Structural Identification and Simulation of the Manduca Sexta Forewing

Maximizing the available lift and thrust force is important for designing efficient flapping wing micro air vehicles. Research to date showed the passive rotation joint between the wing and four-bar linkage is an important design aspect. Two key hinge parameters are the angle of attack stop and passive rotation joint stiffness. In this work these design parameters were independently varied. Their impact on lift and thrust force generation, and the ratio of the first and second system resonance frequencies were measured and compared through experiments utilizing prototype hardware of varying design. The prototype hardware and flapping wing controller is based on previous work, focused on using biomimetic wings combined with a design that only requires two piezoelectric actuators, and will be briefly reviewed. The angle of attack stops tested were 30˚, 40˚, 45˚, 50˚, and 60˚. Five different passive rotation joints were tested of varying stiffness. Optimal angle of attack stops and passive rotation joint designs were found from the experimental results and combined into a best design, which was tested and compared to the optimal results from the independent designs. Results show that while individual selection of angle stop and passive rotation joint stiffness can be optimized, the intersection between the two precludes simply choosing the best of both as the best combined. φ Stroke angle or phase angle ω Flapping frequency Subscript c Carbon fiber h Passive rotation joint hinge m Maximum value n Natural frequency p Predicted s Angle of attack stop L Left wing R Right wing 1 First resonant mode 2 Second resonant mode 1. BACKGROUND The Air Force Institute of Technology's (AFIT) flapping wing micro air vehicle (FWMAV) research program is focused on creating a minimally actuated, power tethered, bio-mimetic flight test vehicle. Current designs utilize two, single degree of freedom piezoelectric actuators to provide control of five of the FWMAV's six degrees of freedom (DOF). The simplified design requires only two drive signals, φ L (t) and φ R (t) for control. A prescriptive method is used to generate these drive signals in an open loop, requiring no feedback of wing dynamics. [1, 2] Previous work has developed a wing that mimics the structural dynamics of the Manduca sexta. [3, 4] Developed FWMAV production techniques have created FWMAVs that generate useful forces and moments, but have yet to achieve a lift to weight ratio greater than one. [5, 1] Research to date showed the passive rotation joint between the wing and four-bar linkage is an important design aspect. Two key joint parameters are the angle of attack stop, α s , and passive rotation joint stiffness, κ h , with the assumption that α s holds the wing at this angle through a wing stroke half-cycle, and κ h determines the ratio of the system second resonant frequency to the first resonant frequency, ω n 2 /ω n 1. Based on previous results, additional work is required to reduce weight and increase lift and thrust forces to achieve the goal of controlled flig...

Section: Single Wing Flapper Mechanism Designmentioning

confidence: 99%

Section: Passive Rotation Joint Stiffnessmentioning

confidence: 99%

Passive Rotation Joint Design Considerations for Lift and Thrust Generation for a Biomimetic Flapping Wing

Lindholm

Cobb

2014

“…The wing hinge is a complicated and difficult mechanical system that is currently impossible to duplicate and not well understood. It has been noticed that many researchers [1], [11] are simply removing M.sexta wings from the thorax and testing the wing properties separately. There are two fundamental problems with this approach.…”

Section: Biological Flapping Mechanismmentioning

confidence: 99%

Biological Investigation of Wing Motion of the Manduca Sexta

Tubbs

Palazotto

Willis

2011

An investigation was conducted assessing the feasibility of reproducing the biological flapping motion of the wings of the hawkmoth, Manduca sexta (M.sexta) by artificially stimulating the flight muscles for Micro Air Vehicle research. Electromyographical signals were collected using bipolar intramuscular fine wire electrodes inserted into the primary flight muscles, the dorsal longitudinal and dorsal ventral muscles, of the adult M.sexta. These signals were recorded and associated with wing movement using high speed video. The signals were reapplied into the corresponding muscle groups with the intention of reproducing similar flapping motion. A series of impulse signals were also directed into the primary flight muscles as a means of observing muscle response through measured forewing angles. This study pioneered electromyographic research on M.sexta at the Air Force Institute of Technology with tests conducted with fine wire electrodes. Through this process, the research showed the deformational structural changes that take place when a wing is removed from an insect and proved that muscular stimulation is a viable method for generating wing movement. This study also assisted in developing an understanding related to the role that a thorax-like fuselage could play in future micro aircraft designs. This study has shown that partial neuromuscular control of the primary flight muscles of M.sexta is possible with electrical stimulants which could be used to directly control insect flight.

