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Fixed-wing MAV with morphing wing configuration is seen as the future design requirements for more aerodynamic efficiency. Wash in twist morphing MAV wings have shown a promising ability by producing smoother lift behavior and exhibited a significant increase in lift performances. However, the wash in twist morphing wings also suffer from massive drag penalties as compared to rigid or membrane (baseline) wings. Thus, the objective of this paper is to explore the aerodynamic performances of another morphing configuration known as wash out twist morphing MAV wing with a view towards the improvement of the drag performances of morphing MAV wing. Technically, the wash out twist morphing (TM) wing has deformation characteristics which are opposite from those of the wash in morphing wing. The force execution of the wash out morphing wing is similar to the wash in wing but with reversed vector direction. The investigation was carried out based on Fluid-Structure-Interaction (FSI) simulation method. The simulation was conducted in a 3D, quasi-static linear structural model combined with a steady-state, incompressible, and turbulent flow model. Three levels of the wash out morphing force (5N, 3N, and 1N) were used here to evaluate the morphing performances together with the baseline wing models (membrane wing and rigid wing). The lift coefficient results show that the wash out TM wings produced inferior lift performances compared to the baseline wings. This is due to weak vortices interactions, which lead to substantial adverse pressure on the TM wings. Meanwhile, TM wings have slight advantages in producing better drag performances than the rigid and membrane wings. Vortices study discovered that the TM wings have a weak tip vortex formation, which subsequently induces lower drag magnitude. However, the drag advantages found on the TM wings are still unable to overcome the lift drawbacks, which in turn, reducing the overall aerodynamics efficiency performances.

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.

This paper establishes and analyzes a high-fidelity nonlinear time-periodic dynamic model and the corresponding state observer for flapping vibration suppression of a novel tailless Flapping Wing Micro Air Vehicle (FWMAV), named NPU-Tinybird. Firstly, a complete modeling of NPU-Tinybird is determined, including the aerodynamic model based on the quasi-steady method, the kinematic and dynamic model about the mechanism of flapping and attitude control, combined with the single rigid body dynamic model. Based on this, a linearized longitudinal pitch dynamic cycle-averaged model is obtained and analyzed through the methods of neural network fitting and system identification, preparing for the design of flapping vibration suppression observer. Flapping vibration is an inherent property of the tailless FWMAV, which arises from the influence of time-periodic aerodynamic forces and moments. It can be captured by attitude and position sensors on the plane, which impairs the flight performance and efficiency of flight controller and actuators. To deal with this problem, a novel state observer for flapping vibration suppression is designed. A robust optimal controller based on the linear quadratic theory is also designed to stabilize the closed-loop system. Simulation results are given to verify the performance of the observer, including the closed loop responses combined with robust optimal controller, the comparison of different parameters of observer and the comparison with several classic methods, such as Kalman filter, H-infinity filter and low-pass filter, which prove that the novel observer owns a fairly good suppression effect on flapping vibration and benefits for the improvement of flight performance and control efficiency.

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...

A computational study is conducted on thin flat plates to simulate flows of Reynolds numbers at 104 to provide understanding and guidance for micro air vehicles and other low-Reynolds-number airfoi...

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.

In recent times, scores of innovations are taking place in the field of unmanned aerial vehicle (UAV) technology that includes continuous development of design of on-board processing, memory, storage, and communication capabilities. Since UAVs are now being used extensively in many areas of expertise that include commercial, military, civilian, agricultural, and environmental applications, it is very essential that these UAVs communicate efficiently. The communication may be of the UAV-to-UAV (U2U) type or it could be with the already existing prevalent networking infrastructures UAV-to-Infrastructure (U2I) type of communication. A new prototype is developed based on the insect flight dynamism. These insect wings are very thin membranous structure. They are subjected to many forces and follow aerodynamic flying and hovering. The current research trend on this subject is the simulation of insect wing structure and utilization to create a prototype for the development of unmanned micro air vehicles. In the present study, three flying insects such as dragon fly, cicada, and jewel beetle are selected and the wing aerodynamic parameters are analyzed by mathematical models. The comparative scanning of the data revealed that cicada wing structure is their aerodynamic characteristics may serve as a prototype. The results are discussed with relation to the base data for the flapping-wing system in micro air vehicle. In this paper, we have tried to put forward an approach that is capable of providing real-time positioning and tracking of a UAV. The approach has three parts: tracking device, backend server, and mobile app.

