Tilt-Wing Rotorcraft Dynamic Analysis Using Multibody Formulation

1992 ◽  
Author(s):  
Patrick J. O’Heron ◽  
Parviz E. Nikravesh ◽  
Ara Arabyan ◽  
Donald L. Kunz
Keyword(s):  
Flight Control ◽  
High Speed ◽  
Equations Of Motion ◽  
Flight Path ◽  
Minimal Set ◽  
Near Wake ◽  
Highly Nonlinear ◽  
Nonlinear Transient ◽  
Nonlinear Transient Dynamics ◽  
Rotor Assembly

Abstract A model is presented that can be used to simulate the highly nonlinear transient dynamics associated with advanced rotorcraft conversion processes. Multibody equations of motion of the fuselage, the tilting wing, and the rotor assembly are derived using a minimal set of coordinates. An enhanced aerodynamics model is employed to account for unsteadiness and nonlinearity in the near-wake aerodynamics, with a dynamic uniform inflow to compute the far-wake aerodynamics, and a flight control system is employed to compute the blade pitch settings that are necessary to achieve a desired flight path. The model is subjected to a demanding flight path simulation to illustrate that it can perform vertical take-off, hover, tilt-wing conversion, and high-speed forward flight maneuvers effectively.

Planing force identification in high-speed underwater vehicles

2016 ◽  
Vol 22 (20) ◽  
pp. 4176-4191 ◽  
Author(s):  
Mojtaba Mirzaei ◽  
Mohammad Eghtesad ◽  
Mohammad Mahdi Alishahi
Keyword(s):  
High Speed ◽  
Hybrid Control ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Underwater Vehicles ◽  
The Body ◽  
Force Identification ◽  
Control Approach ◽  
Control Scheme ◽  
Highly Nonlinear

One of the most important issues, which high-speed underwater vehicles (HSUV) deal with, is the so-called planing force. The dynamic of HSUV includes two separate phases called planing phase and non-planing phase. Ideally, in perfect flight, the vehicle should fly within the cavity walls. However, in practice, the vehicle impacts on the cavity boundaries due to disturbances. The magnitude of the planing force is large and has a strong effect on dynamics of HSUV. However, planing force modeling is often too simple and therefore inaccurate, due to the nonlinear interaction among the solid, liquid, and gaseous phases, which is not well understood yet. Consequently, planing force identification is of great importance and should be studied in details. The present paper discusses the identification of the planing force in HSUV. For this purpose, the equations of motion are developed for the HSUV in the planing phase while the tail and the body end impact on the cavity wall. Then, a robust hybrid switching control approach is employed to deal with the highly nonlinear behavior of the underwater vehicle as it is influenced by the liquid-gas boundary interactions. An on-line planing force identification based on Lyapunov function is considered within designing controller procedure, thus the stability of the system is guaranteed. Lateral and longitudinal planing force identification are achieved and discussed. Compared to the proportional-integral-derivative control scheme, the hybrid control scheme seems to increase the stabilization of HSUV, which is useful in avoiding unsteady changes of cavity shape.

scholarly journals Flight-Path Tracking Control of an Aircraft Using Backstepping Controller

2015 ◽  
Vol 15 (2) ◽  
pp. 270
Author(s):  
Labane Chrif ◽  
Zemalache Meguenni Kada ◽  
Tahar Mohamed
Keyword(s):  
Linear Models ◽  
Equations Of Motion ◽  
Path Tracking ◽  
Flight Path ◽  
Primary Control ◽  
Feedback Form ◽  
Nonlinear Simulation ◽  
Stabilizing Controller ◽  
External Loop ◽  
Highly Nonlinear

For transportation aircraft, the primary control objective for an autopilot system engaged during approach and landing is relative to the flight path tracking on the basis of highly simplified linear models of flight dynamics. The dynamics governing the flight path of an aircraft are in general highly nonlinear and involve complex physics for which no accurate models are available. In this paper a nonlinear model describing the longitudinal equations of motion in strick feedback form is derived. Backstepping is utilized for the construction of a globally stabilizing controller with a number of free parameters. It is implemented a controller with an internal loop controls involving the pitch rate of the aircraft and an external loop which includes angle of attack, path angle and pitch angle. Finally, nonlinear simulation results for a longitudinal model of a transportation aircraft are displayed and discussed.

