Flight Mode Research Articles

Adaptive Neural Network Extended State Observer-Based Finite-Time Convergent Sliding Mode Control for a Quad Tiltrotor UAV

The internal and external disturbance of the quad tiltrotor UAV stem from its rotor tilting motion and wind disturbance, which affect the control stability of the quad tiltrotor UAV in full flight. This paper proposes a control law design method based on the Adaptive Neural Network Extended State Observer-based Finite-Time Convergent Sliding Mode Control (ANNESO-FTCSMC). The adaptive neural network obtains the unknown total disturbance term that needs to be compensated in the finite-time convergent sliding mode control. An extended state observer is used to estimate the state variables of the controlled plant. The stability of the ANNESO-FTCSMC controller is proved with the Lyapunov stability theory. The unknown total disturbance as the expanded state variable of the state observer has the advantage of high adaptability, and the ANNESO-FTCSMC has a strong ability to compensate for the internal and external disturbances of the system. Compared with traditional sliding mode control, ANNESO-FTCSMC does not contain switching terms, so ANNESO-FTCSMC is chattering-free and converges faster. Based on this method, the flight control system of the quad tiltrotor UAV is designed and verified by hardware-in-loop simulation. The hardware-in-loop simulation results of attitude control in different flight modes and trajectory tracking control in full flight show that the ANNESO-FTCSMC controller is suitable for the flight control of quad tiltrotor UAV. Compared with the PID controller and ADRC controller, ANNESO-FTCSMC controller has more stable flight state of quad tiltrotor UAV under different flight modes and the same total disturbance. The transition process of ANNESO-FTCSMC controller from helicopter mode to airplane mode is also smoother and will not have large fluctuations. Therefore, ANNESO-FTCSMC controller has strong anti-disturbance and robustness.

Neural Network Method for Detecting and Diagnostics Helicopters Turboshaft Engines Surge at Flight Modes

Neural Network Method for Detecting and Diagnostics Helicopters Turboshaft Engines Surge at Flight Modes

Thermal soaring over the North Sea and implications for wind farm interactions

Seabirds use several flight modes at sea, including thermal soaring, in which thermal uplift is used to gain altitude and save energy. An increase in flight altitude may have consequences for wind farm interactions if it results in birds spending more time within the rotor-swept zone (RSZ). To understand conditions under which thermal soaring occurs and potential implications for wind farm interactions, we investigated thermal soaring in relation to atmospheric conditions in June and July at 2 study areas in the North Sea, west and north of the Dutch coast. We developed algorithms that identified thermal soaring in GPS tracks of lesser black-backed gulls Larus fuscus and radar tracks of seabirds. By combining species-specific 3-dimensional information on flight behaviour from bio-logging with the continuous spatiotemporal coverage of radar positioned at wind parks, we obtained a more comprehensive overview of thermal soaring at sea than either method would obtain alone. Our results showed that birds flew at higher altitudes during thermal soaring than non-soaring flight, increasing the proportion of flight time within the RSZ. Thermal soaring occurred inside offshore wind farms to a similar degree as outside. Thermal soaring was positively correlated with positive temperature differences (ΔT) between sea surface and air (at 2 m above sea level), and north and north-westerly winds. We show that the probability of thermal soaring over the North Sea, inside and outside wind farms, increases with larger temperature differences, resulting in increased time spent within the RSZ and an increased collision risk for seabirds.

