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aircraft-dynamics
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Near-optimal terrain collision avoidance trajectories using elevation maps
, Article 2006 IEEE Aerospace Conference, Big Sky, MT, 4 March 2006 through 11 March 2006 ; Volume 2006 , 2006 ; 1095323X (ISSN); 0780395468 (ISBN); 9780780395466 (ISBN) ; Abbasi, A ; Sharif University of Technology
2006
Abstract
The main attempt of this paper is to present a new methodology to model a generic low-level flight close to terrain, which guarantees terrain collision avoidance. Benefiting the advantages of high-speed computer technology, this method uses satellite elevation maps to generate so called 'Quad-tree forms'. The latter is then used to find the optimal trajectories for low-level flights. The novelty of this approach, entitled the 'cost map', lies in the integration of aircraft dynamics into the segmented map. This procedure results in some near-optimal trajectories with respect to aircraft dynamics that could easily be used for minimization of flight path together with pilot effort. Different...
Compensator Design to Prevent Pilot_Induced Oscillations in Aircrafts
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor) ; Khayyat, Amir Ali Akbar (Supervisor)
Abstract
Pilot-Induced Oscillations is an unwanted, inadvertent phenomenon which has the ability to damage the aircraft completely. This thesis suggests a novel control method that can damp PIO after predicting its occurrence. The specific point of this control algorithm is that it contains a preprocessor that will not let the controller become activated unless in the case of probable PIOs, so pilot forces will not be disturbed in normal flight situations. Besides, with regard to the tendency of pilot towards establishing PIO, this control algorithm decides on pilot and controller shares in the loop. This research focuses on those groups of phenomena which take place as a result of a sudden...
A Sustainable Approach to Discover and Keep a Formation Flight
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
According to predictions of big airlines, demand of aerial transportation is rapidly increasing. This jump in aerial traffic is concerning environment activists as well as air traffic control centers. New proposed solutions such as designing new aircrafts and new fuels, require basic infrastructure and take a lot of time. Among these solutions, formation flight is an available answer to the problem as it is consistent with existing infrastructure. In this study, a robust model is proposed in which any kind of aircraft can decide to whether enter or exit a formation, and the formation problem is changed from a static problem to a dynamic one. The runtime is of a scale which can be used as an...
Trajectory design for cooperative combat missions
, Article 2008 IEEE Aerospace Conference, AC, Big Sky, MT, 1 March 2008 through 8 March 2008 ; 2008 ; 1095323X (ISSN) ; 1424414881 (ISBN); 9781424414888 (ISBN) ; Sharif University of Technology
2008
Abstract
In this paper, a hierarchical method for trajectory design for cooperative combat missions (CCM) is presented. In a military environment, in addition to physical constraints (aircraft dynamics and mountains) there are threats made by Radars or Artillery. So an important constraint, "Avoid Threats", is added to physical constraints. Major steps in trajectory design are: "Target Assignment", "Path Planning", "Path Smoothing and Trajectory Design". The most important points and a brief algorithm for each step is presented in this paper. Finally the method is applied to special case and the results presented. ©2008 IEEE
Multimodel ELM-based identification of an aircraft dynamics in the entire flight envelope
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 55, Issue 5 , 2019 , Pages 2181-2194 ; 00189251 (ISSN) ; Roudbari, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
The development of a multiple model-based identification algorithm is addressed in this paper for nonlinear modeling of a conventional aircraft in the entire flight envelope. The dynamic model of an aircraft varies significantly depending on changes in the flight condition of the air vehicle including the altitude and the equivalent air speed. Therefore, the conventional identification approaches for generating a single nonlinear model with time-invariant parameters cannot be used in the entire flight envelope of an aircraft. Accordingly, a multiple model-based approach using nonlinear autoregressive exogenous neural networks is introduced in this paper as a powerful tool in identifying...
A new approach to nonlinear modeling of highly maneuverable aircraft using neural networks
, Article 25th Congress of the International Council of the Aeronautical Sciences 2006, Hamburg, 3 September 2006 through 8 September 2006 ; Volume 5 , 2006 , Pages 3134-3140 ; Heravi, B. M ; Sharif University of Technology
Curran Associates Inc
2006
Abstract
Artificial Neural networks offer viable solution to identification and modeling of aerospace dynamic systems. This paper proposes a new approach to the nonlinear modeling of agile aircraft which is applicable to develop flight simulators. In contrary to classical methods, neural-network-based modeling of aircraft dynamics does not require any aerodynamic or propulsion model and a few flight test measured data suffice. The obtained model is shown valid for arbitrary pilot inputs within a region of mach-altitude around the pre-specified flight condition
Prediction of aerial-image motion blurs due to the flying vehicle dynamics and camera characteristics in a virtual environment
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 227, Issue 7 , 2013 , Pages 1055-1067 ; 09544100 (ISSN) ; Malaek, S. M. B ; Sharif University of Technology
2013
Abstract
This study presents comprehensive studies on practical means to predict aerial-image motion blurs due to the flying vehicle dynamics, including flying altitude; cruising speed; and angular velocities and finally installed camera characteristics; such as, frame rate and image size. The resulting predictions of blur values are in-turn used to generate blurry images to be fed as input data for later use in a de-blurring-in-the-loop of a Mono-simultaneous localization and mapping system. The whole process is coordinated by means of an integrated aerial virtual environment. The integrated aerial virtual environment consists of a three-dimensional graphical engine which could communicate with a...
