patterns and runtime flight conditions. To this end, we employ a long short-term memory (LSTM) autoencoder model to learn complex features of regular flight data. While flying the UAV, the trained model estimates the degree of outlierness of the incoming data and assesses abnormal behavior of UAV by adaptively considering its movement. This way, the proposed method accurately detects structural anomalies in UAVs regardless of the runtime environment or flight mission. Our experiment results with an off-the-shelf UAV show that the proposed approach detects diverse structural anomalies by an average of 98.6% specificity and 90.3% sensitivity.

Flow physics and boundary layer optimization over a NACA airfoil by camber morphing at subsonic speeds

In this paper, the variable camber morphing strategy is adopted in a NACA airfoil through computational investigation to enhance the lift to drag ratio ([Formula: see text] specifically for military UAV applications. The typical mission profile is also focused on enhancing the aerodynamic performance of the UAV during various flight segments by variable camber morphing. The airfoil camber is changed dynamically at different instances based on the mission profile requirements thereby altering the [Formula: see text] characteristics. The concept of bio-inspired aerodynamics has received a greater attention in recent years because of the proven nature oriented real-time application. Hence, the concept of bio-inspired variable camber morphing is proposed herein that minimizes the use of unconventional control surfaces to attain the required performance at different segments of flight. MQ9 Reaper UAV model is chosen to implement the proposed variable camber morphing strategy at the mission flight segments. NACA 4412 cambered airfoil has been considered as the baseline model airfoil for the present study because of its higher zero lift angle characteristics. The lower camber of the airfoil section is changed from 1% to 3% at different angles of attack (AoA) for the time instances such as 1[Formula: see text]s, 2[Formula: see text]s and 3[Formula: see text]s, respectively. The lift coefficient ([Formula: see text] of the airfoil is also significantly increased through camber morphing at different flight segments during each time step with negligible flow separation as observed through streamline patterns. Hence, the friction drag coefficient is also retained under optimum level as concluded through the boundary layer profiles.

Climate-Optimised Intermediate Stop Operations: Mitigation Potential and Differences from Fuel-Optimised Configuration

Saving fuel by splitting a flight mission with an intermediate stop for refuelling is described by the concept of intermediate stop operations. This can also be beneficial to the climate impact of aviation, if the flight level and intermediate stop airport are selected accordingly. This study aims to estimate the mitigation potential of an implementation of climate-optimised intermediate stop operations for European long-haul flights and compare it to fuel-optimal operations. For this purpose, fuel consumption and emissions are simulated along four-dimensional trajectories for the selected annual flight plan, and their average temperature response is calculated. A comparison between the reference case and climate-optimised as well as fuel-optimised scenarios shows a significant climate mitigation potential and reveals a shift of trajectories to lower latitudes and altitudes. However, increased flight times and fuel consumption limit implementation from stakeholders’ perspectives.

Offline Imagery Checks for Remote Drone Usage

Drones are increasingly used for a wide range of applications including mapping, monitoring, detection, tracking and videography. Drone software and flight mission programs are, however, still largely marketed for “urban” use such as property photography, roof inspections or 3D mapping. As a result, much of the flight mission software is reliant upon an internet connection and has built-in cloud-based services to allow for the mosaicking of imagery as a direct part of the image collection process. Another growing use for drones is in conservation, where drones are monitoring species and habitat change. Naturally, much of this work is undertaken in areas without internet connection. Working remotely increases field costs, and time in the field is often aligned with specific ecological seasons. As a result, pilots in these scenarios often have only one chance to collect appropriate data and an opportunity missed can mean failure to meet research aims and contract deliverables. We provide a simple but highly practical piece of code allowing drone pilots to quickly plot the geographical position of captured photographs and assess the likelihood of the successful production of an orthomosaic. Most importantly, this process can be performed in the field with no reliance on an internet connection, and as a result can highlight any missing sections of imagery that may need recollecting, before the opportunity is missed. Code is written in R, a familiar software to many ecologists, and provided on a GitHub repository for download. We recommend this data quality check be integrated into a pilot’s standard image capture process for the dependable production of mosaics and general quality assurance of drone collected imagery.

