scholarly journals Experimental Characterization of Drag Coefficient of an UAV Recovery Parachute

2021 ◽  
Vol 31 (2) ◽  
pp. 67-74
Keyword(s):  
Drag Coefficient ◽  
Unmanned Aerial Vehicles ◽  
Drag Force ◽  
Aerodynamic Drag ◽  
Experimental Characterization ◽  
Aerial Vehicles ◽  
Flat Type ◽  
Suspension Line ◽  
The Impact

Parachute recovery systems are proved to be an efficient method to recovery and rescue unmanned aerial vehicles (UAV) as it follows most requirements of reliability and airworthiness in flights. Parachutes are key components of the recovery systems and the drag coefficient of parachutes plays a crucial role in evaluating parachute’s performance. The purpose of the research is to determine and compare the impact of some factors on aerodynamic drag force during the inflation of a parachute. The canopy’s shape (flat circular type and extended skirt 10% flat type), of the length of suspension lines (be in proportion to nominal diameter from 0.6 to 1.5) are considered. Measurement of the drag force of the parachute models is carried out in an open return wind tunnel. Experimental results show that flat circular canopy has a higher drag coefficient than extended skirt 10% flat model in the range of low speed from 3 to 6 m/s. However, when wind speed is greater than 6 m/s, the drag coefficients of both two parachute types are nearly 0.85. In terms of the suspension line, the longer length would significantly raise the coefficient of drag force.

Characterization of small Brushless motors for unmanned aerial vehicles/ Caracterização de motores Brushless de pequeno porte para veículos aéreos não tripulados

2021 ◽  
Vol 7 (6) ◽  
pp. 63447-63463
Author(s):  
Ivo Z. L. Meyer ◽  
José E. M. Barros ◽  
José E. M. Barros
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Motor Performance ◽  
Test Bench ◽  
Experimental Characterization ◽  
Servo Motor ◽  
Great Efficiency ◽  
Brushless Motors ◽  
Speed Controller ◽  
Aerial Vehicles

Brushless motors are increasingly present in our lives and to get the best out of them it is important to know their performance. The objective of this work is to create a methodology of experimental characterization of this type of motor. As a methodology, research was done on similar works, it was built a test bench and an acquisition system to obtain the data. The variables measured were: rotation, torque, temperature, current and voltage. In addition to possessing a servo motor that acts like brake prony type to vary the load applied to the system. The results obtained allowed the analysis of the motor performance. It was also possible to design a mathematical model that represents the system, using the information obtained and the equations present in the literature. It was possible to conclude that the bench and the methodology used were valid, and that the ESC (electronic speed controller) is a great efficiency limiter of the motors.

scholarly journals Practical Endurance Estimation for Minimizing Energy Consumption of Multirotor Unmanned Aerial Vehicles

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2221 ◽  
Author(s):  
Myeong-hwan Hwang ◽  
Hyun-Rok Cha ◽  
Sung Yong Jung
Keyword(s):  
Drag Coefficient ◽  
Unmanned Aerial Vehicles ◽  
Estimation Method ◽  
Flight Test ◽  
Flight Time ◽  
Average Error ◽  
Practical Applications ◽  
Aerial Vehicles ◽  
Vehicle Shape ◽  
Battery Discharge

The practically applicable endurance estimation method for multirotor unmanned aerial vehicles (UAVs) using a battery as a power source is proposed. The method considers both hovering and steady-level flights. The endurance, thrust, efficiency, and battery discharge are determined with generally available data from the manufacturer. The effects of the drag coefficient related to vehicle shape and payload weight are examined at various forward flight speeds. As the drag coefficient increases, the optimum speed at the minimum required power and the maximum endurance are reduced. However, the payload weight causes an opposite effect, and the optimal flying speed increases with an increase in the payload weight. For more practical applications for common users, the value of S × Cd is determined from a preliminary flight test. Given this value, the endurance is numerically estimated and validated with the measured flight time. The proposed method can successfully estimate the flight time with an average error of 2.3%. This method would be useful for designers who plan various missions and select UAVs.

scholarly journals Supplementary material to "Characterization of the Particle Emission from Ships Operating at Sea Using Unmanned Aerial Vehicles"

2017 ◽  
Author(s):  
Tommaso F. Villa ◽  
Reece Brown ◽  
E. Rohan Jayaratne ◽  
L. Felipe Gonzalez ◽  
Lidia Morawska ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Particle Emission ◽  
Aerial Vehicles ◽  
Supplementary Material

scholarly journals Enhanced Particle Swarm Optimization for Path Planning of Unmanned Aerial Vehicles

2020 ◽  
Vol 14 (1) ◽  
pp. 67-78
Author(s):  
Kai Yit Kok ◽  
Parvathy Rajendran
Keyword(s):  
Particle Swarm Optimization ◽  
Path Planning ◽  
Unmanned Aerial Vehicles ◽  
Particle Swarm ◽  
Swarm Optimization ◽  
Aerial Vehicles ◽  
Trial And Error Method ◽  
The Impact ◽  
Enhanced Particle Swarm Optimization ◽  
Error Method

This paper presents an enhanced particle swarm optimization (PSO) for the path planning of unmanned aerial vehicles (UAVs). An evolutionary algorithm such as PSO is costly because every application requires different parameter settings to maximize the performance of the analyzed parameters. People generally use the trial-and-error method or refer to the recommended setting from general problems. The former is time consuming, while the latter is usually not the optimum setting for various specific applications. Hence, this study focuses on analyzing the impact of input parameters on the PSO performance in UAV path planning using various complex terrain maps with adequate repetitions to solve the tuning issue. Results show that inertial weight parameter is insignificant, and a 1.4 acceleration coefficient is optimum for UAV path planning. In addition, the population size between 40 and 60 seems to be the optimum setting based on the case studies.

