scholarly journals Stabilization of unmanned aerial vehicle on trajectory in high wind conditions

2021 ◽  
pp. 55-63
Author(s):  
Vitalii Burnashev
Keyword(s):  
Wind Speed ◽  
Unmanned Aerial Vehicle ◽  
Three Dimensional ◽  
Landing Site ◽  
Flight Simulation ◽  
Vertical Shear ◽  
Average Wind Speed ◽  
Control Laws ◽  
Starting Point ◽  
Aerial Vehicle

Stationary proportional control laws have been synthesized to ensure stable motion of an unmanned aerial vehicle along a trajectory under the action of a storm wind. We give the values of the regulator coefficients for all sections of the trajectory from the starting point to the landing. Shown are the realizations of wind disturbances and the parameters of the controlled motion of the aircraft under their action. We consider the accuracy of altitude control and the error of the coordinates of the landing site. The control laws use the values of constant coefficients obtained at five points of the trajectory. Three points are used for the climb phase and one for level flight and one for descent. We took into account the wind speed as the sum of the three-dimensional turbulent component, the average horizontal component, considering the vertical shear, and discrete vertical gusts. The parameters of the Dryden shaping filters, as well as the vertical shear, are calculated for an average wind speed at a height of 6 m equal to 23.15 m / s. The speed of discrete upward gusts is 40 m/s, and downward -25 m / s. In such conditions, the unmanned aerial vehicle successfully passes the specified trajectory from the launch to the landing. For thirty realizations of flight simulation, the standard deviation of the landing site error from the wind acting was calculated.

scholarly journals Method of an unmanned aerial vehicle composition route in space

2021 ◽  
Vol 5 (4) ◽  
pp. 26-33
Author(s):  
Denys Voloshyn ◽  
Veronika Brechko ◽  
Serhii Semenov
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Spatial Location ◽  
Starting Point ◽  
Aerial Vehicle ◽  
The Difference ◽  
Extended Graph ◽  
Three Dimensional Space ◽  
Vehicle Routes

The article is devoted to the development of a method of composition of the route of an unmanned aerial vehicle in three-dimensional space. The main difference of the presented method is the complex consideration of the features of the environment, which reflects the possible obstacles (active or passive) and other limitations of the problem when composing the route of the unmanned aerial vehicle in three-dimensional space. This allowed to increase the safety of the task in autonomous flight conditions. The article analyzes the main approaches to the composition of unmanned aerial vehicle routes in space. The conclusion about the shortcomings of the two-dimensional representation is made. The method presents four stages of the task. This is the stage of modeling the environment that reflects possible obstacles (active or passive) and other limitations of the task. Stage of construction of an extended graph of unmanned aerial vehicle routes in space. The difference of this stage is the adaptive consideration of the spatial location of active obstacles in space. The next stage is the route search stage, which connects the starting point with the end and bypasses all obstacles and allows you to build a starting route in the form of a broken line, which is formed by a sequence of waypoints, and connects the starting point with the end, bypassing obstacles. The last is the stage of obtaining the final result, which is provided by smoothing the obtained broken line. In this part of the composition method, to solve the problem of smoothing the trajectory of the unmanned aerial vehicle in space on the selected route, the expediency of using the method of non-uniform cubic B-spline is proved. With the help of this method the task of selection and optimization of the smoothing parameter is set and solved.

scholarly journals PRELIMINARY EVALUATION OF ATMOSPHERIC TEMPERATURE AND WIND PROFILES OBTAINED USING UNMANNED AERIAL VEHICLE BASED ACOUSTIC TOMOGRAPHY

2019 ◽  
Vol XLII-2/W13 ◽  
pp. 283-287 ◽  
Author(s):  
A. Finn ◽  
K. Rogers ◽  
J. Meade ◽  
J. Skinner ◽  
A. Zargarian
Keyword(s):  
Wind Velocity ◽  
Unmanned Aerial Vehicle ◽  
Sound Speed ◽  
Three Dimensional ◽  
Atmospheric Temperature ◽  
Preliminary Evaluation ◽  
Sound Fields ◽  
Aerial Vehicle ◽  
Wind Profiles ◽  
Virtual Temperature

<p><strong>Abstract.</strong> An acoustic signature generated by an unmanned aerial vehicle is used in conjunction with tomography to remotely sense temperature and wind profiles within a volume of atmosphere up to an altitude of 120&amp;thinsp;m and over an area of 300&amp;thinsp;m&amp;thinsp;&amp;times;&amp;thinsp;300&amp;thinsp;m. Sound fields recorded onboard the aircraft and by an array of microphones on the ground are compared and converted to sound speed estimates for the ray paths intersecting the intervening medium. Tomographic inversion is then used to transform these sound speed values into three-dimensional profiles of virtual temperature and wind velocity, which enables the atmosphere to be visualised and monitored over time. The wind and temperature estimates obtained using this method are compared to independent measurements taken by a co-located mid-range ZephIR LIDAR and sensors onboard the aircraft. These comparisons show correspondences to better than 0.5&amp;thinsp;&amp;deg;C and 0.3&amp;thinsp;m/s for temperature and wind velocity, respectively.</p>

