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The force-generation mechanism of a dovelike flapping-wing micro air vehicle was studied by numerical simulation and experiment. To obtain the real deformation pattern of the flapping wing, the digital image correlation technology was used to measure the dynamic deformation of the wing. The dynamic deformation data were subsequently interpolated and embedded into the CFD solver to account for the aeroelastic effects. The dynamic deformation data were further used to calculate the inertial forces by regarding the wing as a system of particles to take into account the wing flexibility. The temporal variation of the forces produced by the flapping wing was measured by a miniature load cell. The numerical results provide more flow details of the unsteady aerodynamics of the flapping wing in terms of vortex formation and evolution. The calculated results of the inertial forces are analyzed and compared with the CFD results which represent the aerodynamic forces. In addition, the total forces, i.e., the sum of the CFD result and inertial result, are compared with the experimental results, and an overall good agreement is obtained.

Instantaneous force and structural deformation experiments were performed on a flexible, structurally characterized, low-aspect-ratio representative flapping wing. A six-component force balance was...

Humans' initial desire for flight stems from the imitation of flying creatures in nature. The excellent flight performance of flying animals will inevitably become a source of inspiration for researchers. Bio-inspired flight systems have become one of the most exciting disruptive aviation technologies. This review is focused on the recent progresses in bio-inspired flight systems and bionic aerodynamics. First, the development path of Biomimetic Air Vehicles (BAVs) for bio-inspired flight systems and the latest mimetic progress are summarized. The advances of the flight principles of several natural creatures are then introduced, from the perspective of bionic aerodynamics. Finally, several new challenges of bionic aerodynamics are proposed for the autonomy and intelligent development trend of the bio-inspired smart aircraft. This review will provide an important insight in designing new biomimetic air vehicles.

We have developed a tailless, two-winged flapping drone with a full span length of 180 mm and a total weight of 20.5 g. The developed flapping drone is characterized by three biomimetic techniques: an anisotropic vein pattern reinforcing the wing surfaces, an elastic flapping mechanism, and gravity center position control in the abdomen. On the basis of experimental and numerical results, the flapping wings are reinforced by a vein pattern made of an anisotropic carbon fiber-reinforced plastic (CFRP) laminate to passively provide appropriate aeroelastic deformation and positively utilize snap-though buckling on the wing surface at stroke reversals to provide a fast feathering rotation. The flapping wing kinematics are provided by a novel flapping mechanism with an energy recovery system using the elasticity of the mechanical system. Unlike other previously developed flapping robots, feedback control to stabilize the pitch and roll angles of the drone’s body is conducted using a technique of gravity center position control, where the tail angles of the body are changed similarly to the abdominal movements of insects in flight. The developed flapping drone has succeeded in an autonomous hovering flight for more than 30 s and a vertical take-off under a wireless condition with the gravity center position control., Sensors and Materials, 33(3), pp. 859-872; 2021

The paper discusses the development of a nonlinear aeroelastic coupled trim model of a twin cyclocopter in forward flight. The twin cyclocopter consists of two cycloidal rotors as main thrusters an...

In this study, the hovering performance of contra rotating ducted rotor (CRDR) for micro air vehicle (MAV) was performed by using computational fluid dynamics technique. A rotor shape with 5-inch diameter and 4.3-inch pitch for MAV was used. Aerodynamic performance and flow structures were investigated for a single rotor (SR), Contra Rotating Open Rotor and CRDR at various operating RPMs. In case of CRDR, thrust increased by 170% compared to that of SR due to the acceleration of flow at the duct inlet, and approximately 20% thrust improvement was observed compared to CROR. Duct of the CRDR was found to produce approximately 30% of the total thrust. Because torque of rear rotor is slightly greater than that of front rotor, adjustment of RPM or rotor blade shape would be necessary for the torque cancellation. Efficiency of each system was compared based on the power loading, and it was found that CRDR configuration is the most efficient configuration to generate thrust by consuming minimum power.

