Authors:Han Bao, Wenqing Yang, Dongfu Ma, Wenping Song, Bifeng Song Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. Bionic micro aerial vehicles have become popular because of their high thrust efficiency and deceptive appearances. Leading edge or trailing edge devices (such as slots or flaps) are often used to improve the flight performance. Birds in nature also have leading-edge devices, known as the alula that can improve their flight performance at large angles of attack. In the present study, the aerodynamic performance of a flapping airfoil with alula is numerically simulated to illustrate the effects of different alula geometric parameters. Different alula relative angles of attack β (the angle between the chord line of the alula and that of the main airfoil) and vertical distances h between the alula and the main airfoil are simulated at pre-stall and post-stall conditions. Results show that at pre-stall condition, the lift increases with the relative angle of attack and the vertical distance, but the aerodynamic performance is degraded in the presence of alula compared with no alula, whereas at post-stall condition, the alula greatly enhances the lift. However, there seems to be an optimal relative angle of attack for the maximum lift enhancement at a fixed vertical distance considering the unsteady effect, which may indicate birds can adjust the alula twisting at different spanwise positions to achieve the best flight performance. Different alula geometric parameters may affect the aerodynamic force by modifying the pressure distribution along the airfoil. The results are instructive for design of flapping-wing bionic unmanned air vehicles. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-26T02:47:31Z DOI: 10.1177/1756829320977989 Issue No:Vol. 12 (2020)
Authors:F Binz, D Moormann Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. Recently, the concept of incremental nonlinear dynamic inversion has seen an increasing adoption as an attitude control method for a variety of aircraft configurations. The reasons for this are good stability and robustness properties, moderate computation requirements and low requirements on modelling fidelity. While previous work investigated the robust stability properties of incremental nonlinear dynamic inversion, the actual closed-loop performance may degrade severely in the face of model uncertainty. We address this issue by first analysing the effects of modelling errors on the closed-loop performance by observing the movement of the system poles. Based on this, we analyse the neccessary modelling fidelity and propose simple modelling methods for the usual actuators found on small-scale electric aircraft. Finally, we analyse the actuator models using (flight) test data where possible. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-21T05:44:29Z DOI: 10.1177/1756829320961925 Issue No:Vol. 12 (2020)
Authors:Zhengyu Qu, Cuichun Li, Yong Hao, Feng Yan, Yanchu Yang Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This paper presents the design details and flight tests validation of printed circuit board fabricated micro gliders. The purpose of the micro glider is to be launched from a super pressure balloon at high altitude, glide to the target position to collect data and upload data to the staying balloon. The mission demand requires the micro glider to finish precise landing with small size and low fabrication cost. To complete this concept, we designed a PCB fabricated aircraft with limited sensors including GPS and IMU. The first part of the article describes the aerodynamic design methods. The second part introduced the control and guidance system design by controlling the roll angle and flight path angle to complete the precise landing. In the simulation results presented in the third part, launch with no wind condition shows desirable precise landing ability. As a contrast, wind direction and magnitude have significant effects on the guidance ability and accuracy. In the last part, two real flight tests conducted in Inner Mongolia of China are described to compare the flight performance with the current aerodynamics and control system design. Returned data indicated the micro gliders could successfully fly at high altitude. The control algorithm can compute the command roll angle only with GPS and IMU, but some design details still need to be improved to achieve precise landing ability. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-17T08:23:03Z DOI: 10.1177/1756829320979955 Issue No:Vol. 12 (2020)
Authors:Liang Lu, Alexander Yunda, Adrian Carrio, Pascual Campoy Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This paper presents a novel collision-free navigation system for the unmanned aerial vehicle based on point clouds that outperform compared to baseline methods, enabling high-speed flights in cluttered environments, such as forests or many indoor industrial plants. The algorithm takes the point cloud information from physical sensors (e.g. lidar, depth camera) and then converts it to an occupied map using Voxblox, which is then used by a rapid-exploring random tree to generate finite path candidates. A modified Covariant Hamiltonian Optimization for Motion Planning objective function is used to select the best candidate and update it. Finally, the best candidate trajectory is generated and sent to a Model Predictive Control controller. The proposed navigation strategy is evaluated in four different simulation environments; the results show that the proposed method has a better success rate and a shorter goal-reaching distance than the baseline method. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-17T06:41:07Z DOI: 10.1177/1756829320924528 Issue No:Vol. 12 (2020)