Dynamic Modeling and Rule-Based Control Design for a Hybrid-Electrified Regional Aircraft

Modeling and control of hybrid-electric propulsion systems (HEPSs) is a challenging area, in particular for regional aircraft. In this research, modeling and rule-based control design for a hybrid-electrified aircraft are presented. For this purpose, real data from the ATR 42-600 as well as the modified CT7-9 turboprop engine, commercial electric machines, and battery experimental characteristics have been used to size a new version of hybrid-electric regional aircraft. Based on the dynamic modeling of HEPS, practical controllers are then designed for the turboprop engine and electric machines. It should be noted that one of the critical tasks of the control strategy for hybrid-electric propulsion is to ensure the aircraft’s safe landing. In this study, a rule-based tunable regulator is proposed to modify the conventional optimal control strategy to achieve the aircraft’s required performance over a real flight mission, in particular, to fulfill the safe landing of aircraft using the remaining battery state of charge (SOC) in the event of all-turbine failure. Finally, the results are presented to demonstrate that the proposed approach is effective for minimizing the HEPS fuel consumption, where the aircraft operational constraints, such as battery SOC and turbine overtemperature, are fulfilled at different phases of the flight mission.

Modeling analysis of a novel hybrid 6-DOF vibration isolation platform for sensitive instruments

The inevitable vibration caused by normal operation of the spacecraft in orbit will interfere sensitive instruments, such as space telescope, reconnaissance camera, space interferometer. Serious vibrations affect the accuracy and reliability of the sensitive instruments, even cause flight mission failed. This paper presents a hybrid 6-DOF vibration isolation platform (HVIP) with six degree-of-freedom for active vibration isolation of the space sensitive instruments. The HVIP is composed of three orthogonal vibration isolation module, which composed of the active piezoelectric actuator and passive rubber isolator. The dynamic model of the HVIP is established based Lagrange equation approach. Finally, the numerical simulations are performed to verify the vibration isolation effect of the HVIP.

Aggressive Quadrotor Flight Using Curiosity-Driven Reinforcement Learning

The ability to perform aggressive movements,which are called aggressive flights, is important for quadrotors during navigation. However, aggressive quadrotor flights are still a great challenge to practical applications. The existing solutions to aggressive flights heavily rely on a predefined trajectory, which is a time-consuming preprocessing step. To avoid such path planning, we propose a curiosity-driven reinforcement learning method for aggressive flight missions and a similarity-based curiosity module is introduced to speed up the training procedure. A branch structure exploration strategy is also applied to guarantee the robustness of the policy and to ensure the policy trained in simulations can be performed in real-world experiments directly. The experimental results in simulations demonstrate that our reinforcement learning algorithm performs well in aggressive flight tasks, speeds up the convergence process and improves the robustness of the policy. Besides, our algorithm shows a satisfactory simulated to real transferability and performs well in real-world experiments.

SEARCH FOR SMALL-SIZED OBJECTS ON THE UNDERLYING SURFACE IN FRONT OF THE AIRCRAFT

The method of searching of small-sized ground or surface objects with unknown coordinates is proposed. The search is carried out using the thermal imaging or other IR remote sensing system (RS) of underlying surface (US) in front of the aircraft. The small size of objects requires the use of narrow fields of view for detection and recognition at ranges that allow to carry out operational actions, which are provided for by the flight mission for rescue operations on land and at sea or for aircraft emergency landing on an unprepared site. Two tasks are solved: 1) the maximization of the guaranteed bandwidth of objects searching on US with given characteristics of RS and aircraft speed; 2) the determination of the optimal characteristics of remote sensing systems and aircraft speed for a given search bandwidth of the US.A periodic change in the azimuthal orientation of the narrow field of view (automatic scanning of the US by the field of view of the IR system) is used for solving given tasks. For a given operating range of the IR system the proposed algorithm ensures that the pilot or operator can view the runway on US without “dead” zones (unseen areas). The optimal value of the search effort corresponding to the detection and recognition of objects is determined. The proposed algorithm implements symmetrical scanning (scanned areas of the same shape are formed to the left and right of the flight path on US). The symmetric scanning equation is derived for prediction search efficiency. The solution of given equation makes it possible to find the dependence of the guaranteed search bandwidth on the operating range of ranges in which detection and recognition are possible for given weather conditions. The examples of using the derived equation when searching for objects in simple and difficult weather conditions are given.