This paper investigates the impacts that vibratory-based actuation mechanisms can have on power consumption for a flapping-wing micro air vehicle. The flapping-wing is characterized by a lumped-parameter single degree of freedom system. Equations of motion are developed which are solved to obtain the flapping angle and lift response of the flapping-wing system. Linear and nonlinear vibratory actuation mechanisms are considered to determine their effects on the power consumption of the flapping-wing drone. Actuation mechanism parameters are varied to enhance and optimize the system’s performance. The results show that the resonance phenomenon can be utilized to minimize the power consumption depending on the system’s parameters. Linear damping is found to be a very critical parameter that is necessary to minimize when designing the system. It is demonstrated that higher transmission ratios are effective at reducing the necessary forcing input, which reduces the input power needed for hovering flight. The results also indicate that the nonlinear softening behavior can be beneficial in further reducing the required power by reducing the necessary input force and excitation frequency. An optimal configuration of actuation mechanism parameters is presented.

Insects wings are subject to wear and tear from collisions and environmental disturbances during flight. They can tolerate both symmetrical and asymmetrical wing damages while maintaining flight capability to some extent. Drawing inspiration from nature's adaptation capabilities, we investigated the consequences of wing damage on a flapping wing micro air vehicle by quantifying the changes in wing kinematics, lift generation, control torque offset, and aerodynamic damping variations in flight tests with intact and damaged wings. For the proposed vehicle, the wing damage affected the lift generation significantly. Compared to the intact wings, the damaged ones result in increased stroke angle amplitude in order to compensate for lift loss and torque imbalance, which causes an increase in power consumption accordingly. Furthermore, asymmetric damages usually require a larger amount of additional control effort for flight stabilization compared to symmetric cases. In addition, aerodynamic damping varies as the wing areas change. All these aspects pose challenges in flight control. An adaptive controller is proposed to cope with the wing damage induced detrimental effects on flight capacity. Flight tests were conducted to validate the control performance. As a result, the robot can effectively overcome such challenges even in the case of a maximum unilateral lift loss of up to $\approx$ 22%. Such a result matches the performance of hovering hawkmoths, which can handle torque asymmetry up to 22.3 $\pm$ 7.8%. To the best of our knowledge, this is the first demonstration of FWMAVs to handle significant wing asymmetry in hover flight.

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

In this study, proposed is a PD (Proportional-Derivative) controller for the roll and yaw motions based on the linearized and non-coupled lateral mode dynamic model of the flapping-wing micro air vehicle (FW-MAV) called KUBeetle. First, the lateral mode dynamics model is cascaded with the dynamics of the sensors, filters, and servos to obtain more accurate dynamic model. Then, the stability and robustness of the closed loop control system is analyzed using root locus and H∞ norm stability criteria. From the analyses, the robustly stabilizing PD control gains are determined. It Is found that the simple PD controller of roll motion has big overshoot and large steady error, even though the closed loop system is very stable. To improve the roll controller performance, a loop shaping compensator is designed and cascaded to the proportional feedback part of the roll control loop. It is shown that the complex compensator improves the roll response, and it does not affect much the closed loop stability robustness of the roll control loop. The real flight test was done to check the performance of the proposed control loop and it shows that lateral motion follows the reference command very well as in the simulation.

We developed an octocopter-based unmanned aerial system (UAS) to monitor remote environments. The system contains various environmental monitoring sensors for measuring wind speed/direction, temperature, relative humidity, atmospheric pressure, fine dust, and multispectral and RGB data. The UAS consists of an unmanned aerial vehicle (UAV), a ground control station, and a server. We studied its electrical, mechanical, and software (SW) configurations. Specifically, we developed hardware (HW) and SW to control the yaw and gimbal pitch directions of the UAV conveying multispectral and RGB cameras. To prevent the obtained solar reflectance from affecting the multispectral and RGB data and to improve the quality of the obtained data, we maneuvered the yaw so that it would always deviate 135° from the solar azimuth angle, with the sun at its rear. Managing the yaw direction involves controlling the UAV based on a micro air vehicle link message-based robot operating system (ROS). To safely test the UAS performance before the maiden flight in an ocean area, we first evaluated PX4 and ROS-based SW through indoor software-in-the-loop simulation (SILS) via the Gazebo tool. Subsequently, we used an F450 UAV and an actual maritime UAV to sequentially perform pre-flight and flight experiments. This paper explains the system operation scenario, UAS component, and simulation and experimental results. The results reveal that the average yaw angle error during the mission, $\bar {\left |{ \theta _{y,des}-\theta _{y} }\right |}$ , is approximately 8°, and the average pitch angle of the gimbal during the mission, $\left |{ 50^{\circ }-\left |{ \bar {\theta _{c}} }\right | }\right |$ , is less than 5°.