Optimized artificial potential field algorithm to multi-unmanned aerial vehicle coordinated trajectory planning and collision avoidance in three-dimensional environment

2019 ◽  
Vol 233 (16) ◽  
pp. 6032-6043 ◽  
Author(s):  
Jun Tang ◽  
Jiayi Sun ◽  
Cong Lu ◽  
Songyang Lao
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Collision Avoidance ◽  
Unmanned Aerial Vehicle ◽  
Trajectory Planning ◽  
Potential Field ◽  
Three Dimensional ◽  
Artificial Potential Field ◽  
Aerial Vehicles ◽  
Aerial Vehicle ◽  
Vehicle Trajectory

Multi-unmanned aerial vehicle trajectory planning is one of the most complex global optimum problems in multi-unmanned aerial vehicle coordinated control. Results of recent research works on trajectory planning reveal persisting theoretical and practical problems. To mitigate them, this paper proposes a novel optimized artificial potential field algorithm for multi-unmanned aerial vehicle operations in a three-dimensional dynamic space. For all purposes, this study considers the unmanned aerial vehicles and obstacles as spheres and cylinders with negative electricity, respectively, while the targets are considered spheres with positive electricity. However, the conventional artificial potential field algorithm is restricted to a single unmanned aerial vehicle trajectory planning in two-dimensional space and usually fails to ensure collision avoidance. To deal with this challenge, we propose a method with a distance factor and jump strategy to resolve common problems such as unreachable targets and ensure that the unmanned aerial vehicle does not collide into the obstacles. The method takes companion unmanned aerial vehicles as the dynamic obstacles to realize collaborative trajectory planning. Besides, the method solves jitter problems using the dynamic step adjustment method and climb strategy. It is validated in quantitative test simulation models and reasonable results are generated for a three-dimensional simulated urban environment.

Numerical Simulation and Experimental Verification of the Deposition Concentration of an Unmanned Aerial Vehicle

2019 ◽  
Vol 35 (3) ◽  
pp. 367-376 ◽  
Author(s):  
Qiang Shi ◽  
Hanping Mao ◽  
Xianping Guan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Unmanned Aerial Vehicle ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Utilization Rate ◽  
Droplet Deposition ◽  
Aerial Vehicle ◽  
Motion Characteristics

Abstract. To analyze the droplet deposition under the influence of the flow field of an unmanned aerial vehicle (UAV), a hand-held three-dimensional (3D) laser scanner was used to scan 3D images of the UAV. Fluent software was used to simulate the motion characteristics of droplets and flow fields under the conditions of a flight speed of 3 m/s and an altitude of 1.5 m. The results indicated that the ground deposition concentration in the nonrotor flow field was high, the spray field width was 2.6 m, and the droplet deposition concentration was 50 to 200 ug/cm2. Under the influence of the rotor flow field, the widest deposition range of droplets reached 12.8 m. Notably, the droplet deposition uniformity worsened, and the concentration range of the droplet deposition was 0 to 500 ug/cm2. With the downward development of the downwash flow field, the overall velocity of the flow field gradually decreased, and the influence interval of the flow field gradually expanded. In this article, the droplet concentration was verified under simulated working conditions by a field experiment, thereby demonstrating the reliability of the numerical simulation results. This research could provide a basis for determining optimal UAV operating parameters, reducing the drift of droplets and increasing the utilization rate of pesticides. Keywords: Unmanned aerial vehicle (UAV), Aerial application, Downwash flow field, Droplet deposition, Simulation analysis.

scholarly journals Three-Dimensional Path Planning of Constant Thrust Unmanned Aerial Vehicle Based on Artificial Fluid Method

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yongqiang Qi ◽  
Shuai Li ◽  
Yi Ke
Keyword(s):  
Path Planning ◽  
Unmanned Aerial Vehicle ◽  
Interpolation Method ◽  
Three Dimensional ◽  
Planning Problem ◽  
Perturbation Matrix ◽  
Fluid Field ◽  
Control Scheme ◽  
Aerial Vehicle ◽  
Tangential Vector

In this paper, a three-dimensional path planning problem of an unmanned aerial vehicle under constant thrust is studied based on the artificial fluid method. The effect of obstacles on the original fluid field is quantified by the perturbation matrix, the streamlines can be regarded as the planned path for the unmanned aerial vehicle, and the tangential vector and the disturbance matrix of the artificial fluid method are improved. In particular, this paper addresses a novel algorithm of constant thrust fitting which is proposed through the impulse compensation, and then the constant thrust switching control scheme based on the isochronous interpolation method is given. It is proved that the planned path can avoid all obstacles smoothly and swiftly and reach the destination eventually. Simulation results demonstrate the effectiveness of this method.