Authors:E Javier Ollervides-Vazquez, Erik G Rojo-Rodriguez, Octavio Garcia-Salazar, Luis Amezquita-Brooks, Pedro Castillo, Victor Santibañez Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This paper presents an algorithm based on fuzzy theory for the formation flight of the multi-quadrotors. For this purpose, the mathematical model of N-quadrotor unmanned aerial vehicles is presented using the Newton-Euler formulation. The strategy of the formation flight is based on a structure composed by a sectorial fuzzy controller and the linear systems whose state variables are the position and velocity of the ith quadrotor. The stability analysis is described as a generalized form for N-quadrotor unmanned aerial vehicles and it is based on the Lyapunov theory. This analysis demonstrates that the closed-loop system is globally asymptotically stable so that the quadrotors unmanned aerial vehicles reach the consensus. Numerical simulation demonstrates the robustness of the proposed scheme for the formation flight even in the presence of disturbances. Finally, experimental results show the feasibility of the proposed algorithm for the formation flight of multiple unmanned aerial vehicles. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-15T05:56:58Z DOI: 10.1177/1756829320973579 Issue No:Vol. 12 (2020)
Authors:DNWM Heitzig, BW van Oudheusden, D Olejnik, M Karásek Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This study investigates the wing deformation of the DelFly II in forward flight conditions. A measurement setup was developed that maintains adequate viewing axes of the flapping wings for all pitch angles. Recordings of a high-speed camera pair were processed using a point tracking algorithm, allowing 136 points per wing to be measured simultaneously with an estimated accuracy of 0.25 mm. The measurements of forward flight show little change in the typical clap-and-peel motion, suggesting similar effectiveness in all cases. It was found that an air-buffer remains at all times during this phase. The wing rotation and camber reduction during the upstroke suggests low loading during the upstroke in fast forward flight. In slow cases a torsional wave and recoil is found. A study of the isolated effects showed asymmetric deformations even in symmetric freestream conditions. Furthermore, it shows a dominant role of the flapping frequency on the clap-and-peel, while the freestream velocity reduces wing loading outside this phase. Citation: International Journal of Micro Air Vehicles PubDate: 2020-12-04T10:45:46Z DOI: 10.1177/1756829320941002 Issue No:Vol. 12 (2020)
Authors:Ana Guerra-Langan, Sergio Araujo-Estrada, Shane Windsor Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. Small unmanned aerial vehicles (SUAVs) are suitable for many low-altitude operations in urban environments due to their manoeuvrability; however, their flight performance is limited by their on-board energy storage and their ability to cope with high levels of turbulence. Birds exploit the atmospheric boundary layer in urban environments, reducing their energetic flight costs by using orographic lift generated by buildings. This behaviour could be mimicked by fixed-wing SUAVs to overcome their energy limitations if flight control can be maintained in the increased turbulence present in these conditions. Here, the control effort required and energetic benefits for a SUAV flying parallel to buildings whilst using orographic lift was investigated. A flight dynamics and control model was developed for a powered SUAV and used to simulate flight control performance in different turbulent wind conditions. It was found that the control effort required decreased with increasing altitude and that the mean throttle required increased with greater radial distance to the buildings. However, the simulations showed that flying close to the buildings in strong wind speeds increased the risk of collision. Overall, the results suggested that a strategy of flying directly over the front corner of the buildings appears to minimise the control effort required for a given level of orographic lift, a strategy that mirrors the behaviour of gulls in high wind speeds. Citation: International Journal of Micro Air Vehicles PubDate: 2020-08-07T05:32:45Z DOI: 10.1177/1756829320941005 Issue No:Vol. 12 (2020)
Authors:Shaoran Liang, Bifeng Song, Jianlin Xuan, Yubin Li Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This paper proposes an attitude control scheme for the Dove flapping wing micro air vehicle in intermittent flapping and gliding flight. The Dove flapping wing micro air vehicle adopts intermittent flapping and gliding flight to make the wing movements more natural; this strategy also has the potential to reduce energy consumption. To implement this specific flight mode, this paper proposes a closed-loop active disturbance rejection control strategy to stabilize the attitude during the processes of flapping flight, transition and gliding flight. The active disturbance rejection control controller is composed of three parts: a tracking differentiator, a linear extended state observer and a nonlinear state error feedback controller. The tracking differentiator estimates the given target signal and the differential signal in real time. The extended state observer estimates the system states and system nonlinearity. Moreover, the bandwidth parameterization method is applied to determine the observer gains. The stability of the closed-loop system is verified using Lyapunov’s theorem. Several outdoor flight experiments have been conducted to verify the effectiveness of the proposed control method, and the results show that the proposed method can guarantee the stability of intermittent flapping and gliding flight. Citation: International Journal of Micro Air Vehicles PubDate: 2020-08-07T05:01:47Z DOI: 10.1177/1756829320943085 Issue No:Vol. 12 (2020)
