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5 pages, 168 KiB

Open AccessEditorial

Autonomous Control of Unmanned Aerial Vehicles

by Victor M. Becerra

Electronics 2019, 8(4), 452; https://doi.org/10.3390/electronics8040452 - 22 Apr 2019

Cited by 30 | Viewed by 5161

Abstract

Unmanned aerial vehicles (UAVs) are being increasingly used in different applications in both military and civilian domains [...] Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

Research

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21 pages, 818 KiB

Open AccessArticle

Recursive Rewarding Modified Adaptive Cell Decomposition (RR-MACD): A Dynamic Path Planning Algorithm for UAVs

by Franklin Samaniego, Javier Sanchis, Sergio García-Nieto and Raúl Simarro

Electronics 2019, 8(3), 306; https://doi.org/10.3390/electronics8030306 - 08 Mar 2019

Cited by 26 | Viewed by 4330

Abstract

A relevant task in unmanned aerial vehicles (UAV) flight is path planning in

3 D

environments. This task must be completed using the least possible computing time. The aim of this article is to combine methodologies to optimise the task in time and [...] Read more.

A relevant task in unmanned aerial vehicles (UAV) flight is path planning in

3 D

environments. This task must be completed using the least possible computing time. The aim of this article is to combine methodologies to optimise the task in time and offer a complete

3 D

trajectory. The flight environment will be considered as a

3 D

adaptive discrete mesh, where grids are created with minimal refinement in the search for collision-free spaces. The proposed path planning algorithm for UAV saves computational time and memory resources compared with classical techniques. With the construction of the discrete meshing, a cost response methodology is applied as a discrete deterministic finite automaton (DDFA). A set of optimal partial responses, calculated recursively, indicates the collision-free spaces in the final path for the UAV flight. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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22 pages, 7651 KiB

Open AccessFeature PaperArticle

Motion Equations and Attitude Control in the Vertical Flight of a VTOL Bi-Rotor UAV

by Sergio Garcia-Nieto, Jesus Velasco-Carrau, Federico Paredes-Valles, Jose Vicente Salcedo and Raul Simarro

Electronics 2019, 8(2), 208; https://doi.org/10.3390/electronics8020208 - 12 Feb 2019

Cited by 18 | Viewed by 6861

Abstract

This paper gathers the design and implementation of the control system that allows an unmanned Flying-wing to perform a Vertical Take-Off and Landing (VTOL) maneuver using two tilting rotors (Bi-Rotor). Unmanned Aerial Vehicles (UAVs) operating in this configuration are also categorized as Hybrid [...] Read more.

This paper gathers the design and implementation of the control system that allows an unmanned Flying-wing to perform a Vertical Take-Off and Landing (VTOL) maneuver using two tilting rotors (Bi-Rotor). Unmanned Aerial Vehicles (UAVs) operating in this configuration are also categorized as Hybrid UAVs due to their ability of having a dual flight envelope: hovering like a multi-rotor and cruising like a traditional fixed-wing, providing the opportunity of facing complex missions in which these two different dynamics are required. This work exhibits the Bi-Rotor nonlinear dynamics, the attitude tracking controller design and also, the results obtained through Hardware-In-the-Loop (HIL) simulation and experimental studies that ensure the controller’s efficiency in hovering operation. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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20 pages, 1401 KiB

Open AccessFeature PaperArticle

Bio-Inspired Autonomous Visual Vertical and Horizontal Control of a Quadrotor Unmanned Aerial Vehicle

by Saul Armendariz, Victor Becerra and Nils Bausch

Electronics 2019, 8(2), 184; https://doi.org/10.3390/electronics8020184 - 05 Feb 2019

Cited by 5 | Viewed by 2914

Abstract

Near-ground manoeuvres, such as landing, are key elements in unmanned aerial vehicle navigation. Traditionally, these manoeuvres have been done using external reference frames to measure or estimate the velocity and the height of the vehicle. Complex near-ground manoeuvres are performed by flying animals [...] Read more.

