Wing Unmanned Aerial Vehicle Research Articles

Design optimization-under-uncertainty of a forward swept wing unmanned aerial vehicle using SAMURAI

In this paper the design optimization-under-uncertainty of a forward swept wing (FSW) blended wing body (BWB) unmanned aerial vehicle (UAV) is examined. Conventional BWBs are often tailless, which leads to a backward swept wing to ensure longitudinal static stability. This in turn can induce flow separation at the tip, leading to a loss of lift, controllability and the appearance of a nose-up pitching moment. A possible solution to this problem is a conceptual redesign by introducing a forward swept wing, which is inherently free of tip-stall, but needs a careful design in order to be controllable. However, fixed wing UAVs are often produced by means of direct injection expanded foam moulding, which is characterized by not negligible production tolerances. This lead to a reliability-based robust design optimization problem, for which a novel framework is employed: SAMURAI. Firstly, the method accounts for computational cost by means of surrogate modelling, an analytical treatment of the problem and an asynchronous updating scheme that balances design space exploration and objective exploitation. Secondly, the method treats the problem as a multi-objective problem, which leads to a Pareto front of robust and reliable designs. The result is a novel series of UAV designs that are inherently free of tip stall, perform robustly and meet the stability requirements with the target reliability obtained with a computationally feasible budget.

Time-optimal of fixed wing UAV aircraft with input and output constraints

<p style='text-indent:20px;'>The route prediction of unmanned aerial vehicles (UAVs) according to their missions is a strategic issue in the aviation field. In some particular missions, the UAV tasks are to start a movement from a defined point to a target reign in the shortest time. This paper proposes a practical method to find the guidance law of the fixed-wing UAV to achieve time-optimal considering the ambient wind. The unique features of this paper are that the environment includes the moving and fixed obstacles as the route constraints, and the fixed-wing UAVs have to keep a given distance from these obstacles. Also, we consider the specific kinematic equation of the fixed-wing UAV and limitations on the flight-path angle and bank-angles as other constraints. We suggest a method for controlling a fixed-wing UAV to get time-optimal using the re-scaling and parameterization techniques. These techniques are useful and effective in maximizing the performance of the gradient-based methods as a sequential quadratic programming method (<inline-formula><tex-math id="M1">\begin{document}$ SQP $\end{document}</tex-math></inline-formula>) for numerical solutions. Then, all constraints of the time-optimal control problem are converted to a constraint using an exact penalty function. Due to being exact, finding the control variables and switching times is more accurate and faster. Finally, some numerical examples are simulated to explore the effectiveness of our proposed study in reality.</p>

Improved ant colony algorithm for path planning of fixed wing unmanned aerial vehicle

Aiming at the problems of long search time and local optimal solution of ant colony algorithm (ACA) in the path planning of unmanned aerial vehicle (UAV), an improved ant colony algorithm (IACA) was proposed from the aspects of simplicity and effectiveness. The flight performance constraints of fixed wing UAVs were treated as conditions of judging whether the candidate expanded nodes are feasible, thus the feasible nodes’ number was reduced and the search efficiency was effectively raised. In order to overcome the problem of local optimal solution, the pheromone update rule is improved by combining local pheromone update and global pheromone update. The heuristic function was improved by integrating the distance heuristic factor with the safety heuristic factor, and it enhanced the UAV flight safety performance. The transfer probability was improved to increase the IACA search speed. Simulation results show that the proposed IACA possesses stronger global search ability and higher practicability than the former IACA.

Reinforcement Learning Training Environment for Fixed Wing UAV Collision Avoidance

In recent years, Unmanned Aerial Vehicles (UAVs) are emerging as a key technology with possible uses for several applications. To fully exploit their potential, UAVs needs to be able to be fully automatized and they need to be allowed to go Beyond Visual Line of Sight (BVLOS). Nowadays, autopilots and Detect and Avoid (DAA) systems, essential components for BVLOS operations, are developed with classical control approaches and classical algorithm for identification and avoidance of collision in the airspace. However, new methods based on Artificial Intelligence and, in particular, on Reinforcement Learning are attracting scientific interest. In order to train an agent with Reinforcement Learning methods, the development of the training environment is of utmost importance. This paper aims to present the development of a training environment to train an agent to avoid collisions in the airspace by setting desired values of roll, pitch and throttle. It will describe the developed training environment and the PID controllers implemented for allowing the own aircraft to receive the roll, pitch and throttle commands and to control the intruders’ trajectory.

