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A key challenge in flapping-wing micro air vehicle (FWMAV) design is to generate high aerodynamic force/torque for improving the vehicle's maneuverability. This paper presents a bio-inspired hover-capable flapping-wing micro air vehicle, named RoboFly.S, using a cross-tail wing to adjust attitude. We propose a novel flapping mechanism composed of a two-stage linkage mechanism, which has a large flapping angle and high reliability. Combined with the experimentally optimized wings, this flapping mechanism can generate more than 34 g of lift with a total wingspan of 16.5 cm, which is obviously superior to other FWMAVs of the same size. Aerodynamic force/torque measurement systems are used to observe and measure the flapping wing and aerodynamic data of the vehicle. RoboFly.S realizes attitude control utilizing the deflection of the cross-tail wing. Through the design and experiments with tail wing parameters, it is proved that this control method can generate a pitch torque of 2.2 N·mm and a roll torque of 3.55 N·mm with no loss of lift. Flight tests show that the endurance of RoboFly.S can reach more than 2.5 min without interferences. Moreover, the vehicle can carry a load of 3.4 g for flight, which demonstrates its ability to carry sensors for carrying out tasks. [ABSTRACT FROM AUTHOR]

This paper describes a dragonfly-inspired Flapping Wing Micro Air Vehicle (FW-MAV), named HiFly-Dragon. Dragonflies exhibit exceptional flight performance in nature, surpassing most of the other insects, and benefit from their abilities to independently move each of their four wings, including adjusting the flapping amplitude and the flapping amplitude offset. However, designing and fabricating a flapping robot with multi-degree-of-freedom (multi-DOF) flapping driving mechanisms under stringent size, weight, and power (SWaP) constraints poses a significant challenge. In this work, we propose a compact microrobot dragonfly with four tandem independently controllable wings, which is directly driven by four modified resonant flapping mechanisms integrated on the Printed Circuit Boards (PCBs) of the avionics. The proposed resonant flapping mechanism was tested to be able to enduringly generate 10 gf lift at a frequency of 28 Hz and an amplitude of 180° for a single wing with an external DC power supply, demonstrating the effectiveness of the resonance and durability improvement. All of the mechanical parts were integrated on two PCBs, and the robot demonstrates a substantial weight reduction. The latest prototype has a wingspan of 180 mm, a total mass of 32.97 g, and a total lift of 34 gf. The prototype achieved lifting off on a balance beam, demonstrating that the directly driven robot dragonfly is capable of overcoming self-gravity with onboard batteries.

Wing rock is a complex phenomenon that occurs as a result of the system's inherent aerodynamic nonlinearities and is dominant only in the roll motion. It has been intensively investigated on heavily swept delta wings, but limited work has been done on rectangular wings, which are becoming increasingly popular in micro aerial vehicles. This research investigates the wing rock features of a rectangular wing using experimental, numerical, and analytical approaches. Initially, free-to-roll wind tunnel tests using an air bearing-based apparatus are performed. Then, a validated numerical method based on solving the three-dimensional incompressible Reynolds-averaged Navier–Stokes equations is utilized in three different approaches: the static tests, the unsteady forced roll tests, and the unsteady free-to-roll tests. Both unsteady approaches are compared, and the flow-field analysis is done with Liutex, a novel vortex identification method. Afterward, using numerical simulation data, an analytical method based on multiple time scales is modeled and the stability properties are determined using bifurcation analysis. The experimental and numerical results are in good agreement. The findings show that the separation bubble's movement and interaction with the wingtip vortices are crucial in inducing the wing rock phenomenon in rectangular wings. [ABSTRACT FROM AUTHOR]

Small insects with flapping wings, such as bees and flies, have flexible wings with veins, and their compliant motion enhances flight efficiency and robustness. This study investigated the effects of integrating wing veins into soft wings for micro-flapping aerial vehicles. Prototypes of soft wings, featuring various wing areas and vein patterns in both the wing-chord and wing-span directions, were fabricated and evaluated to determine the force generated through flapping. The results indicated that the force is not solely dependent upon the wing area and is influenced by the wing vein pattern. Wings incorporating wing-chord veins produced more force compared to those with wing-span veins. In contrast, when the wing area was the specific wing area, wings with crossed wing veins, comprising both wing-span veins and wing-chord veins, produced more force. Although wing-chord veins tended to exert more influence on the force generated than the wing-span veins, the findings suggested that a combination of wing-span and wing-chord veins may be requisite, depending upon the wing area.

