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International Journal of Micro Air Vehicles
Journal Prestige (SJR): 0.368
Citation Impact (citeScore): 1
Number of Followers: 11  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1756-8293 - ISSN (Online) 1756-8307
Published by Sage Publications Homepage  [1175 journals]
  • Rapid extraction of propeller geometry using photogrammetry

    • Authors: Ellande Tang, Soon-Jo Chung
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      As small Uninhabited Aerial Vehicles (sUAS) increase in popularity, computational analysis is increasingly being used to model and improve their performance. However, although propeller performance is one of the primary elements in modelling an aircraft, most manufacturers of propellers for this size of vehicle do not publish geometric information for the propeller. The lack of available geometric data makes simulation of propeller aerodynamics challenging. While techniques exist to accurately extract the 3D geometry of a propeller, these methods are often very expensive, time-consuming, or labor intensive. Additionally, typical 3D scanning techniques produce a 3D mesh that is not useful for techniques such as Blade Element Theory (BET), which rely on knowledge of the 2D cross sections along the propeller span. This paper describes a novel workflow to produce point clouds using readily available photo equipment and software and subsequently extract airfoil and propeller blade parameters at specified stations along the propeller span. The described process can be done with little theoretical knowledge of photogrammetry and with minimal human input. The propeller geometry generated is compared against results of established methods of geometry extraction and good agreement is shown.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-10-26T07:29:02Z
      DOI: 10.1177/17568293221132044
      Issue No: Vol. 14 (2022)
  • Robust design of compact axial compressor

    • Authors: Cong Zeng, Shaowen Chen, Hongyan Liu
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      The method of connection weights in neural networks was used to analyze the sensitivity of the compressor rotor, and the Back Propagation Neural Network (BPNN) was used to construct the analysis relationship between the compressor rotor's geometries and the performance based on the training and learning of the data base, and the prediction accuracy can reach more than 99.99%. Then the modified Grason Algorithm based on the neural network connect weights was used to quantify the contribution of the geometrical effects on its performance. The result shows that the tip clearance contributes 11.43% (efficiency sensitivity analysis) and 10.18% (pressure ratio sensitivity analysis) to compressor performance changes. This study focuses mainly on the robust optimization of tip clearance. Non-intrusive probability collection point method (NIPC) was adopted for the uncertainty propagation. The robust optimization method based on BPNN agent model coupled with multi-objective genetic algorithm Non-dominated sorting genetic algorithm-II (NSGA II) was used to perform the optimization. Compared to the design prototype, the variance of robust compressor rotor's efficiency could be reduced by 21.04%.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-09-19T05:04:08Z
      DOI: 10.1177/17568293221125847
      Issue No: Vol. 14 (2022)
  • An experimental study of the unsteady vortex structures of a clapping-wing
           micro air vehicle

    • Authors: Yanwei Zhang, Zhonglai Wang
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      It is a challenge to explore the unsteady vortex structures of flexible flapping wings of X-shaped flapping-wing micro air vehicles (also known as clapping-wing micro air vehicles (CWMAVs)). The objective of this paper is to obtain the influence of wind speed, flapping frequency, and angle of attack (AoA) on the instantaneous and average force coefficients of CWMAVs, investigate flow visualization of the leading-edge vortex (LEV), trailing-edge vortex (TEV) and wake vortex (WV) structures and identify some novel flow mechanisms of flapping propulsion. This paper proposes a mechanics and particle image velocimetry (PIV) measuring platform in a low-speed tunnel. In addition, cross-correlation peak analysis and kriging image reconstruction are applied for postprocessing to enhance PIV image recognition. Combining the time evolution of the forces, the force coefficients, and the flow visualization, we find the evolution and effects of LEV, TEV and WV structures.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-09-14T05:07:26Z
      DOI: 10.1177/17568293221125846
      Issue No: Vol. 14 (2022)
  • Design, development, and flight testing of a tube-launched coaxial-rotor
           based micro air vehicle