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...

This paper presents the real-time implementation of an altitude-embedded flight controller using proportional, integral, and derivative (PID) control, adaptive PID (APID) control, and adaptive PID control with a fuzzy compensator (APIDFC) for a micro air vehicle (MAV), specifically, for a Parrot Mambo Minidrone. In order to obtain robustness against disturbance, the adaptive mechanism, which was centered on the second-order sliding mode control, was applied to tune the classical parameters of the PID controller of the altitude controller. Additionally, a fuzzy compensator was introduced to diminish the existence of the chattering phenomena triggered by the application of the sliding mode control. Four simulation and experimental scenarios were conducted, which included hovering, as well as sine, square, and trapezium tracking. Moreover, the controller’s resilience was tested at 1.1 m above the ground by adding a mass of about 12.5 g, 15 s after the flight launch. The results demonstrated that all controllers were able to follow the reference altitude, with some spike or overshoot. Although there were slight overshoots in the control effort, the fuzzy compensator reduced the chattering phenomenon by about 6%. Moreover, it was found that in the experiment, the APID and APIDFC controllers consumed 2% and 4% less power, respectively, when compared to the PID controller used to hover the MAV.

A large variety of gusts that develop in the atmospheric boundary layer affect aerial vehicles. This study, performed in water tow tanks, compares the response of a flat plate wing to transverse ve...

Paper plane has a high potential to be upgraded as a Micro Air Vehicle (MAV). Due to its simplicity, paper plane offers easier design option compared to the biological inspired designs as shown in recent MAV development. However, researchers have underestimate and overlook the basic aerodynamic performance induced by these paper planes. This is due to its common usage as toys and wide range of paper plane design. Thus, the objective for current work is to analyse and compare the aerodynamics forces and its performance for selected paper plane design known as Glider, Wide Stunt Glider Plane and Stunt plane. A series of CFD simulations on each paper plane was executed by using ANSYS-CFX module. A steady state, incompressible flow Navier-Stokes equation (RANS) combined with Shear Stress Turbulence (SST) model were used in this works to solve flow problem over the paper planes. The analysis is mainly conducted to study and compare the lift coefficient (), drag coefficient ()and aerodynamic efficiency () performances for each paper planes. The results show that the Glider paper plane has managed to produce better performances in terms overall magnitude, stall angle, wider angle of attack (?) envelope and higher maximum lift coefficient magnitude compared to the other paper plane design. However, Glider paper plane has the least distributions by producing at least 14.3% larger magnitude compared to the other plane design at certain ? region. Instead, The Wide Stunt has promisingly produced better distribution by producing lower value compared to the other plane design. Based on performance, the Wide Stunt paper plane has produced better and maximum aerodynamic efficiency () magnitudes compared to the other design. Wide Stunt paper plane induced at least 6.4% better magnitude compared to the other paper plane design. Based on these results, it can be concluded that Wide Stunt paper plane has promising advantages which are very crucial for the paper plane especially during hovering operation, take-off and landing manoeuvre.

This paper analyzes the effects of propeller flow on the linear coupled longitudinal and lateral dynamics of a 150 mm wingspan fixed wing micro air vehicle (MAV). The effects propeller flow on the lift, drag, pitching moment and side force is obtained through wind tunnel tests. The aerodynamic forces and moments are modeled as a function of angle of attack, sideslip angle, control surface deflection and propeller rotation per minute. The nonlinear six degrees of freedom model is linearized about straight and constant altitude flight conditions for different trim airspeed to obtain linear coupled longitudinal and lateral state space model. The eigenvalues and eigenvectors of linear coupled longitudinal and lateral state space model are compared with and without propeller flow effects. The variation in the natural frequencies and damping ratios of short period mode, phugoid mode and Dutch roll mode are analyzed for various trim airspeed. An increase in the natural frequency is observed for phugoid mode and Dutch roll mode with propeller effects. The stability of the spiral mode is enhanced by the propeller flow and also the response of the roll subsidence mode is faster with propeller effects. Detailed analysis of eigenvalues and eigenvectors shows the importance of incorporating propeller flow in analyzing the dynamics of the MAV.