Dynamic Model of a Vertical Piano Action Mechanism

2009 ◽  
Author(s):  
Ramin Masoudi ◽  
Stephen Birkett ◽  
John McPhee
Keyword(s):  
High Speed ◽  
Equations Of Motion ◽  
Geometrical Parameters ◽  
Action Mechanism ◽  
High Speed Imaging ◽  
Multibody Model ◽  
Highly Nonlinear ◽  
Scanned Images ◽  
Grand Piano ◽  
Real Action

The dynamic behavior of a vertical piano action mechanism is studied using a simulation model and compared qualitatively to observations obtained by high-speed imaging of a real action. The simulated response of all components is obtained for two different prescribed input force profiles applied at the key front. These inputs represent in simplified form the general shape of a typical force input by a pianist measured at the key surface for a strong (forte) strike, or two key strikes in rapid succession. The graph-theoretic multibody model constructed represents the components and their interactions. Explicit contact edges provide forces generated between two bodies as a function of their kinematic states, using a special contact model to represent the compression of felt lined interfaces that can separate during the key stroke. Masses and geometrical parameters of the action were measured by importing scanned images from a real action into CAD software. The highly nonlinear system of five ordinary differential equations of motion was derived symbolically and solved by a numerical stiff solver in Maple. The effects of two components not present in the horizontal grand piano action, the bridle strap and hammer butt spring, were examined using simulations. The butt spring is seen to serve an important function in assisting the return of the hammer to its rest position on key release. The model will be useful in future studies to compare vertical actions to horizontal grand piano actions, as these are known to exhibit quite different playing characteristics.

Application of robust H-infinity controller in transition flight modeling of autonomous VTOL convertible Quad Tiltrotor UAV

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Navya Thirumaleshwar Hegde ◽  
V. I. George ◽  
C. Gurudas Nayak ◽  
Aldrin Claytus Vaz
Keyword(s):  
Mathematical Modeling ◽  
Flight Control ◽  
High Speed ◽  
Equations Of Motion ◽  
H Infinity ◽  
Content Type ◽  
Helicopter Flight ◽  
Aerial Vehicles ◽  
H Infinity Control ◽  
And Performance

PurposeThis paper aims to provide a mathematical modeling and design of H-infinity controller for an autonomous vertical take-off and landing (VTOL) Quad Tiltrotor hybrid unmanned aerial vehicles (UAVs). The variation in the aerodynamics and model dynamics of these aerial vehicles due to its tilting rotors are the key issues and challenges, which attracts the attention of many researchers. They carry parametric uncertainties (such as non-linear friction force, backlash, etc.), which drives the designed controller based on the nominal model to instability or performance degradation. The controller needs to take these factors into consideration and still give good stability and performance. Hence, a robust H-infinity controller is proposed that can handle these uncertainties.Design/methodology/approachA unique VTOL Quad Tiltrotor hybrid UAV, which operates in three flight modes, is mathematically modeled using Newton–Euler equations of motion. The contribution of the model is its ability to combine high-speed level flight, VTOL and transition between these two phases. The transition involves the tilting of the proprotors from 90° to 0° and vice-versa in 15° intervals. A robust H-infinity control strategy is proposed, evaluated and analyzed through simulation to control the flight dynamics for different modes of operation.FindingsThe main contribution of this research is the mathematical modeling of three flight modes (vertical takeoff–forward, transition–cruise-back, transition-vertical landing) of operation by controlling the revolutions per minute and tilt angles, which are independent of each other. An autonomous flight control system using a robust H-infinity controller to stabilize the mode of transition is designed for the Quad Tiltrotor UAV in the presence of uncertainties, noise and disturbances using MATLAB/SIMULINK. This paper focused on improving the disturbance rejection properties of the proposed UAV by designing a robust H-infinity controller for position and orientation trajectory regulation in the presence of uncertainty. The simulation results show that the Tiltrotor achieves transition successfully with disturbances, noise and uncertainties being present.Originality/valueA novel VTOL Quad Tiltrotor UAV mathematical model is developed with a special tilting rotor mechanism, which combines both aircraft and helicopter flight modes with the transition taking place in between phases using robust H-infinity controller for attitude, altitude and trajectory regulation in the presence of uncertainty.

scholarly journals Assessment of Linearization Approaches for Multibody Dynamics Formulations

2017 ◽  
Vol 12 (4) ◽  
Author(s):  
Francisco González ◽  
Pierangelo Masarati ◽  
Javier Cuadrado ◽  
Miguel A. Naya
Keyword(s):  
Mechanical System ◽  
Multibody Dynamics ◽  
Equations Of Motion ◽  
Differential Algebraic Equations ◽  
Algebraic Equations ◽  
Practical Applications ◽  
Linearization Methods ◽  
Highly Nonlinear ◽  
Wide Range ◽  
The Way

