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Modeling and Simulation Technologies Conference and Exhibit, AIAA 1998

作者： Perhinschi, Mario G. Flight Dynamics and Control Laboratory National Aerospace Research Institute Bucharest Romania

The purpose of this paper is to present the development of a simple turbulence representation suitable for helicopter dynamic simulation, stability and performance analysis, as well as pilot-in-the-loop rotorcraft handling qualities assessment. The frozen field hypothesis and linear approximation are assumed. Components of the uniform field velocity are included as additive perturbations affecting aerodynamic terms of the state matrix. Effects of the spatial gradients on parts of the helicopter other than rotor are considered as equivalent rotations. Effects of the spatial gradients on the rotor are considered by means of equivalent blade pitch angle perturbations. Vertical gradients are neglected. Equivalent blade pitch angle perturbations are determined such that total aerodynamic forces and moments over the rotor disc are conserved. The approach leads to a linear system with part of the input random. Some simulation results are presented to illustrate behavior and use of the model. © 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Linear systems

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A simulation model of an uninhabited aircraft

A simulation model of an uninhabited aircraft

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Modeling and Simulation Technologies Conference 2000

作者： Perhinschi, Mario G. Flight Dynamics and Control Laboratory National Aerospace Research Institute Bucharest Romania

The purpose of this paper is to present the general conceptual frame of a simulation package for the flight of an uninhabited aircraft that is currently under development as pan of a virtual design environment at the National Aerospace research Institute of Bucharest, Romania. The major components are defined according to the tasks that need to be performed. Their structural architecture, content, interconnecting relationships and informational flow are identified and described. General dynamic equations of motion of a rigid body airvehicle with rotating parts and variable center of mass position are derived using Kane's method. A partial, preliminary implementation has been performed and numerical results are presented to illustrate it. © 2000 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： flight simulators

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A study of helicopter handling qualities in turbulence using a human pilot structural model 23rd

A study of helicopter handling qualities in turbulence using...

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23rd Atmospheric flight Mechanics Conference, 1998

作者： Perhinschi, Mario G. Flight Dynamics and Control Laboratory National Aerospace Research Institute Bucharest Romania

In this paper the impact of atmospheric turbulence on helicopter handling qualities is investigated using a simple random turbulence representation and a structural human pilot model. Linear approximation of the turbulence field and the frozen field concept are assumed. Effects of uniform field component and spatial gradients in the horizontal plane are individually evaluated on each axis. Turbulence intensity is varied from low to medium and severe, at low and high altitude. Simple, single axis missions on each of the four control channels are considered. Several different aircraft configurations that yield various handling qualities levels, as evaluated using classic criteria, are compared to each other and consistency of handling qualities prediction is assessed. Contributions of every turbulence field component to degradation of handling qualities are evaluated. Some results suggest that handling qualities hierarchy hi still air is not necessarily preserved in turbulence. Plots to illustrate major observed trends are presented. © 1998, by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Atmospheric turbulence

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Parameter optimization via genetic algorithm of fuzzy controller for autonomous airvehicle

Parameter optimization via genetic algorithm of fuzzy contro...

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Guidance, Navigation, and control Conference and Exhibit, 1999

作者： Perhinschi, Mario G. Flight Dynamics and Control Laboratory National Aerospace Research Institute Bucharest Romania

In this paper, an optimal controller for the longitudinal channel of an autonomous helicopter model is designed by blending together two artificial intelligence techniques, genetic algorithms and fuzzy control. An evaluation index that captures the complex, constrained, multiple objective character of the problem was built based on several design requirements expressed in terms of the time response of the controlled system. The parameters of the fuzzy controller are optimized to maximize the evaluation index using a genetic algorithm. The parameters subject to optimization are: the shape and width of the membership functions, number of linguistic values, defuzzification method and scaling factors. The genetic algorithm is based on binary genetic representation, a roulette wheel selection technique with elitist selection strategy and classic genetic operators: mutation and crossover. The performance of the resulting optimal controller is compared with performance obtained with standard design. Observations are made regarding influences of fuzzy controller parameters on the general performance of the controlled system. © 1999 The American Institute of Aeronautics and Astronautics Inc. All right reserved.

关键词： Genetic algorithms

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Development of non-linear, low-speed aerodynamic model for the F-16/VISTA 22nd

Development of non-linear, low-speed aerodynamic model for t...

