Prototype Unmanned Aerial Vehicle Research Articles

Long-Range 3D Reconstruction Based on Flexible Configuration Stereo Vision Using Multiple Aerial Robots

Aerial robots, or unmanned aerial vehicles (UAVs), are widely used in 3D reconstruction tasks employing a wide range of sensors. In this work, we explore the use of wide baseline and non-parallel stereo vision for fast and movement-efficient long-range 3D reconstruction with multiple aerial robots. Each viewpoint of the stereo vision system is distributed on separate aerial robots, facilitating the adjustment of various parameters, including baseline length, configuration axis, and inward yaw tilt angle. Additionally, multiple aerial robots with different sets of parameters can be used simultaneously, including the use of multiple baselines, which allows for 3D monitoring at various depth ranges simultaneously, and the combined use of horizontal and vertical stereo, which improves the quality and completeness of depth estimation. Depth estimation at a distance of up to 400 m with less than 10% error using only 10 m of active flight distance is demonstrated in the simulation. Additionally, estimation of a distance of up to 100 m with flight distance of up to 10 m on the vertical axis and horizontal axis is demonstrated in an outdoor mapping experiment using the developed prototype UAVs.

Computer simulation of the deformed state and strength of the frame structure of a heavy uav

COMPUTER SIMULATION OF THE DEFORMED STATE AND STRENGTH OF THE FRAME STRUCTURE OF A HEAVY UAV
 The paper is devoted to the presentation of the computer simulation results of the stress-strain state and evaluation of the low-cycle strength of the frame structure of a heavy unmanned aerial vehicle (UAV) of the quadcopter type, the prototype of which was developed at NTU "KhPI". The quadcopter is built on the basis of the use of four internal combustion engines (ICE), which provide lifting power. The cycle of calculations of the stress-strain state of the frame structure, carried out to select the option required from the point of view of ensuring the required stiffness and strength, was performed using the Finite Element Method (FEM). A macro has been developed for use in the engineering software, which allows you to select the best parameters from the point of view of the required stiffness and strength of the frame. The results of calculations of the variant implemented in the design of the created UAV prototype are presented. According to the results of the analysis of the stress-strain state, it is shown that the structural parameters chosen for the steel frame of the prototype fully satisfy the conditions of minimal deformation and short-term strength. The constants included in the evolution equation for the damage parameter describing low-cycle loading, which occurs during UAV abnormal landings, have been determined. An elastic-plastic analysis of the frame structure deformation for the conditions of dangerous landing of the quadcopter was performed. Calculations of hidden damage accumulation processes in the most heavily loaded frame beams have been carried out. For the steel frame implemented in the created prototype, the possibility of satisfactory resistance to low-cycle deformation under abnormal landing conditions is demonstrated. It is shown that due to the insufficient low-cycle strength of the aluminum alloy structure, it is necessary to make structural changes in the new version of the UAV frame that is being designed.
 Key words: computer simulation, quadcopter, macro, beam structure, stress-strain state, FEM, low-cycle strength, damage.

Air Pollution Monitoring in Remote Areas using Smart UAV based System

Real time monitoring of air pollution and measurement of pollutant gases is very challenging task and needs more numbers of sensors and lots of observation. In this paper, Unmanned Aerial Vehicle (UAV) based system equipped with different micro sensor, is introduced for monitoring of air quality. It will offer a new approach in environmental pollution assessment instead of ground based monitoring system. Air pollution concentration data is collected by different sensors present in UAV, are effectively monitored in personal computer or mobile devices. The main objective of this paper is to elaborate the performance capability of UAV for effective monitoring of air pollution and measure health hazard air pollutants with high sensitivities in a particular area where human cannot reach. As it is quite recent field, a fruitful effort has dedicated to develop an integrated sensing system and optimization of its crucial features as dimension, weight and energy autonomy. The effectiveness of the developed system is evaluated by performing some field experiments using a hardware prototype UAV model.