Formulating the dynamics equations of a mechanical system following a multibody dynamics approach often leads to a set of highly nonlinear differential-algebraic equations (DAEs). While this form of the equations of motion is suitable for a wide range of practical applications, in some cases it is necessary to have access to the linearized system dynamics. This is the case when stability and modal analyses are to be carried out; the definition of plant and system models for certain control algorithms and state estimators also requires a linear expression of the dynamics. A number of methods for the linearization of multibody dynamics can be found in the literature. They differ in both the approach that they follow to handle the equations of motion and the way in which they deliver their results, which in turn are determined by the selection of the generalized coordinates used to describe the mechanical system. This selection is closely related to the way in which the kinematic constraints of the system are treated. Three major approaches can be distinguished and used to categorize most of the linearization methods published so far. In this work, we demonstrate the properties of each approach in the linearization of systems in static equilibrium, illustrating them with the study of two representative examples.

Highly nonlinear polarization maintaining dispersion compensating fiber for high-speed transmission system

2013 ◽  
Vol 52 (11) ◽  
pp. 116112 ◽  
Author(s):  
Md. Imran Hasan ◽  
Md. Samiul Habib ◽  
Md. Selim Habib ◽  
S. M. Abdur Razzak
Keyword(s):  
High Speed ◽  
Transmission System ◽  
Nonlinear Polarization ◽  
Highly Nonlinear ◽  
Polarization Maintaining

The Calculation of Train Slipstreams on Platform of Underground High-Speed Rail Station

2013 ◽  
Vol 842 ◽  
pp. 445-448
Author(s):  
Wei Chao Yang ◽  
Chuan He ◽  
Li Min Peng
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Horizontal Distribution ◽  
Wake Flow ◽  
Railway Tunnel ◽  
Long Distance ◽  
Near Wake ◽  
High Speed Rail ◽  
Numerical Work ◽  
Rail Station

This paper describes the results of numerical work to determine the flow structures of the slipstream and wake of a high speed train on platforms of underground rail station using three-dimensional compressible Euler equation. The simulations were carried out on a model of a simplified three-coach train and typical cross-section of Chinese high-speed railway tunnel. A number of issues were observed: change process of slipstreams, longitudinal and horizontal distribution characteristics of train wind. Localized velocity peaks were obtained near the nose of the train and in the near wake region. Maximum and minimum velocity values were also noticed near to the nose rear tip. These structures extended for a long distance behind the train in the far wake flow. The slipstream in platform shows the typical three-dimensional characteristics and the velocity is about 4 m/s at 6 m away from the edge of platform.

Design of sliding mode flight control system for a flexible aircraft

2021 ◽  
pp. 095441002110455
Author(s):  
Majeed Mohamed ◽  
Madhavan Gopakumar
Keyword(s):  
Control System ◽  
Rigid Body ◽  
Flight Control ◽  
High Speed ◽  
Sliding Mode ◽  
Flight Mechanics ◽  
Frequency Separation ◽  
Flight Control System ◽  
Flexible Aircraft ◽  
Aircraft Dynamics

The evolution of large transport aircraft is characterized by longer fuselages and larger wingspans, while efforts to decrease the structural weight reduce the structural stiffness. Both effects lead to more flexible aircraft structures with significant aeroelastic coupling between flight mechanics and structural dynamics, especially at high speed, high altitude cruise. The lesser frequency separation between rigid body and flexible modes of flexible aircraft results in a stronger interaction between the flight control system and its structural modes, with higher flexibility effects on aircraft dynamics. Therefore, the design of a flight control law based on the assumption that the aircraft dynamics are rigid is no longer valid for the flexible aircraft. This paper focuses on the design of a flight control system for flexible aircraft described in terms of a rigid body mode and four flexible body modes and whose parameters are assumed to be varying. In this paper, a conditional integral based sliding mode control (SMC) is used for robust tracking control of the pitch angle of the flexible aircraft. The performance of the proposed nonlinear flight control system has been shown through the numerical simulations of the flexible aircraft. Good transient and steady-state performance of a control system are also ensured without suffering from the drawback of control chattering in SMC.

3-D nonlinear transient analysis and design of eddy current brake for high-speed trains

2012 ◽  
Vol 40 (3) ◽  
pp. 205-214 ◽  
Author(s):  
Bo Zhang ◽  
Tao Peng ◽  
Qiao Chen ◽  
Quan-Liang Cao ◽  
Kai Ji ◽  
...  
Keyword(s):  
Eddy Current ◽  
High Speed ◽  
Transient Analysis ◽  
Analysis And Design ◽  
High Speed Trains ◽  
Nonlinear Transient ◽  
Nonlinear Transient Analysis
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