НАЗЕМНО-БОРТОВІ СИСТЕМИ ВИПРОБУВАНЬ ТА ДІАГНОСТИКИ ВЕРТОЛІТНИХ РЕДУКТОРІВ

The article is an overview and information. An effective direction of operational diagnostics of the most stressed units - gear drives of GTE gearboxes are methods for analyzing vibration signals of the engine casing.The theoretical and experimental substantiation of vibration diagnostics of GTE gears and helicopter gearboxes in-dicates that the main function that characterizes the energy efficiency of torque transmission and is sensitive to the initiation of defects in gear teeth can be considered the deviation of the parameter of the first derivative of the angular velocity of re-coupling of the teeth.The system for collecting and processing flight information is divided into onboard and ground parts. The onboard sub-system in the form of hardware and software systems provides for the collection and preliminary processing of primary infor-mation - vibration signals, synchronization, temperature, etc. It interacts with the standard equipment of the helicopter to obtain information regarding the modes of operation and flight of the helicopter. The on-board subsystem, as a rule, contains vibration sensors, speed sensors and accumulation and pre-processing blocks.The ground subsystem is a set of hardware and software tools that provide automatic express analysis and extended analysis of information recorded on board. The ground subsystem of the diagnostic system can be divided into local and central (support center). The local part is the software for processing the information accumulated during the flight and the database, which are hosted by the organization operating the helicopters.At present, methods are already being used for servicing machines according to the actual state or identifying parts without disassembling them based on vibration diagnostic tests. Their use allows to simultaneously reduce the cost of adjust-ment work and improve their quality, since not only the condition of the parts of the product is checked, but also how they are assembled, whether there are misalignments of bearings or gears during assembly.After the flight, the accumulated data is transferred to the ground subsystem of the operating organization, where post-flight analysis is carried out, processing results are issued and the results are stored in a local database. Further, the processing results are synchronized with the database of the support center to provide information on the technical condition to the devel-opers of helicopters and their units, as well as to operating organizations

Handling multi-objective optimization problems with a comprehensive indicator and layered particle swarm optimizer.

The multi-objective particle swarm optimization algorithm has several drawbacks, such as premature convergence, inadequate convergence, and inadequate diversity. This is particularly true for complex, high-dimensional, multi-objective problems, where it is easy to fall into a local optimum. To address these issues, this paper proposes a novel algorithm called IMOPSOCE. The innovations for the proposed algorithm mainly contain three crucial factors: 1) an external archive maintenance strategy based on the inflection point distance and distribution coefficient is designed, and the comprehensive indicator (CM) is used to remove the non-dominated solutions with poor comprehensive performance to improve the convergence of the algorithm and diversity of the swarm; 2) using the random inertia weight strategy to efficiently control the movement of particles, balance the exploration and exploitation capabilities of the swarm, and avoid excessive local and global searches; and 3) offering different flight modes for particles at different levels after each update to further enhance the optimization capacity. Finally, the algorithm is tested on 22 typical test functions and compared with 10 other algorithms, demonstrating its competitiveness and outperformance on the majority of test functions.

Development of simulation models of the hydraulic system of passenger and transport aircraft in normal and failure situations

The paper presents a simulation model of the hydraulic system of an aircraft containing a block supply with a variable flow pump, the discharge line of which is presented in the form of a certain container with liquid, the modulus of elasticity of which is constant, and a hydraulic accumulator is installed in the discharge line a certain capacity and pre-charge pressure, resistance of the discharge and drain lines. The developed simulation model allows failure situations, such as: violation of the internal and external tightness, changing the parameters of the accumulator, reducing the pressure of zero flow due to a change in the stiffness of the springs of the control spool and the servo piston of the regulator, jamming regulator in an intermediate position, etc. In addition, the model allows you to calculate the heat losses associated both with the aircraft flight mode and with changes in the hydrodynamic parameters of the system in regular and failure modes.

Design of a PEM fuel cell powered autonomous quadcopter

The purpose of this paper is to design a PID controller for a detailed nonlinear model of a custom-made quadcopter and utilise the power requirements in designing a proton exchange membrane (PEM) fuel cell system. The first principles methodology to commence with unmanned aerial vehicle architecture is delineated. The empirical actuator response of the brushless DC (BLDC) is obtained which further adds accuracy to the mathematical model of the system. The paper also presents simulations for nonlinear open loop and closed loop feedback with PID controller. The controller gains are obtained from the simulations for hover flight mode. The experimental implementation of battery powered quadcopter is validated with simulation results of PID control design. Finally, for the designed quadcopter, a mathematical model of a PEM fuel cell system to replace battery-specific power requirements is obtained. The key limitation of this paper is the absence of experimental data for fuel cell model due their high cost and low-availability.