About revising the computational dynamic scheme of an unmanned aerial vehicle based on the results of ground-based modal test operations in the aeroelasticity problems

The problem of revising the computational dynamic scheme of an unmanned aerial vehicle (UAV), based on the results of ground-based modal test operations, in order to study the UAV flutter and to assess the aeroelastic stability of an UAV with an automatic control system (ACS), is considered. It is noted that at the design stage, when there is no UAV prototype or its units yet, the determination of modal characteristics, specifically natural frequencies, modes and generalized masses, is carried out using the computational dynamic scheme developed according to the design documentation. However, the similar computations, performed even with the use of modern finite-element software systems, do not give sufficiently precise values of the parameters of the UAV design elastic-mass schematization. In this regard, it is relevant and important to specify the parameters of the design schematization in conformity with data of ground test operations for UAV prototypes. The provisions, allowing us to achieve satisfactory results when revising the UAV computational dynamic scheme, are made. The criteria of revising are considered. The features of revising the computational dynamic scheme, while studying the flutter and aeroelastic stability of the ACS-fitted UAV, are presented. It is noted that along with the provisions that are universal for dynamic aeroelasticity problems, specifically for flutter, and related to compensating of natural frequencies, modes and coefficients of structural damping for the UAV model according to the results of ground modal tests. In the problems of aeroelastic stability study of the UAV equipped with the ACS, it is also crucial to correct the UAV body transfer function from the section, corresponding to the axis of controls rotation, to the section where ACS sensors are installed. This is because the UAV hull is an integral part of the UAV stabilization loop and significantly affects its stability margin. The example of revising the computational dynamic scheme of a maneuverable cruciform UAV is given.

Survey on Unmanned Aerial Vehicle for Mars Exploration: Deployment Use Case

In recent years, the area of Unmanned Aerial Vehicles (UAVs) has seen rapid growth. There has been a trend to build and produce UAVs that can carry out planetary exploration throughout the past decade. The technology of UAVs has tremendous potential to support various successful space mission solutions. In general, different techniques for observing space objects are available, such as telescopes, probes, and flying spacecraft, orbiters, landers, and rovers. However, a detailed analysis has been carried out due to the benefits of UAVs relative to other planetary exploration techniques. The deployment of UAVs to other solar bodies has been considered by numerous space agencies worldwide, including NASA. This article contributes to investigating the types of UAVs that have been considered for various planetary explorations. This study further investigates the behaviour of UAV prototypes on Mars’ surface in particular. It has been discovered that a prototype UAV flight on Mars has a higher chance of success. In this research, a prototype UAV has been successfully simulated to fly on Mars’ surface. This article discusses the opportunities, challenges, and future scope of deploying UAVs on Mars.

Swarm-based counter UAV defense system

Unmanned Aerial Vehicles (UAVs) have quickly become one of the promising Internet-of-Things (IoT) devices for smart cities. Thanks to their mobility, agility, and onboard sensors’ customizability, UAVs have already demonstrated immense potential for numerous commercial applications. The UAVs expansion will come at the price of a dense, high-speed and dynamic traffic prone to UAVs going rogue or deployed with malicious intent. Counter UAV systems (C-UAS) are thus required to ensure their operations are safe. Existing C-UAS, which for the majority come from the military domain, lack scalability or induce collateral damages. This paper proposes a C-UAS able to intercept and escort intruders. It relies on an autonomous defense UAV swarm, capable of self-organizing their defense formation and to intercept the malicious UAV. This fully localized and GPS-free approach follows a modular design regarding the defense phases and it uses a newly developed balanced clustering to realize the intercept- and capture-formation. The resulting networked defense UAV swarm is resilient to communication losses. Finally, a prototype UAV simulator has been implemented. Through extensive simulations, we demonstrate the feasibility and performance of our approach.

UAV prototype for localization and identification of radioactive contamination and emitters

The Dragon (Drone for RAdiation detection of Gammas and Neutrons) prototype aims at designing and developing an unmanned aerial vehicle (UAV) equipped with a detection system able to identify radioactive materials, spread over an area or located in a specific position. The system is focused on the localization of the unknown emitter and its subsequently identification. The proposed prototype is made up of two easily interchangeable detection systems, one will be used as a counter while the second will be aimed to perform goodresolution gamma spectroscopy. Both solutions have neutron gamma discrimination capability in order to be suitable for special nuclear materials (SNM) detection in gamma contamination background. The data acquisition module is made up of a compact digitizer board (RedPitaya, sampling rate of 125 MHz and 14 bits of resolution.), a mini computer (Raspberry, for example). This combination allows to install an embedded operating system (e.g. Linux) that can run the necessary software for the Data Acquisition (DAQ), like the ABCD distributed DAQ. Our contribution will be aimed to show a comprehensive characterization of the two detection systems, a medium size CLLB scintillation detector, and a large plastic scintillator, EJ-276, in order to assess their potential use in a UAV-based radiation monitoring system.