    • Authors: Hunter Denton, Moble Benedict, Hao Kang
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      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.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-09-14T05:06:37Z
      DOI: 10.1177/17568293221117189
      Issue No: Vol. 14 (2022)
  • Numerical study on aerodynamic characteristics of two-dimensional
           propulsive wing in cruise and hover

    • Authors: Jiaxin Lu, Yang Lu, Junjie Wang, Mengxue Shao
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      The propulsive wing vehicle is a new concept vehicle, which is driven by a cross-flow fan (CFF) embedded in the trailing edge of the wing. The propulsive wing vehicle is capable of cruising and hovering at high angles of attack with very high aerodynamic force coefficients, and has the potential to become a new type of vertical take-off and landing (VTOL) vehicle. The cruise and hover states of the propulsive wing vehicle are defined, and a numerical model of the two-dimensional propulsive wing is established. Based on the computational fluid dynamics (CFD) method, the rotation of the CFF is simulated by using the sliding mesh technique. The effects of cruise speed, angle of attack and CFF rotation speed on the aerodynamics of the two-dimensional propulsive wing are evaluated, and the mechanism of the propulsive wing flow field changes is revealed. The results show that the propulsive wing has a very high lift coefficient of up to 60 at low speed and high angle of attack cruise, and a high thrust coefficient of up to 40 at low speed and small angle of attack cruise. The aerodynamic force of the propulsive wing fluctuates periodically with the rotation of the CFF, and the amplitude of the fluctuation is related to the vorticity of the CFF blade shedding vortex. In hover, the flow field of the propulsive wing is affected by the geometry and wake deflection into an asymmetric distribution, forming a vortex on each side of the airfoil, and the vortex diameter varies with the CFF rotation speed, which in turn has an impact on the hovering performance of the propulsive wing.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-09-13T02:49:21Z
      DOI: 10.1177/17568293221122170
      Issue No: Vol. 14 (2022)
  • Vortex particle method with iterative Brinkman penalization for simulation
           of flow past sharp-shape bodies

    • Authors: Viet Dung Duong, Lavi Rizki Zuhal
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      This paper presents a Lagrangian vortex method combined with iterative Brinkman penalization for the simulation of incompressible flow past a complex geometry. In the proposed algorithm, particle and penalization domains are separately introduced. The particle domain is for the computation of particle convection and diffusion, while the penalization domain is the enforcement of the wall boundary conditions. In iterative Brinkman penalization, the no-slip boundary condition is enforced by applying penalization force in multiple times within each time step. This enables large time step size reducing computational cost and maintains the capability in handling complex geometries. The method is validated for benchmark problems such as an impulsively started flow past a circular cylinder, normal to a flat plate, and a symmetric airfoil at Reynolds numbers ranging from 550 to 1000. The vorticity and streamline contours, drag, and lift coefficients show a good agreement with those reported in literature.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-07-14T06:10:59Z
      DOI: 10.1177/17568293221113927
      Issue No: Vol. 14 (2022)
  • Wind tunnel tests of a wing at all angles of attack

    • Authors: Ziqing Ma, Ewoud J.J. Smeur, Guido C.H.E. de Croon
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      Tailsitters have complex aerodynamics that make them hard to control throughout the entire flight envelope, especially at very high angle of attack (AoA) and reverse flow conditions. The development of controllers for these vehicles is hampered by the absence of publicly available data on forces and moments experienced in such conditions. In this paper, wind tunnel experiments are performed under different flap deflections and throttle settings at all possible AoA. The dataset is made open access. Our analysis of the data shows for the tested wing, flap deflections greatly affect the lift coefficient and stall occurs at [math] AoA as well as [math]. Wing-propeller interaction is studied by analyzing the propeller induced force in the axis orthogonal to the thrust axis, which is dependent on AoA, airspeed, flap deflections and thrust in a nonlinear and coupled manner. The influence of inverse flow on the wing is also discussed: The data confirm that when the airflow over the wing is reversed, flap deflections will affect the pitch moment in an opposite way compared to the non-reversed case, but this opposite effect can be avoided by increasing the throttle setting. The data show the exact relationship between flap deflections and forces in this condition. Moreover, it is found that the flap control effectiveness for a wing with or without spinning propellers is usually higher around zero degrees AoA than at [math] and it is more effective to change the flaps from [math] to [math] than from [math] to the respective [math].
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-07-06T01:38:57Z
      DOI: 10.1177/17568293221110931
      Issue No: Vol. 14 (2022)
  • Analyzing visual imagery for emergency drone landing on unknown