In this study, a 3D model of the bio-inspired blowfly wing Callphere Erytrocephala is created and aeroelastic analysis is performed to calculate its aerodynamical characteristics by use of numerical methods. To perform the flapping motion, a sinusoidal input function is created. The scope of this study is to perform aeroelastic analysis by synchronizing computational fluid dynamics (CFD) and structural dynamic analysis models and to investigate the unsteady lift formation on the aeroelastic flapping wing for different angles of attack.

In this paper, aiming to drive the unmanned aerial vehicle (UAV) to the optimal position of the vertical plane in the close formation flight, a control method that is based on extended state observ...

Investigated and revealed are new insights into the individual, decoupled effects of induced camber and spanwise bending on the lift, drag, and endurance for an optimum flexibility membrane-and-fra...

This study designs a method to improve the robustness of the micro air vehicle (MAV) yaw angle estimation for low-cost inertial navigation system/global positioning system (INS/GPS) integration by using a tri-axial magnetometer. Observability properties of the integration navigation system are first analysed, indicating that all attitude angles have great observability with the aid of the heading measurement by a magnetometer, while the observability of yaw angle is low in traditional INS/GPS. To improve the robustness of yaw angle estimation, the authors calibrate the tri-axial magnetometer according to the rotating ellipsoid model and establish a fault detection and isolation mechanism to adjust the weight of magnetic-measurement adaptively and dynamically in integration navigation. The simulation and experiment results show that the proposed method can calibrate the tri-axial magnetometer properly and screen out the abnormal magnetic measurement for the robustness of yaw angle estimation, suggesting that this technique is a viable candidate for MAV navigation and control applications in complex magnetic fields.

To design a flapping-wing micro air vehicle (FWMAV), the hovering flight action of a beetle species (Protaetia brevitarsis) was captured, and various parameters, such as the hindwing flapping frequency, flapping amplitude, angle of attack, rotation angle, and stroke plane angle, were obtained. The wing tip trajectories of the hindwings were recorded and analyzed, and the flapping kinematics were assessed. Based on the wing tip trajectory functions, bioinspired wings and a linkage mechanism flapping system were designed. The critical parameters for the aerodynamic characteristics were investigated and optimized by means of wind tunnel tests, and the artificial flapping system with the best wing parameters was compared with the natural beetle. This work provides insight into how natural flyers execute flight by experimentally duplicating beetle hindwing kinematics and paves the way for the future development of beetle-mimicking FWMAVs.

Hoverable Flapping Wing Micro Air Vehicle (FWMAV) is a new concept aircraft which imitates the flight mode of hummingbirds or insects. It has excellent mobility, flexibility, concealment, and can demonstrate hovering, forward flight and other maneuvers, which has attracted wide attention. In this research, a prototype of hoverable FWMAVs is designed and built for the research of control method, and the research on flight attitude estimation and attitude control algorithm are carried out. The hardware devices such as flight control board and remote control are designed and developed independently, also we devised the software control system to realize the communication between software and hardware, then the algorithm is verified on the experimental platform. The prototype of the aircraft weighs 27.24g, and can take off under the flapping frequency of 20Hz. On the experimental platform, relying on the hardware control circuit and software control algorithm, it can realize the attitude control of roll and pitch, and demonstrate hovering flight for two minutes.

An amendment to this paper has been published and can be accessed via the original article.

An enhanced nonlinear aeroelastic-coupled-flight dynamics framework that enables the investigation of propeller aerodynamics and inertial effects on the response of a very flexible aircraft is pres...

At low Reynolds numbers, revolving wings become less efficient in generating lift for hovering flight due to the increasing adverse viscous effects. Flying insects use reciprocating revolving wings...

Demand is growing for unmanned air vehicles (UAVs) with greater autonomy, including the ability to navigate without GPS information, such as indoors. In this work, a novel visual odometry algorithm...

Insects have a small mass and size and a low flying Reynolds number. Consequently, they serve as an excellent bionic representation of a micro air vehicle (MAV). Coleoptera (popularly referred to as beetles) have different characteristics from other flying insects. Not only can they fly at a low Reynolds number, but they also have deployable hindwings, which directly leads to a reduction in the size of their bodies. In narrow working spaces or unfavorable environments, a beetle's hindwings can fold automatically under the hard elytron. When the environment becomes conducive to flight, the hindwings can extend and help the beetle take off. This characteristic provides inspiration for the design of a bionic deployable wing system. In this paper, the structures and mechanical properties of hindwings and the mechanism of hindwing movement are reviewed, in addition to research on bioinspired deployable wings.