A flapping wing is considered as one of the most effective aerodynamic systems for micro air vehicles (MAVs). Many numerical studies have been attempted to investigate the flow field around a flapping wing; nevertheless, the long-term flow characteristics, which can cause a non-negligible effect on long-term hovering operations of MAVs have not been adequately clarified owing to the high computational cost involved. This study numerically investigates the long-term flow characteristics around a flapping flat-plate wing during hovering flight at a chord-based Reynolds number of 2.5 × 104. Based on the finite-volume method with the arbitrary Lagrangian-Eulerian (ALE) method, two-dimensional laminar flow analyses were performed for 40 periods of flapping motions with stroke inversion angles of β = 30°, 45°, and 60°. The results showed that the lift coefficient CL was not completely periodic despite the periodic motion. To identify the CL characteristics for each β case, a half-stroke-period-based phase-average of CL was calculated over different time segments. Then, the phase-averaged CL using the fifth to 30th periods sufficiently provided converged aerodynamic characteristics: the β = 30° and 45° cases had a single peak of CL, whilst the β = 60° had double peaks; the second peak taking the maximum CL in the β = 60° case was delayed compared to others. The results of this study provide a guideline for the number of periods required in the numerical estimation of the CL characteristics and associated flow fields around flapping-type MAVs, which contributes to their further improvement of them.

This study presents the design, implementation, and assessment of a combined passive and active flow control technique with the aim of increasing the aerodynamic performance of fixed-wing Micro Air Vehicles (MAVs). Power consumption restrictions in MAVs support the choice of passive flow control solutions such as the use of a modified (tubercled) wing leading edge. This strategy successfully allows to delay and mitigate aerodynamic stall but detrimental effects are found at pre-stall operating conditions. In order to retrieve the lift-generation capabilities of the baseline wing at pre-stall, a subsidiary active flow control method making use of air blowing was designed and installed in the modified wing. Guidance to the selection of optimum settings was provided by experimental and computational analyses. The resulting hybrid flow control system demonstrated its effectiveness, thus producing generalized lift enhancements irrespectively of the attitude of the wing. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Wing flexibility is critical to flapping rotary wings (FRWs), and in that the deformation is bilaterally coupled with aerodynamic forces and thus determines the performance. Conventional solutions to this fluid-structure interaction (FSI) topic require considerable computational resources. In this paper, an efficient FSI model is proposed to calculate the aerodynamic force and passive twisting of FRWs. The passive pitching is regulated by a torsional spring, and the twisting is simplified as a quadratic distribution. A well-verified quasi-steady model is employed to estimate the aerodynamic forces. Our results show that the performance of rigid FRWs is superior to twistable FRWs within an upper limit of the wing-root stiffness k1, which is around 3×10-3 N·m·rad-¹. At higher k1 values, the twistable FRWs generate comparable lift to rigid FRWs at a higher efficiency. An increase in flapping frequency can remarkably reduce the efficiency of twistable FRWs despite the lift enhancement, while a concomitant reduction of flapping amplitude can moderate the loss of efficiency at higher flapping frequencies. Our model provides an efficient tool for the quick estimation of the aeroelastic performance of twistable FRWs and can thus contribute to the wing stiffness design. [ABSTRACT FROM AUTHOR]

