Multirotor Drones Research Articles

Evaluation of Selected Algorithms for Air Pollution Source Localisation Using Drones

Polluted air causes enormous damage to human health. There is a high demand to find a solution for locating the places of illegal waste incineration due to the persistent smog problem. The use of multi-rotor drones for that purpose has now become one of the important research topics. The aim of the work was to check the possibility of using simple algorithms to search for the source of pollution. The algorithms that require low computing power, which may be part of the robot’s measurement and the control system’s internal software, were considered. The focus was on building a system based on a single robot that independently searches an area of a certain size. The simulation of the accuracy and scalability of the three different search algorithms was analysed for areas up to 200 m × 200 m. Two multi-rotor robots were prepared for the fieldwork. The validation of the two selected algorithms was carried out in outdoor environmental conditions. The fieldwork tests were carried out in areas with a maximum size of 100 m × 100 m. The obtained results were different, in particular on the wind speed and direction and the intensity of the pollution source. The random influence of these factors can verify the operation of the proposed system in practical applications. The difference between the true and the position of the source indicated by the robot was up to 15 m. That difference depended on the mutual arrangement of the measurement points and the pollution source location.

Detecting spider monkeys from the sky using a high-definition RGB camera: a rapid-assessment survey method?

Commercial, off-the-shelf, multirotor drones are increasingly employed to survey wildlife due to their relative ease of use and ability to cover areas quicker than traditional methods. Such drones fitted with high-resolution visual spectrum (RGB) cameras are an appealing tool for wildlife biologists. However, evaluations of the application of drones with RGB cameras for monitoring large-bodied arboreal mammals are largely lacking. We aimed to assess whether Geoffroy’s spider monkeys (Ateles geoffroyi) could be detected in RGB videos collected by drones in tropical forests. We performed 77 pre-programmed grid flights with a DJI Mavic 2 Pro drone at a height of 10 m above the maximum canopy height covering 45% of a 1-hectare polygon per flight. We flew the drone directly over spider monkeys who had just been sighted from the ground, detecting monkeys in 85% of 20 detection test flights. Monkeys were detected in 17% of 18 trial flights over areas of known high relative abundance. We never detected monkeys in 39 trial flights over areas of known low relative abundance. Proportion of spider monkey detections during drone flights was lower than other commonly employed survey methods. Agreement between video-coders was high. Overall, our results suggest that with some changes in our research design, multirotor drones with RGB cameras might be a viable survey method to determine spider monkey presence in closed-canopy forest, although its applicability for rapid assessments of arboreal mammal species′ distributions seems currently unfeasible. We provide recommendations to improve survey design using drones to monitor arboreal mammal populations.

DESIGN OF UAV CONTROL SYSTEM WITH FUZZY LOGIC CONTROLLER AND ITS IMPORTANCE IN THE ECONOMY

This article presents a model of the control system of a multi-rotor Unmanned aerial vehicle (uav) using Fuzzy logic controller. During the execution of the work, the Simulink environment of the MATLAB software system was used as a tool. As it is known, multi-rotor drones have a clear place in the modern world and are used in almost all areas of the economy, that is why a designed control system is a necessity. During the work, membership functions were calculated and defined, the adjustment of which was made by means of an automatic adjustment tool created in the form of a graphical interface, which selects independent values in the defined range, giving the Fuzzy inference system as an input. Mamdani fuzzy method (if and then) was selected as Fuzzy logic algorithm. At the end of the article, the results obtained from the designed graphic interface and control system are presented.

ECONOMIC SIGNIFICANCE AND EFFICIENCY OF CONTROL SYSTEM DESIGN OF MULTIROTOR UAV BY USING PYTHON OPENCV

This article presents the implementation of a control system for a multirotor unmanned aerial vehicle with a controller and an object recognition system based on Python programming language. The DJI Tello drone was used as the main drone to get accurate real-world values and see the operation behavior in practice. Multirotor drones are an integral part of the development of the modern world. This article presents a control model for an unmanned aerial vehicle using the Python programming language, which is based on object recognition using the OpenCV library and, based on the results, determining the trajectory of the quadrupole by the system itself. The work was carried out in accordance with the parameters of the DJI TELLO drone and the efficient operation of the algorithm in real conditions was demonstrated. To get the direction and speed of a multi-rotor unmanned aerial vehicle, in our case a four-rotor, 3 parameters are checked: roll, pitch, yaw, the latter is controlled using a comparative, integratordifferentiating controller.