Performance evaluation of unmanned aerial vehicle wing made from sterculiasetigeradelile fiber and pterocarpuserinaceus wood dust epoxy composite using finite element method abaqus and structural testing

Performance evaluation of unmanned aerial vehicle wing made from sterculiasetigeradelile fiber and pterocarpuserinaceus wood dust epoxy composite using finite element method abaqus and structural testing

Launchable rotary wing UAV designs and launch mechanism designs for rotary wing UAV

In recent years, rotary-wing unmanned aerial vehicles have been used in many areas. Rotary wing unmanned aerial vehicle (UAV) can carry different payloads according to their duties. For example; if they carry cameras, they are used for reconnaissance / surveillance, cargo if they carry cargo, agriculture if they carry pesticides, mapping if they carry an advanced camera and mapping system, and communication if they carry a base station or relay. Rotary-wing unmanned aerial vehicles are usually commanded to take off manually by a trained UAV operator. Before takeoff, the rotary-wing unmanned aerial vehicle is prepared for take-off by the UAV operator and this preparation takes approximately five minutes. It takes time for rotary-wing unmanned aerial vehicles to take off from the runway and reach their cruising speed, causing time loss in critical areas. A rotary-wing unmanned aerial vehicle launch assembly and a rotary-wing unmanned aerial vehicle with an opening mechanism that can open the thrust arms after launch and continue to fly can be the solution to this time loss. Rotary-wing drones capable of launching and without the intervention of the UAV operator will play an important role in emergency response and defense, where situational awareness is often required. For example; firefighters responding to fires can take advantage of the ability to quickly launch rotary-wing unmanned aerial vehicles from a stationary or moving fire truck. Thanks to the day / thermal camera on the launched rotary wing unmanned aerial vehicles, valuable information can be obtained about the progress of the fire and the damage caused by the fire. Thanks to rapid awareness, the fire can be intervened and fought faster. Similarly, military personnel can quickly deploy launchable rotary-wing drones for reconnaissance and surveillance and perform their duties. In order to be applicable to various types of missions, it is important that the rotary wing unmanned aerial vehicle be portable and low in volume. Since the launchable rotary-wing unmanned aerial vehicle proposed in the thesis has an arm release mechanism after launch, it can automatically open and generate thrust after launching its arms. In this way, it helps lower volume coverage before being launched. This also reduces air friction during launch. It can be deployed to autonomous systems effortlessly as it has closed package, mobile and self-arm management. Different mechanisms will be studied to create an efficient design. A mechanism that allows it to open its arms in a short time will be used in the self-arm-opening management design. Throwable rotary wing unmanned aerial vehicle and launch mechanism will be designed and 3D printers will be used for prototype.

Modal Characterization, Aerodynamics, and Gust Response of an Electroactive Membrane

Flexibility and electric field sensitivity of dielectric elastomer membranes motivate the consideration of their applications in the wings of unmanned aerial vehicles. Applied electric field excitation expands the dielectric elastomer in the in-plane direction by compressing it into the thickness direction, which causes a change in the tension and ultimately affects the dynamic behavior of the elastomer. This study outlines the modal characteristics and fluid-structural dynamic behavior of the very high bond 4910 membrane, a type of dielectric elastomer, especially in an abrupt flow environment. An experimental shaker arrangement along with the digital image correlation system is used for experimental vibration testing. A finite element model is developed to study the modal characteristics and validate the experimental results. A fluid–structure interaction model of the electroactive membrane and its surrounding airflow is also developed to investigate the aerodynamic responses of the structure. Gust environments are predicted using the von Kármán and Dryden gust models, and the effect of different gust velocities on the aerodynamic lift and drag are obtained from the numerical fluid–structure interaction models. A wind tunnel, equipped with a data acquisition system, is used to study the aerodynamic responses and validate the numerical results experimentally. The modal analysis shows that the resonance frequencies decreased as the applied electric field excitation is increased. The coefficients of lift and drag fluctuate with the stochastic gust distribution, and the effects of von Kármán and Dryden gust profiles on aerodynamic characteristics are comparable. The values of the coefficients of lift and drag increase with the increase of applied voltage. The numerical results for the modal and aerodynamic responses show a good agreement with their corresponding experimental findings.