Cooling system design for the internal combustion engine of a BWB UAV prototype

The current study presents an analytical design methodology for a compact thermal management system (cooling system) of a high-power density internal combustion rotary engine. The engine is installed on a fixed wing, tactical Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) prototype that has been developed for the aerial delivery of cargo and lifesaving supplies. The design methodology is based mainly on a low-fidelity thermodynamic model and on high-fidelity Computational Fluid Dynamics (CFD) analyses. The results are validated against wind tunnel experiments for the cooling system of the engine. The overall methodology is divided into two distinct segments, the design of the heat exchanger (HEX) and the sizing of the cold-air inlet ducts. The low-fidelity thermodynamic model is based on 0D and 1D textbook methods and well-established formulae from the existing literature. The thermodynamic model is used for the calculation of the geometrical characteristics of the HEX. The high-fidelity CFD modeling is employed to yield a more detailed investigation of the flow field around the HEX and provide information about whether the airflow velocity requirements, for the 0D and 1D model, are met. Additionally, the detailed CFD computations assist the design of high-efficiency inlet ducts, in order to secure optimal airflow through the HEX and around the engine compartment. Using the proposed methodology, a functional HEX experimental prototype is designed and manufactured, as a proof of concept, in order to be thoroughly examined on a test rig in laboratory conditions. Multiple experiments are conducted in a variety of inlet temperatures and airflow velocities, for the validation and fine-tuning of the overall proposed design methodology. The study concludes with the final HEX design, as well as an analysis of its integration aspects on the tactical BWB UAV prototype.

Design of a tilting mechanism for a VTOL flying wing UAV

In this paper, the detailed design of a mechanism for the transition from vertical to horizontal flight of a Vertical Take-off and Landing (VTOL) fixed wing Unmanned Aerial Vehicle (UAV) is presented. The UAV, which is being developed in the framework of the MPU research project, under the designation MPU RX-4, is a lightweight, all electric driven UAV with a flying wing layout. The MPU RX-4 is capable of performing both conventional flight, like a regular fixed wing aerial vehicle, as well as vertical hovering, like a multicopter, adapting on different operational demands. To achieve that, the development of a robust transition procedure from one flight phase to the other is required. This procedure is based on mechanisms capable of altering the flying characteristics of the UAV. More specifically, these mechanisms should be designed in order to change the orientation of the thrust vectors from horizontal to vertical and vice versa. MPU RX-4 uses a configuration of three electric motors (two mounted on the canards, and one in the main body) in order to perform both flight phases. For the transition from the hovering phase to the level flight, the two frontal motors have to be tilted from the vertical position to the horizontal, and the rear motor to be nested in its proprietary position, using four external hatches. Two separate mechanisms are designed, one for the canards’ tilting movement and another one for the extension and retraction of the rear motor hatches. Finite Element Analysis is carried out for the structural sizing of the mechanism (i.e. internal loads, linkages cross-section, joints sizing). The aerodynamic loads, acting on the mechanisms, are derived from Computational Fluid Dynamics analysis performed for the various flight phases (hovering, level flight and transition) of the UAV. Finally, the designed mechanisms are presented as integrated parts of the prototype UAV.

Numerical analysis issues in the evaluation of the helicopter’s main rotor stability

The paper presents selected aspects of numerical analyses on the assessment of the helicopter’s main rotor operational stability, presents key issues for stability assessment, and discusses the application of the co-simulation methodology for helicopter’s main rotor exampled by a prototype unmanned aerial vehicle rotor. The presented approach enables the analysis and mapping of the rotor’s operation taking into account the effects of the aeroelasticity of the blade itself. The impact of wind on the tested structure is presented for two cases and thrust force for the cases of starting the rotor for front and crosswind was evaluated. The transition of the rotor between the idle and working revolutions at a small collective angle does not generate unstable states independently in the wind direction.

Response to comment on “Flying by the Sun only: The Solarcopter prototype”, Aerosp. Sci. Technol. 45 (2015) 209-214

The Solarcopter proof of concept demonstrated the world's first purely solar-powered rotary-wing aircraft to fly, highlighting the feasibility of powering a rotary-wing unmanned aerial vehicle (UAV) exclusively by solar power. Absolutely no form of energy storage was utilised on this UAV prototype in any way. The novelties of the presented prototype include the exclusion of energy storage, utilising the central surface area of a quadrotor setup to maximise solar panel performance, and employing an ultra-lightweight, rigid, space frame structure. These key factors enabled the thrust-to-weight ratio of the presented prototype to be substantially greater than unity making the concept capable of continuous flight beyond the ground effect, provided sufficient solar energy is available. The presented concept and design was successfully validated with flight tests conducted in real-world conditions. The calculations and conclusions presented in the comments regarding the flight capability of the Solarcopter are premised on use of the Medusa 4000 rather than the Turnigy 800 motor that was implemented on the Solarcopter prototype. It is therefore unsurprising that the authors of the comments were unable to replicate the results presented for the Solarcopter.