DEVELOPMENT TRENDS IN PLASMA AERODYNAMICS

The most promising areas of research in the field of plasma aerodynamics are proposed. On the basis of the presented experimental data obtained recently, the possibilities of using the volumetric force effect on the gas flow in aerodynamic applications, which is realized with the help of near-surface electric discharges, are considered. One of these applications is to increase the length of the laminar section of the boundary layer on the swept wing in order to reduce the aerodynamic drag of the aircraft in the cruise flight mode. The second direction is associated with the control of the three-dimensional separation of the boundary layer on the elements of the mechanization of the swept wing in the take-off and landing modes. And the third direction is the reduction of surface friction in the turbulent boundary layer, which is realized on most of the surface of modern near- and supersonic aircraft. The proposed studies are not only of applied, but also of fundamental importance due to the physical complexity of the studied phenomena.

Optimal Transition Trajectory of a Quadrotor Biplane Tailsitter

This work focuses on transition trajectory generation for a special class of hybrid vertical takeoff and landing (VTOL) vehicles called quadrotor biplane tailsitter. The transition refers to the change of flight modes for a hybrid VTOL vehicle. A transition maneuver is challenging as the vehicle undergoes in low-speed high angle of attack condition which is highly unstable. This work proposes methods to generate an optimal trajectory for the forward transition of the vehicle. A simplified 3-degree-of-freedom (3-DOF) model of the vehicle is considered for generating the transition trajectory. The optimization problem is solved using nonlinear programming with appropriate dynamic and physical constraints. The work considers multiple optimality conditions that include minimal control effort, minimal transition time, and a combination of them. The results of different approaches are compared considering the feasibility of implementation on a physical vehicle.

Flight dynamics in forward flights of cabbage white butterfly

We conducted measurements of a butterfly’s motion in forward flight and numerical simulations using a computational model reflecting its motion. We measured the motion of a cabbage white butterfly (Pieris rapae), and then we constructed a computational model composed of a thorax, an abdomen, and four wings (i.e., left and right wings with fore and hind parts). Furthermore, we calculated the flow field and aerodynamic force and torque generated by the butterfly model using the immersed boundary–lattice Boltzmann method. In this simulation, we considered two types of periodic motions corresponding to slightly-descending and ascending forward flights. As a result, we found that the wing-tip and leading-edge vortices are formed on the wings and then released backward and downward in both flights. The major difference between the two flights is the flapping amplitude, indicating that the butterfly changes the flapping amplitude for each period and increases it to ascend. In addition, we considered a chimera model whose motion is based on the slightly-descending flight but partly given by the ascending flight. As a result, we found that the pitching angle and the angle of attack determine the traveling direction, but simply changing these angles does not achieve the ascending flight due to insufficient lift force. Thus, the butterfly should adjust the flapping and lead–lag angles in response to the pitching angle and the angle of attack to change the flight mode.

Statement and general technique for solving problem of oscillation of a hereditarily deformable aircraft

This article provides a general statement and a technique for solving the problem of oscillations of a hereditarily deformable aircraft in a gas flow with a finite number of degrees of freedom. Using the Lagrange equations and the variational principle of the hereditary theory of viscoelasticity, the equations of motion of the problem under consideration are derived. The generalized forces acting on the aircraft in the subsonic flight mode are determined according to the stationarity hypothesis. As a result, closed interconnected weakly singular integro-differential equations are obtained that describe the mathematical model of the problem with a finite number of degrees of freedom. General schemes for the numerical solution of these equations are outlined. As an example, the flexural-torsional-aileron flutter of the transient process of a hereditarily deformable wing with a finite freedom number is considered.

