Model Of UAV Research Articles

Hopf Bifurcation for UAV Path Planning in Autonomous Surveillance and Landing on an UGV

A novel path planning approach based on the bifurcation theory is proposed for a quadrotor UAV to track a ground vehicle in motion. For this purpose, a brief description of the mathematical model of the quadrotor UAV and the ground vehicle is presented, and the Hopf bifurcation method around a mobile balance point is used to design the path planning for a quadrotor UAV, and autonomously it generates a circular surveillance relative to a moving ground vehicle. The stability analysis based on Lyapunov theory is presented in order to demonstrate that the trajectory satisfies the bifurcation properties. Simulation and experimental tests are carried out to validate the proposed approach.

Mapping spatially explicit vegetation gaps in Florida rosemary scrub using unmanned aerial vehicles

AbstractAdvances in remote sensing technologies offer new means to monitor habitats of importance on large scales. Florida rosemary scrub is one such threatened habitat, found in patches across the landscape in relatively elevated areas, and is often characterized by shrub‐less areas (gaps) among the dominant shrubs, which provide favorable microhabitats for many endemic and endangered plants and animals. However, gaps are difficult and time‐consuming to characterize, especially across large areas, using traditional ground‐based field methods. We developed and tested a method for rapidly classifying gaps using an unmanned aerial vehicle (UAV or drone). Aerial data were collected by a UAV‐mounted camera in April 2018, and stratified, random ground surveys to verify UAV data were conducted March through April 2018 at Archbold Biological Station in south‐central Florida, USA. We used mosaicked and georeferenced digital surface and terrain models to calculate vegetation height across 33 rosemary scrub sites (~230,000 m2 at 0.064 m2 pixel resolution). Gaps were defined as >1 m2 areas where vegetation height was <10 cm. We found that gap areas from UAV models and field surveys were significantly correlated across varying gap sizes, times‐since‐fire, and relative elevations. We also observed a significant decrease in mean gap area and percent gap space with increasing time‐since‐fire, a pattern consistent with smaller‐scale, ground‐based sampling, and a marginally significant increase in gap area with relative elevation. This remote sensing method lends itself to better exploration of how gap areas, their spatiotemporal patterns, and associated fire history, elevation, soil, and other geographic data affect structural vegetation dynamics across the landscape. This study illustrates the success of UAV modeling of gap space in Florida rosemary scrub, a result of regional consequence for the southeastern United States, but more broadly, it encourages the use of UAV technology as a tool to enhance traditional field‐based methods in systems globally. As habitat fragmentation and loss become increasingly problematic for the conservation of threatened habitats, understanding these complex spatial dynamics is crucial to the conservation and management of vegetation communities and their biodiversity.

Cooperative Jamming of Multi UAVs to Netted Radar

This paper analyzes the cooperative jamming problem of multi UAVs to netted radar, controls the given constraints, adopts the optimal control algorithm to analyze the movement law of UAVs in layers. Based on the single UAV track model, the cooperative jamming track model of multiple UAVs is established, and the optimal UAV track number and the number of false target tracks are calculated, The movement law of UAV track and false target track is analyzed. Firstly, according to the range deception principle of cooperative jamming of UAV to netted radar, the kinematics model of single UAV is established, and the motion parameters of false target point and UAV are obtained; on the basis of single UAV, the motion model of multiple UAVs Cooperative jamming netted radar is established, and the motion parameters of false target point and UAV are also determined. Since multiple UAVs need to meet the “homology test” of Netted Radars, it is necessary to select the optimal control algorithm to optimize the control of multiple UAVs to obtain the optimized UAV and false target track, so as to achieve the purpose of cooperative jamming. Then, according to the optimal trajectory of UAV, the change of speed is determined, and the number of UAVs is determined by selecting the number of time points of UAV moving in a straight line with uniform speed by optimizing the value of speed. In this paper, by layering the tracks of potential false targets, several reasonable tracks which are most likely to exist are selected, and then the tracks and motion laws of the other two UAVs are determined by the linear equation between these track points and the other two radars which determine the track points, flight altitude and flight speed.

Energy-efficient decentralized navigation of a team of solar-powered UAVs for collaborative eavesdropping on a mobile ground target in urban environments

This paper considers using a team of solar-powered UAVs to collaboratively eavesdrop on a mobile ground target in an urban environment. A practical application is that the police department uses UAVs to collect the transmitted data from a criminal suspect so that the transmitted content can be understood. Using UAVs in this task is a much more cost-effective and also less suspicious option than the conventional surveillance by a police helicopter. We focus on the online and decentralized path planning for the solar-powered UAV team. We formulate a multi-objective optimization problem which forces the UAVs to complete the uninterrupted eavesdropping task, not enter any No-fly space (NFS), keep a safe distance from each other and harvest as much energy as possible. We propose a Rapidly-exploring Random Tree (RRT) based path planning method, consisting of an initial planning phase and an online planning phase. In the online planning phase, each UAV plans its own path based on the shared information across the team. Since the UAV model can be taken into account in the planning phase, the obtained UAV paths are feasible without any later adjustment. More importantly, this method is easily implementable in real-time.