A short bibliographic report on Small UAV design

This article presents a detailed example for the design of all aspects of a prototype unmanned aerial vehicle, also dealing with the use of multi-segmented flight control surfaces of these UAV’s wings. Adding multiple segments to the UAV wings creates smaller control surfaces. By introducing smaller control surfaces, a wing can make refined adjustments to UAV’s performance while airborne. This unique technique brings several benefits, as follows: applying localized correcting forces to the UAV reduces structural deformation, minimizes the drag action due to the control surface actuation, suppresses and controls the structural resonance due to lift forces and vibrational modes, reduces the weight of the structure, and improves the endurance of flight by using the solar cell. This study is a part of a more comprehensive work for my Ph.D. thesis which proposes the construction of a UAV prototype equipped with a solar propulsion system. This system meets the requirements of missions specific to the Ministry of Internal Affairs: both the autonomy capabilities and the performance of the communication systems on and off the ground.

Control of Hybrid Unmanned Aerial Vehicle Motion in Transitional Modes

Results of investigations of the flight control system for a hybrid unmanned aerial vehicle prototype in transitional modes are presented. The hybrid vehicle is equipped with a quadrotor and main propulsion units. The control system developed in the study includes subsystems for attitude stabilization, vertical take-off, hovering, and landing, as well as a control subsystem operating in transitional modes from quadrotor to aircraft modes and back.

Developing a Modular Unmanned Aerial Vehicle (UAV) Platform for Air Pollution Profiling.

The unmanned aerial vehicle (UAV) offers great potential for collecting air quality data with high spatial and temporal resolutions. The objective of this study is to design and develop a modular UAV-based platform capable of real-time monitoring of multiple air pollutants. The system comprises five modules: the UAV, the ground station, the sensors, the data acquisition (DA) module, and the data fusion (DF) module. The hardware was constructed with off-the-shelf consumer parts and the open source software Ardupilot was used for flight control and data fusion. The prototype UAV system was tested in representative settings. Results show that this UAV platform can fly on pre-determined pathways with adequate flight time for various data collection missions. The system simultaneously collects air quality and high precision X-Y-Z data and integrates and visualizes them in a real-time manner. While the system can accommodate multiple gas sensors, UAV operations may electronically interfere with the performance of chemical-resistant sensors. Our prototype and experiments prove the feasibility of the system and show that it features a stable and high precision spatial-temporal platform for air sample collection. Future work should be focused on gas sensor development, plug-and-play interfaces, impacts of rotor wash, and all-weather designs.

Design of a Low-Cost Fixed Wing UAV

This research will try to design a low cost of fixed-wing unmanned aerial vehicle (UAV) using low-cost material that able to fly autonomously. Six parameters of UAV’s structure will be optimized based on basic airframe configuration, wing configuration, straight wing, tail configuration, fuselage material, and propeller location. The resulted and manufactured prototype of fixed-wing UAV will be tested in autonomous fight tests. Based on the flight test, the developed UAV can successfully fly autonomously following the trajectory command. The result shows that low-cost material can be used as a body part of fixed-wing UAV.

PENGEMBANGAN SISTEM PENYEMPROTAN PADA PLATFORM PESAWAT TANPA AWAK BERBASIS QUADCOPTER UNTUK MEMBANTU PETANI MENGURANGI BIAYA PERTANIAN DALAM MENDORONG KONSEP PERTANIAN PINTAR (SMART FARMING)

This study aims to develop the technology of unmanned aircraft for agricultural purposes in realizing the food security of Indonesia. One of the main problems of agriculture in Indonesia is the high cost of agriculture especially the use of chemicals, fertilizer to labor. During this time farmers spend resources such as fertilizer to all plants without the required portion. So it should be attempted an engineering that can reduce the cost of agriculture in terms of labor usage for fertilizing activities and spraying of pests are relatively expensive. The method that will be used for the problem is to make a prototype of pest spraying system by using liquid media on platform unmanned Aerial Vehicle (UAV) with quadcopter base. Stages in this research include: desk assessment, making of design requirement objective, conceptual making and basic design and making real prototype UAV. The performance of the spraying results is done flight stability test and pest spraying performance. The test results show that the prototype UAV platform using 0.5 litres liquid media, capable of spraying an area of 2 m2 with a flying time of 10 minutes with a height of 70 cm from the ground. The results of this test will be developed further to be made a larger platform dimensions and capability of transport.