In this paper, the functionalities of microstructures for dragonfly wing during gliding flight are investigated. Three dragonfly-mimic airfoil-shaped wings with hybrid structures were designed and fabricated as: flat wing, zigzag-edged wing and zigzag-edged wing with pillar structure. Based on the wind tunnel experiments, the zigzag-edged wing structure significantly reduces the drag force in the gliding flight. Moreover, the drag reduction is more effective on the combination of the surface pillar and zigzag-edged structure. In addition, the zigzag-edged wing structure has less influence of Karman vortex street, and the surface pillars reduce the frictional drag and stabilized the streamline in the lower vortex region. Overall, the microstructure of the dragonfly wing is an important element in the aerodynamic study. These findings can enhance the knowledge of insect-mimic wing structure and facilitate the application of Micro Air Vehicle (MAV) in the gliding flight.

In this paper, an integrated and systematic modeling of all components and subsystems of a flapping bird robot is developed using the bond graph method. The wings kinematic is independently implemented with the aim of evaluating lateral movements of the bird and aerodynamic forces are accurately extracted by assuming quasi-steady theory. In the present dynamic model, the aeroelastic bending behavior of flexible wing of the flapping bird is revealed by the bond graph method. In this regard, three elastic bending modes and one rigid motion mode of the wing are added to the model. In the following, the performance evaluation of the flapping bird and parametric study are carried out around important quantities such as frequency, initial incidence angle, torsional stiffness, and flapping amplitude of the wings, which results in applicable and attractive consequences. As an innovation, the initial classification and presentation of the comparative characteristic curves for generating lateral forces without using an additional control surface and only based on asymmetry in the flapping kinematic using the bond graph approach is done, which is essential to perform lateral-directional maneuvers. Some important correlations are achieved, which are presented in detail in the text. As an example, the relation between lateral force and phase difference between wings is quasi-linear in a variety of velocities. Therefore, this parameter can be used as input in design of lateral control system. On the other hand, the sensitivity of the lateral force to active pitch angle is more than other quantities; as a result, such mechanism can be effectively used in rapid maneuvers. Finally, based on the presented bond graph model, it would be easily possible to study the effects of design variables, mechanical properties, geometric constraints, and specially flapping kinematics on a wide range of functional and performance indices.

The influence of Center of Gravity (CG) location on longitudinal dynamic stability of hovering KUBeetle, a tailless Flapping-Wing Micro Air Vehicle (FW-MAV), is reported in this paper. The rigid-body approximation was assumed, allowing application of the standard equations of motion used for fixed-wing aircraft. For each considered location of CG, stability derivatives were obtained using the computational fluid dynamics method via the commercial software of ANSYS Fluent. The dynamic stability was studied using technique of eigenvalue analysis. There exists a narrow stable region for CG between 23%–24% of mean chord above the wing pivot point, where the longitudinal hovering of KUBeetle is passively stable. When CG is located below the stable region, the analysis identifies two subsidence modes and one unstable oscillatory mode, which makes the hovering of KUBeetle unstable. However, it can be stabilized using pitching rate feedback. When CG is located above the stable region, the system yields one stable oscillatory mode, one subsidence mode, and one divergence mode. Because of the divergence mode, the system remains unstable even with the angular rate feedback. These results share similar characteristics to another FW-MAV and insects. This study may provide a reference for FW-MAV developers.

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

Because of the highly integrated nature of their dynamics, flapping-wing micro air vehicles exhibit significant coupling, including interactions between aeroelastic wing behavior, actuator dynamics...