Near-ground manoeuvres, such as landing, are key elements in unmanned aerial vehicle navigation. Traditionally, these manoeuvres have been done using external reference frames to measure or estimate the velocity and the height of the vehicle. Complex near-ground manoeuvres are performed by flying animals with ease. These animals perform these complex manoeuvres by exclusively using the information from their vision and vestibular system. In this paper, we use the Tau theory, a visual strategy that, is believed, is used by many animals to approach objects, as a solution for relative ground distance control for unmanned vehicles. In this paper, it is shown how this approach can be used to perform near-ground manoeuvres in a vertical and horizontal manner on a moving target without the knowledge of height and velocity of either the vehicle or the target. The proposed system is tested with simulations. Here, it is shown that, using the proposed methods, the vehicle is able to perform landing on a moving target, and also they enable the user to choose the dynamic characteristics of the approach. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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16 pages, 8113 KiB

Open AccessArticle

Longitudinal Attitude Control Decoupling Algorithm Based on the Fuzzy Sliding Mode of a Coaxial-Rotor UAV

by Kewei Li, Yiran Wei, Chao Wang and Hongbin Deng

Electronics 2019, 8(1), 107; https://doi.org/10.3390/electronics8010107 - 18 Jan 2019

Cited by 11 | Viewed by 5422

Abstract

A longitudinal attitude decoupling algorithm based on the fuzzy sliding mode control for a small coaxial rotor unmanned aerial vehicle (UAV) is presented in this paper. The attitude system of a small coaxial rotor UAV is characterized by nonlinearity, strong coupling and uncertainty, [...] Read more.

A longitudinal attitude decoupling algorithm based on the fuzzy sliding mode control for a small coaxial rotor unmanned aerial vehicle (UAV) is presented in this paper. The attitude system of a small coaxial rotor UAV is characterized by nonlinearity, strong coupling and uncertainty, which causes difficulties pertaining to its flight control. According to its six-degree-of-freedom model and structural characteristics, the dynamic model was established, and a longitudinal attitude decoupling algorithm was proposed. A fuzzy sliding mode control was used to design the controller to adapt to the underactuated system. Compared with the uncoupled fuzzy sliding mode control, simulation results indicated that the proposed method could improve the stability of the system, presented with a better adapting ability, and could effectively suppress the modeling error and external interference of the coaxial rotor aircraft attitude system. The proposed method also has the advantages of high accuracy, good stability, and the ease of implementation. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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15 pages, 5433 KiB

Open AccessFeature PaperArticle

Preliminary Design of an Unmanned Aircraft System for Aircraft General Visual Inspection

by Umberto Papa and Salvatore Ponte

Electronics 2018, 7(12), 435; https://doi.org/10.3390/electronics7120435 - 14 Dec 2018

Cited by 25 | Viewed by 5769

Abstract

Among non-destructive inspection (NDI) techniques, General Visual Inspection (GVI), global or zonal, is the most widely used, being quick and relatively less expensive. In the aeronautic industry, GVI is a basic procedure for monitoring aircraft performance and ensuring safety and serviceability, and over [...] Read more.

Among non-destructive inspection (NDI) techniques, General Visual Inspection (GVI), global or zonal, is the most widely used, being quick and relatively less expensive. In the aeronautic industry, GVI is a basic procedure for monitoring aircraft performance and ensuring safety and serviceability, and over 80% of the inspections on large transport category aircrafts are based on visual testing, both directly and remotely, either unaided or aided via mirrors, lenses, endoscopes or optic fiber devices coupled to cameras. This paper develops the idea of a global and/or zonal GVI procedure implemented by means of an autonomous unmanned aircraft system (UAS), equipped with a low-cost, high-definition (HD) camera for carrying out damage detection of panels, and a series of distance and trajectory sensors for obstacle avoidance and inspection path planning. An ultrasonic distance keeper system (UDKS), useful to guarantee a fixed distance between the UAS and the aircraft, was developed, and several ultrasonic sensors (HC-SR-04) together with an HD camera and a microcontroller were installed on the selected platform, a small commercial quad-rotor (micro-UAV). The overall system concept design and some laboratory experimental tests are presented to show the effectiveness of entrusting aircraft inspection procedures to a small UAS and a PC-based ground station for data collection and processing. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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29 pages, 46543 KiB

Open AccessArticle

High-Order Sliding Mode-Based Fixed-Time Active Disturbance Rejection Control for Quadrotor Attitude System

by Chunlin Song, Changzhu Wei, Feng Yang and Naigang Cui

Electronics 2018, 7(12), 357; https://doi.org/10.3390/electronics7120357 - 26 Nov 2018

Cited by 18 | Viewed by 4549

Abstract

This article presents a fixed-time active disturbance rejection control approach for the attitude control problem of quadrotor unmanned aerial vehicle in the presence of dynamic wind, mass eccentricity and an actuator fault. The control scheme applies the feedback linearization technique and enhances the [...] Read more.