Pengembangan Sistem Penyemprotan pada Platform Pesawat Tanpa Awak Berbasis Quadcoper untuk Membantu Petani Mengurangi Biaya Pertanian dalam Mendorong Konsep Pertanian Pintar (Smart Farming)

This study aims to develop the technology of unmanned aircraft for agricultural purposes in realizing the food security of Indonesia. One of the main problems of agriculture in Indonesia is the high cost of agriculture especially the use of chemicals, fertilizer to labor. During this time farmers spend resources such as fertilizer to all plants without the required portion. So it should be attempted an engineering that can reduce the cost of agriculture in terms of labor usage for fertilizing activities and spraying of pests are relatively expensive. The method that will be used for the problem is to make a prototype of pest spraying system by using liquid media on plaform unmanned Aerial Vehicle (UAV) with quadcopter base. Stages in this research include: desk assessment, making of design requirement objective, conceptual making and basic design and making real protoripe UAV. Meanwhile, to know the performance performance of the spraying results is done flight stability test and pest spraying performance . The test results show that with prototype UAV platform using 0.5 Litre liquid media, capable of spraying an area of 2 m2 with a flying time of 10 minutes with a height of 70 cm from the ground. The results of this test will be developed further to be made a larger platform dimensions and capability of transport.

Comparison of GA and PSO approaches for the direct and LQR tuning of a multirotor PD controller

In the present paper different approaches for flight control stabilization tuning of a prototype of Unmanned Aerial Vehicle (UAV) are investigated. The mathematical model of a multirotor airframe is presented and its dynamical system is described by means of Newton-Euler equations for a rigid body. The proposed controller systems for the stabilization of the altitude and the attitude of the multirotor around its hovering configuration are based on Proportional Derivative (PD) regulator tuned by optimization techniques such as Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) or, for the linearized system, by means of Linear Quadratic Regulator (LQR). In this case, PSO and GA are applied to set entries of LQR scheme. Control flight simulation results have been compared in terms of minimization of work carried out by the control actions. Performed simulations pointed out that all approaches lead to zero the error of the position along gravity acceleration direction, stop the rotation of UAV around body axes and stabilize the multirotor. The direct PSO tuning of the PD parameters (PD-PSO) shows better results in terms of errors, performance and speed of convergence.

Reactive Collision Avoidance of UAVs with Simple Pin-hole Camera Based Passive Stereovision Sensing

An effective reactive collision avoidance algorithm is presented in this paper for unmanned aerial vehicles (UAVs) using two simple inexpensive pinhole cameras. The vision sensed data, which consists of the azimuth and elevation angles at the two camera positions, is first processed through a Kalman filter formulation to estimate the position and velocity of the obstacle. Once the obstacle position is estimated, the collision cone philosophy is used to predict the collision over a short period of time. In case a collision is predicted, steering guidance commands are issued to the vehicle to steer its velocity vector away using the nonlinear differential geometric guidance. A new cubic spline based post-avoidance merging algorithm is also presented so that the vehicle rejoins the intended global path quickly in a smooth manner after avoiding the obstacle. The overall algorithm has been validated using the point mass model of a prototype UAV with first-order autopilot delay. Both extended Kalman filtering (EKF) and unscented Kalman filtering (UKF) have been experimented. Both are found to be quite effective. However, performance of UKF was found to be better than EKF with minor compromise in computational efficiency and hence it can be a better choice. Note that because of two cameras, stereovision signature gets associated with optical flow signature thereby making the overall signature quite strong for obstacle position estimation. This leads to a good amount of success as compared to the usage of a single pinhole camera, results of which has been published earlier.

Needs and potential of unmanned vehicles in sewers

Sewer systems are complex and large structures located under the ground. Their good functioning is a strategic issue which requires regular inspections and maintenance operations. These interventions involve important risks and constraints regarding health and security of operators as well as accessibility to structures and cost of these operations. In this context, unmanned vehicles offer new opportunities to reduce or simplify human interventions in the sewers. As an example, Suez Water Spain has developed a first prototype of unmanned aerial vehicle dedicated to inspection of underground retention tanks and big sewer pipes. The information collected by the drone are automatically integrated into the information system and the decision-making process. Even if the first tests performed with this drone have been successful, there are still a number of pending technological issues that needs to be solved for operational use: positioning, data transmission, trajectory, etc.