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1 – 10 of 278Tandralee Chetia, Dhayalan Rajaram and Kumaran G. Sreejalekshmi
Flapping-wing vehicles show various advantages as compared to fixed wing vehicles, making flapping-wing vehicles' study necessary in the current scenario. The present study aims…
Abstract
Purpose
Flapping-wing vehicles show various advantages as compared to fixed wing vehicles, making flapping-wing vehicles' study necessary in the current scenario. The present study aims to provide guidelines for fixing geometric parameters for an initial engineering design by a simple aerodynamic and flight dynamic parametric study.
Design/methodology/approach
A mathematical analysis was performed to understand the aerodynamics and flight dynamics of the micro-air vehicle (MAV). Only the forces due to the flapping wing were considered. The flapping motion was considered to be a combination of the pitching and plunging motion. The geometric parameters of the flapping wing were varied and the aerodynamic forces and power were observed. Attempts were then made to understand the flight stability envelope of the MAV in a forward horizontal motion in the vertical plane with similar parametric studies as those conducted in the case of aerodynamics.
Findings
From the aerodynamic study, insights were obtained regarding the interaction of design parameters with the aerodynamics and feasible ranges of values for the parameters were identified. The flapping wing was found to have neutral static stability. The flight dynamic analysis revealed the presence of an unstable oscillatory mode, a stable fast subsidence mode and a neutral mode, in the forward flight of the MAV. The presence of unstable modes highlighted the need for active control to restore the MAV to equilibrium from its unstable state.
Research limitations/implications
The study does not take into account the effects of control surfaces and tail on the aerodynamics and flight dynamics of the MAV. There is also a need to validate the results obtained in the study through experimental means which shall be taken up in the future.
Practical implications
The parametric study helps us to understand the extent of the impact of the design parameters on the aerodynamics and stability of the MAV. The analysis of both aerodynamics and dynamic stability provides a holistic picture for the initial design. The study incorporates complex mathematical equations and simplifies such to understand the aerodynamics and flight stability of the MAV from an engineering perspective.
Originality/value
The study adds to already existing knowledge on the design procedures of a flapping wing.
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Harijono Djojodihardjo, Riyadh Ibraheem Ahmed, Abd Rahim Abu Talib and Azmin Shakrine Mohd Rafie
The purpose of this paper is to reformulate the governing equations incorporating major variables and parameters for the design a Micro Air Vehicle (MAV), to meet the desired…
Abstract
Purpose
The purpose of this paper is to reformulate the governing equations incorporating major variables and parameters for the design a Micro Air Vehicle (MAV), to meet the desired mission and design requirements.
Design/methodology/approach
Mathematical models for various spherical and cylindrical Coandă MAV configurations were rederived from first principles, and the performance measures were defined. To verify the theoretical prediction to a certain extent, a computational fluid dynamic (CFD) simulation for a Coandă MAV generic models was performed.
Findings
The major variables and parameters of Coandă MAV have been formulated into practical guidelines, which relate the lift (or thrust) produced for certain input variables, particularly the Coandă MAV jet momentum coefficient. The influences of the geometrical parameters are elaborated.
Research limitations/implications
The present analysis on Coandă jet-configured MAV is focused on the lift generation due to the Coandă jet effect through a meticulous analysis. The effects of viscosity, the Coandă jet thickness, the radius of curvature of the surface and the stability of Coandă jet are not considered and will be the subject of the following work.
Practical implications
The results obtained can be used for sizing in the preliminary design of Coandă MAVs.
Originality/value
Physical and mathematical models were developed which can describe the physical phenomena of the flow field near the Coandă MAV surfaces influenced by Coandă jet sheets and for obtaining a relationship between relevant variables and parameters to the lift of practical interest.
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Jih‐Lung Lin, Chin‐Yi Wei and Chi‐Yu Lin
This study aims to design and test some fixed‐wing micro aerial vehicles (MAV).
Abstract
Purpose
This study aims to design and test some fixed‐wing micro aerial vehicles (MAV).
