Applied Sciences

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12 pages, 6061 KiB

Open AccessArticle

Aerodynamic Optimization of a Micro Quadrotor Aircraft with Different Rotor Spacings in Hover

by Yao Lei and Hengda Wang

Appl. Sci. 2020, 10(4), 1272; https://doi.org/10.3390/app10041272 - 13 Feb 2020

Cited by 18 | Viewed by 3106

In order to study the aerodynamic performance of the quadrotor with different rotor spacings in hover, experiments were performed together with numerical simulations. For experimental study, an experimental platform was designed to measure the thrust and power consumption of the quadrotor with different [...] Read more.

In order to study the aerodynamic performance of the quadrotor with different rotor spacings in hover, experiments were performed together with numerical simulations. For experimental study, an experimental platform was designed to measure the thrust and power consumption of the quadrotor with different rotor spacings (L/R = 2.2, 2.6, 3.0, 3.2, 3.6, and 4.0), and to attempt to find out the optimal rotor configuration which makes the quadrotor have the best aerodynamic performance. In addition, the pressure distribution, vorticity of the blade tip, and velocity vector of quadrotor in the flow field were obtained by Computational Fluid Dynamics (CFD) method to visually analyze the aerodynamic interference between adjacent rotors. By the comparison of experimental results and numerical simulations, the final results show that the aerodynamic performance of the quadrotor varies obviously with the change of rotor spacing, and it has a negative impact on hover efficiency if rotor spacing is too much small or large. The rotors pacing at L/R = 3.6 with larger thrust and smaller power is considered to be the best aerodynamic configuration for the quadrotor with better aerodynamic characteristics. Furthermore, compared with the isolated rotor, moderate aerodynamic interference is proved to help improve the aerodynamic performance of the quadrotor with a larger thrust, especially for a rotor spacing at L/R = 3.6. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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14 pages, 7901 KiB

Open AccessArticle

End-To-End Controls Using K-Means Algorithm for 360-Degree Video Control Method on Omnidirectional Camera-Equipped Autonomous Micro Unmanned Aircraft Systems

by Jeonghoon Kwak and Yunsick Sung

Appl. Sci. 2019, 9(20), 4431; https://doi.org/10.3390/app9204431 - 18 Oct 2019

Cited by 2 | Viewed by 2209

Abstract

Micro unmanned aircraft systems (micro UAS)-related technical research is important because micro UAS has the advantage of being able to perform missions remotely. When an omnidirectional camera is mounted, it captures all surrounding areas of the micro UAS. Normal field of view (NFoV) [...] Read more.

Micro unmanned aircraft systems (micro UAS)-related technical research is important because micro UAS has the advantage of being able to perform missions remotely. When an omnidirectional camera is mounted, it captures all surrounding areas of the micro UAS. Normal field of view (NFoV) refers to a view presented as an image to a user in a 360-degree video. The 360-degree video is controlled using an end-to-end controls method to automatically provide the user with NFoVs without the user controlling the 360-degree video. When using the end-to-end controls method that controls 360-degree video, if there are various signals that control the 360-degree video, the training of the deep learning model requires a considerable amount of training data. Therefore, there is a need for a method of autonomously determining the signals to reduce the number of signals for controlling the 360-degree video. This paper proposes a method to autonomously determine the output to be used for end-to-end control-based deep learning model to control 360-degree video for micro UAS controllers. The output of the deep learning model to control 360-degree video is automatically determined using the K-means algorithm. Using a trained deep learning model, the user is presented with NFoVs in a 360-degree video. The proposed method was experimentally verified by providing NFoVs wherein the signals that control the 360-degree video were set by the proposed method and by user definition. The results of training the convolution neural network (CNN) model using the signals to provide NFoVs were compared, and the proposed method provided NFoVs similar to NFoVs of existing user with 24.4% more similarity compared to a user-defined approach. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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22 pages, 6967 KiB

Open AccessArticle

Sensitivity Analysis and Technology Evaluation for a Roadable Personal Air Vehicle at the Conceptual Design Stage

by Seok-Beom Kim, Ju-Yeol Yun and Ho-Yon Hwang

Appl. Sci. 2019, 9(19), 4121; https://doi.org/10.3390/app9194121 - 2 Oct 2019

Cited by 5 | Viewed by 3521

Abstract

In this study, the technology identification, evaluation, and selection (TIES) method was implemented to explore an optimum design space appropriate for a personal air vehicle (PAV) at the conceptual design stage. A morphological matrix was employed to identify possible alternative configurations and performance [...] Read more.