    • Authors: Oghuz Bektash, Jacob Juul Naundrup, Anders la Cour-Harbo
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      Autonomous landing is a fundamental aspect of drone operations which is being focused upon by the industry, with ever-increasing demands on safety. As the drones are likely to become indispensable vehicles in near future, they are expected to succeed in automatically recognizing a landing spot from the nearby points, maneuvering toward it, and ultimately, performing a safe landing. Accordingly, this paper investigates the idea of vision-based location detection on the ground for an automated emergency response system which can continuously monitor the environment and spot safe places when needed. A convolutional neural network which learns from image-based feature representation at multiple scales is introduced. The model takes the ground images, assign significance to various aspects in them and recognize the landing spots. The results provided support for the model, with accurate classification of ground image according to their visual content. They also demonstrate the feasibility of computationally inexpensive implementation of the model on a small computer that can be easily embedded on a drone.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-06-30T06:31:23Z
      DOI: 10.1177/17568293221106492
      Issue No: Vol. 14 (2022)
  • Editorial

    • Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.

      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-06-24T06:09:00Z
      DOI: 10.1177/17568293221104967
      Issue No: Vol. 14 (2022)
  • Design optimization-under-uncertainty of a forward swept wing unmanned
           aerial vehicle using SAMURAI

    • Authors: Jolan Wauters
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      In this paper the design optimization-under-uncertainty of a forward swept wing (FSW) blended wing body (BWB) unmanned aerial vehicle (UAV) is examined. Conventional BWBs are often tailless, which leads to a backward swept wing to ensure longitudinal static stability. This in turn can induce flow separation at the tip, leading to a loss of lift, controllability and the appearance of a nose-up pitching moment. A possible solution to this problem is a conceptual redesign by introducing a forward swept wing, which is inherently free of tip-stall, but needs a careful design in order to be controllable. However, fixed wing UAVs are often produced by means of direct injection expanded foam moulding, which is characterized by not negligible production tolerances. This lead to a reliability-based robust design optimization problem, for which a novel framework is employed: SAMURAI. Firstly, the method accounts for computational cost by means of surrogate modelling, an analytical treatment of the problem and an asynchronous updating scheme that balances design space exploration and objective exploitation. Secondly, the method treats the problem as a multi-objective problem, which leads to a Pareto front of robust and reliable designs. The result is a novel series of UAV designs that are inherently free of tip stall, perform robustly and meet the stability requirements with the target reliability obtained with a computationally feasible budget.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-05-11T07:36:58Z
      DOI: 10.1177/17568293221092139
      Issue No: Vol. 14 (2022)
  • Dynamic Modeling and Control Law Design of a Fuel-electric Hybrid
           Multi-rotor UAV

    • Authors: Xice Xu, Yang Lu, Xufeng Wu
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      In this paper, the design of control law for a new concept fuel-electric hybrid multi-rotor UAV with lift/attitude control separation is investigated. The remarkable feature of the UAV is that it has a large proportion of fuel weight. Firstly, based on the quasi-coordinate Lagrangian equation and sloshing equivalent model using the multi-mass-spring analogy, the non-linear dynamic model of the UAV considering the fuel slosh dynamics is established. Compared with the existing multi-rotor modeling method, it is more intuitive and accurate to describe the non-linear coupling process of sloshing and UAV's motion degrees of freedom. Secondly, the attitude control law is designed based on the finite-time sliding mode observer and cascaded continuous sliding mode controller to eliminate the adverse effects of fuel sloshing and mass changing, and only using the measurable angles. Furthermore, aiming at the problem of power redundancy of the altitude channel, a memoryless non-linear altitude authority assignment controller based on vertical acceleration is proposed for improving the control performance. Finally, the simulation results of the waypoint flight illustrate the feasibility and effectiveness of the proposed control strategy.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-02-15T05:46:23Z
      DOI: 10.1177/17568293221078925
      Issue No: Vol. 14 (2022)
  • On association of lift generation, wake topology and kinematics of
           oscillating foils