Flapping-wing micro air vehicles (FWMAVs) inspired by the nature are interesting flight platforms due to their efficiency, concealment and agility. However, most studies have been conducted in indoor environments where external disturbance is excluded because these FWMAVs are susceptible to disturbance due to their complex dynamics and small size. In order for these bio-inspired robots to perform various tasks outside, a capability to react robustly to external disturbance is essential. In this letter, we propose an algorithm that allows a FWMAV to fly well even under external disturbance. First, we derive the attitude dynamics of the FWMAV based on flight data. Then, we design a robust attitude controller using DOBC based on the dynamics. Also, we add a flight mode selector to recognize disturbance autonomously and switch to the robust control mode. Finally, we experiment outdoor flight of the FWMAV with wind disturbance. The FWMAV recognizes the existence of disturbance autonomously, and produces additional control inputs to compensate the disturbance. The proposed algorithm is validated with experiments.

This paper presents a proportional-integral-derivative (PID) flight controller for a quadrotor micro air vehicle (MAV). The MAV (Parrot Mambo minidrones) is small, therefore, a slight perturbation will affect its performance. Hence, for the actuated dynamics, roll (ϕ), pitch (θ), yaw (ψ), and z stabilization, a PID control scheme is proposed. Furthermore, the same controller technique is also applied for under-actuated dynamics x and y position control. The newtonian model is simulated using simulink with a normal Gaussian noise of force as external disturbances. using simulink support package for Parrot Minidrones by MATLAB and based on the simulation parameter, the algorithm is deployed using Bluetooth® Low energy connection via personal area network (PAN). A slight force by hand is applied as perturbation during hovering to investigation system performances. Finally, the simulation and experimental on this commercial MAV, Parrot Mambo minidrones shows good performance of the flight controller scheme in the presence of external disturbances.

The aerodynamic performance of clap-and-fling mechanism in a KU-Beetle—a tailless two-winged flapping-wing micro air vehicle—was investigated for various horizontal free-stream inflows. Three inflow speeds of 0 (hovering), 2.52 m/s and 5.04 m/s corresponding to advance ratios of 0, 0.5 and 1 were considered. The forces and moments for two wing distances of 16 mm (in which the clap-and-fling effect was strong) and 40 mm (in which the clap-and-fling effect was diminished) were computed using commercial software of ANSYS-Fluent 16.2. When the advance ratio increased from 0 to 0.5 and 1, the lift enhancement due to clap in the down-stroke reversal increased from 1.1% to 1.7% and 1.9%, while that in the up-stroke reversal decreased from 2.1% to −0.5% and 1.1%. Thus, in terms of lift enhancement due to clap, the free-stream inflow was more favorable in the down stroke than the up stroke. For all investigated inflow speeds, the clap-and-fling effect augmented the lift and power consumption but reduced the lift-to-power ratio. The total contributions of the fling phases to the enhancements in lift, torque, and power consumption were more than twice those of the clap phases. For the advance ratio from 0 to 0.5 and 1, the enhancement in average lift slightly decreased from 9.9% to 9.4% and 9.1%, respectively, and the augmentation in average power consumption decreased from 12.3% to 10.5% and 9.7%. Meanwhile, the reduction in the average lift-to-power ratio decreased from 2.1% to 1.1% and 0.6%, implying that in terms of aerodynamic efficiency, the free-stream inflow benefits the clap-and-fling effect in the KU-Beetle.

Wireless ranging measurements have been proposed for enabling multiple Micro Air Vehicles (MAVs) to localize with respect to each other. However, the high-dimensional relative states are weakly observable due to the scalar distance measurement. Hence, the MAVs have degraded relative localization and control performance under unobservable conditions as can be deduced by the Lie derivatives. This paper presents a nonlinear model predictive control (NMPC) by maximizing the determinant of the observability matrix to generate optimal control inputs, which also satisfy constraints including multi-robot tasks, input limitation, and state bounds. Simulation results validate the localization and control efficacy of the proposed MPC method for range-based multi-MAV systems with weak observability, which has faster convergence time and more accurate localization compared to previously proposed random motions. A real-world experiment on two Crazyflies indicates the optimal states and control behaviours generated by the proposed NMPC.

