Reduction of the head-up pitching moment of small quad-rotor unmanned aerial vehicles in uniform flow

Otsuka, Hiroko; Sasaki, Daisuke; Nagatani, Keiji

doi:10.1177/1756829317745318

Cited by 8 publications

(5 citation statements)

References 14 publications

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“…Additionally, for preflight planning, Barnas et al [85] suggested fixed-wing systems' stability is optimized by flying directed to the crosswind rather than into headwind or tailwind. For multirotors flying into headwinds, slanting the rotors by 20 degrees can reduce upwards pitching by 26% [137]. Heavy, bulky equipment should be avoided, such as the Sirius Pro from MAVinci, the UX5 from Trimble, of the Q-200 from Quest UAS for applications in high elevation [34].…”

Section: Discussion and Recommendationsmentioning

confidence: 99%

Applications of Unmanned Aerial Vehicles in Cryosphere: Latest Advances and Prospects

2020

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Owing to usual logistic hardships related to field-based cryospheric research, remote sensing has played a significant role in understanding the frozen components of the Earth system. Conventional spaceborne or airborne remote sensing platforms have their own merits and limitations. Unmanned aerial vehicles (UAVs) have emerged as a viable and inexpensive option for studying the cryospheric components at unprecedented spatiotemporal resolutions. UAVs are adaptable to various cryospheric research needs in terms of providing flexibility with data acquisition windows, revisits, data/sensor types (multispectral, hyperspectral, microwave, thermal/night imaging, Light Detection and Ranging (LiDAR), and photogrammetric stereos), viewing angles, flying altitudes, and overlap dimensions. Thus, UAVs have the potential to act as a bridging remote sensing platform between spatially discrete in situ observations and spatially continuous but coarser and costlier spaceborne or conventional airborne remote sensing. In recent years, a number of studies using UAVs for cryospheric research have been published. However, a holistic review discussing the methodological advancements, hardware and software improvements, results, and future prospects of such cryospheric studies is completely missing. In the present scenario of rapidly changing global and regional climate, studying cryospheric changes using UAVs is bound to gain further momentum and future studies will benefit from a balanced review on this topic. Our review covers the most recent applications of UAVs within glaciology, snow, permafrost, and polar research to support the continued development of high-resolution investigations of cryosphere. We also analyze the UAV and sensor hardware, and data acquisition and processing software in terms of popularity for cryospheric applications and revisit the existing UAV flying regulations in cold regions of the world. The recent usage of UAVs outlined in 103 case studies provide expertise that future investigators should base decisions on.

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Section: Discussion and Recommendationsmentioning

confidence: 99%

Applications of Unmanned Aerial Vehicles in Cryosphere: Latest Advances and Prospects

2020

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“…The trimmed variables are the pitch angle and the left and right rotor speeds denoted by θ, Ω and Ωr , respectively. Setting the position and pitch rates and accelerations to zero in ( 13)- (22) gives…”

Section: Vehicle Trimmentioning

confidence: 99%

“…and the aerodynamic forces, T i , H i , are dependent upon the state, x, control, u and wind disturbance V W . The dynamic equations, ( 13)- (22), are linearized at a set of trim points using the second order finite difference method ( [37], p. 200). This gives the small perturbation model…”

Section: Model With Rotor Aerodynamicsmentioning

confidence: 99%

“…It is commonly used as a model for testing multirotor control concepts, e.g., [20]. Note that the idea of reducing the gust sensitivity by rotor tilt was also proposed by Otsuka and Nagatani [21] who conducted some experimental studies to measure the pitch/roll moment effect [22].…”

Section: Introductionmentioning

confidence: 99%

“…The pitching into the wind that results from outwards rotor tilt could also be achieved by aerodynamic 'tailoring' of the vehicle body shape, a detailed study of aerodynamic design trade-off remains for future work. Finally, validation of the effect of outward tilt requires experimental validation, both by wind tunnel test to add to that of Otsuka, Sasaki and Nagatani [22] and by flight test.…”

mentioning

confidence: 99%

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Effect of Rotor Tilt on the Gust Rejection Properties of Multirotor Aircraft

Whidborne

Mendez

Cooke

2022

Drones

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In order to operate safely in windy and gusty conditions, multirotor VTOL aircraft require gust resilience. This paper shows that their gust rejection properties can be improved by applying a small amount of fixed outward rotor tilt. Standard aerodynamic models of the rotors are incorporated into two dynamic models to assess the gust rejection properties. The first case is a conceptual birotor planar VTOL aircraft. The dependence of the trim and stability on the tilt angle are analyzed. The aircraft is stabilized using a pole-placement approach in order to obtain consistent closed-loop station-keeping performance in still air. The effect of gusts on the resulting response is determined by simulation. The second case study is for a quadrotor with a 10∘ outward rotor tilt. The aerodynamic coefficients are analyzed for trimmed station-keeping over a range of steady wind speeds. An LQR controller is used to apply station-keeping that includes integral action, and the gust responses are again obtained using simulation. The results show that the outward rotor tilt causes the aircraft to pitch down into a lateral gust, providing lateral force that opposes the gust and so significantly improving the gust rejection properties.

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Effects of rotor–rotor interaction for a small tandem rotor operating in a crosswind

Chae,

Lee,

Hwang

et al. 2024

Physics of Fluids

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This study investigates the effects of rotor–rotor interaction on the wake and thrust characteristics of a small tandem rotor operating in a crosswind. Flow velocity and force measurements were conducted in a wind tunnel with two rotors arranged parallel to a crosswind. The results show that the rotor–rotor interaction significantly influences the wake characteristics and thrust generations of the tandem rotor and its effects vary depending on the crosswind speed and distance between rotor tips. In the tandem rotor configuration, the front rotor wake prevents the crosswind flow from reaching the rear rotor wake, thereby reducing the crosswind influence on it. However, under the strong rotor–rotor interaction, such as that caused by high crosswind speeds and short distances between rotor tips, the wakes of both rotors collide with each other and rapidly break down as they proceed downward. Tip-vortex characteristics are also affected by rotor–rotor interaction, which is investigated in terms of variations in the time-averaged tip-vortex trajectory and dissipation ratio with the strength of rotor–rotor interaction. These wake variations by rotor–rotor interaction lead to a decrease in thrust coefficients of the front and rear rotors, with a more significant reduction observed for the rear rotor. The thrust of the rear rotor is more significantly reduced as the crosswind speed increases and the distance between rotor tips narrows. This is mainly attributed to the increased axially induced velocity near the leading tips on the advancing side, retreating side, and centerline.

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Reduction of the head-up pitching moment of small quad-rotor unmanned aerial vehicles in uniform flow

Cited by 8 publications

References 14 publications

Applications of Unmanned Aerial Vehicles in Cryosphere: Latest Advances and Prospects

Applications of Unmanned Aerial Vehicles in Cryosphere: Latest Advances and Prospects

Effect of Rotor Tilt on the Gust Rejection Properties of Multirotor Aircraft

Effects of rotor–rotor interaction for a small tandem rotor operating in a crosswind

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