Design/methodology/approach
The MAV wing planform in this study was designed based on previous results and the need to reduce the weight of the MAV. The MAV had a wing planform with a 6 percent Gottingen‐329 camber airfoil, a 20° swept‐back leading edge and a straight trailing edge. The fuselage was designed to contain a motor, an electronic control system and a video camera with a built‐in transmitter. The battery was located outside the fuselage to trim the center of gravity and enable the battery to be changed easily when it has run out. Two exaggerated vertical stabilizers were installed to prevent the MAV from rolling. The materials, the power plant and the electronics used to fabricate the MAV herein were either the lightest or the smallest from that could be obtained off‐the‐shelf. Since, MAVs should be expendable, the cost was kept under US$250 (including the cost of an onboard video camera system, which costs US$170).
Findings
Flight tests were performed following fabrication. The MAV was launched by hand, flew within a radius of 30 ∼ 50 m, and eventually glided to a grassy ground. The flight was stable and the quality of the downlink video was acceptable for surveillance purpose. The MAVs presented in this work were proven to have successful designs.
Originality/value
MAVs were successfully designed herein based on previous results. The materials and the fabrication processes were carefully selected and tested, to keep the mass of a flyable MAV under 65 g, while ensuring it has sufficient structural strength. The cost was reduced to US$250, making the MAV truly expendable.
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Abstract
Purpose
This study seeks to explore the aerodynamic performance of wings with different shapes at low Reynolds numbers.
Design/methodology/approach
The airfoils of these wings are made from aluminum plates, and the maximum cord length and wingspan are 15 cm. Wings A to D are plates with 6 percent Gottingen camber but different wing planforms. The forward‐half sections of wings E and F are dragonfly‐like, whereas the rear‐half sections of wings E and F are flat and positively cambered, respectively. The aspect ratios of these wings are close to one, and the ratios of plate thickness to the maximum cord length are 1.3 percent. Experimental results indicate that the wings with Gottingen camber have a superior lift and lift‐to‐drag ratio, whereas the wings with dragonfly‐like airfoils perform well in terms of drag and pitch moment.
Findings
The aerodynamic measurements of the wings demonstrate that the wing with the Gottingen camber airfoil, a swept‐back leading edge and a straight trailing edge is suitable for use in micro aerial vehicle (MAV). An MAV is fabricated with this wing and the aerodynamic performance of the MAV is examined and compared with the bare wing data.
Originality/value
This study develops several criteria to the design of MAV‐sized wings. For example, the thickness ratio of airfoil must be small, usually less than 2 percent. Besides, the airfoil must be cambered adequately. Furthermore, a wing planform with a swept‐back leading edge and a straight trailing edge would be contributive to the successful flights of MAVs.
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Lin Chi Mak, Mark Whitty and Tomonari Furukawa
The purpose of this paper is to present a localisation system for an indoor rotary‐wing micro aerial vehicle (MAV) that uses three onboard LEDs and base station mounted active…
Abstract
Purpose
The purpose of this paper is to present a localisation system for an indoor rotary‐wing micro aerial vehicle (MAV) that uses three onboard LEDs and base station mounted active vision unit.
Design/methodology/approach
A pair of blade mounted cyan LEDs and a tail mounted red LED are used as on‐board landmarks. A base station tracks the landmarks and estimates the pose of the MAV in real time by analysing images taken using an active vision unit. In each image, the ellipse formed by the cyan LEDs is used for 5 degree of freedom (DoF) pose estimation with yaw estimation from the red LED providing the 6th DoF.
Findings
About 1‐3.5 per cent localisation error of the MAV at various ranges, rolls and angular speeds less than 45°/s relative to the base station at known location indicates that the MAV can be accurately localised at 9‐12 Hz in an indoor environment.
Research limitations/implications
Line‐of‐sight between the base station and MAV is necessary while limited accuracy is evident in yaw estimation at long distances. Additional yaw sensors and dynamic zoom are among future work.