Backstepping and dynamic inversion control techniques for automatic landing of fixed wing unmanned aerial vehicles

The landing control of the unmanned aerial vehicles is a very difficult task having in mind both the external disturbances and their strong nonlinear dynamics with channel interferences. Motivated by this fact, this paper deals with the design of a novel automatic landing system (ALS) for a tailless and fixed blended wing unmanned aerial vehicle (UAV) having mobile centre of mass. By using the backstepping and the dynamic inversion control techniques, a novel auto-landing system is designed and software validated to control the aircraft during all the three landing phases (final approach, glide slope phase, flare) and handle the external disturbances such as the atmospheric turbulences and the errors of the measurement sensors. The dynamics of the aircraft involves the interconnection between the motions in the longitudinal and lateral-directional planes in contrast to other works where the dynamics has been separately linearized before developing of the control laws. The auto-landing system consists of two controllers (for the attitude angles and the forward speed of the UAV), an adaptive observer (for the estimation of the atmospheric turbulences), four reference models (to obtain the desired attitude angles and forward speed). This novel control architecture also uses the desired landing geometry and the operating conditions associated to a default trajectory defined by means of the calculated attitude angles and velocity of the UAV. The first controller (based on the backstepping control technique) provides the deflections of the three control surfaces, while the second one (based on the dynamic inversion technique) provides the throttle command to maintain a constant airspeed. The deviation of the UAV from the runway is cancelled and the desired landing trajectory is followed accurately. The results of the numerical simulations show the fulfilment of all the control objectives, including here the steady and the transient performances of the tracking errors, as well as the robustness relative to the atmospheric turbulences, the errors of the measurement sensors, and the motion of the mass centre.

Stability Analysis and Augmentation Design of a Bionic Multi-Section Variable-Sweep-Wing UAV Based on the Centroid Self-Trim Compensation Morphing

In this study, a design scheme for a high-aspect-ratio bionic multi-section variable-sweep wing unmanned aerial vehicle (UAV) that utilizes the reverse coordinated change in the sweep angle of the inner and outer wing sections is proposed, which improves the aerodynamic performance and realizes the self-trim compensation of the wing’s centroid. According to the layout characteristics of this type of UAV, a reasonable distribution design of the wingspan ratio of the inner and outer sections is explored, to reduce the impact of aerodynamic center movement and moment of inertia change. The calculation and analysis results show that the coordinated variable-sweep scheme can significantly improve the influence of sweep angle change on the longitudinal static stability margin of UAVs with a high aspect ratio. The coordinated sweep angle change in the inner and outer wing sections can not only reduce the drag during high-speed flight, but also play a significant role in improving the performance of the aircraft at different stages in the mission profile. Appropriately increasing the wingspan proportion of the inner section can reduce the trim resistance of the V-tail, reduce the thrust of the engine, and increase the range and duration of the UAV. From the perspective of stability change, the multi-section variable-sweep wing UAV with a wingspan ratio of the inner and outer sections that is between 1.41 and 1.78 has better dynamic stability performance. Among them, the UAV with a wingspan ratio of the inner and outer sections that is equal to 1.41 has better longitudinal stability performance, while the UAV with a wingspan ratio of the inner and outer sections that is equal to 1.78 has better lateral/directional stability performance.

Bioinspired Feathered Flapping Wing UAV Design for Operation in Gusty Environment

The flight of unmanned aerial vehicles (UAVs) has numerous associated challenges. Small size is the major reason of their sensitivity towards turbulence restraining them from stable flight. Turbulence alleviation strategies of birds have been explored in recent past in detail to sort out this issue. Besides using primary and secondary feathers, birds also utilize covert feathers deflection to mitigate turbulence. Motivated from covert feathers of birds, this paper presents biologically inspired gust mitigation system (GMS) for a flapping wing UAV (FUAV). GMS consists of electromechanical (EM) covert feathers that sense the incoming gust and mitigate it through deflection of these feathers. A multibody model of gust-mitigating FUAV is developed appending models of the subsystems including rigid body, propulsion system, flapping mechanism, and GMS-installed wings using bond graph modeling approach. FUAV without GMS and FUAV with the proposed GMS integrated in it are simulated in the presence of vertical gust, and results’ comparison proves the efficacy of the proposed design. Furthermore, agreement between experimental results and present results validates the accuracy of the proposed design and developed model.