A key challenge in flapping-wing micro air vehicle (FWMAV) design is to generate high aerodynamic force/torque for improving the vehicle’s maneuverability. This paper presents a bio-inspired hover-capable flapping-wing micro air vehicle, named RoboFly.S, using a cross-tail wing to adjust attitude. We propose a novel flapping mechanism composed of a two-stage linkage mechanism, which has a large flapping angle and high reliability. Combined with the experimentally optimized wings, this flapping mechanism can generate more than 34 g of lift with a total wingspan of 16.5 cm, which is obviously superior to other FWMAVs of the same size. Aerodynamic force/torque measurement systems are used to observe and measure the flapping wing and aerodynamic data of the vehicle. RoboFly.S realizes attitude control utilizing the deflection of the cross-tail wing. Through the design and experiments with tail wing parameters, it is proved that this control method can generate a pitch torque of 2.2 N·mm and a roll torque of 3.55 N·mm with no loss of lift. Flight tests show that the endurance of RoboFly.S can reach more than 2.5 min without interferences. Moreover, the vehicle can carry a load of 3.4 g for flight, which demonstrates its ability to carry sensors for carrying out tasks.

A biomimetic wing is designed by considering the wing of a natural flyer (Passer domesticus) as a reference. Since the birds have thin wings, Bergey BW-3, a thin and highly cambered airfoil, is used to design the wing cross section. To investigate the aerodynamic characteristics of the biomimetic wing, numerical and experimental studies are carried out at low Reynolds number (Re) ranging from 2.5 × 104 to 1 × 105. It is observed that the numerical findings have the similar trend as that of the experimental observations. The performance of the biomimetic wing is compared with rectangular and elliptical wings at Re = 5 × 104. It is observed that the separation bubble formed over the surface of the biomimetic wing at Re = 2.5 × 104 is not strong enough to influence the lift coefficient but increases the drag coefficient dramatically when the mean angle of attack exceeds 18°. It is observed that the drop in the lift coefficient of rectangular wing is higher than that of the other wings due to the presence of sharp edges in the planform. The lowest drag coefficient is witnessed in the elliptical wing but it also has the lowest lift coefficient due to the interaction between the separation bubble and tip vortices. On the other hand, the biomimetic wing offers the highest lift coefficient with a considerable amount of drag. Overall, a 57.9% increase in lift coefficient is observed for the biomimetic wing than that of the elliptical wing under the same conditions. A 22.4% increase in the lift to drag ratio of the biomimetic wing is observed over that of the rectangular wing. It is also observed that the flow separates dramatically as the mean angle of attack increases beyond the stall angle in the rectangular and elliptical wings. But a delay in the flow separation is observed in case of the biomimetic wing after the stall angle. It is also observed that the suction over the wing surface of the biomimetic wing is more at the wing root (fixed end) than that at the wing tip (free end), which may provide good stability during flight conditions. The enhanced aerodynamic performance of the biomimetic wing is due to change in shape of the wing along the span which has a strong influence over its effective angle of attack with respect to the incoming flow. [ABSTRACT FROM AUTHOR]

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

This study presents a computational tool to accurately simulate the flow around a flapping-wing micro air vehicle in free flight. The flow around the vehicle is obtained by solving the Navier–Stokes equations of the incompressible flow using an immersed boundary method. The motion of the vehicle subject to aerodynamic and gravity forces is obtained by solving the rigid body equations using a quaternion formulation for the vehicle's orientation. Both sets of equations are solved in a coupled way. The methodology is illustrated by simulating the flow around a model vehicle in uncontrolled, symmetric, forward flight at low Reynolds number, where the wing kinematics is externally imposed. The analysis is performed on the initial stages after the vehicle is released, with particular emphasis on the aerodynamic forces and the flow around the vehicle. [ABSTRACT FROM AUTHOR]

This paper describes the development and flight testing of a compact, re-configurable, hover-capable rotary-wing micro air vehicle that could be tube launched for increasing mission range. The vehicle design features a coaxial rotor with foldable blades, thrust-vectoring mechanism for pitch/roll control and differential rpm for yaw control. The vehicle was stabilized using a cascaded feedback controller implemented on a 1.7-gram custom-designed autopilot. Wind tunnel tests conducted using a single-degree-of-freedom stand demonstrated gust-tolerance up to 5 m/s, which was verified via flight testing. Finally, the 366-gram vehicle was launched vertically from a pneumatic cannon followed by a stable projectile phase, passive rotor unfolding, and transition to a stable hover from arbitrarily large attitude angles demonstrating the robustness of the controller. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

