Arbitrary Attitude Hovering Control of Quad Tilt Rotor Helicopter

2016 ◽  
Vol 28 (3) ◽  
pp. 328-333 ◽  
Author(s):  
Masafumi Miwa ◽  
◽  
Shinji Uemura ◽  
Akitaka Imamura ◽  
◽  
...  
Keyword(s):  
Long Range ◽  
High Speed ◽  
Mode Transition ◽  
Thrust Vectoring ◽  
Tilt Rotor ◽  
Flight Mode ◽  
Initial Stage ◽  
Yaw Angle ◽  
Hovering Control ◽  
Multirotor Helicopter

[abstFig src='/00280003/08.jpg' width=""300"" text='Arbitrary attitude hovering' ] The quad tilt rotor helicopter (QTRH), a tilt-rotor aircraft prototype, has fixed wings for long-range high-speed flight. Its rotor-tilt mechanism controls 4 rotor-tilt angles independently and controls its roll and pitch angles similarly to a multirotor helicopter. It controls yaw angle by thrust vectoring and moves forward and backward by tilting its rotors. Rotor-tilting maneuvers are the initial stage of flight-mode transition between helicopter and fixed-wing modes.

ADVANCES IN LONG-RANGE, HIGH-SPEED OPTICAL COMMUNICATION

1981 ◽  
Vol 93 (4) ◽  
pp. 39-48
Author(s):  
SIDNEY FELDMAN ◽  
GEORGE G. BARTON
Keyword(s):  
Long Range ◽  
Optical Communication ◽  
High Speed

scholarly journals Design of a Symmetrical Quad-rotor Biplane Tail-Sitter Aircraft without Control Surfaces and Experimental Verification

2018 ◽  
Vol 151 ◽  
pp. 04009
Author(s):  
Hongyu Wang ◽  
Xun Zhao ◽  
Hui Bai ◽  
Cunyue Lu ◽  
Baomin Zhang ◽  
...  
Keyword(s):  
Attitude Control ◽  
Superior Performance ◽  
Mode Transition ◽  
Yaw Control ◽  
Flight Mode ◽  
Vtol Uav ◽  
Wide Range ◽  
Potential Applications ◽  
The Military ◽  
Control Surfaces

This paper presents the design of a symmetrical quad-rotor biplane tail-sitter VTOL UAV (Vertical Take-off and Landing Unmanned Aerial Vehicle) which is composed of four rotors and two symmetrically mounted fixed wings. This aircraft achieves high accuracy in the attitude control and smooth flight mode transition with four rotors rather than the conventional VTOL UAVs using control surfaces. The proposal of angled rotor mounting is adopted to address the issue of insufficient yaw control authority. The layout of symmetrically mounted fixed wings makes the aircraft have capability of rapid bidirectional flight mode transition to improve maneuverability. To validate the performance of the aircraft, simulation and flight experiments are both implemented. These results show that the aircraft has a rapid yaw response under condition of the stable attitude control. In comparative experiment, it is shown that the aircraft is more flexible than other similar configuration of aircrafts. This symmetrical quad-rotor biplane tail-sitter VTOL UAV will have a wide range of potential applications in the military and civilian areas due to its superior performance..

Acoustic Measurements of High-Speed Jets from Rectangular Nozzle with Thrust Vectoring

AIAA Journal ◽  
2009 ◽  
Vol 47 (6) ◽  
pp. 1482-1490 ◽  
Author(s):  
Adam E. Goss ◽  
Jérémy Veltin ◽  
Jaehyung Lee ◽  
Dennis K. McLaughlin
Keyword(s):  
High Speed ◽  
Acoustic Measurements ◽  
Thrust Vectoring ◽  
Rectangular Nozzle

A High Fidelity Roll Dependent Aerodynamic Model for a Long Range, High Speed Missile

2022 ◽  
Author(s):  
Bradley T. Burchett ◽  
Justin L. Paul ◽  
Joseph D. Vasile ◽  
Joshua Bryson
Keyword(s):  
Long Range ◽  
High Speed ◽  
High Fidelity ◽  
Aerodynamic Model

Representative Time Series Fractal Analysis of the Traffic Flows of a Dedicated High-Speed Link

2021 ◽  
Author(s):  
Ginno Millan ◽  
manuel vargas ◽  
Guillermo Fuertes
Keyword(s):  
Time Series ◽  
Traffic Flow ◽  
Long Range ◽  
Computer Networks ◽  
Fractal Analysis ◽  
High Speed ◽  
Long Range Dependence ◽  
Traffic Flows ◽  
Speed Computer