Realisation and testing of novel fully articulated bird-inspired flapping wings for efficient and agile UAVs

AbstractLarge birds have evolved an effective wing anatomy and mechanics, enabling airborne mastery of manoeuvres and endurance. For these very reasons, they are difficult to replicate and study. The aim of the present work is to achieve active wing articulations to mimic natural bird flapping towards efficient and agile Unmanned Aerial Vehicles (UAVs). The proposed design, bio-mimicking the black-headed gull, Larus ridibundus, has three active and independent servo-controlled wing joints at the shoulder, elbow and wrist to achieve complex controls. The construction of the wing is realised through a polymeric skin and carbon fibre–epoxy composite spars and ribs. The wing movements (flapping, span reduction and twisting) envelopes of the full-scale robotic gull (Robogull) are examined using the Digital Image Correlation (DIC) technique and laser displacement sensing. Its aerodynamic performance was evaluated in a wind tunnel at various flapping parameters, wind speeds and angles of attack. It is observed that a flapping amplitude of 45 $^\circ$ is more favourable than 90 $^\circ$ for generating higher lift and thrust, while also depending on the presence of span reduction, twist and wind speed. The model performs better at a flying velocity of 4m/s as compared with 8m/s. Both lift and thrust are high at a higher flapping frequency of 2.5Hz. Combined variation of the flapping frequency and stroke ratio should be considered for better aerodynamic performance. The combination of a lower stroke ratio of 0.5 with a flapping frequency of 2.5Hz generates higher lift and thrust than other combinations. Span reduction and wing twist notably and independently enhance lift and thrust, respectively. An increase in the angle-of-attack increases lift but decreases thrust. The model can also generate a significant rolling moment when set at a bank angle of 20 $^\circ$ and operated with independently controlled flapping amplitudes for the wings (45 $^\circ$ for the left wing and 90 $^\circ$ for the right wing). Based on the optimal values for the flapping amplitude (45 $^\circ$ ), flapping frequency (2.5Hz) and flying velocity (4m/s), the Strouhal number (St) of the Robogull model is 0.24, lying in the optimal range ( $0.2 < \mathrm{St} < 0.4$ ) for natural flyers and swimmers.

Design and Development of a Multi-Application Hexacopter

The technology of the fixed wing and the rotary wing unmanned aerial vehicles have been emerging and the applications have been focused widely to numerous regions. This paper focuses on some applications where we have tested our multicopter and in future the further improvement shall incorporate. Our main focus was to build an aerial Covid warrior considering mainly three different and useful applications particularly for remote village areas where many facilities are not always available. First application is the delivery of the medical supplies to the people in need. Second, use of the onboard speaker, which can relay valuable information during emergency or the valuable health related awareness remotely by respective department. And the third application is use of the sanitizer spray arrangement for the larger area disinfection. The prototype has been tested in a typical village area in different conditions and has provided required performance due to optimized design. This paper is to facilitate other users to explore the capabilities of the multicopters for any situations like we suggested with this project considering this pandemic.

Software in Loop Simulation based Waypoint Navigation for Fixed Wing UAV

Software in loop simulation (SILS) based waypoint navigation test platform being presented in this paper for fixed wing unmanned aerial vehicle. The proposed platform helps to test waypoint navigation algorithm before implementing into real time environment. Matlab/Simulink and X-plane flight simulator are chosen for the proposed platform. The interface between these two platforms are done by using user datagram protocol (UDP). The waypoint navigation which is to be tested is run in Matlab/Simulink environment where as fixed wing model runs in X-plane simulator. Inverted T tail fixed wing unmanned aerial vehicle configuration is chosen for this research work to verify both its inner loop (attitude control) and outer loop (navigation control). Navigation algorithm executed in Matlab/Simulink compares difference between current and desired latitude longitude position to command flight simulator to reach its desired waypoint. Navigation towards a desired waypoint will be achieved by varying inner loop attitude command of an unmanned aerial vehicle. Finally results are observed and performances are verified in X-plane simulator.

Gull-inspired joint-driven wing morphing allows adaptive longitudinal flight control.