“…They were designed through i) careful dissection of numerous biological specimens; ii) medical Computer Tomography (CT) scanning of the inner venation patterns to catalog their thickness and stiffness; iii) 3-D scanning laser tomography, with and without scales, to capture the precise wing planform shape; iv) 3-D finite element modeling to model the 1 st and 2 nd bending and torsion modes of the wing to aide in the design of a carbon fiber lay-up schematic so the man-made analog mimics the thickness, taper, camber and stiffness of the Hawkmoth, and accurately reproduces the same system structural dynamics; and v) an exhaustive precision laser CNC cutting technique developed to ensure accurate and repeatable manufacturing [22,23,24,25,26]. Figure 5 shows the finite element model of the engineered wing made from the material properties, modal testing, and 3-D rendering of the Manduca Sexta biological representative.…”

Section: Afit Engineered Wingsmentioning

confidence: 99%

An Experimental Investigation into the Effect of Flap Angles for a Piezo-Driven Wing

DeLuca¹,

Reeder

Cobb

2013

This article presents a comparison of results from six degree of freedom force and moment measurements and Particle Image Velocimetry (PIV) data taken on the Air Force Institute of Technology's (AFIT) piezoelectrically actuated, biomimetically designed Hawkmoth, Manduca Sexta, class engineered wing, at varying amplitudes and flapping frequencies, for both trimmed and asymmetric flapping conditions to assess control moment changes. To preserve test specimen integrity, the wing was driven at a voltage amplitude 50% below the maximum necessary to achieve the maximal Hawkmoth total stroke angle. 86˚ and 65˚ stroke angles were achieved for the trimmed and asymmetric tests respectively. Flapping tests were performed at system structural resonance, and at ±10% off system resonance at a single amplitude, and PZT power consumption was calculated for each test condition. Two-dimensional PIV visualization measurements were taken transverse to the wing planform, recorded at the mid-span, for a single frequency and amplitude setting, for both trimmed and asymmetric flapping to correlate with the 6-DoF balance data. Linear velocity data was extracted from the 2-D PIV imagery at ± 1/2 and ±1 chord locations above and below the wing, and the mean velocities were calculated for four separate wing phases during the flap cycle. The mean forces developed during a flap cycle were approximated using a modification of the Rankine-Froude axial actuator disk model to calculate the transport of momentum flux as a measure of vertical thrust produced during a static hover flight condition. Values of vertical force calculated from the 2-D PIV measurements were within 20% of the 6-DOF force balance experiments. Power calculations confirmed flapping at system resonance required less power than at off resonance frequencies, which is a critical finding necessary for future vehicle design considerations.= balance moment in y-direction I or V rms = root mean square current/voltage P = mean power u = x-direction velocity w = z-direction velocity INTRODUCTIONThe confluence between biologists and engineers over the past 10-20 years have produced considerable research into the aerodynamics and flight mechanisms responsible for insect flight. Research, mainly from biologists, has revealed these amazing fliers develop more lift than their wings alone can generate through a standard aerodynamic static, or quasi-static treatment; meaning the additional lift is generated through the complex interaction of the flapping motion of the wings and the surrounding fluid medium. It is the study of this aerodynamic phenomenon, its characterization, and its particular application to the AFIT Flapping Wing Micro Air Vehicle (FWMAV) program, which is the topic of this research effort. With all the remarkable discoveries, and the litany of impressive military and civilian aircraft developed over the past 100 years, it was not until the last two decades that aerodynamicists have earnestly investigated the flight physics of nature's smallest fliers-insects. To ...