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22nd Atmospheric flight Mechanics Conference, 1997

作者： Kay, Jacob Ralston, John N. Lash, Stanley F. Bihrle Applied Research Inc. HamptonVA United States Control Dynamics Branch Wright Laboratory Flight Dynamics Directorate Flight Control Division WPAFB OH United States

A new low-speed aerodynamic database for the F-16/VISTA was developed from low-speed data sets obtained from NASA Langley's 30x60 facility and 20-ft vertical wind tunnel and NASA Ames' 12-ft pressure tunnel. This new model was designed to be continuous from-80° to +90° angle of attack, -30° to +30° of sideslip, and to incorporate all sideslip and control effectiveness interactions in a fully non-linear structure. The aerodynamic data set also includes wind-axis and body-axis damping terms and is configured to utilize these data separately for high-fidelity modeling of dynamic conditions. The purpose of this effort is to demonstrate the benefits of a completely nonlinear aerodynamic data base to capture the dependencies that occur while maneuvering at high angle of attack. This model was validated against a set of high angle of attack flight data from the F-16 VISTA/MATV flight test program. Minimal refinements to the data set were required to produce an excellent correlation between the simulation model and the flight test results for maneuvers in and above the stall regime. © 1997, American Institute of Aeronautics and Astronautics, Inc.

关键词： NASA

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PC-based simulation of the F-16/MATV

PC-based simulation of the F-16/MATV

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Modeling and Simulation Technologies Conference, 1997

作者： O’Rourke, Matthew J. Ralston, John N. Bell, Jeffery W. Lash, Stanley F. Bihrle Applied Research Inc. HamptonVA23666 United States Control Dynamics Branch Wright Laboratory Flight Dynamics Directorate Flight Control Division WPAFB OH45433 United States

The Wright laboratory (WL) F-16 simulation model has been re-hosted on a personal computer running a unique six-degree-of-freedom simulation environment. This model contains over 1000 two dimensional aerodynamic data tables and a complex flight control system (PCS) modeled by thousands of lines of FORTRAN computer code. The PCS model can emulate several different configurations including a standard Block 40 F-16 and the F-16 Variable In-flight Stability Aircraft (VISTA) with Multi-Axis Thrust Vectoring (MATV) in numerous modes. In addition to re-hosting the WL F-16 model, the high-angle-of-attack database was extended to include nonlinear effects at moderate to high angles of attack. These additional data greatly improve the ability of the simulation model to predict the in-flight maneuvering characteristics of the F-16 with active MATV. © 1997 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： flight control systems

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Multi‐GNSS Processing Combining GPS, GLONASS, BDS and GALILEO Observations

Multi‐GNSS Processing Combining GPS, GLONASS, BDS and GALIL...

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第五届中国卫星导航学术年会

作者： Cui Hongzheng Tang Geshi Hu Songjie Song Baiyan Liu Huicui Sun Jing Zhang Peng Li Cuilan Ge Maorong Han Chao Flight Dynamics Laboratory Beijing Aerospace Control Center School of Astronautics Beijing University of Aeronautics and Astronautics German Research Center for Geosciences

ISBN: (纸本)9783642547393

Coexistence and development of four kinds of Global Satellite Navigation System, GPS, GLONASS, BDS, and GALILEO have initially established. In order to benefit from multi-GNSS applications, including increase in usable SVs, signals and frequencies, increase in availability and coverage, more robust and reliable services, and so on, firstly we need to obtain the precise multi-GNSS orbit and clock in a unified space and time frame. Based on the knowledge of the EPOS and EPOS-RT (Earth Parameter and Orbit determination System in Real-Time) software package, Beijing Aerospace control Center (BACC) has been working on his own software package for multi-GNSS data processing. This paper firstly introduces the multi-GNSS processing strategies in detail, and adopts additional inter system biases parameter (ISB) except the normal IGS and GFZ observation model and dynamic model. On the basis of above strategies and the observation data from a network of multi-GNSS capable receivers from the IGS Multi-GNSS EXperiment (MGEX) and a regional BDS station network operated by China, the experiments and simulation are carried out. The results are validated against products from other institutes and by overlap comparison. The impact on orbit and clock precision by combined processing against single system processing is investigated and the improvement on precise point positioning (PPP) is also evaluated.