    • Authors: Suyash Verma, Muhammad S.U. Khalid, Arman Hemmati
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      The association of lift generation and evolution of wake topology behind an oscillating foil with combined heaving and pitching motion is investigated numerically at a range of bluereduced frequency (0.16 [math] 0.48), phase offset (0[math] [math] 315[math]) and Reynolds number (1000 [math] 4000). The pitch-dominated kinematics that coincide with the range of [math] 120[math] and [math] 225[math] suggests that leading edge vortices are suppressed while trailing edge vortices dominate the wake with increasing reduced frequency. This corresponds to a transition in wake topology from a [math] to a reverse Von Kármán wake mode. Contrarily, heave dominated kinematics (120[math] [math] 225[math]) did not exhibit any wake topology transition with increasing [math]. The temporal lift variation associated with heave-dominated regime further revealed a symmetric feature in terms of the time taken to attain peak lift generation within an oscillation cycle. This temporal symmetry was, however, lost as kinematics transitioned from heave- to pitch-dominated regime. Analyzing the wake evolution and lift features at quarter phase of an oscillation cycle revealed the existence of a correspondence between the two processes during the heave- and pitch-dominated kinematics.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-24T01:04:37Z
      DOI: 10.1177/17568293211073959
      Issue No: Vol. 14 (2022)
  • Aeroacoustic optimization of MAV rotors

    • Authors: Pietro Li Volsi, David Gomez-Ariza, Romain Gojon, Thierry Jardin, Jean-Marc Moschetta
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      The more restrictive airspace regulations force drone manufacturers to take into account the noise emitted by the drone during the design phase, along with its aerodynamic performance to increase the flight time. A Non-Linear Vortex Lattice Method (NVLM), coupled with the Farassat Formulation-1A of the Ffowcs-Williams and Hawkings acoustic analogy is used to evaluate the aerodynamic and aeroacoustic performance of MAV rotors. Pymoo, a Python-based optimization framework, is employed to modify the geometry, evaluate its performance and extract the set of Pareto optimal solutions. The two objectives are the aerodynamic Figure-of-Merit and the Sound Pressure Level of the Blade Passing Frequency tone for a microphone located at a far-field distance of 1.62 m and 30[math] below the rotor plane. The approach proposed in this paper takes into account up to ten different parameters, ranging from the twist and chord distributions, to the rake and skew angles.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-24T01:04:07Z
      DOI: 10.1177/17568293211070827
      Issue No: Vol. 14 (2022)
  • Nonlinear model predictive control for improving range-based relative
           localization by maximizing observability

    • Authors: Shushuai Li, Christophe De Wagter, Guido C. H. E. de Croon
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      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.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-21T12:41:33Z
      DOI: 10.1177/17568293211073680
      Issue No: Vol. 14 (2022)
  • Extended incremental non-linear control allocation (XINCA) for quadplanes

    • Authors: H.J. Karssies, C. De Wagter
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      Hybrid UAVs have gained a lot of interest for their combined vertical take-off & landing (VTOL) and efficient forward flight capabilities. But their control is facing challenges in over-actuation and conflicting requirements depending on the flight phase which can easily lead to actuator saturation. Incremental Non-linear Control Allocation (INCA) has been proposed to solve the platform’s control allocation problem in the case of saturation or over-actuation by minimizing a set of objective functions. This work demonstrates INCA on quadplanes, an in-plane combination between a quadrotor and a conventional fixed-wing, and proposes an extension to control the outer loop. The novel controller is called Extended INCA (XINCA) and adds the wing orientation as a force-generating actuator in the outerloop control optimization. This leads to a single controller for all flight phases that avoids placing the wing at negative angles of attack and minimizes the load on hover motors. XINCA has low dependence on accurate vehicle models and requires only several optimization parameters. Flight simulations and experimental flights are performed to demonstrate the performance.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-21T12:41:14Z
      DOI: 10.1177/17568293211070825
      Issue No: Vol. 14 (2022)
  • An implementation framework for vision-based bat-like inverted perching
           with bi-directionalthrust quadrotor

