Download or read book Rotorcraft Blade Pitch Control Through Torque Modulation written by James J. Paulos and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro air vehicle (MAV) technology has broken with simple mimicry of manned aircraft in order to fulfill emerging roles which demand low-cost reliability in the hands of novice users, safe operation in confined spaces, contact and manipulation of the environment, or merging vertical flight and forward flight capabilities. These specialized needs have motivated a surge of new specialized aircraft, but the majority of these design variations remain constrained by the same fundamental technologies underpinning their thrust and control. This dissertation solves the problem of simultaneously governing MAV thrust, roll, and pitch using only a single rotor and single motor. Such an actuator enables new cheap, robust, and light weight aircraft by eliminating the need for the complex ancillary controls of a conventional helicopter swashplate or the distributed propeller array of a quadrotor. An analytic model explains how cyclic blade pitch variations in a special passively articulated rotor may be obtained by modulating the main drive motor torque in phase with the rotor rotation. Experiments with rotors from 10 cm to 100 cm in diameter confirm the predicted blade lag, pitch, and flap motions. We show the operating principle scales similarly as traditional helicopter rotor technologies, but is subject to additional new dynamics and technology considerations. Using this new rotor, experimental aircraft from 29 g to 870 g demonstrate conventional flight capabilities without requiring more than two motors for actuation. In addition, we emulate the unusual capabilities of a fully actuated MAV over six degrees of freedom using only the thrust vectoring qualities of two teetering rotors. Such independent control over forces and moments has been previously obtained by holonomic or omnidirection multirotors with at least six motors, but we now demonstrate similar abilities using only two. Expressive control from a single actuator enables new categories of MAV, illustrated by experiments with a single actuator aircraft with spatial control and a vertical takeoff and landing airplane whose flight authority is derived entirely from two rotors.

Download or read book Individual Blade Pitch Control IBC for Vibration Reduction of Lift offset Coaxial Rotor Vehicles with Auxiliary Propulsion written by Jessica Beyer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combination of a lift-offset coaxial main rotor with auxiliary propulsion results in a compound rotorcraft with both low-speed maneuverability and high-speed capabilities beyond 250 knots. In high-speed edgewise flight, the stiff rotor blades used for the coaxial main rotor generate severe vibratory loads which necessitate advanced vibration reduction techniques to limit aircrew and airframe fatigue. The present study examines the hub vibratory load reduction potential of individual blade pitch control (IBC) for a lift-offset coaxial main rotor. The present study investigates the high-speed aeromechanics of the XH-59A. This investigation expands upon previous simulations using the Rotorcraft Comprehensive Analysis System (RCAS). Parametric sweeps with varying lift-offset values and rotor RPM demonstrated a significant impact on rotor performance and hub vibratory loads. The ideal lift-offset value to minimize vibrations and maximize performance was shown to vary with the flight conditions. The lift-offset value minimizing the hub vibratory loads increased from 0.2 at 80 knots to 0.4 at 240 knots. At 200 knots, decreasing rotor RPM from 100% to 90% increased rotor performance by 20% but also increased hub vibratory loads by 60%. Open-loop, single harmonic IBC sweeps of varying amplitude, phase, and harmonic are conducted at several forward flight speeds to quantify the effects of IBC on the hub vibration index and rotor effective lift-to-drag ratio. Applying a 4/rev 1° periodic pitch input at 0° phase to both rotors decreased hub vibrations by 64% at 200 knots and only decreased rotor performance by 2%. Single harmonic IBC retained its vibration reduction potential with varying flight speed with a maximum 56% decrease at 160 knots and a 69% decrease at 240 knots. IBC inputs with increased pitch amplitude demonstrated increased vibration reduction as forward flight speed increased. Analysis of the sine and cosine components of the vibratory hub loads with IBC applied demonstrated the dependence of the vibration reduction potential on the periodic pitch amplitude and input phase. Offsetting the IBC input phase angle between the upper and lower rotors increased the vibration reduction potential of open-loop 3/rev, 2° amplitude single harmonic IBC by 32% by decreasing the 3/rev hub vertical force by 84%. The results of the present study demonstrate the potential for significant reduction of high-speed rotor vibratory loads using individual blade pitch control for a lift-offset coaxial main rotor. This conclusion is consistent with recently published results by other investigators.