The flight dynamics of Micro Air Vehicles (MAVs) exhibit significant nonlinear characteristics, which cannot be ignored in simulation or analysis. In this study, a full nonlinear simulation of the flight dynamics characteristics of a fixed-wing MAV is performed. To strengthen the developed nonlinear mathematical modeling, the MAV’s mass properties and propulsion characteristics are experimentally investigated. Moreover, the aerodynamic characteristics of the designed fixed-wing MAV are experimentally measured in a wind tunnel. The experimental aerodynamics investigation includes the propeller wash effect and the same flight conditions of the MAV. These measured data are fed to the nonlinear flight dynamics model to improve its accuracy and ensure the nonlinear aerodynamics effect on the flight dynamics. The enhanced model is then validated against response experimental measurements of the MAV in the wind tunnel that is free to pitch at different control inputs and initial conditions. Furthermore, it is compared to the response of the system identification model. The nonlinear simulation and dynamic testing investigations indicate many nonlinear phenomena, such as the appearance of the limit cycle in the longitudinal flight. This paper shows that the aerodynamic center of MAV with a low aspect ratio in the low Reynolds number regime of flow can move as a response to flap deflection. The validated nonlinear mathematical model was used to evaluate the MAV’s dynamics, design and evaluate a PID controller in flight conditions similar to the MAV’s actual flying mission. Moreover, the presented model can be used for flapping-wing MAVs using time-dependent experimental measurements.

Many previous studies have shown that wing corrugation of an insect wing is only structurally beneficial in enhancing the wing&rsquo, s bending stiffness and does not much help to improve the aerodynamic performance of flapping wings. This study uses two-dimensional computational fluid dynamics (CFD) in aiming to identify a proper wing corrugation that can enhance the aerodynamic performance of the KUBeetle, an insect-like flapping-wing micro air vehicle (MAV), which operates at a Reynolds number of less than 13,000. For this purpose, various two-dimensional corrugated wings were numerically investigated. The two-dimensional flapping wing motion was extracted from the measured three-dimensional wing kinematics of the KUBeetle at spanwise locations of r = (0.375 and 0.75)R. The CFD analysis showed that at both spanwise locations, the corrugations placed over the entire wing were not beneficial for improving aerodynamic efficiency. However, for the two-dimensional flapping wing at the spanwise location of r = 0.375R, where the wing experiences relatively high angles of attack, three specially designed wings with leading-edge corrugation showed higher aerodynamic performance than that of the non-corrugated smooth wing. The improvement is closely related to the flow patterns formed around the wings. Therefore, the proposed leading-edge corrugation is suggested for the inboard wing of the KUBeetle to enhance aerodynamic performance. The corrugation in the inboard wing may also be structurally beneficial.

The basis for properly verified R&D works is to provide reliable prototyping tools at three most important stages: computer simulation, laboratory tests and real-world experiments. In the laboratory-limited conditions, particular importance is attributed to the first two stages, especially in the context of the safety development of autonomous flights of unmanned aerial vehicle (UAV) groups in various missions. The open-source framework Aerostack support those needs and its effectiveness has been proven in the International Micro Air Vehicle Indoor Competitions (IMAV 2013, 2016, 2017) and Mohammed Bin Zayed International Robotics Challenge (MBZIRC 2020). In the paper, the exemplary functionalities for the new version of Aerostack Version 3.0 Distribution Sirocco (Aerial robotics framework for the industry), extended additionally with a library of new behaviors, are presented. The mission of UAVs can be developed fast and effectively in order to conduct test flights with real drones in lab, before one will decide to fly autonomously outdoor. The representative results obtained for low-cost AR.Drone 2.0 UAV models in two missions, are presented. The first mission is autonomous patrolling the area by a pair of UAVs, the second – intercepting the intruder in guarded area by the guard UAV.