An Architectural Model of a Software Module for Piloting UAV Constellations

Technology behind unmanned aircraft vehicles (UAVs) has been rapidly advancing in the recent years. This propelled the adoption rate and widened the range of UAV uses, such as in sport activities, cartography, surveillance, transportation, and military. While using single, individually controlled UAVs is already very common, using UAV constellations is becoming increasingly popular due to advantages in flexibility, scalability and sensing power. However, the use of UAV constellations remains limited to very specific applications due to number of challenges involved. One of the challenges is the lack of generic software system that would allow controlling UAV constellations in different types of flight missions. In order to address this problem, we propose an architectural model of a software module for UAV constellation piloting.

Multivehicle Point-to-Point Network Problem Formulation for UAM Operation Management Used with Dynamic Scheduling

In this paper, we introduce a new formulation of the multivehicle point-to-point network problem to be utilised in urban air mobility (UAM) vertiport-to-vertiport network operations. Vehicle routing problems (VRPs) and their variants have previously been studied and applied in real-world situations, but these problems require additional depot locations, and not all the vehicles can travel to all the locations. In UAM operations, additional depot locations may not be required, and all vehicles can travel to all locations, meaning that existing routing problems are not suitable for application to the management of UAMs. Therefore, we propose a new formulation for UAM vertiport-to-vertiport operation by introducing new constraints. In addition, we integrate dynamic scheduling with the flight mission by controlling cruise speed and waiting in each UAM at each vertiport location to generate an arrival and departure schedule for different vertiports that can avoid collisions and increase the number of vehicles. A computational experiment is conducted using an MILP model, and the results show that although our formulation satisfies the problem definition, the computation time increases exponentially with an increase in the problem size. A case study is conducted in the Seoul area involving five vertiports, with 10- and 15-vehicle scenarios studied. This case study shows that the cruise speed variable is active only for the lower and upper bounds under dynamic scheduling, whereas the waiting time variable can be controlled between user-defined limits that can be applied to the management of vertiport-to-vertiport UAM operations.

Striated Muscle Evaluation Based on Velocity and Amortization Ratio of Mechanical Impulse Propagation in Simulated Microgravity Environment.

Long-duration space flight missions impose extreme physiological stress and/or changes, such as musculoskeletal function degradation, on the crew due to the microgravity exposure. A great deal of research studies have been conducted in order to understand these physiological stress influences and to provide countermeasures to minimize the observed negative effects of weightlessness exposure on musculoskeletal function. Among others, studies and experiments have been conducted in DI analogue Earth-based facilities in order to reproduce the weightlessness negative effects on the human body. This paper presents a complex muscular analysis of mechanical wave propagation in striated muscle, using MusTone, a device developed in-house at the Institute of Space Science, Romania. The data were collected during a 21-day DI campaign in order to investigate muscle fibers' behavior in longitudinal direction, after applying a mechanical impulse, taking into account two particular parameters, namely propagation velocity and amortization ratio. The parameters were determined based on the wave-propagation data collected from five points (one impact point, two distal direction points, and two proximal direction points) along the muscle fiber. By statistically analyzing propagation velocity and amortization ratio parameters, the study revealed that muscle deconditioning is time dependent, the amortization ratio is more significant in the distal direction, and the lower fibers are affected the most.

Guidance, Navigation and Control for Autonomous Quadrotor Flight in an Agricultural Field: The Case of Vineyards.

In this paper, we present a complete and efficient solution of guidance, navigation and control for a quadrotor platform to accomplish 3D coverage flight missions in mapped vineyard terrains. Firstly, an occupancy grid map of the terrain is used to generate a safe guiding coverage path using an Iterative Structured Orientation planning algorithm. Secondly, way-points are extracted from the generated path and added to them trajectory's velocities and accelerations constraints. The constrained way-points are fed into a Linear Quadratic Regulator algorithm so as to generate global minimum snap optimal trajectory while satisfying both the pointing and the corridor constraints. Then, when facing unexpected obstacles, the quadrotor tends to re-plan its path in real-time locally using an Improved Artificial Potential Field algorithm. Finally, a geometric trajectory tracking controller is developed on the Special Euclidean group SE(3). The aim of this controller is to track the generated trajectory while pointing towards predetermined direction using the vector measurements provided by the inertial unit. The performance of the proposed method is demonstrated through several simulation results. In particular, safe guiding paths are achieved. Obstacle-free optimal trajectories that satisfy the way-point position, the pointing direction, and the corridor constraints, are successfully generated with optimized platform snap. Besides, the implemented geometric controller can achieve higher trajectory tracking accuracy with an absolute value of the maximum error in the order of 10-3 m.