    • Authors: Pengfei Yu, KC Wong
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      This paper presents an implementation framework to perform a vision-guided, bat-like inverted perching maneuver with a bi-directional thrust quadrotor platform. The framework consists of several distinct modules (guidance, motion planning, control, state estimation) that can be easily be individually customized in the future to meet specific research requirements. The main contribution of this paper lies in the whole framework pipeline with a modular structure developed for implementing a generalized framework for an agile quadrotor to achieve inverted perching. A computationally-light guidance module has been developed as an example to demonstrate the capability while being independent of accurate pre-known target information, and does not require the state estimation of the quadrotor to be provided by an external motion capture system as in our previous work. A motion planning module based on an optimization method has been introduced to generate a two-stage inverted perching trajectory aiming at minimizing altitude loss during the half-flip maneuver. A control module has been developed to enable a bi-directional quadrotor to fly in both upright and inverted states and closely follow the intended trajectory. The compensation strategy used in the control module is key to minimizing the transition time between the upright and inverted states. Finally, an experimental flight platform has been developed to demonstrate the capabilities of the framework. During testing, the proposed framework has achieved an 80 % success rate. To the best of our knowledge, this paper presents the first time a quadrotor has achieved the inverted perching maneuver using onboard vision guidance.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-18T11:56:06Z
      DOI: 10.1177/17568293211073672
      Issue No: Vol. 14 (2022)
  • Estimating wind using a quadrotor

    • Authors: Gautier Hattenberger, Murat Bronz, Jean-Philippe Condomines
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      The aim of this work is to estimate the average wind influencing a quadrotor drone only based on standard navigation sensors and equations of motion. It can be used in several situation, including atmospheric studies, trajectory planning under environmental constraints, or as a reference for studying flights in shear layer. For this purpose, a small quadrotor drone with spherical shape has been developed. Flight data are recorded from telemetry during indoor and outdoor flight tests and are post-processed. The proposed solution is based on a calibration procedure with global optimization to extract the drag model and a Kalman Filter for online estimation of the wind speed and direction. Finally, an on-board implementation of the real-time estimation is demonstrated with real flights in controlled indoor environment.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-13T01:05:53Z
      DOI: 10.1177/17568293211070824
      Issue No: Vol. 14 (2022)
  • Field report: Deployment of a fleet of drones for cloud exploration

    • Authors: Gautier Hattenberger, Titouan Verdu, Nicolas Maury, Pierre Narvor, Fleur Couvreux, Murat Bronz, Simon Lacroix, Grègoire Cayez, Gregory C. Roberts
      Abstract: International Journal of Micro Air Vehicles, Volume 14, Issue , January-December 2022.
      Drones are commonly used for civil applications and are accessible to those with limited piloting skills in several scenarios. However, the deployment of a fleet in the context of scientific research can lead to complex situations that require an important preparation in terms of logistics, permission to fly from authorities, and coordination during the flights. This paper is a field report of the flight campaign held at the Barbados Island as part of the NEPHELAE project. The main objectives were to fly into trade wind cumulus clouds to understand the microphysical processes involved in their evolution, as well as to provide a proof of concept of sensor-based adaptive navigation patterns to optimize the data collection. After introducing the flight strategy and context of operation, the main challenges and the solutions to address them will be presented, to conclude with the evaluation of some technical evolution developed from these experiments.
      Citation: International Journal of Micro Air Vehicles
      PubDate: 2022-01-10T01:30:02Z
      DOI: 10.1177/17568293211070830
      Issue No: Vol. 14 (2022)
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