Insect-like Flapping-wing Micro Research Articles

Development of an Insect-like Flapping-Wing Micro Air Vehicle with Parallel Control Mechanism

Most traditional flapping-wing micro air vehicles (FMAVs) adopt a serial control mechanism, which means that one drive corresponds to one degree of freedom. However, the serial mechanism often struggles to meet FMAV requirements in terms of stiffness, size, and reliability. In order to realize a compact reliable control mechanism, we developed a two-wing insect-like FMAV with a parallel control mechanism. The prototype possesses an optimized string-based flapping wing mechanism, a 2RSS/U parallel control mechanism, and an onboard power supply and controller. The pulley’s profile of the string-based mechanism was refined to reduce the deformation and impact of the string. The parameters of the parallel mechanism were designed to enable the stroke plane to rotate a large angle to produce control torque. The prototype had a flapping frequency of 25 Hz, a full wingspan of 21 cm, and a total weight of 28 g. A PID controller with a decoupler based on the kinetics solution of parallel mechanism was designed to control the FMAV. A force and torque (F/T) experiment was carried out to obtain the lift and control torque of the prototype. The measured data showed that the flapping wing mechanism provided sufficient lift and the control mechanism generated a toque caused by the stroke plane rotation and trailing edge movement and were linear to the control input. A flight test was carried out to verify the flight stability of the prototype. The result shows that the attitude angle only fluctuates within a small range, which proved that the control mechanism and control strategy were successful.

Effect of Wing Corrugation on the Aerodynamic Efficiency of Two-Dimensional Flapping Wings

Many previous studies have shown that wing corrugation of an insect wing is only structurally beneficial in enhancing the wing’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.

Fibrous Orientation Effects on the Deformation and Stress of an Insect-like Flapping-wing Micro Aerial Vehicle Based on ACP

This paper examines the effect of different orientation of composite material on the deformation and stress of dragonfly-like flapping-wing micro aerial vehicles (FWMAVs). After billions of years of evolution, insects employing flapping-wing tend to have excellent flight capabilities. To understand the bionic wings will be helpful to design high performance aircrafts. FEM analysis of flapping wing structure simulating dragonfly wings having three layers Epoxy carbon composite material and resin epoxy is glue for adhesive two layers. In the process, the flapping wing model was created in ANSYS Workbench ACP (pre), ACP (post) and then the loading of the flapping wing in each phase will be calculated. Finally, the graphs showing the changes of the maximum deformation displacement and maximum stress can be worked out. It can be known that for the first principle stress, -35° is the best performance because -35° stresses is lowest stress and +35° is the worst performance because this angle is the highest stress. For the second principle stress the -25° is the best performance because -25° have the lowest stress. For the third principle stress, -45° is the worst performance because -45° is the highest stress, +45° is the best performance because here stress is the lowest and 0° is the worst because here stress is the highest. The findings are helpful in answering why insect wings are so impeccable, thus providing possibility of improving the design of flapping wing aerial vehicles. This paper will found why insect wings are impeccable.

Design and evaluation of a deformable wing configuration for economical hovering flight of an insect-like tailless flying robot

Studies on wing kinematics indicate that flapping insect wings operate at higher angles of attack (AoAs) than conventional rotary wings. Thus, effectively flying an insect-like flapping-wing micro air vehicle (FW-MAV) requires appropriate wing design for achieving low power consumption and high force generation. Even though theoretical studies can be performed to identify appropriate geometric AoAs for a wing for achieving efficient hovering flight, designing an actual wing by implementing these angles into a real flying robot is challenging. In this work, we investigated the wing morphology of an insect-like tailless FW-MAV, which was named KUBeetle, for obtaining high vertical force/power ratio or power loading. Several deformable wing configurations with various vein structures were designed, and their characteristics of vertical force generation and power requirement were theoretically and experimentally investigated. The results of the theoretical study based on the unsteady blade element theory (UBET) were validated with reference data to prove the accuracy of power estimation. A good agreement between estimated and measured results indicated that the proposed UBET model can be used to effectively estimate the power requirement and force generation of an FW-MAV. Among the investigated wing configurations operating at flapping frequencies of 23 Hz to 29 Hz, estimated results showed that the wing with a suitable vein placed outboard exhibited an increase of approximately 23.7% ± 0.5% in vertical force and approximately 10.2% ± 1.0% in force/power ratio. The estimation was supported by experimental results, which showed that the suggested wing enhanced vertical force by approximately 21.8% ± 3.6% and force/power ratio by 6.8% ± 1.6%. In addition, wing kinematics during flapping motion was analyzed to determine the reason for the observed improvement.