Mathematical modeling and fault tolerant control of uav with wing layout

As the flying wing layout unmanned aerial vehicle (uav) extensive research and task environment increasingly complex, Yu Feiyi layout unmanned aerial vehicle (uav) for fault tolerant control gradually become the main technical means of the flight control, according to the established mathematical model of the flying wing layout of unmanned aerial vehicle (uav) set the actuator failure effect, with adaptive fault-tolerant algorithm, is given for unmanned aerial vehicle (uav) horizontal lateral movement in the MATLAB/simulink, realize the rapid and stable, the control command and response to complete the fault-tolerant control of flying wing uavs.

An unsupervised learning neural network for planning UAV full-area reconnaissance path

To plan a UAV's full-area reconnaissance path under uncertain information conditions, an unsupervised learning neural network based on the genetic algorithm is proposed. Firstly, the environment model, the UAV model and evaluation indexes are presented, and the neural network model for planning the UAV's full-area reconnaissance path is established. Because it is difficult to obtain the training samples for planning the UAV's full-area reconnaissance path, the genetic algorithm is used to optimize the unsupervised learning neural network parameters. Compared with the traditional methods, the evaluation indexes constructed in this paper do not need to specify UAV maneuver rules. The offline learning method proposed in the paper has excellent transfer performances. The simulation results show that the UAV based on the unsupervised learning neural network can plan effective full-area reconnaissance paths in the unknown environments and complete full-area reconnaissance missions.

Design of UAV yaw Angle controller based on variable domain fuzzy PID

Four-rotor UAV is widely used in reconnaissance missions, UAV usually needs to adjust the yaw angle before reconnaissance aerial photography. To improve the speed of the four-rotor uav at the adjustment of yaw angle, this paper presents a variable-domain fuzzy PID controller. First, we established the nonlinear dynamic model of four-rotor UAV. Then, we fuzzed the corresponding variables in the governing equation, formulated fuzzy rules and introduced variable theory to adjust domain of discourse. Finally, we used simulink software to carry out experiments. The experiment result shows that variable-domain fuzzy PID controller has some undoubtedly advantages in performance evaluation compared to traditional PID controller, which including dynamic property and steady state error, and can be used to improve the quality of the adjustment of yaw angle.

Influences of distributed propulsion system parameters on aerodynamic characteristics of a BLI-BWB UAV

Focusing on the aerodynamic characteristics of the blended wing body (BWB) aircraft with boundary layer ingestion(BLI) distributed propulsion system; the influences of propulsion system parameters under the condition of cruise and takeoff are studied. Firstly, based on the momentum source method (MSM), the NASA ducted propeller model is simulated, which verifies the reliability of the numerical method in this paper. Then, by using the method of structural grid and S-A turbulence model to solve the Reynolds averaged Navier-Stokes (RANS) equation, the aerodynamic characteristics of the BLI UAV model with D80 ducted fan in cruise state are numerically calculated. It is proved that the advantage of the BLI distributed propulsion system is superior in increasing lift. And the aerodynamic characteristics of the BLI UAV with different propulsion system parameters are compared. At last, the aerodynamic effect of ducted fan thrust on the BLI UAV is carried out. The results show that, due to the suction function of the BLI distributed propulsion system, the air flow velocity near the BWB fuselage is effectively accelerated, and the flow along the spanwise is restrained, which improves the lift coefficient about 16% and lift-to-drag ratio about 10%. Under the condition of equal thrust, the D80 ducted fan brings larger load of the propeller, which makes the static pressure at the inlet and outlet smaller. Compared with D150 ducted fan, the lift-to-drag ratio is increased by 15%. When aircraft takes off, increasing the thrust of the ducted fan can reduce the possibility of flow separation on the upper surface of the fuselage, which is conducive to the safety.

A Low-Cost Solution for Leader-Follower Formation Control of Multi-UAV System Based on Pixhawk

In recent years, cooperative multi-UAV systems have shown great performance in a variety of potential applications. Aiming at the problem of fixed-wing UAVs cooperative formation flight, this paper presents a low-cost system based on Pixhawk autopilot for keeping the shape of the formation. The kinematic relationship of a leader-follower UAV formation is established and a fuzzy PID control law is designed for the follower to maintain the expected position relative to the leader. Wireless data transmission between the leader and followers is achieved by using several radio telemetry modules. The proposed formation control system is validated by a series of successful flight experiments using 3 small-scaled UAV models, which has proven its feasibility and reliability.