Made available in DSpace on 2020-12-12T01:38:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Throughout the last decade, there has been an increased demand for intricate flapping-wing drones with different capabilities than larger drones. The design of flapping-wing drones is focused on endurance and stability, as these are two of the main challenges of these systems. Researchers have recently been turning towards bioinspiration as a way to enhance aerodynamic performance. In this work, the propulsion system of a flapping-wing micro air vehicle is investigated to identify the limitations and drawbacks of specific designs. Each system has a tandem wing configuration inspired by a dragonfly, with wing shapes inspired by a bumblebee. For the design of this flapping-wing, a sizing process is carried out. A number of actuation mechanisms are considered, and two different mechanisms are designed and integrated into a flapping-wing system and compared to one another. The second system is tested using a thrust stand to investigate the impact of wing configurations on aerodynamic force production and the trend of force production from varying flapping frequency. Results present the optimal wing configuration of those tested and that an angle of attack of two degrees yields the greatest force production. A tethered flight test is conducted to examine the stability and aerodynamic capabilities of the drone, and challenges of flapping-wing systems and solutions that can lead to successful flight are presented. Key challenges to the successful design of these systems are weight management, force production, and stability and control. Department of Mechanical and Aerospace Engineering New Mexico State University Department of Mechanical Engineering New Mexico Institute of Mining and Technology Department of Aeronautical Engineering São Paulo State University (Unesp), Campus of São João da Boa Vista Department of Aeronautical Engineering São Paulo State University (Unesp), Campus of São João da Boa Vista CNPq: 311082/2016-5 CAPES: 88881.302889/2018-01

A micro air vehicle (MAV) is a class of miniature unmanned aerial vehicles that has a size restriction and may be autonomous. Fixed-wing MAVs are very attractive for outdoor surveillance missions since they generally offer better payload and endurance capabilities than rotorcraft or flapping-wing vehicles of equal size. This research paper describes the methodology applying indicial function theory and artificial neural networks for identification of aerodynamic derivatives for fixed-wing MAV. The formulation herein proposed extends well- known aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to strake wing planforms. Using results from dynamic water tunnel tests and indicial functions approach allowed to identify MAV aerodynamic derivatives. The experiments were conducted in a water tunnel in the course of dynamic tests of periodic oscillatory motion. The tests program range was set at high angles of attack and a wide scope of reduced frequencies of angular movements. Due to a built-in propeller, the model&rsquo, s structure test program was repeated for a turned-on propelled drive system. As a result of these studies, unsteady aerodynamics characteristics and aerodynamic derivatives of the micro-aircraft were identified as functions of state parameters. At the Warsaw University of Technology and the Air Force Institute of Technology, a &ldquo, Bee&rdquo, fixed wings micro aerial vehicle with an innovative strake-wing outline and a propeller placed in the wing gap was worked. This article is devoted to the problems of identification of aerodynamic derivatives of this micro-aircraft. The result of this research was the identification of the aerodynamic derivatives of the fixed wing MAV &ldquo, as non-linear functions of the angle of attack, and reduced frequency. The identification was carried out using the indicial function approach.

In this paper, a contact-aided compliant flapping wing for micro air vehicle (MAV) is presented. The design consists of a perforated plate, covered with flaps which allow motion in one direction only. In order to arrest the motion of flaps in the other direction, a contact stopper is provided. When the wing (i.e., perforated plate along with flaps) is making a flapping motion in a fluid environment, it experiences different drag forces in forward and reverse strokes. The wing is made with acrylic (Poly (methyl methacrylate) or PMMA) sheet having 2 mm thick. The flaps are connected to perforated plate by compliant joints that act as torsional springs. Furthermore, these compliant joints aid in moving flaps from open to a closed position. Experiments were carried out in both air and water medium for various plate configurations. It is observed that only 14.71% of input power is saved during a reverse stroke of four-flap perforated plate while flapping in air. Hence, the advantage is less in air, wing thickness needs to be reduced substantially to get an advantage in air medium. But in a water medium, input power is saved by 32.80% for the current dimensions. This increment is due to the fact that the density of water is more compared to air. It is also noticed that there is no advantage beyond 65 and 70% of area reduction in air and water mediums respectively as it is the minimum power required to drive the servomotor.