Multi-Objective Genetic Algorithm for Hover Stabilization of an Insect-Like Flapping Wing

This paper describes latest results obtained on modeling, simulation and controller design of an insect-like Flapping Wing Micro Air Vehicle (FWMAV). Because of the highly nonlinear and time varying nature of insect flight and the inability to find an equilibrium point, linearization of the model without compromising the accuracy is not possible. Therefore, to address the problem of designing a controller capable of stabilizing and controlling the FWMAV around a hovering point, a metaheuristic optimization approach is proposed, based on the time averaging theorem. The results show that a controller, designed using the proposed method, is capable of stabilizing the FWMAV effectively around its hovering point.

Time-Periodic Stability of a Flapping Insect Wing Structure in Hover

The wings of insectlike flapping-wing micro air vehicles experience time-periodic inertial stiffnesses during flapping motion. By modeling the wing structure as a thin beam, a linear time-periodic assumed-modes analysis is developed. The equations of motion of a flapping wing undergoing out-of-plane bending and torsion are derived. The homogeneous assumed-modes equations are nondimensionalized. It is shown that the nondimensional strain stiffness varies with the ratio of the wing's nonrotating natural frequencies to the flapping frequency, whereas the nondimensional, time-periodic inertial stiffnesses vary with the amplitudes of flapping and feathering motion. The parametric stability of a representative wing is assessed by applying Floquet analysis to the nondimensional equations of motion, and a scalable stability diagram is presented. Parametric instabilities of the wing structure, caused by time-periodic stiffnesses, are characterized and plotted in the time domain. The effects of important structural design properties on parametric stability are examined.

Materials challenges in the design of an insect-like flapping wing mechanism based on a four-bar linkage

This paper describes materials challenges, and how they were met, in the design of a four-bar linkage mechanism driving a test-bed for an insect-like flapping wing micro air vehicle. In the design process, both aerodynamic and dynamic simulations were made, but could not resolve all uncertainties regarding the forces acting on the mechanism. This difficulty was resolved by a combination of: (1) a simulation parametric study; (2) an experimental programme devised according to the results of the study; (3) by the use of carbon/epoxy composite for critical elements. Application of carbon/epoxy composites not only allowed to overcome uncertainties, but also provided a potential for future research and development. A complete mechanism was manufactured, assembled and tested; it works reliably and generates useful data for further aeromechanical research.

Modeling and simulation study of an insect-like flapping-wing micro aerial vehicle

The goal of this paper is to show some of the most important features of flying insects from a control point of view, describe in details the kinematics of insects during flapping flight, establish the corresponding kinematics equations of flying insects, analyze the force and moment acting on the flying insects, and establish the corresponding aerodynamic equations. Through the kinematics equations and aerodynamic equations of flying insects, the trajectory equations and attitude equations have also been established. A detailed mathematical model of flying insects is presented in this paper, which including 3 d.o.f. of wings kinematics, i.e., flapping, lagging and feathering, and 6 d.o.f. of insects body, i.e., yaw, roll, up–down flight, left–right flight and fore–back flight. All these motions of flying insects are interrelated by the kinematics equations, attitude equations, aerodynamics model and dynamics equations of the insects' centroid. In the findal part of this paper, the mathematical simulation model of flapping-wing insects is set up and the corresponding simulation curve created.

Insect-like flapping wing mechanism based on a double spherical Scotch yoke.

We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a "figure-of-eight" or a "banana" and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held), weighing 50-100g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application, insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Since the semi-span of the insect wing is constant, the kinematics are spatial; in fact, an approximate figure-of-eight/banana is traced on a sphere. Hence a natural mechanism implementing such kinematics should be (i) spherical and (ii) generate mathematically convenient curves expressing the figure-of-eight/banana shape. The double spherical Scotch yoke design has property (i) by definition and achieves (ii) by tracing spherical Lissajous curves.