Practical implications
Provided an unmanned ground vehicle (UGV) as the base station equipped with its own localisation sensor, the developed system encourages the use of autonomous indoor rotary‐wing MAVs in various robotics applications, such as urban search and rescue.
Originality/value
The most significant contribution of this paper is the innovative LED configuration allowing full 6 DoF pose estimation using three LEDs, one camera and no fixed infrastructure. The active vision unit enables a wide range of observable flight as the ellipse generated by the cyan LEDs is recognisable from almost any direction.
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Paula J. Durlach, John L. Neumann and Laticia D. Bowens
The goal of our initial study was to assess the usability of the prototype OCU and establish associated training issues. Seven participants completed self-paced training, guided…
Abstract
The goal of our initial study was to assess the usability of the prototype OCU and establish associated training issues. Seven participants completed self-paced training, guided by a training manual produced by ARI. Training was divided into three modules: (1) introduction and autonomous control, (2) manual control, and (3) creating and editing autonomous missions. Primary focus was on how to use the OCU to fly the MAV. Modules did not include elements such as fueling, setup, or tactics. A facilitator was present at all times to observe user interaction with the system and to manage the software. Data captured included time to complete each training module and related practical exercises, user feedback on questionnaires, and a written test on training content. Participants had either graduate-level experience in human factors psychology, prior military experience, or both. They were, therefore, able to provide valuable insights while they learned to operate the simulated MAV.
Xiangjian Chen, Di Li, Zhijun Xu and Yue Bai
Quadrotor micro aerial vehicle (MAV) is nonlinear and under actuated plant, and it is difficult to obtain an accurate mathematical model for quadrotor MAV due to uncertainties…
Abstract
Purpose
Quadrotor micro aerial vehicle (MAV) is nonlinear and under actuated plant, and it is difficult to obtain an accurate mathematical model for quadrotor MAV due to uncertainties. The purpose of this paper is to propose one robust control strategy for quadrotor MAV to accommodate system uncertainties, variations, and external disturbances.
Design/methodology/approach
The robust control strategy is composed of two self‐organizing interval type‐II fuzzy neural networks (SOIT‐IIFNNs) and one PD controller: the PD controller is adopted to control the attitude and position; one of the SOIT‐IIFNNs is designed to learn the inverse model of quadrotor MAV online; the other SOIT‐IIFNNs is the copy of the former one to compensate for model errors, system uncertainties and external disturbances, both structure and parameters of SOIT‐IIFNNs are tuned online at the same time, and then the stability of the resulting quadrotor MAV closed‐loop control system is proved using Lyapunov stability theory.
Findings
The validity of the proposed control method has been verified through real‐time experiments. The experimental results show that the performance of SOIT‐IIFNNs is significantly improved compared with Backstepping‐based controller.
Practical implications
This approach has been used in quadrotor MAV, the controller works well, and it could guarantee quadrotor MAV control system with good performances under uncertainties, variations, and external disturbances.
Originality/value
The proposed SOIT‐IIFNNs controller is interesting for the design of an intelligent control scheme. The main contributions of this paper are: the overall closed‐loop control system is globally stable, demonstrated by Lyapunov stable theory; the tracking error can be asymptotically attenuated to a desired small level around zero by appropriate chosen parameters and learning rates; and the quadrotor MAV control system based on SOIT‐IIFNNs controller can achieve favorable tracking performance.
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Syam Narayanan S. and Asad Ahmed R.
The purpose of this study is to experimentally analyse the effect of flexible and stiffened membrane wings in the lift generation of flapping micro air vehicle (MAV).
Abstract
Purpose
The purpose of this study is to experimentally analyse the effect of flexible and stiffened membrane wings in the lift generation of flapping micro air vehicle (MAV).