Investigation of future applications of self-engineering using drones

Self-engineering (SE) systems aim to autonomously respond to a loss of function and take action to return functionality. Recently there have been a number of demonstrations of SE using multi-rotor drones to inspect and repair systems (such as repairing potholes), though many of these systems do not meet all the requirements of a SE system. This research identifies and explores new ideas for SE where drones could be utilised. Five ideas were successfully identified from consultations with experts and authors. The five ideas created are: 1) self-repair in enclosed spaces of ships, 2) self-cleaning roads, 3) self-repairing air conditioning systems, 4) autonomous underwater pipe repair, and 5) self-repair of damaged building cladding. Possible inspection and repair actions that a drone could perform are identified for each proposed system. From a short industry survey and further interviews, idea 1) (self-repair in enclosed spaces) was identified as the most promising for future development. The potential cost of building the system is discussed at the end of the paper; however, detailed cost estimation is too uncertain because of the difficulty in estimating the cost of developing autonomous capabilities.

Simulation-based Long-range Flight Performance Evaluation of an Unmanned Aerial Vehicle (UAV)

As Unmanned Aerial Vehicles (UAV) which can fly only by controlling the rotor thrust are expected to be used in various fields in the future, so the demand for long-range flight is expected to increase. For instance, it is an effective application that UAVs is used to inspect offshore wind power generations but wind, flight paths or navigations affect flight efficiency and flyable range when operating in a real environment. It is useful for optimizing flight performance to use simulations in various cases before flying there to obtain parameters. Therefore, this study constructs an aircraft model and flight environment that are close to an actual environment and perform simulations in some simple cases. In the future, the parameters will be applied to multi-rotor drones or vertical take-off and landing aircrafts (VTOL) and inspect offshore wind power generations using them. The report explain research into the development of a simulation using MATLAB/Simulink that considering wind effects and the flight evaluation of long-range flight.

Computational studies of the rotors aerodynamic characteristics of multirotor drones

The article presents the results of computational studies of aerodynamic characteristics for unmanned lift-generating multi-rotor drones of various configurations. The distinctive features of rotors flow were characterized. The rotor interaction was evaluated. The computations were based on the nonlinear rotor blade vortex theory in a non-stationary arrangement. The combinations of four, eight (four coaxial) and fourteen two-bladed rotors at velocity V = 100, 150, 200 km/h were considered. Semi-empirical methods were employed to select the rotor angles of attack, rotation speed, blade installation angles and geometric parameters at the given take-off weight for each combination of rotors and flight airspeed. The computations showed that for a four-rotor lift-generating design (quad-rotor), two rotors installed downstream, depending on the velocity due to the mutual effect, have values of the thrust coefficients ≈10...20% less than those of the rotors located upstream. For a coaxial quad-copter, the effect of the upper front rotor on the upper rear rotor is similar to the effect of the front rotors on the rear ones in a four-rotor lift-generating design. The effect of the upper front rotor on the lower rear rotor does not vary in terms of the average thrust value, and variations are only local in nature. The interaction of other rotors is identical to that of the four-rotor version. A fourteen-rotor lift-generating multi-rotor drone has a complex flow pattern, which generates deviance in the thrust coefficients variation with respect to time. Depending on the mode and rotors location, the average rotor thrust coefficient can vary approximately twice. The computations showed that with the similar geometric parameters and kinematics characteristics, rotors thrust is substantially subject to variation, which causes destabilizing moments to a significant degree without additional control input. Thrust pulsations and, respectively, vibrations grow in intensity as the flight airspeed increases. Probably, the right choice of the rotor configuration and the automatic control system can counterbalance thrust surge by so-called "phasing", i.e. selecting an initial azimuth angle for each rotor.