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.

Highly automated Unmanned Aerial Vehicles (UAVs) or "flying robots" are rapidly becoming an important asset to society. The last decade has seen the advent of an impressive number of new UAV types and applications. For many applications, the UAVs need to be safe, highly automated, and versatile. Safety is a prerequisite to allowing their use in society. While flight safety comprises many aspects, one important safety factor is the total system mass. The common thread through this research is therefore to minimize the system mass while maintaining mission capabilities to increase safety. Flight automation is required to reach many applications' full potential by addressing operational labor costs and scalability. But despite great advances in ground-based robotics, the weight and power constraints of flying robots still constitute important challenges. Last but not least, many applications also require versatile aircraft that combine the ability to hover and fly fast efficiently. Hover is required for precision take-off & landing in confined areas at a growing number of locations and for the close-up inspection of assets. Fast and efficient flight is needed to reach distant locations, perform large surveys, cope with high headwind conditions, or simply reach destinations quickly. Unfortunately, the requirements for hover and fast flight are conflicting, and this drives the search for solutions to ``combine hover with fast flight in mission-capable flying robots while cost-effectively minimizing their size and maximizing their safety.'' To investigate the minimal feasible mass of mission-capable robots, in this thesis, a novel 20 g tailed flapping-wing robot called DelFly Explorer is presented that can autonomously explore unknown unprepared rooms. It was equipped with a 4 g micro stereo-vision system which necessitated algorithms that were optimized for tiny microcontrollers with low memory. Combined with a navigation strategy that keeps the area in front of the robot free of obstacles, a 0.9 g autopilot, and DelFly's novel stable slow hovering flight regime, this led to the lightest flying indoor exploration robot that could navigate in unknown environments. But to combine passive dynamic longitudinal stability at slow hover and fast flight in tailed ornithopters, a shift in the center of gravity location was shown to be needed. Moreover, the aerodynamically stabilizing tail also causes sensitivity to turbulence. Therefore, by using four pairs of flapping wings, a new tail-less flapping-wing concept called Quad-thopter was created which can hover precisely and transition to fast forward flight. The cranked-rocker-based mechanism contains no expensive parts and by re-using the main propulsion motors for attitude control, powerful control moments can be created which are very important in disturbance rejection. This design represents one of the first tailless flapping wing designs that was sufficiently light and agile for performing real missions while featuring a mechanism simple enough to permit large-scale production. Versatility of flight is also an asset for outdoor flight. Theory predicts that the most efficient hover is achieved by using a single large rotor while the most efficient forward flight is performed by using high aspect ratio fixed wings to generate lift. The combination of both has led to a novel helicopter-with-wings concept called DelftaCopter. The control of this platform yields unique challenges such as the inertia of the large fixed-wing interferes with the dynamics of the helicopter rotor. A controller was derived, and the dynamics were identified in hover and forward flight. The real-world performance of this flying robot is presented by analyzing the results of its participation in the outback medical challenge, showing that large single-rotor-equipped fixed-wing aircraft combine powerful attitude control, efficient hover, and efficient forward flight. Since efficiency in forward flight is not sufficient to achieve a very long endurance in electrically powered flying robots, a novel platform was developed around a hydrogen pressure cylinder and a fuel cell. The concept focuses on versatility, minimal weight, good control, and redundancy. A 12-motor tail-sitter is presented that re-uses all its motors for attitude control, hover, and forward flight and uses the wing structure to carry the propulsion. A dual automotive CAN-bus control network and dual flight modes remove the most critical single points of failure. The platform is called the NederDrone and is shown to fly 3h38 in a test departing from a moving ship at sea in 5 Beaufort wind conditions. While reaching fast flight in large free blocks of air is mainly a challenge for the design of the airframe and its energy source, as soon as obstacles are introduced, new bottlenecks appear and the weight and power consumption of sensing and processing become driving design considerations. Increasing the flight speed of flying robots in obstacle-packed or GPS-denied environments highlights the need for very lightweight fast but intelligent systems, as the processing weight and power not only reduce the flight times but also reduce the maneuvering capabilities and the maximum speed. Therefore, in this work, an extreme example is studied in the context of autonomous drone racing. A computationally light Artificial Intelligence (AI) based monocular navigation system is presented for indoor flight through obstacles. It enabled the flying robot to fly at higher speeds than what was possible with state-of-the-art visual-inertial odometry solutions. Overall, aerospace platforms require extreme optimization as every gram kept in the air requires constant energy. The consequence is that different missions will require vastly different platforms, while traditionally a lot of flying robot applications are still performed by multicopters. This thesis contributes to the design of intelligent flying robots that can both hover and fly fast, by solving several fundamental problems in novel concepts optimized around the five key requirements of mass, agility, efficiency, range, and speed-near-obstacles. These concepts are expected to contribute to the improvement of the mission capabilities of minimal-size flying robots to address the needs of society.