This paper explores the optimal flight condition of an insect-like flapping-wing micro air vehicle (FWMAV) while ascending vertically at constant speeds. The FWMAV is assumed to have the same mass properties and wing geometry as those of the hawkmoth Manduca sexta. The optimization is conducted through the combination of an artificial neural network and a genetic algorithm. The training data for the artificial neural network are provided by the unsteady vortex-lattice method written in the programming language FORTRAN using parallel computation techniques. The results show that the FWMAV has to alter its wing kinematics and flapping frequency to sustain vertically ascending flight. Moreover, while ascending, the FWMAV requires more energy than that in hover. The findings from this work are useful for the design of control strategies used for insect-like FWMAVs

International audience; Micro air vehicles are used for both civil and military applications, like rescue or surveillance. The aerodynamic performance of the rotor is known to be lower than for classical large rotors, due to increased drag at low Reynolds numbers. However, the rotor performance can be improved by taking advantage of the flow unsteadiness and considering unsteady rotor kinematics, like a periodic variation of the rotor pitch. To study such behaviors, it is necessary to develop numerical methods adapted to these fluid–structure interaction phenomena, which are the main objectives of this paper. The method relies on the implementation of fluid–structure interaction capabilities in a lattice–Boltzmann flow solver, which is implemented in a monolithic fashion using generalized coordinates. The validation is first conducted on a vortex-induced vibration test case. Then, numerical simulations are performed for a rotor test case 1) with a forced motion and 2) by coupling the flow with the equation of the dynamics. Some semianalytical models are derived and validated against the numerical simulations to predict the effects of pitching, flapping, and surging on the thrust. The results show that flapping and surging significantly increase the rotor thrust, but at the price of a penalty on the power consumption.

Flying birds, bats and insects have always inspired humans to venture into developing bio-inspired flying machines. Such vehicles imitate flapping wing concept are also known as Ornithopters. Efforts to build such vehicles date back to 9th-century work by famous Arab scientist Abbas-Ibn-Firnas. Despite many efforts, design and development of such vehicle remained a challenge. The major limitation in this regard is the limited knowledge of related aerodynamic concepts like, Low-Reynolds number phenomenon, vortex induced lift, non-linear fluid structure interaction, high flapping frequency, low weight, complex mechanics, stabilization and controls algorithms. This review paper is aimed to provide an insight into recent developments in understanding the complex dynamics of flapping wing vehicles. Notable experimental works and numerical investigations have been discussed in details; special emphasis has been laid on computational techniques for analysing complex dynamics and design of flapping wing vehicles. Moreover, the modern trends in design, power requirement, motion control and mathematical modelling are also explored.

One hundred years following the first powered ground-breaking flight of the Wright Brother in Kitty Hawk, Carolina, on 17 December 1903, aerospace engineers countenance defy within sympathetic along with controlling flight path and physics. While human space and space flight started in the 20th century, this may mark the start of autonomous uninhabited, computer-controlled flight in the 21st century. Uninhabited air vehicles (UAVs), which were inspired by a variety of civilian, national security and military goals, have evolved as the choice of platform for war fighters conducting surveillance and identification maneuver in hostile upbringing. Due to their comparatively low-down expenditure and tendency to provide perfect monitoring in sequence, plentiful UAV expansion programs cover been launched around the world. As specified in Figure 1, characteristic UAVs encompass a wingspan of more than 1 meter and a “GTOW” of more than five kg. Nonetheless, a novel rank of UAV has arisen in the past decade, which is at least a smaller order of magnitude and two lighter order of magnitude than earlier urbanized airplane. This novel UAV rank call a Micro Air Vehicle (MAV) or is also called a micro UAV. The size of these vehicles is no longer of about six feet, amid unpleasant starting weights of about two hundred g or less. These systems, a novel rank of aircraft, face many unique challenges which are difficult to design and design. In a very sensitive regime for Reynolds numbers, for example, micro air vehicles work. Many complex flow phenomena occur in the boundary layer under this regime. Separation, transition, and reattachment may take place within a short distance along a wing or rotor chord line and may have a significant impact on lifting surface performance.

The aerodynamic coefficients, forces, sizing parameters, and performance of fixed wing drones in different solar system bodies are investigated. Before carrying out the aerodynamic analysis and study of the performance of fixed wing drones, the physical and atmospheric features of various solar system bodies are first determined. Two drones are considered, namely, a fixed wing micro air vehicle with Inverse Zimmerman planform and a tilt-rotor unmanned air vehicle. The effects of Reynolds number on the performance of these drones from an aerodynamic point of view are determined. Furthermore, a parametric study for sizing of fixed wing drones are also investigated. These analyses ultimately lead to the optimum sizing process of fixed wing drones to be used in solar system bodies with different physical and atmospheric features. The comparison between different atmospheric characteristics on the performance of drones is needed to design efficient fixed wing drones which are capable of flight in other planets.

Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, thepw−ARratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs.

© 2018 Elsevier Ltd Micro Air Vehicles (MAVs) have the potential to revolutionize our capabilities in gathering information, monitoring situations, and surveillance. They are required to maneuver in and around obstacles as well as negotiate atmospheric disturbances whilst holding accurate trajectories and minimizing rotation which can blur imagery. A study of existing literature on MAV control challenges found that current turbulence mitigation systems and control surface configurations lack the speed of response and control authority required to maintain steady flight in turbulence. Improved control response may come from unconventional designs, bio-inspired systems, or from careful manipulation of the flow mechanics. As such, in this paper, key unsteady aerodynamic parameters are also reviewed and considered prior to deriving potential control solutions that could help MAVs fly well in turbulence.

We present direct numerical simulations of the flow around a simplified model of a flapping-wing micro air vehicle in uncontrolled forward flight at low Reynolds number, including the vehicle dynamics. A simple model for the vehicle is employed, including wings, tail and fuselage. Only a symmetric flight condition will be discussed. The wing kinematics are externally imposed and the vehicle moves as a result of the aerodynamic forces and gravity. The simulations are initialized by keeping the vehicle fixed in space in the presence of a free-stream of constant speed, flapping the wings for several periods. The gravity is adjusted using the average lift during this initial transient, after which the vehicle is released. We analyze the initial stages after the release of the vehicle, placing emphasis on how the aerodynamic forces and the flow around the vehicle are modified once the vehicle is released.

An integrated navigation scheme based on multiple optical flow sensors and a strapdown inertial navigation system (SINS) are presented, instead of the global position system (GPS) aided. Multiple optical flow sensors are mounted on a micro air vehicle (MAV) at different positions with different viewing directions for detecting optical flow around the MAV. A fault-tolerant decentralized extended Kalman filter (EKF) is performed for estimating navigation errors by fusing the inertial and optical flow measurements, which can prevent the estimation divergence caused by the failure of the optical flow sensor. Then, the estimation of navigation error is inputted into the SINS settlement process for correcting the SINS measurements. The results verify that the navigation errors of SINS can be effectively reduced (even more than 9/10). Moreover, although the sensor is in a state of failure for 400 seconds, the fault-tolerant integrated navigation system can still work properly without divergence.

The stability of small unmanned air systems can be challenged by turbulence during low-altitude flight in cluttered urban environments. This paper explores the benefits of a tandem wing aircraft configuration with the implementation of a pressure-based phase-advanced turbulence sensory system on a small unmanned air system for gust mitigation. The objective was to utilise passive and active methods to minimise gust-induced perturbations. Experimentation in repeatable turbulence within a wind tunnel’s test section was conducted. The experiments focus on the roll axis, which is isolated through a specially designed roll-axis rig. The results show improvement over conventional aircraft. This work is part of a larger research project aimed at enabling safe, stable and steady small unmanned air systems flight in urban environments.

We present a novel design of a tailless flapping wing micro air vehicle, which uses four independently driven pairs of flapping wings in order to fly and perform agile maneuvers. The wing pairs are arranged such that differential thrust generates the desired roll and pitch moments, similar to a quadrotor. Moreover, two pairs of wings are tilted clockwise and two pairs of wings anti-clockwise. This allows the micro air vehicle to generate a yaw moment. We have constructed the design and performed multiple flight tests with it, both indoors and outdoors. These tests have shown the vehicle to be capable of agile maneuvers and able to cope with wind gusts. The main advantage is that the proposed design is relatively simple to produce, and yet has the capabilities expected of tailless flapping wing micro air vehicles.