Download or read book 2023 Asia Pacific International Symposium on Aerospace Technology APISAT 2023 Proceedings written by Song Fu and published by Springer Nature. This book was released on with total page 1991 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotorcraft Dynamics 1984 written by and published by . This book was released on 1985 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flight Control Design for Rotorcraft with Variable Rotor Speed written by Wei Guo and published by . This book was released on 2009 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flight control design issues for rotorcraft with variable rotor speed are investigated, and new design methodologies are developed to deal with the challenges of variable rotor speed. The benefits of using variable rotor speed for rotorcraft are explored with a rotor speed optimization study using a modified GENHEL model of UH-60A Blackhawk. The optimization results recommend to use the optimal rotor speed in each flight condition to improve the helicopter performance. The efforts are made to accommodate the optimal rotor speed schedule into the flight control system design and also address the stability issues due to the rotor speed variation. The rotor speed optimization results show significant performance improvements can be achieved with moderate reductions in rotor speed. The objective of the control design is to accommodate these rotor speed variations, while achieving desired flying qualities and maneuver performance. A gain scheduled model following/model inversion controller is used to control the roll, pitch, yaw, heave, and rotor speed degrees of freedom. Rotor speed is treated as a redundant control effector for the heave axis, and different control allocation schemes are investigated. The controllers are evaluated based on step responses and the ADS-33E height response requirement. Results show that dynamic variation in rotor speed can improve maximum climb rate and flying qualities for moderate to large commands in vertical speed, but that non-linear effects present significant challenges when integrating control of the aircraft and the engine. The effects of reduced rotor speeds on stability margins, torque required, and stability issues are also studied. A power command system in the vertical axis is designed to incorporate variable rotor speed while handling torque limits and other constraints. The vertical axis controller uses a fixed nonlinear mapping to find the combination of collective pitch and rotor speed to optimize performance in level flight, climbing/descending flight, and steady turns. In this scheme, the controller is open-loop, making it an inexpensive and reliable solution. The mapping is designed to produce a desired power level for a given pilot input. Thus the mapping can take into account the performance limits associated with the vertical axis such as power limits, torque limits, and maximum rate of descent. A model following controller is implemented for the pitch, roll, and yaw axes. The piloted simulation was performed to evaluate the controller. The impact of variable rotor speed on closed loop stability of rotorcraft is discussed. The model following controller can provide high bandwidth control and improve performance using variable rotor speed. However, reduction of rotor speed can result in rotor body coupling and even instability. A rotor state feedback control law can be designed independently and easily integrated into the baseline model following control architecture. Simulations were performed to verify the effectiveness of RSF control to stabilize the rotorcraft dynamics or improve the command tracking performance in the presence of reduced rotor RPM.

Download or read book Lecture Notes in Rotorcraft Engineering written by Antonio Filippone and published by Springer Nature. This book was released on 2023-01-27 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a multi-disciplinary compendium that includes several aspects of rotorcraft technology. It introduces the reader to the aerodynamic aspects of rotary wings and presents experimental techniques for aerodynamics. The chapters also cover rotorcraft engines and rotorcraft steady-state flight performance and stability. It explores several aspects of the tiltrotor configuration and lists challenges in their design, modelling and simulation. The reader will also find an introductory overview of flight control systems for rotorcraft, as well as the conceptual and preliminary design concepts for a conventional helicopter. This textbook contains video recordings of computer simulations that can be used alongside the main text.

Download or read book Rotorcraft Flying Handbook written by and published by . This book was released on 2000 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Suppression of Transmitted Harmonic Rotor Loads by Blade Pitch Control written by Hamilton Daughaday and published by . This book was released on 1967 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method is developed for computing the pitch angle inputs required to eliminate the transmission of harmonic vertical forces from a helicopter rotor to its driving shaft. The inertia and aerodynamic forces due to dynamic blade motions are taken into account in the computations. In finding the aerodynamic loads, a realistic model is used which represents the wake vorticity by a mesh of segmented vortex filaments. Results of computations for three flight conditions are presented for a rotor which is approximately the same as the UH-1A configuration except for assumed differences in pitch control. (Author).

Download or read book Kinematics and Constraints Associated with Swashplate Blade Pitch Control written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important class of techniques to reduce helicopter vibration is based on using a Higher Harmonic controller to optimally define the Higher Harmonic blade pitch. These techniques typically require solution of a general optimization problem requiring the determination of a control vector which minimizes a performance index where functions of the control vector are subject to inequality constraints. Six possible constraint functions associated with swashplate blade pitch control were identified and defined. These functions constrain: (1) blade pitch Fourier Coefficients expressed in the Rotating System, (2) blade pitch Fourier Coefficients expressed in the Nonrotating System, (3) stroke of the individual actuators expressed in the Nonrotating System, (4) blade pitch expressed as a function of blade azimuth and actuator stroke, (5) time rate-of-change of the aforementioned parameters, and (6) required actuator power. The aforementioned constraints and the associated kinematics of swashplate blade pitch control by means of the strokes of the individual actuators are documented. Leyland, Jane A. Ames Research Center RTOP 505-61-51...