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...

The limited in-flight battery lifetime of centimeter-scale flying robots is a major barrier to their deployment, especially in applications which take advantage of their ability to reach high vantage points. Perching, where flyers remain fixed in space without use of flight actuators by attachment to a surface, is a potential mechanism to overcome this barrier. Electroadhesion, a phenomenon where an electrostatic force normal to a surface is generated by induced charge, has been shown to be an increasingly viable perching mechanism as robot size decreases due to the increased surface-area-to-volume ratio. Typically electroadhesion requires high (>1 kV) voltages to generate useful forces, leading to relatively large power supplies that cannot be carried on-board a micro air vehicle. In this letter, we motivate the need for application-specific power electronics solutions for electroadhesive perching, develop a useful figure of merit (the “specific voltage”) for comparing and guiding efforts, and walk through the design methodology of a system implementation. We conclude by showing that this high voltage power supply enables, for the first time in the literature, tetherless electroadhesive perching of a commercial micro quadrotor.

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...

A configurable multi-segment morphing system for a micro air vehicle (MAV) is presented in this study. One of the novelties is the development of an adaptive control allocation algorithm that provides fast, simultaneous and independent operation of four morphing segments using shape memory alloy (SMA) actuators. The SMA operation is time-staggered in microsecond resolution to ensure that only one SMA draws power from the MAV battery at a time. The other novelties are the in-flight measurement of morphing angle using dual flex-sensors and morphing of leading edges such that the ‘morphing-line’ is diagonal (45º) to the MAV’s lateral axis. The system was implemented on an open source autopilot controller and operated using the MAV battery. It was ground-tested under propeller ON conditions and a droop rate of 35º/s and ability to track a 1 Hz sinusoidal variation of droop angle were realised.

In the present study, we propose a trajectory optimization and replanning algorithm for micro air vehicles (MAVs) in cluttered environments. To generate the path of an MAV in a cluttered environment, we first design an offline global path optimization algorithm. This algorithm generates a global trajectory for safe aerial delivery; this trajectory enables an MAV to avoid static obstacles marked in the navigation map and satisfies the MAV's initial and arrival velocities. The MAV's trajectory is replanned by exploiting dynamic movement primitives (DMPs) and a time adjustment algorithm to enable computationally efficient unknown obstacle avoidance in local path planning. To validate the applicability of the proposed algorithm, we compare simulation results with those obtained using an existing approach based on DMPs. Furthermore, an autonomous flight is demonstrated in an outdoor environment using a custom-made MAV driven by the proposed approach.

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.

This paper focuses on the development of the speech interface for controlling a Micro Air Vehicle (MAV). A speech interface in such control applications will have two distinct modules. One is the Automatic Speech Recognition (ASR) module and the other is the Natural Language Processing (NLP) module. The ASR is developed using the models built using CMU Sphinx toolkit. The NLP scheme is proposed and developed using Natural Language Toolkit (NLTK). Understanding of the speech is very important in such kind of control applications. The NLP outcome is used to invoke the Ground Control Station (GCS) commands. The results are validated in a Flight Gear simulator using Mission Planner GCS configured for MAV.

The stability of flying of a hummingbird-like flapping-wing micro air vehicle (MAV) has been challenging. In this paper, experimental studies are reported on the tail shapes of hummingbird-like flapping-wing MAVs, since tails play an important role in-flight stability. Dynamics parameters of hummingbird tails are firstly studied and evaluated. Then man-made tails inspired by the natural hummingbirds are designed, manufactured and optimized for experimental tests. The results show that lift generated by the tail is independent of a fan angle, whereas the pitch moment is related to the fan angle. Further, the tail can be applied to stabilising hovering twin-wing flapping wing MAVs.