Near-optimal terrain collision avoidance trajectories using elevation maps
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 47, Issue 4 , October , 2011 , Pages 2490-2501 ; 00189251 (ISSN) ; Abbasi, A ; Sharif University of Technology
2011
Abstract
The main attempt of this paper is to present a new methodology to model a generic low-level flight close to terrain, which guarantees terrain collision avoidance. Benefiting the advantages of high-speed computer technology, this method uses satellite elevation maps to generate so-called "quad-tree forms". The latter is then used to find the optimal trajectories for low-level flights. The novelty of this approach, entitled the "cost map," lies in the integration of aircraft dynamics into the segmented map. This procedure results in some near-optimal trajectories with respect to aircraft dynamics that could easily be used for minimization of flight path together with pilot effort. Different...
Generalization of ANN-based aircraft dynamics identification techniques into the entire flight envelope
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 52, Issue 4 , 2016 , Pages 1866-1880 ; 00189251 (ISSN) ; Saghafi, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
Abstract
In this paper, an approach has been proposed in order to extend the applicability of artificial neural network (ANN) techniques for flight dynamics identification into the entire flight envelope. In general, the aircraft flight dynamics is a nonlinear and coupled system whose modeling by ANNs is only possible to a limited degree around an operational point. Therefore, it cannot be expected that an ANN trained at a specific Mach and altitude will have satisfactory results in various flight conditions. Most recent studies on ANN-based identification and modeling of aircraft dynamics have been carried out primarily at specific Mach and altitudes. In this study, by introducing a new approach...
Identification of aircraft dynamics, using neural network simultaneous optimization algorithm
, Article 19th Annual European Simulation and Modelling Conference, ESM 2005, Porto, 24 October 2005 through 26 October 2005 ; 2005 , Pages 172-176 ; Heravi, B. M ; Sharif University of Technology
EUROSIS
2005
Abstract
In this paper, the ability of the neural network based system identification for aircraft modeling and simulation is investigated. The focus of this paper is to obtain methods for improving generalization of the neural network based aircraft models which are going to be used in aircraft simulators. The genetic algorithm is used to simultaneously train and optimize a modified Elman network architecture. It is shown that this method improves generalization in system identification of aircraft dynamics
Design of a Table Top Wind Tunnel with 3 Axis Balance for Airplane Identification
, M.Sc. Thesis Sharif University of Technology ; Pourtakdoust, Hossein (Supervisor)
Abstract
Experimental determination of aircraft aerodynamic characteristics is of prim importance in evaluation of its trimability and stability requirements. One of the most common tools for experimental identification of aircraft is the wind tunnel equipped with aerodynamic force and moment balance system. Design and development of wind tunnel equipped with such system for measuring aerodynamic forces and moments can affect the accuracy and quality of identifying the aircraft dynamics. However, since procurement of such professional systems is very expensive, the primary goal of this project is focused on initial design of a tabletop wind tunnel with a force and moment balance system. In addition,...
An integrated virtual environment for feasibility studies and implementation of aerial MonoSLAM
, Article Virtual Reality ; Volume 16, Issue 3 , September , 2012 , Pages 215-232 ; 13594338 (ISSN) ; Malaek, S. M. B ; Sharif University of Technology
2012
Abstract
This work presents a complete framework of an integrated aerial virtual environment (IAVE), which could effectively help implementing MonoSLAM (single-camera simultaneous localization and mapping) on an aerial vehicle. The developed system allows investigating different flight conditions without using any preloaded maps or predefined features. A 3D graphical engine integrated with a full 6 DOF aircraft dynamic simulator together with its trajectory generator completes the package. The 3D engine generates and accumulates real-time images of a general camera installed on the aerial vehicle. We effectively exploit C++ to develop the 3D graphics engine (3DGE) and all its associated visual...
Vision-based navigation in autonomous close proximity operations using neural networks
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 47, Issue 2 , April , 2011 , Pages 864-883 ; 00189251 (ISSN) ; Saghafi, F ; Sharif University of Technology
Abstract
Tight unmanned aerial vehicle (UAV) autonomous missions such as formation flight (FF) and aerial refueling (AR) require an active controller that works in conjunction with a precise sensor that is able to identify an in-front aircraft and to estimate its relative position and orientation. Among possible choices vision sensors are of interest because they are passive in nature and do not require the cooperation of the in-front aircraft in any way. In this paper new vision-based estimation and navigation algorithms based on neural networks is developed. The accuracy and robustness of the proposed algorithm have been validated via a detailed modeling and a complete virtual environment based on...
Vision-based trajectory tracking controller for autonomous close proximity operations
, Article 2008 IEEE Aerospace Conference, AC, Big Sky, MT, 1 March 2008 through 8 March 2008 ; 2008 ; 1095323X (ISSN) ; 1424414881 (ISBN); 9781424414888 (ISBN) ; Khansari Zadeh, S. M ; Sharif University of Technology
2008
Abstract
Tight unmanned aerial vehicle (UAV) autonomous missions such as formation flight and aerial refueling (AR) requires an active controller that works in conjunction with a precise vision-based sensor that is able to extract In-front aircraft relative position and orientation from captured images. A key point in implementing such a sensor is its robustness in the presence of noises and other uncertainties. In this paper, a new vision-based algorithm that uses neural networks to estimate the In-front aircraft relative orientation and position is developed. The accuracy and robustness of the proposed algorithm has been validated via a detailed modeling and a complete virtual environment based on...