Design/methodology/approach
This is analysed by the rectangle wing made up of polyethylene terephthalate sheets of 100 microns. MAV is tested for the free stream velocity of 2 m/s, 4 m/s, 6 m/s and k* of 0, 0.25, 1, 3, 8. This test is repeated for flapping MAV of the free flapping frequency of 2 Hz, 4 Hz, 6 Hz, 10 Hz and 12 Hz.
Findings
This study shows that the membrane wing with proper stiffeners can give better lift generation capacity than a flexible wing.
Research limitations/implications
Only a normal force component is measured, which is perpendicular to the longitudinal axis of the model.
Practical implications
In MAVs, the wing structures are thin and light, so the effect of fluid-structure interactions is important at low Reynold’s numbers. This data are useful for the MAV developments.
Originality/value
The effect of chord-wise flexibility in lift generation is the study of the effect of a flexible wing and rigid wing in MAV. It is analysed by the rectangle wing. The coefficient of normal force at different free stream conditions was analysed.
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Hoang Vu Phan, Quang-Tri Truong and Hoon-Cheol Park
The purpose of this paper is to demonstrate the uncontrolled vertical takeoff of an insect-mimicking flapping-wing micro air vehicle (FW-MAV) of 12.5 cm wing span with a body…
Abstract
Purpose
The purpose of this paper is to demonstrate the uncontrolled vertical takeoff of an insect-mimicking flapping-wing micro air vehicle (FW-MAV) of 12.5 cm wing span with a body weight of 7.36 g after installing batteries and power control.
Design/methodology/approach
The forces were measured using a load cell and estimated by the unsteady blade element theory (UBET), which is based on full three-dimensional wing kinematics. In addition, the mean aerodynamic force center (AC) was determined based on the UBET calculations using the measured wing kinematics.
Findings
The wing flapping frequency can reach to 43 Hz at the flapping angle of 150°. By flapping wings at a frequency of 34 Hz, the FW-MAV can produce enough thrust to over its own weight. For this condition, the difference between the estimated and average measured vertical forces was about 7.3 percent with respect to the estimated force. All parts for the FW-MAV were integrated such that the distance between the mean AC and the center of gravity is close to zero. In this manner, pitching moment generation was prevented to facilitate stable vertical takeoff. An uncontrolled takeoff test successfully demonstrated that the FW-MAV possesses initial pitching stability for takeoff.
Originality/value
This work has successfully demonstrated an insect-mimicking flapping-wing MAV that can stably takeoff with initial stability.
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Jacek Mieloszyk, Cezary Galiński, Janusz Piechna and Jacek Brzozowski
This is the second of two companion papers presenting the results of research into a contra‐rotating propeller designed to drive a super manoeuvrable micro air vehicle (MAV) and…
Abstract
Purpose
This is the second of two companion papers presenting the results of research into a contra‐rotating propeller designed to drive a super manoeuvrable micro air vehicle (MAV) and is devoted to the experimental results. The first paper presented the design process and numerical analyses.
Design/methodology/approach
Most of experiments were conducted in the wind tunnel. Both contra‐rotating and conventional propellers were tested. The test procedures and equipment are described first. The attention is focused on the design of an aerodynamic balance used in the experiment. Then, the measurement error is discussed, followed by presentation of the wind tunnel results. Finally, an initial flight test of the MAV equipped with contra‐rotating propeller is briefly described.
Findings
Wind tunnel experiment results fall between theoretical results presented in the first part of the paper. The application of contra‐rotating propeller allowed to develop the propulsion system with zero torque. Moreover, the efficiency achieved appeared to be a few percent greater than that for a standard conventional propulsion system. The concept was finally proved during the first test flight of the new MAV.
Research limitations/implications
The propeller was designed for a fixed wing aeroplane, not for helicopter rotor. Therefore, only conditions characteristic for fixed wing aeroplane flight are tested.
Practical implications
The designed contra‐rotating propeller can be used in fixed wing aeroplane if torque equal to zero is required.
Originality/value
Original design of the balance is described for the first time, as well as test procedures applied in this experiment. Most of wind tunnel test results are also new and never published before.
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