To solve the attitude control problem of bird-like flapping wing micro air vehicles (FWMAVs) during automatic landing, an active disturbance rejection control (ADRC) architecture is proposed in this paper. This control scheme takes into account the attitude control of flapping, transition and gliding modes in the process of automatic landing. To verify the control effect, the aerodynamic estimation method of the flapping wing based on quasi-steady theory and the dynamics of an FWMAV in Lagrangian form are applied in the simulation. The proposed control architecture consists of two independent ADRC controllers to stabilize the attitude of the pitch and roll channels. The system disturbance and the coupling effects between channels are estimated by an extended state observer (ESO) and compensated in real time in the control output. The convergence of the ESO and ADRC is proven. Simulation results show that even if the aircraft is in different flight modes, the ADRC controller can track the target trajectory quickly and accurately. Then, to realize automatic landing in a real environment, a simplified two-stage landing trajectory is designed. A landing test is carried out on this basis. The test results show that ADRC can not only stabilize the flight attitude in flapping mode but also obtain a satisfactory control accuracy and convergence speed when the aircraft is in the transition and gliding modes, confirming its usefulness in automatic landing.

Flapping-wing micro air vehicles (FWMAVs) are interesting flight platforms due to their energy efficiency, camouflage ability and agility. However, these FWMAVs produce limited forces and moments due to their small scale and complex dynamics, so most studies have been conducted in indoor environments where external disturbance is excluded. In order for these bio-inspired robots to perform various tasks in outside, an ability to react robustly to external disturbance is essential. In this paper, we employ a robust controller called disturbance observer for attitude control of a FWMAV. Before designing a controller, we derive the attitude dynamics of the FWMAV based on experimental data. Then, we validate the proposed algorithm with a flight experiment in a laboratory condition with wind disturbance similar to outdoor flight.

An experimental aerodynamic analysis is performed to obtain aerodynamic characteristics and performance of a blended wing-body aircraft (BWB) using Low Speed Wind Tunnel. The BWB design concept is a revolutionary way of understanding the hike of fuel cost, increase in air travelers and environmental concern. Recognizing the potential of the aircraft an experimental analysis is conducted on BWB to understand aerodynamic performance parameters like lift coefficient (CL), drag coefficient (CD) and the Lift-to-Drag (L/D) ratio .The aluminium BWB model is manufactured using CNC machine and is tested in Wind tunnel at different angle of attack varying from 0° to 16° at speed of 12 m/s ,25 m/s and 35 m/s velocity. The present BWB UAV design has achieved an unprecedented capability in terms of sustainability of flight at high angle of attack, low parasite drag coefficient and decent maximum lift coefficient. This study indicates some significant benefits for the BWB relative to the conventional aircraft configuration. KEYWORDS: Blended Wing Body (BWB), Aerodynamics, Unmanned Aerial Vehicle (UAV), Wind Tunnel

This article presents the implementation of closed-loop simple adaptive control on fixed-wing micro air vehicle dynamics to improve flight performance characteristics. It is known that to retain the micro air vehicle system performance during the entire flight regime is difficult due to model uncertainties, large parameter variation and wind disturbances compared to flight velocity. An adaptive controller can adapt to the uncertainties but the complexity involved in their implementation is high due to unavailability of required sensor information and computational resources on a micro air vehicle platform. Lack of flight test results in the open literature incorporating adaptive control so far can be partially attributed to this complexity. In this case, adaptive control architecture is implemented in such a way that only the uncertainties in the system dynamics are taken care of by the adaptive control and desired nominal plant performance is achieved by the basic controller. The proposed adaptive controller architecture is implemented in real flight test, and improvement of tracking performance over a proportional–integral–derivative controller is demonstrated which illustrates superior performance to conventional architectures. The proposed design approach can be implemented easily to an existing system, and system performance can be enhanced in the presence of unmodelled and uncertain system dynamics.