Birds dynamically adapt to disparate flight behaviours and unpredictable environments by actively manipulating their skeletal joints to change their wing shape. This in-flight adaptability has inspired many unmanned aerial vehicle (UAV) wings, which predominately morph within a single geometric plane. By contrast, avian joint-driven wing morphing produces a diverse set of non-planar wing shapes. Here, we investigated if joint-driven wing morphing is desirable for UAVs by quantifying the longitudinal aerodynamic characteristics of gull-inspired wing-body configurations. We used a numerical lifting-line algorithm (MachUpX) to determine the aerodynamic loads across the range of motion of the elbow and wrist, which was validated with wind tunnel tests using three-dimensional printed wing-body models. We found that joint-driven wing morphing effectively controls lift, pitching moment and static margin, but other mechanisms are required to trim. Within the range of wing extension capability, specific paths of joint motion (trajectories) permit distinct longitudinal flight control strategies. We identified two unique trajectories that decoupled stability from lift and pitching moment generation. Further, extension along the trajectory inherent to the musculoskeletal linkage system produced the largest changes to the investigated aerodynamic properties. Collectively, our results show that gull-inspired joint-driven wing morphing allows adaptive longitudinal flight control and could promote multifunctional UAV designs.

Adaptive Control and Estimation of the Condition of a Small Unmanned Aircraft Using a Kalman Filter

The article was motivated by the design of adaptive control algorithms for the control of a a fixed wing unmanned aerial vehicle (UAV). An adaptive system is a system that, with its structure or parameters, adapts to changes in the behavior of the object and based on the knowledge of variable properties, maintains the quality of its regulatory transition. The knowledge gained on this small UAV can be applied to larger aircraft. The creation of the proposed adaptive control into the UAV consisted of the creation of a simulation model of the aircraft based on known physical laws, the properties of the aircraft and a mathematical description. An adaptive PID controller for stabilization with changing coefficients based on the airspeed of the aircraft was designed and simulated. A validated control of the mathematical model of an unmanned aircraft was designed and simulated using the methods of estimation and identification of the UAV model parameter based on measured data from flight tests. Identifying dynamic parameters is a challenging task due to several factors, such as random vibration noise, interference, and sensor measurement uncertainty. The designed adaptive UAV control provides very promising results in improving the controllability of the aircraft while reducing the effect of speed changes on the stability and controllability of the system compared to the conventional PID controller. The comparison was performed on three selected types of PID controllers. The first type had fixed coefficients for the entire range of speeds calculated using the Control toolbox in MatLab. The second type also had constant coefficients over the entire range of speeds calculated using the Naslin method. The third adaptive type of PID controller had variable coefficients based on approximate polynomials dependent on the change in flight speed. The reason for the comparison was to show an increase in margin of stability using the method of variable coefficients of the PID controller based on the change of flight speeds. The obtained results show that the proposed adaptive control algorithm is robust enough to control the movement of the aircraft in the longitudinal plane and due to the introduced process and measurement errors, while the used Kalman filter effectively eliminates these errors.

Bio‐Inspired Large‐Area Soft Sensing Skins to Measure UAV Wing Deformation in Flight

AbstractBiological organisms demonstrate remarkable agility in complex environments, especially in comparison to engineered robotic systems. In part, this is due to an organism's ability to detect disturbances and react to them quickly. To address the challenge of quickly sensing these same disturbances in robotic systems, this study proposes and demonstrates large‐area soft sensing skins designed to sense disturbances on unmanned aerial vehicles (UAVs) in flight. These skins are enabled by high‐resolution soft strain sensors embedded into a large‐area skin through a modular molding process that spans feature sizes from tens of microns to 0.675 m. The electronics of the sensing system enable the soft skins to be sampled fast enough to capture dynamic loads on a wing. Overall, the large‐area soft sensing skin demonstrates high sensitivity, mechanical robustness, and consistent sensor readings across static and dynamic tests. The use of the soft sensing skin during UAV flight demonstrates that the sensing skin can capture relevant flight dynamics on small UAVs. These results pave the way to large‐area soft sensing skins for fast and robust control of a wide variety of robotic systems.