Vision-based pose estimation of a multi-rotor unmanned aerial vehicle

2019 ◽  
Vol 7 (3) ◽  
pp. 120-132
Author(s):  
Kashish Gupta ◽  
Bara Jamal Emran ◽  
Homayoun Najjaran
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Three Dimensional ◽  
Processing System ◽  
Training Procedure ◽  
Autonomous Landing ◽  
Content Type ◽  
Landing Platform ◽  
Aerial Vehicle ◽  
Autopilot Systems ◽  
Practical Implications

Purpose The purpose of this paper is to facilitate autonomous landing of a multi-rotor unmanned aerial vehicle (UAV) on a moving/tilting platform using a robust vision-based approach. Design/methodology/approach Autonomous landing of a multi-rotor UAV on a moving or tilting platform of unknown orientation in a GPS-denied and vision-compromised environment presents a challenge to common autopilot systems. The paper proposes a robust visual data processing system based on targets’ Oriented FAST and Rotated BRIEF features to estimate the UAV’s three-dimensional pose in real time. Findings The system is able to visually locate and identify the unique landing platform based on a cooperative marker with an error rate of 1° or less for all roll, pitch and yaw angles. Practical implications The proposed vision-based system aims at on-board use and increased reliability without a significant change to the computational load of the UAV. Originality/value The simplicity of the training procedure gives the process the flexibility needed to use a marker of any unknown/irregular shape or dimension. The process can be easily tweaked to respond to different cooperative markers. The on-board computationally inexpensive process can be added to off-the-shelf autopilots.

Spray Application Efficiency from a Multi-Rotor Unmanned Aerial Vehicle Configured for Aerial Pesticide Application

2019 ◽  
Vol 62 (6) ◽  
pp. 1447-1453 ◽  
Author(s):  
Brian Richardson ◽  
Carol A. Rolando ◽  
Mark O. Kimberley ◽  
Tara M. Strand
Keyword(s):  
Wind Speed ◽  
Unmanned Aerial Vehicle ◽  
Droplet Size ◽  
Small Range ◽  
Surprising Result ◽  
Spray Application ◽  
Size Classes ◽  
Fine Droplet ◽  
Application Efficiency ◽  
Aerial Vehicle

HighlightsThe swath pattern was measured from an Agras MG-1 UAV spraying fine and extra-coarse droplet spectra.The recommended lane separation of 3.6 m did not differ for the two droplet size classes tested in this study.The applied spray deposited within the swath was higher with extra-coarse (&gt;90%) than with fine (73%) droplets.There was potential for substantial downwind drift with fine droplets, even when flying close to the ground at low speed.Abstract. While there is increasing interest in the use of small, multi-rotor UAVs for application of agrichemicals, there is also uncertainty about their performance. Consequently, the purpose of this study was to quantify the performance of an Agras MG-1 with modified nozzle positions that, at the time of writing, was being used for commercial spraying in New Zealand. The approach was to release spray from the UAV along a single 50 m line. Spray deposits were measured using horizontal collectors placed on the ground in three 15 m transects centered on, and perpendicular to, the flight line. Airborne deposits were measured with a 10 m mast that supported spherical samplers at 1 m vertical intervals. Analysis of deposition data was undertaken to quantify factors influencing overall swath pattern variability, lane separation associated with a coefficient of variation (CV) of deposition of 30%, and spray application efficiency, which is the proportion of applied spray deposited within the swath. For two droplet size classes (extra-coarse and fine), the lane separation associated with a CV of 30% was about 3.6 m, with no significant effect of droplet size. This is a surprising result and may reflect the relatively small range of environmental conditions experienced during the field tests, including wind speed, which was relatively low for all tests. We speculate that this result may also be a consequence of the strong downwash. The swath width was positively correlated with wind speed. Spray efficiency was shown to be high (&gt;90%) for the extra-coarse droplets but dropped significantly (73%) with the fine droplet spectrum. Combining in-swath deposition with the amount of airborne spray sampled in a 10 m vertical profile close to the edge of the swath accounted for 98.0% of the spray released with the extra-coarse spectrum but only 88.6% of the spray with the fine droplet spectrum. These results highlight that even with UAVs flying relatively close to the ground at a low forward speed, there is potential for substantial drift downwind of the swath when using smaller droplet size classes. Overall, the swath pattern was reasonably consistent across the two droplet size classes and for the narrow range of operational and meteorological conditions tested. Keywords: Aerial spraying, Pesticides, Spray application efficiency, Spray deposition, Swath pattern, UAV, Unmanned aerial vehicle.

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