Image processing based autonomous landing zone detection for a multi-rotor drone in emergency situations

Flight safety and reliability improvement is an important research issue in aerial applications. Multi-rotor drones are vulnerable to motor failures leading to potentially unsafe operations or collisions. Therefore, researchers are working on autonomous landing systems to safely recover and land the faulty drone in on a desired landing area. In such a case, a suitable landing zone should be detected rapidly in for emergency landing. Majority of the works related with autonomous landing utilize a marker and GPS signals to detect landing site. In this work, we propose a landing system framework that involves only the processing of images taken from the onboard camera of the vehicle. First, the objects in the image are determined by filtering and edge detection algorithm, then the most suitable landing zone is searched. The area that is free from obstacles and closest to the center of the image is defined as the most immediate and suitable landing zone. The method has been tested on 25 images taken from different heights and its performance has been evaluated in terms runtime on a single board computer and detection precision and recall values. The average measured runtime is 2.4923 seconds and 100% of precision and recall values are achieved for the images taken from 1m and 2m. The smallest precision and recall values are 79.1% and 81.2%, respectively.

Power Line Charging Mechanism for Drones

The use of multirotor drones has increased dramatically in the last decade. These days, quadcopters and Vertical Takeoff and Landing (VTOL) drones can be found in many applications such as search and rescue, inspection, commercial photography, intelligence, sports, and recreation. One of the major drawbacks of electric multirotor drones is their limited flight time. Commercial drones commonly have about 20–40 min of flight time. The short flight time limits the overall usability of drones in homeland security applications where long-duration performance is required. In this paper, we present a new concept of a “power-line-charging drone”, the idea being to equip existing drones with a robotic mechanism and an onboard charger in order to allow them to land safely on power lines and then charge from the existing 100–250 V AC (50–60 Hz). This research presents several possible conceptual models for power line charging. All suggested solutions were constructed and submitted to a field experiment. Finally, the paper focuses on the optimal solution and presents the performance and possible future development of such power-line-charging drones.

Fanwing Aircraft- Scope as an Agricultural Aircraft

The objective of this paper is to apply the concept of fan wing to agricultural aircrafts which are conventionally fixed wings aircrafts or multi-rotor drones. Fan wing is capable of producing good amount of lift at a sufficiently low speed without stalling, thus is apt for agricultural processes of irrigation, spraying pesticides, etc. Fan wing has a special ability that it doesn’t stalls (for the practical range of AOA), making this spraying method reliable. A fanwing aircraft is modelled using CATIA V5 and the flow visualizations for the same are performed on the ANSYS. This aircraft is then compared with three different existing agricultural aircrafts on different parameters, namely payload capacity, work efficiency and ease of operation. The comparison shows that such fanwing vehicle is a good substitute over the conventional fixed wings and multi-rotor drones.

3D path planning and real-time collision resolution of multirotor drone operations in complex urban low-altitude airspace

Drones have been greatly developed to facilitate the progress of various industries. The safe operation of drones in the urban airspace is critical to ensure a reliable and high-efficient urban air traffic system. This work presents a fusion scheme to achieve autonomous drone collision-free path planning considering static obstacles and dynamic threats detected. Firstly, a 3D voxel jump point search (JPS) based path planning model is developed to generate the static collision-free reference path. With the optimization, the reference path is then de-diagonalized, reconstructed, and smoothed to obtain the desired path. Subsequently, a local collision resolution method is proposed to avoid near mid-air collision of the dynamic threats. The method is based on the Markov decision process (MDP) to implement real-time dynamic collision avoidance. Simulations are conducted to verify the performance of the proposed model. The simulation results demonstrate that the proposed model is effective to achieve the autonomous path planning and real-time collision resolution of multirotor drones.

Drone use to combat COVID-19: Adaptive tuning proposal of the control system under variable load

The spread of COVID-19 is rapidly increasing, and the fight against it is a priority globally. Multirotor drones can be utilized in fighting the pandemic by disinfecting the environment using sanitizers, thus, reducing the risk of contamination. Propellers are used to control the flight behavior of multirotor drones, but it is challenging to control propellers under conditions subjected to variable loads, such as the spraying of sanitizers. In this study, a prototype quadrotor was developed to collect flight data under loading conditions. We used white-box mathematical models of the quadrotor, considering the physical quantities and black-box mathematical models, to identify practical data models. The proportional-integral-derivative control system was applied, in addition to particularizing the system tuning using the ZieglerNichols (ZN) theory applied to the quadrotor. The results of the ZN theory applied to the quadrotor with and without load and those applied to the quadrotor with variable load were validated. It was found that the performance improved by up to 75%. The developed quadrotor with improved tuning sanitizing drone controllers can be used in the fight against COVID-19, achieving ease of implementation and low cost.