This article presents a fixed-time active disturbance rejection control approach for the attitude control problem of quadrotor unmanned aerial vehicle in the presence of dynamic wind, mass eccentricity and an actuator fault. The control scheme applies the feedback linearization technique and enhances the performance of the traditional active disturbance rejection control (ADRC) based on the fixed-time high-order sliding mode method. A switching-type uniformly convergent differentiator is used to improve the extended state observer for estimating and attenuating the lumped disturbance more accurately. A multivariable high-order sliding mode feedback law is derived to achieve fixed time convergence. The timely convergence of the designed extended state observer and the feedback law is proved theoretically. Mathematical simulations with detailed actuator models and real time experiments are performed to demonstrate the robustness and practicability of the proposed control scheme. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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18 pages, 4779 KiB

Open AccessArticle

An Efficient SC-FDM Modulation Technique for a UAV Communication Link

by Sukhrob Atoev, Oh-Heum Kwon, Suk-Hwan Lee and Ki-Ryong Kwon

Electronics 2018, 7(12), 352; https://doi.org/10.3390/electronics7120352 - 25 Nov 2018

Cited by 11 | Viewed by 5474

Abstract

Since the communication link of an unmanned aerial vehicle (UAV) and its reliability evaluation represent an arduous field, we have concentrated our work on this topic. The demand regarding the validity and reliability of the communication and data link of UAV is much [...] Read more.

Since the communication link of an unmanned aerial vehicle (UAV) and its reliability evaluation represent an arduous field, we have concentrated our work on this topic. The demand regarding the validity and reliability of the communication and data link of UAV is much higher since the environment of the modern battlefield is becoming more and more complex. Therefore, the communication channel between the vehicle and ground control station (GCS) should be secure and provide an efficient data link. In addition, similar to other types of communications, the data link of a UAV has several requirements such as long-range operation, high efficiency, reliability, and low latency. In order to achieve an efficient data link, we need to adopt a highly efficient modulation technique, which leads to an increase in the flight time of the UAV, data transmission rate, and the reliability of the communication link. For this purpose, we have investigated the single-carrier frequency division multiplexing (SC-FDM) modulation technique for a UAV communication system. The results obtained from the comparative study demonstrate that SC-FDM has better performance than the currently used modulation technique for a UAV communication link. We expect that our proposed approach can be a remarkable framework that will help drone manufacturers to establish an efficient UAV communication link and extend the flight duration of drones, especially those being used for search and rescue operations, military tasks, and delivery services. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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19 pages, 3601 KiB

Open AccessArticle

Research on Air Confrontation Maneuver Decision-Making Method Based on Reinforcement Learning

by Xianbing Zhang, Guoqing Liu, Chaojie Yang and Jiang Wu

Electronics 2018, 7(11), 279; https://doi.org/10.3390/electronics7110279 - 27 Oct 2018

Cited by 56 | Viewed by 4665

Abstract

With the development of information technology, the degree of intelligence in air confrontation is increasing, and the demand for automated intelligent decision-making systems is becoming more intense. Based on the characteristics of over-the-horizon air confrontation, this paper constructs a super-horizon air confrontation training [...] Read more.

With the development of information technology, the degree of intelligence in air confrontation is increasing, and the demand for automated intelligent decision-making systems is becoming more intense. Based on the characteristics of over-the-horizon air confrontation, this paper constructs a super-horizon air confrontation training environment, which includes aircraft model modeling, air confrontation scene design, enemy aircraft strategy design, and reward and punishment signal design. In order to improve the efficiency of the reinforcement learning algorithm for the exploration of strategy space, this paper proposes a heuristic Q-Network method that integrates expert experience, and uses expert experience as a heuristic signal to guide the search process. At the same time, heuristic exploration and random exploration are combined. Aiming at the over-the-horizon air confrontation maneuver decision problem, the heuristic Q-Network method is adopted to train the neural network model in the over-the-horizon air confrontation training environment. Through continuous interaction with the environment, self-learning of the air confrontation maneuver strategy is realized. The efficiency of the heuristic Q-Network method and effectiveness of the air confrontation maneuver strategy are verified by simulation experiments. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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19 pages, 1764 KiB

Open AccessArticle

Multiple UAV Systems for Agricultural Applications: Control, Implementation, and Evaluation

by Chanyoung Ju and Hyoung Il Son

Electronics 2018, 7(9), 162; https://doi.org/10.3390/electronics7090162 - 24 Aug 2018

Cited by 130 | Viewed by 9568

Abstract

The introduction of multiple unmanned aerial vehicle (UAV) systems into agriculture causes an increase in work efficiency and a decrease in operator fatigue. However, systems that are commonly used in agriculture perform tasks using a single UAV with a centralized controller. In this [...] Read more.