Authors:Aaron Lopez Luna, Israel Cruz Vega, Jose Martinez-Carranza Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. In this work, we present a novel design for vertical surface contact using a two degree of freedom robotic arm attached to a Micro Air Vehicle. To achieve this, we propose a controller based on a Gain-Scheduled Proportional–Integral–Derivative approach. In previous works, the Gain-Scheduled Proportional–Integral–Derivative method was used to control the attitude of the Micro Air Vehicle, thus mitigating the perturbations induced by the movement of the arm. The novel approach of this work focuses on the achievement of an automatized full-contact with a rigid vertical surface using a Micro Air Vehicle with a robotic arm. We have improved the capabilities of the Gain-Scheduled Proportional–Integral–Derivative control to consider the inherent issues of approximating to a flat structure in order to carry out an aerial interaction task successfully. For the Micro Air Vehicle’s position feedback, a motion capture system is used in this work. A paintbrush attached to the end effector of the arm is used to draw over a whiteboard surface to show the full contact of the aerial manipulator. A distance sensor is added to the on-board sensors to measure the distance between the vertical surface and the system to ensure a correct distance and achieve a safe contact. Experimental testing results show that the controller can maintain a stable flight with sufficient accuracy to complete the aerial interaction tasks. Citation: International Journal of Micro Air Vehicles PubDate: 2020-07-10T05:08:20Z DOI: 10.1177/1756829320938745 Issue No:Vol. 12 (2020)
Authors:Li Ding, Yangmin Li Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. The robust control problem in attitude tracking of an unmanned aerial vehicle quadrotor is a challenging task due to strong parametric uncertainties, large nonlinearities and high couplings in flight dynamics. In this paper, a continuous nonsingular fast terminal sliding mode controller based on linear extended state observer is proposed for attitude tracking control of a quadrotor under lumped disturbances. The proposed control method requires no prior knowledge of the attitude dynamics. It can ensure rapid convergence rate and high tracking precision due to terminal sliding mode surface and fast reaching law. The controller uses the linear extended state observer to reject the influence of both parametric uncertainties and external disturbances. Meanwhile, the nonsingular fast terminal sliding mode control strategy is designed to ensure the state variables to slide to desired points in finite time. To enhance the control performance, a self-adaptive fruit fly optimization algorithm is applied to parameters tuning of the proposed controller. The effectiveness of the proposed control approach is illustrated through numerical simulations and experimental verification. Citation: International Journal of Micro Air Vehicles PubDate: 2020-06-05T05:44:05Z DOI: 10.1177/1756829320923563 Issue No:Vol. 12 (2020)
Authors:Pascual Campoy, Paloma de la Puente, Adrian Carrio Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020.
Citation: International Journal of Micro Air Vehicles PubDate: 2020-06-05T05:43:25Z DOI: 10.1177/1756829320927593 Issue No:Vol. 12 (2020)
Authors:Aldrich A Cabrera-Ponce, J Martinez-Carranza, Caleb Rascon Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. In this work, we address the problem of UAV detection flying nearby another UAV. Usually, computer vision could be used to face this problem by placing cameras onboard the patrolling UAV. However, visual processing is prone to false positives, sensible to light conditions and potentially slow if the image resolution is high. Thus, we propose to carry out the detection by using an array of microphones mounted with a special array onboard the patrolling UAV. To achieve our goal, we convert audio signals into spectrograms and used them in combination with a CNN architecture that has been trained to learn when a UAV is flying nearby, and when it is not. Clearly, the first challenge is the presence of ego-noise derived from the patrolling UAV itself through its propellers and motor’s noise. Our proposed CNN is based on Google’s Inception v.3 network. The Inception model is trained with a dataset created by us, which includes examples of when an intruder UAV flies nearby and when it does not. We conducted experiments for off-line and on-line detection. For the latter, we manage to generate spectrograms from the audio stream and process it with the Nvidia Jetson TX2 mounted onboard the patrolling UAV. Citation: International Journal of Micro Air Vehicles PubDate: 2020-05-20T05:48:41Z DOI: 10.1177/1756829320925748 Issue No:Vol. 12 (2020)
Authors:Bart Theys, Joris De Schutter Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020. This paper presents experimental results on the relation between forward airspeed, pitch angle, and power consumption of a quadcopter unmanned aerial vehicle. The quadcopter consists of an interchangeable spherical body, four cylindrical arms, and small propellers mounted at 1 m diagonal distance to minimize interference between body and propellers. This simple geometry facilitates results reproduction and comparison with simulation. Two different takeoff masses and four diameters of spherical bodies are tested for their steady-state speed and power for pitch angles up to [math]. The steady-state horizontal flight is recorded with on-board sensors at the end of flying long straight lines at a constant pitch angle in wind-still conditions. The best effective lift-to-drag ratio increases for smaller bodies and occurs at higher speeds for increasing mass. Results show that the equivalent frontal surface stays constant for pitch angles further than [math] up to the maximum recorded [math] and increases linearly with the frontal surface of the body. Citation: International Journal of Micro Air Vehicles PubDate: 2020-05-13T06:48:19Z DOI: 10.1177/1756829320923565 Issue No:Vol. 12 (2020)
Authors:Jacson MO Barth, Jean-Philippe Condomines, Murat Bronz, Jean-Marc Moschetta, Cédric Join, Michel Fliess Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020.
Citation: International Journal of Micro Air Vehicles PubDate: 2020-04-03T05:09:00Z DOI: 10.1177/1756829320914264 Issue No:Vol. 12 (2020)
Authors:Shanyong Zhao, Zhen Liu, Penglei Che, Bingfei Li, Tianjiao Dang, Chen Bu Abstract: International Journal of Micro Air Vehicles, Volume 12, Issue , January-December 2020.
Citation: International Journal of Micro Air Vehicles PubDate: 2020-02-03T08:56:27Z DOI: 10.1177/1756829319900886 Issue No:Vol. 12 (2020)
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