Analysis of flows and prediction of CH10 airfoil for unmanned arial vehicle wing design

The unmanned aerial vehicle (UAV) is becoming popular from last two decades and it has been utilizing in enormous applications such as aerial monitoring, military purposes, rescue missions, etc. Hence, the present work focused on the design of the UAV wing considering the CH10 airfoil. In this paper, the computational fluid dynamic analysis on CH10 cambered airfoil has been conducted to achieve the preliminary results on the aerodynamic lift and drag coefficients. The airfoil has a chord length of 1 meter and has been subjected to low Reynolds numbers of 500 000, which is the standard operating Reynolds number for UAV wing design. The C-type fluid domain has been constructed at 30C upstream and downstream of the airfoil to initialize the boundary conditions. The angle of attack ranging from 0

Design, aerodynamic analysis and test flight of a bat-inspired tailless flapping wing unmanned aerial vehicle

This paper provided a design of bat-inspired tailless flapping wing unmanned aerial vehicle (UAV) based on the biological data of the large flying fox. The wing span of the UAV is 1.68 m and the total mass is 289 g. Aerodynamic characteristics at design cruise speed were analyzed based on the computational fluid dynamics (CFD) method. Selected variables within the analysis are angle of attack and flapping frequency. Prototype of the UAV has been manufactured follows the design parameters. The flapping mechanism employed a 2-DOFs revolute-spherical-spherical-revolute (RSSR) system to reflect the flapping attitude of bats. An outdoor test flight was then processed with the manufactured prototype. Onboard flight data recorder (FDR) was equipped to conserve the flight data such as flight speed, pitching angle and the three-dimensional position of the flight. It is shown by the data obtained from the FDR that the bat-inspired UAV is able to achieve the stable cruise with circular route at flight speed 6.8 m/s with the average angle of attack 4.1 degrees and flapping frequency 3.7 Hz. Test flight shows that the UAV is able to provide a 5 minutes free outdoor cruise with the equipped Li-Po battery. Research proves that the tailless configuration flapping wing UAV is able to sustain a stable flight, which provides a new design possibility for future researches.

The Effect of Wing Spar Cross-Sectional Profile Variation on the Unmanned Aerial Vehicle (UAV) Natural Frequency

Natural frequency is a critical dynamic parameter in designing the unmanned aerial vehicle (UAV) wing structure. The low-value natural frequency causes the aircraft wing to deflect easily while flying. Furthermore, the low-value natural frequency can causes resonance when this natural frequency is closest to the wind frequency. An increase in the UAV natural frequency can be conducted by increasing the wing structural stiffness. However, increased stiffness by enlarging dimensions is often followed by an increase in mass that is avoided in the design of aircraft structures. One technique that can be used to increase UAV natural frequency is by increasing the cross-sectional moment of inertia of the wing spar. In this study, an analysis of the effect of the wing spar cross-sectional inertia variations on the UAV natural frequency is conducted. Several wings spar cross-sectional profiles with different cross-sectional inertia are evaluated, such as U profile, circular, T profile, square, L profile, I profile, and Z profile. The results of the investigation showed that the wing spar using T profile is better than other profiles in increasing the wing structure natural frequency. This profile could increase the 1st elastic natural frequency by 22.9%, with only a 3.4 % increase in mass.

Irradiation, thermal and mechanical properties of ethylene-tetrafluoroethylene copolymer for use in wings of unmanned aerial vehicle

To study the properties of ethylene-tetrafluoroethylene (ETFE) copolymer materials in wings of unmanned aerial vehicles, electron beam irradiation was performed to prepare the corresponding irradiated ETFE for air atmosphere. All these irradiated samples were characterized by SEM, FTIR, TGA, DSC, flexural fatigue measurement and tensile test. The results revealed that the logarithm of the flexural fatigue of ETFE decreased with the irradiation dose increased, which could be explained by the growing effect of chain scission. The elongation-at-break decreased with the dose increase, while the tensile strength was kept constant. As shown in FTIR results, the scission of the macromolecular chains induced by irradiation resulted in the relative oxidation of groups, such as carbonyl groups. TGA analysis showed that the initial and maximum decomposition temperatures increased with dose increase due to the inherent cross-linking structures. Besides, the number of the crystalline regions with regular formation (such as crystallization temperature, crystallization degree and crystallization enthalpy) decreased with the dose increase as a result of the formation of unsaturated structures after the elimination of HF from the broken chains, which was confirmed by FTIR. It is expected that our findings can provide important information to promote the development of aircraft materials.