The introduction of multiple unmanned aerial vehicle (UAV) systems into agriculture causes an increase in work efficiency and a decrease in operator fatigue. However, systems that are commonly used in agriculture perform tasks using a single UAV with a centralized controller. In this study, we develop a multi-UAV system for agriculture using the distributed swarm control algorithm and evaluate the performance of the system. The performance of the proposed agricultural multi-UAV system is quantitatively evaluated and analyzed through four experimental cases: single UAV with autonomous control, multiple UAVs with autonomous control, single UAV with remote control, and multiple UAVs with remote control. Moreover, the performance of each system was analyzed through seven performance metrics: total time, setup time, flight time, battery consumption, inaccuracy of land, haptic control effort, and coverage ratio. Experimental results indicate that the performance of the multi-UAV system is significantly superior to the single-UAV system. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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21 pages, 42895 KiB

Open AccessArticle

Super-Twisting Extended State Observer and Sliding Mode Controller for Quadrotor UAV Attitude System in Presence of Wind Gust and Actuator Faults

by Di Shi, Zhong Wu and Wusheng Chou

Electronics 2018, 7(8), 128; https://doi.org/10.3390/electronics7080128 - 26 Jul 2018

Cited by 24 | Viewed by 7528

Abstract

This article addresses the problem of high precision attitude control for quadrotor unmanned aerial vehicle in presence of wind gust and actuator faults. We consider the effect of those factors as lumped disturbances, and in order to realize the quickly and accurately estimation [...] Read more.

This article addresses the problem of high precision attitude control for quadrotor unmanned aerial vehicle in presence of wind gust and actuator faults. We consider the effect of those factors as lumped disturbances, and in order to realize the quickly and accurately estimation of the disturbances, we propose a control strategy based on the online disturbance uncertainty estimation and attenuation method. Firstly, an enhanced extended state observer (ESO) is constructed based on the super-twisting (ST) algorithm to estimate and attenuate the impact of wind gust and actuator faults in finite time. And the convergence analysis and parameter selection rule of STESO are given following. Secondly, in order to guarantee the asymptotic convergence of desired attitude timely, a sliding mode control law is derived based on the super-twisting algorithm. And a comprehensive stability analysis for the entire system is presented based on the Lyapunov stability theory. Finally, to demonstrate the efficiency of the proposed solution, numerical simulations and real time experiments are carried out in presences of wind disturbance and actuator faults. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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18 pages, 3910 KiB

Open AccessArticle

Harmonic Extended State Observer Based Anti-Swing Attitude Control for Quadrotor with Slung Load

by Di Shi, Zhong Wu and Wusheng Chou

Electronics 2018, 7(6), 83; https://doi.org/10.3390/electronics7060083 - 29 May 2018

Cited by 22 | Viewed by 5436

Abstract

During the flight of the quadrotor, the existence of a slung load will exert a swing effect on the system and the motion of which will significantly change the dynamics of the quadrotor. The external torque caused by the slung load can be [...] Read more.

During the flight of the quadrotor, the existence of a slung load will exert a swing effect on the system and the motion of which will significantly change the dynamics of the quadrotor. The external torque caused by the slung load can be considered as a kind of disturbance and it is a threat to the attitude control stability of the system. In order to solve this problem, a high precision disturbance compensation method is presented in this paper, based on the harmonic extended state observer (HESO). Firstly, a generic mathematical model for the quadrotor-slung load system is obtained via the Lagrangian mechanics, and according to the analysis of the slung load motion, we obtain the disturbance as a form of periodic equation. Secondly, based on the dynamic model of the disturbance, we propose a HESO to achieve high precision disturbance estimation and its stability is proved by Lyapunov theory. Thirdly, we designed an attitude tracking controller based on backstepping method, and discussed the stability of the entire system. Finally, numerical simulations and real time experiments are carried out to evaluate the performance of the proposed method. Our results show that the robustness of the quadrotor subject to slung load has been improved. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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19 pages, 2694 KiB