This paper shows some guidelines to improve the estimation accuracy of a navigation system, which is based on wide‐field‐integration (WFI) of optic flow. Optic flow is a vector field of relative velocities obtained by photoreceptors in image sensors, and WFI of optic flow enables motion estimation robust by integrating wide range of optic flow. Since the system has several attractive features (small size, light weight, and low computation), it is applicable to an autonomous control system of micro air vehicles. However, due to some restrictions of real systems, WFI of optic flow theory should be applied while considering sensor arrangement for better estimation. In this paper, first an adequate number and adequate optical‐axes of image sensors are investigated. Then, a new estimation system combining a gyro sensor with WFI of optic flow is discussed by numerical simulations. Finally, the essential effect for the number of cameras are verified in experiments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A solution to the waypoint navigation problem for the fixed wing micro air vehicles (MAV) having a severe coupling between longitudinal and lateral dynamics, in the framework of integrated guidance and control (IGC) is addressed in this paper. IGC yields a single step solution to the waypoint navigation problem, unlike conventional multiple loop design. The pure proportional navigation (PPN) guidance law is integrated with the coupled MAV dynamics. A multivariable static output feedback (SOF) controller is designed for the linear state space model formulated in IGC framework. A waypoint navigation algorithm is proposed that handles the minimum turn radius constraint of the MAV and also evaluates the feasibility of reaching a waypoint. Non-linear simulations with and without wind disturbances are performed on a high fidelity 150 mm wingspan MAV model to demonstrate the proposed waypoint navigation algorithm. [ABSTRACT FROM AUTHOR]

Since the birth of bio-inspired flapping-wing micro air vehicles, a controversial topic, i.e., whether and to what extent a flapping wing can outperform conventional micro rotors, has existed in the field of micro-to pico-scale unmanned aircraft. However, instead of answering this debate, an alternative idea that combines the flapping-wing and rotary-wing layouts was proposed and has been extensively studied over the last ten years. By merging bionic features of flapping wings into micro rotors, this novel layout, i.e., flapping rotary wing (FRW), can maintain autorotation with no driving torque and achieve both a superb lift generation and a moderate efficiency at a Reynolds number between 103 and 104, presenting an additional choice for micro air vehicles when facing a task to balance the payload and energy cost. As the first review of FRW, this paper overviews the concept, bionic features, aerodynamic principles, and development of flyable prototypes since 2010, from fundamental aerodynamic mechanisms to key points in prototype design, including wing structure, actuator, transmission system, energy source, etc. The advantages and disadvantages of this novel layout over conventional flapping wings and micro rotors are discussed. Four challenging directions are then suggested to improve the flight performance of this layout and thus boost its application in military and civilian fields. [ABSTRACT FROM AUTHOR]

Food security is one of the societal challenge topics. As one-third of all food consumed by humans relies on animal pollination currently, this research provides an emerging solution to food supply reduction caused by population shrinking of natural pollinators, so as to reduce its impact on ecological relationships, ecosystem conservation and stability, genetic variation in the crop plant community, floral diversity, specialisation and evolution. This paper develops a conceptual technical roadmap of autonomous pollination for future farming using robotic micro air vehicle pollinators (MPrs). The research provides new insights into autonomous design and manufacture and into possible ways to increase the production efficiency which shortens the time from lab to market. The autonomous MPrs are realized using artificial intelligence and human expertise in the loop for smart agricultural industry. Further, this work identifies scientific and technological advances that are expected to translate, within proposed regulatory frameworks, into the pervasive use of MPrs for agricultural applications and beyond.

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. [ABSTRACT FROM AUTHOR]

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.