Fractal behavior and long-range dependence are widely observed in measurements and characterization of traffic flow in high-speed computer networks of different technologies and coverage levels. This paper presents the results obtained when applying fractal analysis techniques on a time series obtained from traffic captures coming from an application server connected to the internet through a high-speed link. The results obtained show that traffic flow in the dedicated high-speed network link exhibited fractal behavior since the Hurst exponent was in the range of 0.5, 1, the fractal dimension between 1, 1.5, and the correlation coefficient between -0.5, 0. Based on these results, it is ideal to characterize both the singularities of the fractal traffic and its impulsiveness during a fractal analysis of temporal scales. Finally, based on the results of the time series analyzes, the fact that the traffic flows of current computer networks exhibited fractal behavior with a long-range dependence was reaffirmed.

scholarly journals Numerical studies on aerodynamics of high-speed railway train subjected to strong crosswind

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988727
Author(s):  
Xu Wang ◽  
Yuanhao Qian ◽  
Zengshun Chen ◽  
Xiao Zhou ◽  
Huaqiang Li ◽  
...  
Keyword(s):  
Wind Speed ◽  
High Speed ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Force Coefficient ◽  
Rolling Moment ◽  
Side Force ◽  
Train Speed ◽  
Yaw Angle

Under the action of strong crosswind, the aerodynamic behavior of a rail vehicle at high speed will be changed significantly, which could directly affect the safe operation of the vehicle. With the help of the shape of train used in China, the aerodynamic characteristics of trains with scale of 1:1 is investigated using computational fluid dynamics numerical simulation method, which consists of the variation of aerodynamics force and moment with wind yaw angle, wind speed, train speed, and nose shape. After an initial validation against Baker’s results from wind tunnel test, the numerical model is then used to investigate the aerodynamic characteristics of the trains. The numerical results indicate that lift coefficient of the M train is slightly higher than TMC1 and TMC2 trains. Regardless of aerodynamics force coefficients, TMC1 reaches the maximum at a yaw angle of 75°. Aerodynamics force coefficient increases with both wind speed and train speed, but the change of which is not linear. Comparing aerodynamic force with different geometric dimensions of train nose, it is shown that height–width ratio is insensitive to side force and rolling moment, but sensitive to lift force from the yaw angle 0°–90°. The side force coefficient, as we most concern, is less than other results, when the length–width ratio is 1 and height–width is 0.87.

scholarly journals A Superhydrophilic Aluminum Surface with Fast Water Evaporation Based on Anodic Alumina Bundle Structures via Anodizing in Pyrophosphoric Acid

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3497 ◽  
Author(s):  
Daiki Nakajima ◽  
Tatsuya Kikuchi ◽  
Taiki Yoshioka ◽  
Hisayoshi Matsushima ◽  
Mikito Ueda ◽  
...  
Keyword(s):  
Contact Angle ◽  
Oxide Film ◽  
High Speed ◽  
Porous Alumina ◽  
Aluminum Surface ◽  
Water Evaporation ◽  
Water Contact ◽  
Initial Stage ◽  
Angle Measuring ◽  
Pyrophosphoric Acid

A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina nanofibers, and completely bent nanofibers. During the water contact angle measurements at 1 s after the water droplet was placed on the anodized surface, the contact angle rapidly decreased to less than 10°, and superhydrophilic behavior with the lowest contact angle measuring 2.0° was exhibited on the surface covered with the pyramidal bundle structures. As the measurement time of the contact angle decreased to 200–33 ms after the water placement, although the contact angle slightly increased in the initial stage due to the formation of porous alumina, at 33 ms after the water placement, the contact angle was 9.8°, indicating that superhydrophilicity with fast water evaporation was successfully obtained on the surface covered with the pyramidal bundle structures. We found that the shape of the pyramidal bundle structures was maintained in water without separation by in situ high-speed atomic force microscopy measurements.

Spatial Filter Design for Dual-Stage Systems

2017 ◽  
Author(s):  
Aleksandra Mitrovic ◽  
Kam K. Leang ◽  
Garrett M. Clayton
Keyword(s):  
Long Range ◽  
High Speed ◽  
Filter Design ◽  
Spatial Filter ◽  
Control Allocation ◽  
Clear Understanding ◽  
Positioning Systems ◽  
Significant Research ◽  
Dual Stage ◽  
Increasing Demand

Increasing demand for high precision positioning systems has motivated significant research in this field. Within this field, dual-stage nanopositioning systems have the unique potential to offer high-speed and long-range positioning by coupling a short-range, high-speed actuator with a long-range, low-speed actuator. In this paper, design considerations for a spatial filter are presented. The spatial filter allows for control allocation based on range of the signal as opposed to more commonly used frequency-based control allocation. In order to understand the spatial filtering approach more fully, this paper analyzes the filter in detail to understand limitations and give the user a more clear understanding of the approach. Simulation results are included to illustrate aspects of the discussion.

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