Changes in Connectivity for Major Asian Airports - Europe and Post-Pandemic Improvement Suggestions

The aviation transport volume in the Asia-Pacific region continues to grow, with many airports aspiring to become aviation hubs. However, in 2020, the aviation industry faced significant disruptions due to the COVID-19 pandemic. In light of this, this study aims to explore the pre-pandemic and post-pandemic airport competitive advantages of major Asian airports. This study selected six major airports, focusing on the quality of transit services and the number of transit flights. Specifically, the study examines two perspectives: quantity (QVC) and quality (QCI), utilizing connectivity indices such as Hub Connectivity Performance Index (HCPI) and Hub Efficiency Index (HEI). Based on connectivity analysis results, Singapore Airport, Suvarnabhumi Airport, and Kuala Lumpur Airport hold a leading position in HEI due to their geographical advantages. These airports should continue to develop Southeast Asia - Europe routes. Hong Kong International Airport follows closely in connectivity, but its flight numbers were significantly affected by the pandemic and the anti-extradition bill protests factors. Efforts to expedite the recovery of the European market are recommended. Incheon Airport benefits from the rapid development of low-cost aviation in recent years, expanding routes and flight frequencies, resulting in a continuous increase in QVC. However, it needs to enhance transit efficiency to elevate its HEI. Taoyuan Airport lags behind the aforementioned airports in both QVC and HEI. To attract more transit passengers, it should increase flights in this market.

INCREASING THE TIME OF USING THE ENERGY RESOURCE OF THE ON-BOARD ACCUMULATORY BATTERY BY IMPROVING THE QUALITY OF CONTROLLING THE ELECTRIC QUADCOPTER'S PROPELLER DRIVES

A review of the current state in quadcopters’ flight control systems showed that the electric drives of their propellers are performed according to single-circuit schemes with feedback on rotational speed in which the error in the results of monitoring the angles of roll, pitch, yaw is worked out by a control system with a PI or PID regulator. There is no astaticism load in such systems and the parameters of the current consumed from the on-board battery are not optimized. The consequence of this is a decrease of service life on-board battery and low quality flight control when the load changes. It is proposed to perform the electric drive system of the quadcopter’s screw according to a two-fold integrating structural scheme in which astaticism is provided during perturbations in control and load.
 A transient speed characteristic based on the optimization results of the double-integration scheme with speed and current circuits in accordance with a symmetrical optimum the parameters of which do not meet the requirements of quadcopter’s high-quality control flight mode was obtained and do not contribute to an increase in the time of using the energy resource of the on-board battery. It is proposed to include additional smoothing differentiating links at its input to eliminate the shortcomings of the obtained transient characteristic of the electric drive system in terms of speed. The parameters of these links were found using the compensation conditions. The obtained transient characteristics of the electric drive system of the quadcopter’s screws in terms of speed and current do not have sudden changes in the adjustable value and do not have overregulation. The result of such parameters in transient characteristics is high-quality control of the quadcopter’s flight mode and an increase in the time of using the energy resource of the on-board battery.

Comparison of Autonomous and Manual UAV Flights in Determining Forest Road Surface Deformations

The deterioration of the surface of forest roads is an important factor affecting the safe navigation of vehicles and traffic safety. In addition to traditional methods, automated methods are also used to determine the deterioration of the road surface. UAV systems, which are among the automated methods, are widely used to determine surface deformations with high accuracy. This study aimed to evaluate the advantages and disadvantages of two different flight modes of UAV, including autonomous flight and manual flight, in mapping road surface deformations. Within the scope of this study, the 50-meter section of the Type B forest road located in Kardüz Forest Management Chief (Düzce/Türkiye), was selected. For this study, first the pros and cons of the autonomous and manual flight data acquisition process were evaluated. Then, the photogrammetric data processing results were compared in terms of data size, with precision and accuracy. In addition, the deformation status on the surface within the selected road was determined using the average Z value differences obtained with two flight methods. The result of the study showed that, the number of images obtained from manual flights was 5.5 times higher than from autonomous flights and the flight time was taken four times longer. The average ground sampling distance of the orthophotos generated from two different light modes indicated that the manual flight mode provided seven times higher resolution than autonomous flight. Moreover, the results from the statistical tests for the two flight modes showed differences. When manual flights and autonomous flights are evaluated in terms of reducing the shadow effect, manual flights can be considered more advantageous. Furthermore, it was found that the dynamic mobility of erosion and accumulation on the road surface continued in time series in both flight methods.