Evaluation of Possibility of Large-scale Digital Map through Precision Sensor Modeling of UAV

Evaluation of Possibility of Large-scale Digital Map through Precision Sensor Modeling of UAV

Nonlinear control for the extended model of the load-suspended UAV based on the experiments

Abstract In recent years, to solve the problem of shortage of delivery staff caused by high demand in the delivery industry, it is expected to carry packages while a UAV tows them. However, when towing, the control performance of the aircraft deteriorates due to the influence of the weight and shaking of the towed object, so it is necessary to control the aircraft in consideration of the behavior of the towed object. To address this issue, an input design with hierarchical linearization has been proposed for the UAV that tows an object, but it has not been experimentally verified. In this paper, we conducted experiments and confirmed the existence of the modeling error. Thus, we built a model reflecting the actual structure of towing of UAV. We applied the redesigned controller to the simulation model and verified its performance.

Design of Sliding Mode Controller for Tilting Quadrotor UAV Based on Predetermined Performance

Aiming at the influence of modeling error and uncertain interference such as external sidewind in the control system of tilting quadrotor UAV, a non-singular fast terminal sliding mode controller based on predetermined performance is designed for its vertical take-off and landing mode. Firstly, based on the classical mechanics theory, the nonlinear dynamics model of tilt-rotor UAV in vertical take-off and landing mode was established. Then, on the basis of the non-singular fast terminal sliding mode controller, the predetermined performance function was introduced to make the system error within the specified performance range, and the final bounded convergence of the tracking error in the closed-loop system was proved based on the Lyapunov stability theory. Finally, the simulation experiment was carried out in MATLAB/Simulink. The simulation results show that the designed method can still achieve the stable tracking of the predetermined trajectory under the circumstance of uncertain external interference, and it has good control performance and anti-interference ability.

Distribution regularity of downwash airflow under rotors of agricultural UAV for plant protection

In the plant protection spray operation of UAVs, the process of droplet from formation to sedimentation target is affected by airflow, easy to form uneven deposition. Accurately description of rotor downwash flow field, clarification of velocity vector distribution at different heights of the UAV rotor flow field, simulation of the flow field with high precision, which are the prerequisites for accurately analyzing the droplet deposition distribution in rotor downwash flow field. Based on CFD method, the detail of rotor flow field was numerically calculated. Taking LTH-100 single-rotor agricultural UAV as the research object, the three-dimensional solid model of UAV was established, the Reynolds average N-S equation was used as the control equation and the RNG κ-ε as the turbulence model to simulate the flow field of UAV in hover and lateral wind conditions, the wind velocity distribution at different altitudes of rotor downwash flow field was studied. The simulation results of the hover state showed that: In the flow field, the peak velocity appears in a circular distribution below the distal axis of the rotor. With the decrease of height, the peak velocity distribution area showed a tendency to expand gradually after small shrinkage; When the distance from the rotor was not more than 1.5 m, the downwash flow field presented an axisymmetric distribution based on the rotor axis, and the variation rate of velocity in the peak velocity was basically the same, turbulence in downwash flow field made the flow field more complex when the distance from rotor was larger than 2.0 m. On this basis, the optimal flight altitude of UAV is 1.5 m. Wind velocity test of the flow field was carried out on a rotor test bench, wind velocities at four altitudes of 0.5 m, 1.0 m, 1.5 m and 2.0 m were measured to verify the coincidence between the simulated and measured values. The test results showed that: the relative error between the measured and simulated values at four measurement heights were between 0.382-0.524, and the overall average relative errors was 0.430, which verified the confidence level of simulated values for measured values. When the lateral wind velocity was 3 m/s, 4 m/s and 5 m/s, the simulation results showed that: The distribution trend of airflow velocity at the same altitude in lateral-wind flow field with different wind speeds was similar; When the lateral wind speed was 5 m/s, the coupling field formed by the lateral wind and rotor airflow cannot reach the height of 2 m below the rotor. The results of this study can provide more accurate environmental conditions for theoretical analysis of droplet deposition regularity in the flow field, and also provide methodological guidance for the related research on rotor flow field of multi-rotor UAV. Keywords: aviation plant protection, downwash flow field, distribution regularity, numerical simulation, single-rotor UAV DOI: 10.25165/j.ijabe.20211403.4036 Citation: Liu X, Zhang W, Fu H B, Fu X M, Qi L Q. Distribution regularity of downwash airflow under rotors of agricultural UAV for plant protection. Int J Agric & Biol Eng, 2021; 14(3): 46–57.