A Particle Filtering Approach for Fault Detection and Isolation of UAV IMU Sensors: Design, Implementation and Sensitivity Analysis.

Sensor fault detection and isolation (SFDI) is a fundamental topic in unmanned aerial vehicle (UAV) development, where attitude estimation plays a key role in flight control systems and its accuracy is crucial for UAV reliability. In commercial drones with low maximum take-off weights, typical redundant architectures, based on triplex, can represent a strong limitation in UAV payload capabilities. This paper proposes an FDI algorithm for low-cost multi-rotor drones equipped with duplex sensor architecture. Here, attitude estimation involves two 9-DoF inertial measurement units (IMUs) including 3-axis accelerometers, gyroscopes and magnetometers. The SFDI algorithm is based on a particle filter approach to promptly detect and isolate IMU faulted sensors. The algorithm has been implemented on a low-cost embedded platform based on a Raspberry Pi board. Its effectiveness and robustness were proved through experimental tests involving realistic faults on a real tri-rotor aircraft. A sensitivity analysis was carried out on the main algorithm parameters in order to find a trade-off between performance, computational burden and reliability.

Attitude Stabilization of Quadrotor Using Adaptive Fuzzy Proportional Integral Derivative Controller

Quadrotor is an unmanned aerial robot from multi-rotor drones group that has high maneuverability, vertical take-off, and landing and stationary flight capabilities. In the most practical applications, the quadrotor system is subjected to external disturbance forces due to wind and unbalanced weight or inertia of the payload. To maintain balance and hold the position, attitude stabilization of the quadrotor is necessary for the presence of disturbances and unbalanced forces. Using conventional controllers with constant gains is not very efficient to eliminate variable disturbances that affect quadrotor motion in different conditions. In this paper, an adaptive fuzzy proportional integral derivative controller is designed for quadrotor attitude stabilization in which controller gains are regulated continuously based on the adaptive laws and the fuzzy inference system. The performance of the proposed controller is examined in the disturbance rejection test and is compared to the conventional proportional integral derivative controller. Also, the performance of the proposed controller is approved by hardware in the loop experimental tests using a 3 degree of freedom pilot platform. The experimental results will show the effectiveness of the adaptive fuzzy proportional integral derivative controller compared with the conventional proportional integral derivative controller.

Sensitivity Study of Design Parameters for a Fuel Cell Powered Multirotor Drone

The use of multirotor drones for industrial applications is accelerating, and fuel cell based propulsion systems are highlighted as a promising approach to improve endurance – one of the current main limitations. Due to multirotor drones’ unique requirements, careful system design is needed to maximize the performance advantage. In this work a sensitivity analysis that quantifies the impact of central system parameters for an X8 multirotor drone with a 2 kW fuel cell hybrid system is presented and discussed. Thrust stand measurements identified a 20–30% efficiency loss from the coaxial configuration, and a ‘single’ configuration can reduce power consumption by 700 W at 25 kg take-off mass. Thus, a smaller fuel cell system can be used, giving an additional 1 kg mass saving and 75–140 W power reduction. Peak endurance is found at a 0.67 energy system weight fraction, and if batteries are improved from 180 Wh/kg to 350 Wh/kg, the energy system mass threshold from where fuel cells are superior rises from 7.4 kg to 8.5 kg. At 700 bar, a 3 L hydrogen cylinder can replace a 6 L at 300 bar, provide a 72-min endurance, and is the preferred option to reach minimum system volume. This work provides guidance in early conceptual stages and insights on how fuel cell based powerplants for multirotors can be improved and optimized to increase their value proposition. Further research can expand the work to cover other system variations and do experimental testing of system performance.