In this study, the technology identification, evaluation, and selection (TIES) method was implemented to explore an optimum design space appropriate for a personal air vehicle (PAV) at the conceptual design stage. A morphological matrix was employed to identify possible alternative configurations and performance targets. The Microsoft Excel add-in JMP, a commercial statistical tool, and a PAV sizing tool developed for this study were used for modelling and simulation. After the screening test, seven design variables having significant impacts on the design were finally chosen, specifically the range, maximum speed, cruise speed, cruise altitude, passengers, takeoff ground roll, and stall speed. Response surface equations (RSEs) were created as a function of the seven design variables. The generated RSEs were then used to perform a Monte Carlo simulation (MCS) to explore a feasible design space. As a result, it was confirmed that all seven design variables can be employed for an optimization process. In addition, k-factor and technology sensitivity analyses were conducted to evaluate applicable technologies quantitatively. Consequently, the selected set includes a flow circulation flap, leading edge blowing, a nanocoating, liquid metal, and an advanced composite material, which are technologies that greatly influenced the target criteria. Furthermore, the target value variations were analyzed as the k factors changed. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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18 pages, 13927 KiB

Open AccessArticle

UAV-Based Air Pollutant Source Localization Using Combined Metaheuristic and Probabilistic Methods

by Noe Yungaicela-Naula, Luis E. Garza-Castañon, Youmin Zhang and Luis I. Minchala-Avila

Appl. Sci. 2019, 9(18), 3712; https://doi.org/10.3390/app9183712 - 6 Sep 2019

Cited by 14 | Viewed by 2604

Abstract

Air pollution is one of the greatest risks for the health of people. In recent years, platforms based on Unmanned Aerial Vehicles (UAVs) for the monitoring of pollution in the air have been studied to deal with this problem, due to several advantages, [...] Read more.

Air pollution is one of the greatest risks for the health of people. In recent years, platforms based on Unmanned Aerial Vehicles (UAVs) for the monitoring of pollution in the air have been studied to deal with this problem, due to several advantages, such as low-costs, security, multitask and ease of deployment. However, due to the limitations in the flying time of the UAVs, these platforms could perform monitoring tasks poorly if the mission is not executed with an adequate strategy and algorithm. Their application can be improved if the UAVs have the ability to perform autonomous monitoring of the areas with a high concentration of the pollutant, or even to locate the pollutant source. This work proposes an algorithm to locate an air pollutant’s source by using a UAV. The algorithm has two components: (i) a metaheuristic technique is used to trace the increasing gradient of the pollutant concentration, and (ii) a probabilistic component complements the method by concentrating the search in the most promising areas in the targeted environment. The metaheuristic technique has been selected from a simulation-based comparative analysis between some classical techniques. The probabilistic component uses the Bayesian methodology to build and update a probability map of the pollutant source location, with each new sensor information available, while the UAV navigates in the environment. The proposed solution was tested experimentally with a real quadrotor navigating in a virtual polluted environment. The results show the effectiveness and robustness of the algorithm. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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25 pages, 4206 KiB

Open AccessArticle

Design and Analysis of a Robust UAV Flight Guidance and Control System Based on a Modified Nonlinear Dynamic Inversion

by Ehab Safwat, Weiguo Zhang, Ahmed Mohsen and Mohamed Kassem

Appl. Sci. 2019, 9(17), 3600; https://doi.org/10.3390/app9173600 - 2 Sep 2019

Cited by 6 | Viewed by 3457

Abstract

The work presented in this paper focuses on the design of a robust nonlinear flight control system for a small fixed-wing UAV against uncertainties and external disturbances. Toward this objective, an integrated UAV waypoints guidance scheme based on Carrot Chasing guidance law (CC) [...] Read more.

The work presented in this paper focuses on the design of a robust nonlinear flight control system for a small fixed-wing UAV against uncertainties and external disturbances. Toward this objective, an integrated UAV waypoints guidance scheme based on Carrot Chasing guidance law (CC) in comparison with the pure pursuit and line of sight-based path following (PLOS) guidance law is analyzed. For path following based on CC, a Virtual Track Point (VTP) is introduced on the path to let the UAV chase the path. For PLOS, the pure pursuit guidance law directs the UAV to the next waypoint, while the LOS guidance law steers the vehicle toward the line of sight (LOS). Nonlinear Dynamic Inversion (NLDI) awards the flight control system researchers a straight forward method of deriving control laws for nonlinear systems. The control inputs are used to eliminate unwanted terms in the equations of motion using negative feedback of these terms. The two-time scale assumption is adopted here to separate the fast dynamics—three angular rates of aircraft—from the slow dynamics—the angle of attack, sideslip, and bank angles. However, precise dynamic models may not be available, therefore a modification of NLDI is presented to compensate the model uncertainties. Simulation results show that the modified NLDI flight control system is robust against wind disturbances and model mismatch. PLOS path-following technique more accurately follows the desired path than CC and also requires the least control effort. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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16 pages, 13516 KiB

Open AccessArticle

Aerodynamic Performance of Quadrotor UAV with Non-Planar Rotors

by Yao Lei and Jinli Wang

Appl. Sci. 2019, 9(14), 2779; https://doi.org/10.3390/app9142779 - 10 Jul 2019

Cited by 14 | Viewed by 4603

Abstract

The mobility of a quadrotor UAV is significantly affected by its aerodynamics, especially when the closely spaced rotors are applied in the multi-rotor system. This paper addresses the aerodynamic modeling of non-planar quadrotor UAV with various rotor spacing (1 d–2 d) [...] Read more.