scholarly journals Approaching birds with drones: first experiments and ethical guidelines

2015 ◽  
Vol 11 (2) ◽  
pp. 20140754 ◽  
Author(s):  
Elisabeth Vas ◽  
Amélie Lescroël ◽  
Olivier Duriez ◽  
Guillaume Boguszewski ◽  
David Grémillet
Keyword(s):  
Best Practices ◽  
Unmanned Aerial Vehicles ◽  
Ecological Research ◽  
Ethical Guidelines ◽  
Wetland Area ◽  
Physiological Indicators ◽  
Approach Distance ◽  
Aerial Vehicles ◽  
Approach Speed ◽  
The Impact

Unmanned aerial vehicles, commonly called drones, are being increasingly used in ecological research, in particular to approach sensitive wildlife in inaccessible areas. Impact studies leading to recommendations for best practices are urgently needed. We tested the impact of drone colour, speed and flight angle on the behavioural responses of mallards Anas platyrhynchos in a semi-captive situation, and of wild flamingos ( Phoenicopterus roseus ) and common greenshanks ( Tringa nebularia ) in a wetland area. We performed 204 approach flights with a quadricopter drone, and during 80% of those we could approach unaffected birds to within 4 m. Approach speed, drone colour and repeated flights had no measurable impact on bird behaviour, yet they reacted more to drones approaching vertically. We recommend launching drones farther than 100 m from the birds and adjusting approach distance according to species. Our study is a first step towards a sound use of drones for wildlife research. Further studies should assess the impacts of different drones on other taxa, and monitor physiological indicators of stress in animals exposed to drones according to group sizes and reproductive status.

In-Flight Detection of Vibration Anomalies in Unmanned Aerial Vehicles

2020 ◽  
Vol 3 (4) ◽  
Author(s):  
Portia Banerjee ◽  
Wendy A. Okolo ◽  
Andrew J. Moore
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Promising Technique ◽  
Bearing Faults ◽  
Vibration Sensors ◽  
Aerial Vehicles ◽  
Flight Operations ◽  
Small Uav ◽  
Close Proximity ◽  
Identification And Characterization

Abstract Owing to the frequency of occurrence and high risk associated with bearings, identification, and characterization of bearing faults in motors via nondestructive evaluation (NDE) methods have been studied extensively, among which vibration analysis has been found to be a promising technique for early diagnosis of anomalies. However, a majority of the existing techniques rely on vibration sensors attached onto or in close proximity to the motor in order to collect signals with a relatively high SNR. Due to weight and space restrictions, these techniques cannot be used in unmanned aerial vehicles (UAVs), especially during flight operations since accelerometers cannot be attached onto motors in small UAVs. Small UAVs are often subjected to vibrational disturbances caused by multiple factors such as weather turbulence, propeller imbalance, or bearing faults. Such anomalies may not only pose risks to UAV’s internal circuitry, components, or payload, they may also generate undesirable noise level particularly for UAVs expected to fly in low-altitudes or urban canyon. This paper presents a detailed discussion of challenges in in-flight detection of bearing failure in UAVs using existing approaches and offers potential solutions to detect overall vibration anomalies in small UAV operations based on IMU data.

scholarly journals The Wane of Command: Evidence on Drone Strikes and Control within Terrorist Organizations

2020 ◽  
pp. 1-20
Author(s):  
ANOUK S. RIGTERINK
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Natural Experiment ◽  
Terrorist Attacks ◽  
Terrorist Organizations ◽  
Aerial Vehicles ◽  
Terrorist Groups ◽  
Drone Strikes ◽  
And Control ◽  
The Impact ◽  
Better Than

This paper investigates how counterterrorism targeting terrorist leaders affects terrorist attacks. This effect is theoretically ambiguous and depends on whether terrorist groups are modeled as unitary actors or not. The paper exploits a natural experiment provided by strikes by Unmanned Aerial Vehicles (drones) “hitting” and “missing” terrorist leaders in Pakistan. Results suggest that terrorist groups increase the number of attacks they commit after a drone “hit” on their leader compared with after a “miss.” This increase is statistically significant for 3 out of 6 months after a hit, when it ranges between 47.7% and 70.3%. Additional analysis of heterogenous effects across groups and leaders, and the impact of drone hits on the type of attack, terrorist group infighting, and splintering, suggest that principal-agent problems—(new) terrorist leaders struggling to control and discipline their operatives—account for these results better than alternative theoretical explanations.

Experimental Study of the Vertical Hydraulic Drag Force on Regular Tetrahedron

2013 ◽  
Vol 860-863 ◽  
pp. 1547-1550
Author(s):  
Rui Le ◽  
Wei Jiang ◽  
Qi Liu ◽  
Nan Chang Sun ◽  
Bing Xu
Keyword(s):  
Experimental Study ◽  
Drag Coefficient ◽  
Drag Force ◽  
Vertical Velocity ◽  
Hydraulic Engineering ◽  
Hydraulic Drag ◽  
Regular Tetrahedron ◽  
Impact Effect ◽  
Drag Forces ◽  
The Impact

It is well known that the hydraulic drag force on objects cant be ignored in computing the movement of objects in water. And the drag forces on sphere and cuboids have long been studied. While in hydraulic engineering, objects with regular tetrahedron shape are widely used to form the foundation and temporary dam for they can interlock each other to obtain a compacted integral. In this article the vertical hydraulic drag force on regular tetrahedron is studied by indoor experiments, the relation of the vertical hydraulic drag coefficient and the vertical velocity is proposed. And the max vertical speeds of different materials are deduced. The result is helpful to compute the movement of regular tetrahedron in water and estimate the impact effect on the groundwork.

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