Traditional knowledge, beliefs and practices on collection of lake flies (chaoborus and chironomus sp.) and their implications on food security

Lake Flies are edible insects with the potential of contributing to food security in that they are an alternative protein and micronutrient food source in freshwater lake regions. The main challenge in exploiting the lake flies is the difficulty in the collection. This study was conducted to identify sustainable traditional collection practices and forecasting techniques of lake flies and was implemented in Rusinga and Mfangano Island in Kenya. The ethnographic study employed multiple methods of data collection: focus group discussion (FGD), observations, and interview schedules. 5 (3 female and 2 male) key informants were selected for interview schedules aged above 60 years. 48 (19 female and 29 male) participants took part in FGDs they were divided into 8 sets each containing 6 participants and an age range between 18 to 40 years. Open data kit (ODK) software was used for data collection while analysis was conducted via thematic analysis framework using Nvivo version 10 software. Questions were administered on traditional lake-flies emergence forecasting, collection techniques, and devices. The emergence of lake flies is determined by moon sightings, the presence of strong winds, and the rainy season. Lake flies can be collected: in mid-air flight mode, in bushes along the shore, and during night operations using a light source (bulb, touch). Lake flies are collected using traditional tools: a woven basket with a stick handle, pots, a plastic basin, and a woven basket with a stick attached. Cultural myths associated with lake flies included: marriage partner/business customers’ attraction. Uses include libido enhancement, remedy for sickness, and good fish harvest indicator. In conclusion, lake flies have the potential to contribute to food and nutrition security as affordable and locally available alternative protein and micronutrient sources.

Determination of Complex Aircraft - Operator Control System Properties

The automatization of particularly fast maneuvering aircraft has greatly reduced the sphere of man's scope by freeing him from routine operator work and moving it to the highest hierarchical level of the system. This forces aerospace manufacturers and users to address questions of a kind in a new way: how to design an ergatic system (ergatic system), how to optimize the coordination or human operator's entry into the "machine part", that has a distinctive feature of artificial intelligence. In this article, the properties of the ergatic system are investigated in order to determine the stability of the system in the longitudinal steady-state equilibrium flight mode at 22 965 ft, Mach 0.8, VTAS = 250 m/s. The Control System Toolbox, which is focused on solving tasks related to the analysis and synthesis of linear time - invariant dynamic systems, was used to solve the example. The basic prerequisite for the use of individual toolbox modules is knowledge mathematical models of controlled processes described in the state space, by means of transfer functions in s - area, z - area, time area, in the form of poles, zeros and amplification.

Influence of flight mode on loads from turbulent air

This paper investigated the influence of altitude and flight speed on the loads arising on the elastic wing of a turbojet aircraft of conventional layout, which falls into turbulent conditions. The aircraft structure is modeled by elastic beams with appropriate weight and stiffness distribution. Performed a modal analysis of the aircraft design and examined the influence of the number of calculated tones own oscillations on the loading of an aircraft wing. Aerodynamic forces and moments are determined by the dipole lattice and constant pressure method (DLM/CPM). Non-stationary characteristics are also taken into account, as required by certification specification. Determining the effect of flight speed showed the need to consider both the minimum and maximum speeds, because at minimum speed the end zone of the wing is loaded more, and at the cruise speed ‒ the root section. When analyzing the effect of flight altitude on the load, determined that the maximum values of transverse force and bending moment occur when flying at minimum altitude, and the torque on the wing reaches the maximum value at altitudes with the maximum Mach number. Separately highlighted loads of aircraft wing at horizontal balanced flight. Also showed that the speed of flight, namely the Mach number, significantly affects the torque that occurs on the wing.