The mobility of a quadrotor UAV is significantly affected by its aerodynamics, especially when the closely spaced rotors are applied in the multi-rotor system. This paper addresses the aerodynamic modeling of non-planar quadrotor UAV with various rotor spacing (1 d–2 d) and disk plane angle (0–50 deg). The inter-rotor interference and the power models are also proposed in this paper. In order to validate the non-planar model, a series of CFD analyses and experiments were conducted. The obtained results demonstrate that the flow field of the non-planar quadrotor is extremely complicated when the unsteady flow is involved. The pulsation of partial angle of attack and pressure distribution is formed when the blade passes through the vortex. The thrust is increasing significantly along with the tilt angle, resulting from the stronger outflow of the non-planar rotors, which is also leading the power increment. However, the thrust increment is not that obvious when the spacing is larger than 1.4 d. The experiments and the numerical simulation results provide consistent trends and demonstrate the effectiveness of the aerodynamic model of the non-planar quadrotor. The comparison with the traditional planar quadrotor validates that the proposed non-planar quadrotor has better aerodynamic and control performances with a larger power loading. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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17 pages, 3970 KiB

Open AccessArticle

Aerial Grasping of an Object in the Strong Wind: Robust Control of an Aerial Manipulator

by Guangyu Zhang, Yuqing He, Bo Dai, Feng Gu, Liying Yang, Jianda Han and Guangjun Liu

Appl. Sci. 2019, 9(11), 2230; https://doi.org/10.3390/app9112230 - 30 May 2019

Cited by 22 | Viewed by 3809

Abstract

An aerial manipulator is a new kind of flying robot system composed of a rotorcraft unmanned aerial vehicle (UAV) and a multi-link robotic arm. It gives the flying robot the capacity to complete manipulation tasks. Steady flight is essential for an aerial manipulator [...] Read more.

An aerial manipulator is a new kind of flying robot system composed of a rotorcraft unmanned aerial vehicle (UAV) and a multi-link robotic arm. It gives the flying robot the capacity to complete manipulation tasks. Steady flight is essential for an aerial manipulator to complete manipulation tasks. This paper focuses on the steady flight control performance of the aerial manipulator. A separate control strategy is used in the aerial manipulator system, in which the UAV and the manipulator are controlled separately. In order to complete tasks in environments with strong wind disturbance, an acceleration feedback enhanced robust H∞ controller was designed for the UAV in the aerial manipulator. The controller is based on the hierarchical inner-outer loop control structure of the UAV and composed of a robust H∞ controller and acceleration feedback enhanced term, which is used to compensate for the wind disturbance. Experimental results of aerial grasping of a target object show that the controller can suppress the wind disturbance effectively, and make the aerial manipulator hover steadily with sufficient accuracy to complete aerial manipulation tasks in strong wind. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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21 pages, 2061 KiB

Open AccessArticle

New Trajectory Tracking Approach for a Quadcopter Using Genetic Algorithm and Reference Model Methods

by Imane Siti, Mostafa Mjahed, Hassan Ayad and Abdeljalil El Kari

Appl. Sci. 2019, 9(9), 1780; https://doi.org/10.3390/app9091780 - 29 Apr 2019

Cited by 31 | Viewed by 4044

Abstract

This paper deals with the trajectory tracking problem for a quadrotor unmanned aerial vehicle (UAV). For this purpose, two control strategies are proposed. First, a flight controller with a hierarchical structure is designed, whereby the complete closed-loop system is divided into two blocks. [...] Read more.

This paper deals with the trajectory tracking problem for a quadrotor unmanned aerial vehicle (UAV). For this purpose, two control strategies are proposed. First, a flight controller with a hierarchical structure is designed, whereby the complete closed-loop system is divided into two blocks. The system has an inner block for attitude control and an outer block for position stabilization, for a total of six proportional-derivative/proportional-integral-derivative (PD/PID) controllers. The second new trajectory tracking strategy is based on attitude stabilization. In addition to a direct stabilization of yaw and altitude, the x and y positions are stabilized by choosing an appropriate control of roll and pitch angles. The relations between positions (x, y) and rotations (roll, pitch) are derived from the natural flight of the quadcopter. In this second approach, with only four controllers, the quadrotor UAV is able to follow any trajectory. In both approaches, the PD/PID controllers are synthesized using the genetic algorithm method, and compared with those obtained by the reference model method. Furthermore, a comparison between PD and PID controller performance is performed. Thereafter, the robustness of the proposed controllers is tested for trajectory tracking in a disturbed environment. Simulation results demonstrate that for the two approaches, PD controllers show a better behavior with respect to quadcopter stabilization than in trajectory tracking under different conditions. Full article

(This article belongs to the Special Issue Autonomous Micro Aerial Vehicles: Methods and Applications)

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