Most admirable and least known features of low Reynolds number flyers are their aerodynamics. Due to the advancements in low Reynolds number applications such as Micro Air vehicles (MAV), Unmanned Air Vehicles (UAV) and wind turbines, researchers' concentrates on Low Reynolds number aerodynamics and its effect on aerodynamic performance. The Laminar Separation Bubble (LSB) plays a deteriorating role in affecting the aerodynamic performance of the wings. The parametric study has been performed to analyse the flow around cambered, uncambered wings with different chord and Reynolds number in order to understand the better flow characteristics, LSB and three dimensional flow structures. The computational results are compared with experimental results to show the exact location of LSB. The presence of LSB in all cases is evident and it also affects the aerodynamic characteristics of the wing. There is a strong formation of vortex in the suction side of the wing which impacts the LSB and transition. The vortex structures impact on the LSB is more and it also increases the strength of the LSB throughout the span wise direction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nowadays, Earth is being affected by the greenhouse effect. A first step to improve the current situation is to track the involved variables under temporal and spatial sampling. In this paper, we propose an integrated system for monitoring the related greenhouse effect gasses and several environmental variables. The system has been designed to be mounted on an unmanned aerial vehicle to overcome the spatial constraints and it also has been designed to work under the Internet of Things paradigm to overcome the temporal constraints. Unlike previous approaches, we have integrated an optimal filtering step with Kalman Filter, improving the reliability and precision of the measurements. Our experiments show that the proposed system can provide the information to the final user in near real-time. In addition, the use of the Kalman filter decreases the mean square error of our system with respect to a reference sensor. [ABSTRACT FROM AUTHOR]

This paper describes the design of a miniature air suction system to house a chemical sensor. It has been designed to improve the aerodynamic chemical sensing efficiency and to have a low weight since it is meant to be mounted on a micro air vehicle. The design is done around a readily available miniature axial flow fan by computational methods. A converging-diverging shape for the air suction system with the sensor disc having a central hole and mounted at the throat is proposed as good design concept. The systematic approach has led to a light weight system with high aerodynamic efficiency even under extreme flow conditions that may be caused by MAV manoeuvre or cross winds. [ABSTRACT FROM AUTHOR]

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 (45°) 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 35°/s and ability to track a 1 Hz sinusoidal variation of droop angle were realised. [ABSTRACT FROM AUTHOR]

The traditional control system cannot determine the specific location of the transmission error of navigation information, the implementation process is complex, and the information sequence needs to be fed back to the source, resulting in reduced transmission efficiency and high delay of navigation information, so that the control effect is unsatisfactory. To this end, a GIS intelligent navigation information control system for micro air vehicle (MAV) is proposed. The BER calculation equation is designed and the principle of turbo encoder is analysed. The pseudo-random sequence is used to process the intelligent navigation information of the MAV to form an intelligent navigation information sequence. Without feedback to the source, the output information sequence can be dispersed due to the error code of sudden interference. Through the MAP method, the absolute value of the posterior probability ratio is regarded as the soft decision output, the code is used to obtain the error position and the transmission error of the intelligent navigation information is controlled, so that the design of the GIS intelligent navigation information control system for MAV is completed. The experimental results show that the improved system can better control the transmission error of navigation information, and the control effect is very satisfactory. [ABSTRACT FROM AUTHOR]

Delayed stall is the most dominant lift enhancing factor in insect flapping motion. Micro air vehicle operates at Reynolds number 104-105; slightly higher than the insects’ Reynolds number (Re). In the present research, thefocus is to investigate “stall-absent” phenomenon at Re representative of the micro air vehicles, the effect of spanwiseflow on the leading edge vortex and also to study the effect of geometry variations on the aerodynamic performance of the wing in unsteady motion. Corrugated dragonfly airfoil with rectangular wing planform is used, however, with wing kinematics restricted to azimuth rotation only. Three-dimensionalfinite-volume method is used, through commercial software Fluent, to numerically solve time-dependent incompressible Navier-Stokes equations. Computed results at Re 34000 and 100,000 reveal the same phenomenon of delayed stall, as observed in the case of insects. Furthermore, the performance of flat plate, profiled and corrugated wing in a sweeping motion at a high angle of attack is also compared.