Determination of Complex Aircraft - Operator Control System Properties

The automatization of particularly fast maneuvering aircraft has greatly reduced the sphere of man's scope by freeing him from routine operator work and moving it to the highest hierarchical level of the system. This forces aerospace manufacturers and users to address questions of a kind in a new way: how to design an ergatic system (ergatic system), how to optimize the coordination or human operator's entry into the "machine part", that has a distinctive feature of artificial intelligence. In this article, the properties of the ergatic system are investigated in order to determine the stability of the system in the longitudinal steady-state equilibrium flight mode at 22 965 ft, Mach 0.8, VTAS = 250 m/s. The Control System Toolbox, which is focused on solving tasks related to the analysis and synthesis of linear time - invariant dynamic systems, was used to solve the example. The basic prerequisite for the use of individual toolbox modules is knowledge mathematical models of controlled processes described in the state space, by means of transfer functions in s - area, z - area, time area, in the form of poles, zeros and amplification.

СИНЕРГЕТИЧЕСКИЙ СИНТЕЗ АВТОПИЛОТА ДЛЯ УПРАВЛЕНИЯ ДВИЖЕНИЕМ САМОЛЕТА-АМФИБИИ БЕ-200 ВО ВРЕМЯ ЗАБОРА ВОДЫ

The article is devoted to solving the problem of controlling the Be-200 amphibious aircraft whentaking water in the gliding mode. The specified mode of flight of an amphibious aircraft (AA) is one ofthe most intense for piloting. Controlling an aircraft in gliding mode requires the highest concentrationfrom the pilot, since the hydrodynamic characteristics decrease, but the aerodynamic ones increase,which causes situations in which the SA becomes uncontrollable. To ensure the safe operation of the AAduring water intake, as well as to ensure a steady takeoff, the pilot is forced to constantly maintain acertain value of speed, trim angle, and engine thrust by moving the engine control stick (ECS). In thisregard, it seems very appropriate to use the technical means of the autopilot, which provides control ofthe speed, engine thrust and trim angle to ensure the stability of the movement of the SA during the intakeof water. The article deals with the problem of synthesizing an autopilot to control the movement ofan amphibian aircraft during water intake, and at the same time the following tasks are solved: thesynthesis of an autopilot to control the longitudinal movement of an amphibian aircraft, as well as controllanding on water, followed by water intake and takeoff from the water. The substantiation of thechoice of a mathematical model of the movement of an aircraft on water is given. A procedure for thesynergistic synthesis of the autopilot controller of an amphibious aircraft in the water intake mode presented.The novelty of the ongoing research lies not only in considering the stable movement of an amphibiousaircraft during its operation on the water surface, but also in modeling the process of water intake in planning mode, which is a more complex task from the point of view of synthesis. As a result,the control laws for the autopilot obtained, which ensure the stable movement of the amphibious aircraftwhen descending along the glide path, landing on water, taking in water and subsequent takeoff withdamping of longitudinal oscillations along the trim angle throughout the entire water intake cycle.

Design and Determination of Aerodynamic Coefficients of a Tail-Sitter Aircraft by Means of CFD Numerical Simulation

Vertical take-off and landing (VTOL) aircraft have become important aerial vehicles for various sectors, such as security, health, and commercial sectors. These vehicles are capable of operating in different flight modes, allowing for the covering of most flight requirements in most environments. A tail-sitter aircraft is a type of VTOL vehicle that has the ability to take off and land vertically on it elevators (its tail) or on some rigid support element that extends behind the trailing edge. Most of the tail-sitter aircraft are designed with a fixed-wing adaptation rather than having their own design. The design of the tail-sitter carried out in this work had the particularity of not being an adaptation of a quad-rotor system in a commercial swept-wing aircraft, but, rather, was made from its own geometry in a twin-rotor configuration. The design was performed using ANSYS SpaceClaim CAD software, and a numerical analysis of the performance was carried out in ANSYS Fluent CFD software. The numerical results were satisfactorily validated with empirical correlations for the calculation of the polar curve, and the performance of the proposed tail-sitter was satisfactory compared to those found in the literature. The results of velocity and pressure contours were obtained for various angles of attack. The force and moment coefficients obtained showed trends similar to those reported in the literature.