This paper presents the analysis of propeller-induced flow effects on the dynamics of a fixed wing biplane micro air vehicle. The analysis is based on wind tunnel tests and mathematical modeling. This analysis plays a pivotal role because the propeller-induced flow has significant effects on the dynamics of fixed wing micro air vehicle due to submergence of a large portion of the wing in propeller slipstream. Although the effect of the propeller-induced flow on the various aerodynamic parameter is reported in the literature; however, its effects on overall forces, moments and vehicle dynamics are not quantified so far. In this paper, propeller-induced flow effects are modeled as a function of motor rotation speed and mathematical analysis is performed to quantify their effects. The wind tunnel test is conducted at different propeller speeds on a biplane micro air vehicle “Skylark”, having wingspan and chord length of 150 mm and 140 mm, respectively. Analysis of results shows that the propeller slipstream increases the overall lift, drag, side force, range, and endurance significantly. Propeller flow also contributes to the rolling moment and the pitching moment, while it has negligible effects on the yawing moment. It is shown that the trim angle of attack is lower when the propeller flow is considered in computing the trim conditions.

This paper numerically studies the aerodynamic performance of a bird-like bionic flapping wing. The geometry and kinematics are designed based on a seagull wing, in which flapping, folding, swaying, and twisting are considered. An in-house unsteady flow solver based on hybrid moving grids is adopted for unsteady flow simulations. We focus on two main issues in this study, i.e., the influence of the proportion of down-stroke and the effect of span-wise twisting. Numerical results show that the proportion of down-stroke is closely related to the efficiency of the flapping process. The preferable proportion is about 0.7 by using the present geometry and kinematic model, which is very close to the observed data. Another finding is that the drag and the power consumption can be greatly reduced by the proper span-wise twisting. Two cases with different reduced frequencies are simulated and compared with each other. The numerical results show that the power consumption reduces by more than 20%, and the drag coefficient reduces by more than 60% through a proper twisting motion for both cases. The flow mechanism is mainly due to controlling of unsteady flow separation by adjusting the local effective angle of attack. These conclusions will be helpful for the high-performance micro air vehicle (MAV) design.

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...

Natural flight was always a source of inspiration to human beings, and by observing it, new technologies emerged, especially in bioinspired aerial vehicle design. The main objective of the present work is to experimentally evaluate the influence of the wing shape on their behavior and power consumption. To accomplish that goal, four wings were selected and an experimental rig was developed. Airflow velocities tested ranged from 0 up to 4 m s−1 with four different throttle positions. Flapping frequency and amplitude were obtained from high-speed camera tests and the power consumption of the wings tested was measured. It is observed that amplitude is between 0.12 m and 0.25 m, frequency between 4 and 15 Hz. Regarding power consumption, the design wings presented lower averaged power-to-weight ratio values when compared to BionicBird wings., Fundação para a Ciência e a Tecnologia

We envision the human body as a platform for fast take-off and landing of drones in entertainment and professional uses such as medical emergencies, rescue missions, or supporting police units. This new interaction modality challenges our knowledge of human-drone experiences, in which interaction usually occurs at a distance from the body. This work explores important factors for understanding the interplay between drones and humans. We first investigated the suitability of various body locations for landing in an online study (N = 159). Our results, presented as body maps, show that the hand and upper back are particularly well-suited body locations. We further tested these findings in a follow-up study (N = 12), in which participants experienced drones landing on their bodies through carefully designed and pre-recorded 360°videos. This immersion into the landing scenarios helped us to identify common themes and research approaches for different body parts. Taken together, the findings provide first insights into location preferences and themes for drones landing on the human body.

Recent progress in flapping-wing micro air vehicles has led to the design of the bird-like main body of a flapping-wing micro air vehicle. Inspired by the Calliope hummingbird, the main body of the flapping-wing micro aerial vehicle is designed, and modifications were made to house all the commercially available components inside the main body such as a battery, motor and camera. All the components were placed inside and the center of gravity position of the main body of bio-inspired MAV was determined. Steady and unsteady computational analysis of the main body was carried out at body angles of 8, 14, 20, 28, 38, 50, 70 and 90 degrees. The effect of change in forward velocity on aerodynamics was also studied at the body angle of 28 degrees, where the lift to drag ratio is maximum. Flow physics analysis made at different body angles shows that flow starts to separate after 50 degrees and stall accurs. Bell and semi S-shaped curves are formed when the coefficient of lift and Drag are plotted against the body angle, respectively.