Creation of a biplan type uav model using a genetic algorithm in flight to help in solving the problem of fires in the Irkutsk region

Creation of a biplan type uav model using a genetic algorithm in flight to help in solving the problem of fires in the Irkutsk region

SECOND ORDER SLIDING MODE CONTROLLER DESIGN WITH OPTIMUM CHARACTERISTIC EQUATION FOR QUADROTORS

Nowadays, small structured micro unmanned aerial vehicles (UAV’s) with four-rotor appears in military and civilian applications. As the usage of these vehicles becomes widespread, the development of controller structures which allow the UAV’s to follow a specified trajectory precisely is a new area of interest for researchers. In this work, nonlinear mathematical model of a four-rotor UAV is obtained. In order to obtain the mathematical model of UAV Newton-Euler equations are used. In the trajectory tracking system of this vehicle, second order sliding mode controller (SOSMC) is designed. Inside of the controller, control process is divided into two subsystems in order to provide position and attitude control. SOSMC is applied to the fully actuated and under actuated subsystems individually. In the next step, coefficients of the SOSMC is determined with optimum characteristic equation. Based on the reference study, boundaries of the predefined characteristic equation is obtained. Later, appropriate values are observed. In final part, simulation results are obtained, and the results are compared with the reference study. As a result, Optimum Characteristic equation results proved its robustness according to the smaller steady state error and more precise flight performance in trajectory. In this study simulation results are obtained using Simulink/MATLAB environment.

Modeling of box-wing tilt-rotor UAV based on Lagrange equation in Hamilton system

Modeling of box-wing tilt-rotor UAV based on Lagrange equation in Hamilton system

Development, Modeling and Control of a Dual Tilt-Wing UAV in Vertical Flight

Hybrid Unmanned Aerial Vehicles (H-UAVs) are currently a very interesting field of research in the modern scientific community due to their ability to perform Vertical Take-Off and Landing (VTOL) and Conventional Take-Off and Landing (CTOL). This paper focuses on the Dual Tilt-wing UAV, a vehicle capable of performing both flight modes (VTOL and CTOL). The UAV complete dynamic model is obtained using the Newton–Euler formulation, which includes aerodynamic effects, as the drag and lift forces of the wings, which are a function of airstream generated by the rotors, the cruise speed, tilt-wing angle and angle of attack. The airstream velocity generated by the rotors is studied in a test bench. The projected area on the UAV wing that is affected by the airstream generated by the rotors is specified and 3D aerodynamic analysis is performed for this region. In addition, aerodynamic coefficients of the UAV in VTOL mode are calculated by using Computational Fluid Dynamics method (CFD) and are embedded into the nonlinear dynamic model. To validate the complete dynamic model, PD controllers are adopted for altitude and attitude control of the vehicle in VTOL mode, the controllers are simulated and implemented in the vehicle for indoor and outdoor flight experiments.

Influence of external disturbances on the flow of straight and swept wings

The paper presents the results of experimental studies of the influence of incoming external disturbances on the flow of straight wing and UAV models at different angles of attack and slip. Using the method of hot-wire anemometry, quantitative data were obtained on the structure of the flow near the surface of the model when it flows around a free stream and in the presence of incident external disturbances. Pictures of the visualization of the flow around models under stall conditionswere obtained. It was found that incident external disturbances under certain conditions can significantly change the flow structure.

Design of Decoupling Fuzzy Logic Controller for Quadrotor UAV

This article first briefly introduces the quadrotor UAV model based on the Newton-Euler method, including kinematics model, dynamic model and force and moment model, and then proposes a decoupling fuzzy controller, which can effectively decouple the position and the orientation of the quadrotor UAV, i.e., the inner loop uses the input and output linearization method to control orientation, and the outer loop uses a fuzzy logic controller to control the position of the quadrotor UAV. Finally, we use Matlab to model the quadrotor UAV and design the decoupling fuzzy controller to control the quadrotor UAV. The results show that the tracking performance is good, which proves the feasibility of the controller algorithm.

A power transfer model-based method for lithium-ion battery discharge time prediction of electric rotatory-wing UAV

This paper develops a power transfer model-based method to estimate real-time state of energy (SOE) and predict end of discharge (EOD) time of rotatory-wing UAVs lithium batteries under dynamic operational conditions. A discrete-time state-space model of battery is first established to model the process of battery power consumption and establish a mapping of battery unobservable state of energy (SOE) to measurable parameters such as voltage and current. Then a power consumption model of UAV is established based on predetermined flight mission of UAV using aerodynamics and momentum theory, which estimates power consumption of UAV under different operational conditions. Its calculation results can be directly used in battery state-space model as its input, while its model parameters are simultaneously updated by online measurements of consumed power. Finally, a Particle Filter (PF) approach with Adam optimization algorithm is developed to estimate SOE and predict EOD time on-line, and better prediction results compared to conventional PF are achieved. Real experiments on UAV verify the effectiveness of the proposed method.