VAGADRONE: Intelligent and Fully Automatic Drone Based on Raspberry Pi and Android

Multirotor drones are widely used currently in several areas of life. Their suitable size and the tasks that they can perform are their main advantages. However, to the best of our knowledge, they must be controlled via remote control to fly from one point to another, and they can only be used for a specific mission (tracking, searching, computing, and so on). In this paper, we intend to present an autonomous UAV based on Raspberry Pi and Android. Android offers a wide range of applications for direct use by the UAV depending on the context of the assigned mission. The applications cover a large number of areas such as object identification, facial recognition, and counting objects such as panels, people, and so on. In addition, the proposed UAV calculates optimal trajectories, provides autonomous navigation without external control, detects obstacles, and ensures live streaming during the mission. Experiments are carried out to test the above-mentioned criteria.

Analysis and Management of Motor Failures of Hexacopter in Hover

This research presents an analysis and management strategy for hovering hexacopter with one or more failing motors. Of late, multirotor drones have become particularly popular, and all drones have been increasing in popularity. Unlike a fixed-wing drone, failure of motors in a multirotor craft may cause safety problems. Numerous published articles have proposed solving this problem by redesigning the control law or control gain. This approach, however, is difficult to implement because change of control gain usually involves connecting external devices. This paper proposes to keep the control gain unchanged but reallocate the thrusts. Simulations are conducted on a hexacopter in various hovering modes. Some hovering state problems are investigated for the linearized dynamics but also numerically verified for the original nonlinear dynamics. In case some motors of a hexacopter fail in flight, an allocation matrix is proposed to redistribute required thrusts to functional motors. Seven cases of motor failure are studied. This paper analytically proves that limited controllability for emergency landing is feasible in four scenarios at the linear level, but the other three scenarios are completely uncontrollable. Numerical simulations are presented to demonstrate the validity of our algorithm. An online video of real flight also confirms our results. This paper potentially helps the design of failure management of rotors and increases the successful rate of emergent landing.

Effects of High Fidelity Modeling of Multirotor Drones

Abstract This paper examines two different factors that will affect energy consumption for multi-rotor drones with more than four rotors. First, the choice of aerodynamic model for the rotor blades is examined. Two aerodynamic models, the blade element theory (BET) model and lumped blade (LB) model, are compared using vertical, roll, pitch, and yaw trajectories. The BET and LB models produced very different trajectories with identical inputs, especially in the vertical and yaw trajectories which differed by 87.9% and 52.5%, respectively. The BET and LB models also result in different energy usages with the LB model consistently predicting 36% more energy consumption. The second factor studied is the choice of rotor groupings. For a multi-rotor drone, different rotor groupings may result in different energy usages; two groupings are considered. The same four basic trajectories are compared. The results show that the two groupings have an energy difference of 4.7–4.9% for each of the roll, pitch, and yaw directions which implies that each grouping has a base energy consumption inherent to it. Then, possible energy compounding effects are explored by examining a complex trajectory. The complex trajectory yields a 9.26% energy difference between the two groupings but further examination reveals that the difference is due to differences in the final trajectory not energy compounding effects. Thus, it is concluded that the aerodynamic model and rotor groupings are two important factors that must be considered when energy consumption needs to be minimized.

Experimental System for Charging and Testing Batteries Specific to Multirotor Drones

The experimental stand created is made for charging, testing and monitoring the processes that take place at a drone, in a static and also dynamic manner. On this platform we have developed, created and tested various kinds of sensors, and charging methods, rechargeable batteries, multicopper drones, automatically without disconnecting or disassembling them from the drones they serve. Also, at this level we fitted a flat zone, that is polarized where the drone will land, in a controlled manner and after a preliminary testing of polarity and of tension level, the charging will begin, as its parameters will carefully monitored.

A review on control and maneuvering of cooperative fixed-wing drones

This paper presents a literature review on current studies in cooperative control of fixed-wing drones, including maneuvering through adjustments of the tail, rotor, and wing configurations. Cooperative fixed-wing drones are important because of their larger area coverage that allows them to complete the assigned task much faster compared to a single fixed-wing drone. In addition, the endurance of cooperative fixed-wing drones is much higher compared to the endurance of cooperative multi-rotor drones. The papers presented in this review were selected to have as wide a variety as possible in terms of cooperation architectures and strategies, as well as in terms of wing, tail, and rotor configurations. With the rapid advancement of computers, sensors, and actuators which are major components of drones in general, the advancement of fixed-wing drone technology is a logical consequence. And further, this can lead to the advancement of cooperative fixed wing drone which have a much bigger capability compared to a single UAV.