Download or read book Suppression of Transmitted Harmonic Vertical and Inplane Rotor Loads by Blade Pitch Control written by John C. Balcerak and published by . This book was released on 1969 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction of the M 85 High speed Rotorcraft Concept written by and published by . This book was released on 1991 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Robust Flight Control of Rotorcraft written by Adam Daniel Pechner and published by . This book was released on 2010 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotorcraft Flight propulsion Control Integration written by James R. Mihaloew and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Helicopter Aerodynamics with CD Extra written by Gordon J. Leishman and published by Cambridge University Press. This book was released on 2006-04-24 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by an internationally recognized teacher and researcher, this book provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft such as tilt rotors and autogiros. The text begins with a unique technical history of helicopter flight, and then covers basic methods of rotor aerodynamic analysis, and related issues associated with the performance of the helicopter and its aerodynamic design. It goes on to cover more advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, and rotor wakes, and rotor-airframe aerodynamic interactions, with final chapters on autogiros and advanced methods of helicopter aerodynamic analysis. Extensively illustrated throughout, each chapter includes a set of homework problems. Advanced undergraduate and graduate students, practising engineers, and researchers will welcome this thoroughly revised and updated text on rotating-wing aerodynamics.

Download or read book Suppression of Transmitted Harmonic Vertical and Inplane Rotor Loads by Blade Pitch Control written by and published by . This book was released on 1969 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method was developed to study the possibility of using higher harmonic pitch-angle inputs to eliminate the transmission of oscillatory vertical and inplane forces from a helicopter rotor to its driving shaft. The aerodynamic loads are computed by using a realistic model which represents the rotor blades by bound vorticity distributions and the wake by a mesh of segmented vortex filaments. Computed results are presented for a two-bladed teetering rotor which was approximately the same as that of the UH-1A configuration except for the assumed differences in pitch control. The required pitch-angle inputs were determined for eliminating various combinations of harmonic root shears for three flight conditions. (Author).

Download or read book Rotorcraft Flight propulsion Control Integration written by James R. Mihaloew and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quad Rotorcraft Control written by Luis Rodolfo García Carrillo and published by Springer Science & Business Media. This book was released on 2012-08-12 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quad Rotorcraft Control develops original control methods for the navigation and hovering flight of an autonomous mini-quad-rotor robotic helicopter. These methods use an imaging system and a combination of inertial and altitude sensors to localize and guide the movement of the unmanned aerial vehicle relative to its immediate environment. The history, classification and applications of UAVs are introduced, followed by a description of modelling techniques for quad-rotors and the experimental platform itself. A control strategy for the improvement of attitude stabilization in quad-rotors is then proposed and tested in real-time experiments. The strategy, based on the use low-cost components and with experimentally-established robustness, avoids drift in the UAV’s angular position by the addition of an internal control loop to each electronic speed controller ensuring that, during hovering flight, all four motors turn at almost the same speed. The quad-rotor’s Euler angles being very close to the origin, other sensors like GPS or image-sensing equipment can be incorporated to perform autonomous positioning or trajectory-tracking tasks. Two vision-based strategies, each designed to deal with a specific kind of mission, are introduced and separately tested. The first stabilizes the quad-rotor over a landing pad on the ground; it extracts the 3-dimensional position using homography estimation and derives translational velocity by optical flow calculation. The second combines colour-extraction and line-detection algorithms to control the quad-rotor’s 3-dimensional position and achieves forward velocity regulation during a road-following task. In order to estimate the translational-dynamical characteristics of the quad-rotor (relative position and translational velocity) as they evolve within a building or other unstructured, GPS-deprived environment, imaging, inertial and altitude sensors are combined in a state observer. The text give the reader a current view of the problems encountered in UAV control, specifically those relating to quad-rotor flying machines and it will interest researchers and graduate students working in that field. The vision-based control strategies presented help the reader to a better understanding of how an imaging system can be used to obtain the information required for performance of the hovering and navigation tasks ubiquitous in rotored UAV operation.