A micro air vehicle that can achieve a versatile flight condition is being designed. One way of achieving such versatility is through biomimicry. One aspect of this design utilizes a bird-like wing that changes shape to match four flight regimes; take-off-and -landing, cruise, high speed dash and one that enhances maneuverability. A joint mechanism using a tendon actuator between the inboard and the outboard portions of the wing is used to modify wing sweep. Macro fiber composites (MFCs) piezoelectric actuators in a bi-morph configuration are incorporated into the MAVs as control mechanism. Camber changes are implemented with tendon actuators. Finite element is used to model the wing section and perform a full-field deformation study and compared with experimental results. Digital image correlation is used to validate the wing deformations predicted by finite element method (FEA).

As relevant technologies become smaller and less expensive, micro air vehicles (MAVs) are transitioning from predominantly military and hobbyist applications to mainstream use. Exciting new applications include the delivery of medical supplies to remote areas, infrastructure inspection, environmental change detection, precision agriculture, survelliance of visible satellites. These issues are particularly prevalent when flying near the ground, where safety and reliability are especially important.

Membranous hind wings of the beetles can be folded under the elytra when they are at rest, and rotate and lift the elytra up only when they need to fly. This characteristic provides excellent flying capability and good environment adaptability. Inspired by the beetles, the new type of the bionic folding wing for the flapping wing Micro Air Vehicle (MAV) was designed. This flapping wing can be unfolded to get a sufficient lift in flight, and can be folded off flight to reduce the wing area and risk of the wing damage. The relationship between the internal pressures of the hydraulic system for the bionic wing folding varies and temperature was analyzed, the results show that the pressure within the system tends to increase with temperature, which proves the feasibility of the schematic design in theory. Stress analysis of the bionic wing was conducted, it was shown that stress distributions and deformation of the bionic wing under the positive and negative side loading are basically the same, which demonstrates that the strength of the bionic folding wing meets the requirements and further proves the feasibility of the schematic design.

The increasing usage of low-Reynolds-number (10,000–100,000 tip Reynolds number) scale quadrotors for civilian and military applications provides the impetus for the development of reliable design ...

Flapping rotary wing is a novel aerodynamic configuration proposed in recent years for micro air vehicles. To understand the aerodynamic characteristics of this wing layout, a computational fluid d...

This paper first analyzed the longitudinal dynamic behavior during vertical takeoff without control of a Flapping-Wing Micro Air Vehicle (FW-MAV). The standard linear flight dynamics based on small disturbances from trim condition was not applicable for our analysis because the initial flight condition, which was at rest on the ground, could be such a large disturbance from the trim condition that the linearization is invalid. Therefore, we derived linearized Equations of Motion (EoM) which can treat an untrimmed flight condition as a reference for disturbances. The Computational Fluid Dynamic (CFD) software ANSYS Fluent was used to compute the aerodynamic forces and pitching moments. Three flight modes were found: a fast subsidence mode, a slow subsidence mode and a divergence oscillatory mode. Due to divergence oscillatory mode, the deviation from the reference flight grew with time; the FW-MAV tumbled without control. The simulation showed for the first 0.5 second after leaving the ground (the time that is long enough for delay of feedback control), the FW-MAV flew up to a height of 6 cm with small horizontal and pitching motion, which is close to a vertical flight.

An optical tracking facility was used to record the free flight of the Monarch butterfly for a large number of sequential flaps. The system automatically tracked reflective markers, which were modi...

This paper introduces robust estimation of micro air vehicle’s linear velocity from captured images using a monocular camera in GPS denied environment. Vehicle’s velocity information can be extracted from matched feature points of consecutive images; however, robust techniques are required for reliable information as these estimations algorithms are prone to high image noise and unavailability of enough matched feature points. In this paper, the estimation technique is considered based on fast estimation method where the estimation error can be made arbitrary small using the high update gain and high bandwidth of low pass filter. The performance bound is only restricted by the computational resources of the hardware. The proposed scheme is built after modification of predictor equation in original fast estimation method which involves driving the predictor dynamics according to estimation error. The velocity states are obtained using the fundamental kinematics motion of world object in camera frame fixed to micro air vehicle. It is assumed that vertical height from the ground is available from other sensors and the object depth information is approximated using the flat earth model. The estimation is carried out in the realistic simulation environment by interfacing of a six-dof nonlinear model and virtual environment. Simulation results show the robustness of the proposed method.