关键词： Multi-GNSS Combined Data Processing Inter System Biases (ISB) Orbit overlap Precise Point Positioning (PPP)

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Vortex breakdown location over 65° delta wings empiricism and experiment 16th

Vortex breakdown location over 65° delta wings empiricism a...

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16th AIAA Applied Aerodynamics Conference, 1998

作者： Jobe, Charles E. Control Dynamics Branch Flight Control Div. Air Force Research Laboratory Wright-Patterson AFB OH United States

Thirty-eight data sets from static tests of various 65° delta wings in many water and wind tunnels are compared with four empirical vortex breakdown location prediction methods and the results of two Navier-Stokes computations to assess their range of validity in pitch." Vortex breakdown is the sudden expansion and subsequent chaotic evolution of the otherwise orderly, spiraling, leading-edge vortex flow over the upper surface. Large fluctuations occur in vortex breakdown location at static test conditions making accurate experimental determination difficult. The prediction methods do not account for the seemingly minor geometric details that vary between the models such as thickness, leadingedge bevel angle and radius, trailing-edge bevel angle, sting mounting, instrument housings, etc. These geometric variations significantly affect the position of vortex breakdown and degrade the accuracy of the predictions. The large changes in the flow produced by small geometric changes indicate that an efficient flow control strategy may be possible. Many of the data sets are not corrected for tunnel wall effects which may account for some of the differences. Data presented herein are as published by the original authors, without additional corrections. © 1998, American Institute of Aeronautics and Astronautics, Inc.

关键词： Vortex flow

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Acoustic cloak constructed with thin-plate metamaterials

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International Journal of Smart and Nano Materials 2015年第1期6卷 73-83页

作者： Pei Li Xuebing Chen Xiaoming Zhou Gengkai Hu Ping Xiang Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Educationand School of Aerospace EngineeringBeijing Institute of Technology100081BeijingChina Systems Engineering Research Institute 100036BeijingChina

We propose a strategy for designing the cylindrical acoustic cloak with thin-plate *** inhomogeneous cloaking shell as derived by transformation acoustics is first discretized into a three-layer anisotropic metafluid,and their material parameters are optimized by minimizing the external *** these metafluids are practically realized by thin-plate structures according to the metamaterial *** an example,an acoustic cloak is designed with nine layers of thin plate and totally 900 plate *** simulations are performed to assess the cloaking performance of the designed structure.

关键词： acoustic cloak thin-plate metamaterial optimization

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Modeling and simulation of flexible flight vehicles

Modeling and simulation of flexible flight vehicles

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Modeling and Simulation Technologies Conference and Exhibit, AIAA 1998

作者： Schmidt, David K. Raney, David L. Flight Dynamics and Control Laboratory University of Maryland College ParkMD20742 United States Dynamics and Control Branch NASA Langley Research Center HamptonVA23681 United States

The effects of flexibility on the flight dynamics of aircraft have been shown to be quite significant, especially as the frequencies of the elastic modes become lower and approach those of the rigid-body modes. The handling characteristics of such vehicles are altered significantly from those of a rigid vehicle, and the design of the flight-control system may become drastically more complex. Consequently, the need to accurately model the dynamics of such vehicles, and to develop valid simulations is becoming particularly acute. In this paper the theoretical development of a generic model will be presented. The resulting model structure is appropriate for any flexible atmospheric flight vehicle. Furthermore, the modeling technique used allows for the flexible degrees of freedom to be added to an existing simulation based on a rigid-body model. The data necessary for modeling a specific vehicle includes aerodynamic stability derivatives, aerodynamic influence coefficients, elastic mode shapes, modal frequencies and damping, and generalized masses. An example will be presented based on the B-l aircraft, which was used to develop a motion-based simulation in NASA Langley's simulation facility. Also to be presented will be examples of the dynamic responses (time and frequency domain) for a generic elastic vehicle. These responses are critical to evaluating hardware and software requirements for simulation fidelity, in terms of visual and motion cues, for example. Furthermore, a brief assessment of the effects of limitations in the simulation will also be presented. Such limitations considered include digital time delay, motion-hardware bandwidth, and motion washout logic. © 1998 by David K. Schmidt Published by AIAA.

关键词： flight control systems

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