Open AccessArticle

Real-Time Ground Vehicle Detection in Aerial Infrared Imagery Based on Convolutional Neural Network

by Xiaofei Liu, Tao Yang and Jing Li

Electronics 2018, 7(6), 78; https://doi.org/10.3390/electronics7060078 - 23 May 2018

Cited by 45 | Viewed by 8143

Abstract

An infrared sensor is a commonly used imaging device. Unmanned aerial vehicles, the most promising moving platform, each play a vital role in their own field, respectively. However, the two devices are seldom combined in automatic ground vehicle detection tasks. Therefore, how to [...] Read more.

An infrared sensor is a commonly used imaging device. Unmanned aerial vehicles, the most promising moving platform, each play a vital role in their own field, respectively. However, the two devices are seldom combined in automatic ground vehicle detection tasks. Therefore, how to make full use of them—especially in ground vehicle detection based on aerial imagery–has aroused wide academic concern. However, due to the aerial imagery’s low-resolution and the vehicle detection’s complexity, how to extract remarkable features and handle pose variations, view changes as well as surrounding radiation remains a challenge. In fact, these typical abstract features extracted by convolutional neural networks are more recognizable than the engineering features, and those complex conditions involved can be learned and memorized before. In this paper, a novel approach towards ground vehicle detection in aerial infrared images based on a convolutional neural network is proposed. The UAV and the infrared sensor used in this application are firstly introduced. Then, a novel aerial moving platform is built and an aerial infrared vehicle dataset is unprecedentedly constructed. We publicly release this dataset (NPU_CS_UAV_IR_DATA), which can be used for the following research in this field. Next, an end-to-end convolutional neural network is built. With large amounts of recognized features being iteratively learned, a real-time ground vehicle model is constructed. It has the unique ability to detect both the stationary vehicles and moving vehicles in real urban environments. We evaluate the proposed algorithm on some low–resolution aerial infrared images. Experiments on the NPU_CS_UAV_IR_DATA dataset demonstrate that the proposed method is effective and efficient to recognize the ground vehicles. Moreover it can accomplish the task in real-time while achieving superior performances in leak and false alarm ratio. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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18 pages, 7498 KiB

Open AccessArticle

Monocular Vision SLAM-Based UAV Autonomous Landing in Emergencies and Unknown Environments

by Tao Yang, Peiqi Li, Huiming Zhang, Jing Li and Zhi Li

Electronics 2018, 7(5), 73; https://doi.org/10.3390/electronics7050073 - 15 May 2018

Cited by 86 | Viewed by 13183

Abstract

With the popularization and wide application of drones in military and civilian fields, the safety of drones must be considered. At present, the failure and drop rates of drones are still much higher than those of manned aircraft. Therefore, it is imperative to [...] Read more.

With the popularization and wide application of drones in military and civilian fields, the safety of drones must be considered. At present, the failure and drop rates of drones are still much higher than those of manned aircraft. Therefore, it is imperative to improve the research on the safe landing and recovery of drones. However, most drone navigation methods rely on global positioning system (GPS) signals. When GPS signals are missing, these drones cannot land or recover properly. In fact, with the help of optical equipment and image recognition technology, the position and posture of the drone in three dimensions can be obtained, and the environment where the drone is located can be perceived. This paper proposes and implements a monocular vision-based drone autonomous landing system in emergencies and in unstructured environments. In this system, a novel map representation approach is proposed that combines three-dimensional features and a mid-pass filter to remove noise and construct a grid map with different heights. In addition, a region segmentation is presented to detect the edges of different-height grid areas for the sake of improving the speed and accuracy of the subsequent landing area selection. As a visual landing technology, this paper evaluates the proposed algorithm in two tasks: scene reconstruction integrity and landing location security. In these tasks, firstly, a drone scans the scene and acquires key frames in the monocular visual simultaneous localization and mapping (SLAM) system in order to estimate the pose of the drone and to create a three-dimensional point cloud map. Then, the filtered three-dimensional point cloud map is converted into a grid map. The grid map is further divided into different regions to select the appropriate landing zone. Thus, it can carry out autonomous route planning. Finally, when it stops upon the landing field, it will start the descent mode near the landing area. Experiments in multiple sets of real scenes show that the environmental awareness and the landing area selection have high robustness and real-time performance. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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