Sharif Digital Repository

This paper presents a new approach to better utilize international air-corridors for formation flights. Using Particle Swarm Optimization, we show how different long-range flights can be brought together to form a formation. The idea serves both to increase international air-corridor capacities together and to decrease fuel consumption up to 8-10%. Case studies show that there are many places which such an approach could effectively be implemented to help cope with increase in fuel price as well as the demand for aerial transport of passengers and goods  

This work investigates the application of Dependency Structure Matrix (DSM) to problems with fast dynamics, such as airspace sectorization. The aim of this paper is to use a powerful mathematical tool to distinguish relevant agents in a busy airspace with a logical and meaningful distribution of the workload among air traffic controllers. This approach will help prevent controllers from getting exhausted in busy airspaces and increase the overall capacity of the airspace. It could also serve as a logical interface to simulate the chance of human error in a controlled aerodrome. Different case-studies by the authors reveal that adding realtime capabilities to the existing platform can be very... 

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... 

The loads induced on the spacecraft orbiting the Earth by the deploying elastic arm are investigated. The coupled equations of motion of the arm with the vehicle orbital mechanics are used to describe the 3D dynamic behavior of the flexible-appendage and the related disturbing loads induced on the spacecraft. To this end, an equivalent dynamical system is derived for the arm by applying an attached Non-Newtonian Reference Frame which is subjected to the orbital motion and geocentric pointing maneuver of the spacecraft. With the help of the Assumed Modes Method, the behavior of the arm attached to the spacecraft in Keplerian orbits is studied. The results show that deploying the arm in some... 

Problems related to the three-dimensional (3D) dynamics of the deploying flexible arms subjected to base angular motions are studied with simulated tip payloads and actual deployment trajectories. To facilitate the solution, an equivalent dynamical system is developed by introducing the inertial reaction forces on the arm, while the equations of motion are derived in the non-Newtonian reference frame attached to the arm. The dynamic behavior of the arm is investigated both by the finite element and assumed Modes methods for the purpose of verification. This study reveals that base angular motions lead to considerable couplings between the two lateral displacements and axial motions.... 

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... 

Purpose - The purpose of this paper is to present a novel approach in terrain following (TF) flight using fuzzy logic. The fuzzy controller as presented in this work decides where and how the aircraft needs to change its altitude. The fast decision-making nature of this method promises real-time applications even for tough terrains in terms of shape and peculiarities. The method could always assist to design trajectories in an off-line manner. Design/methodology/approach - To achieve the aforementioned goal, the method effectively incorporates the dynamics of the aircraft. Basically, the mathematical method employs special relationships among existing slope of the terrain and its derivative... 

This work describes the essential tools and architecture of a simulation environment, which could help enhance general aviation training as well as safety issues, especially while dealing with flights over unfamiliar environments. It also describes how the authors could effectively generate any desired flight path and its associated surrounding images through implementing a virtual single camera with simultaneous localization and mapping (monocular simultaneous localization and mapping) techniques. The overall package enjoys an aerial three-dimensional (3D)/graphical engine integrated with a full six-degrees-of-freedom aircraft dynamics, which serves as its trajectory generator, together... 

Deployment inertial effects of a spacecraft appendage on its flexible dynamics are investigated. The Euler-Bernoulli beam theory and the actual deployment profile, in which appendage axial motion accelerates from static state and then decelerates to end at zero velocity and acceleration, are employed. The study is concentrated on the arm dynamic stiffness introduced by inertial effects of the arm deployment, and the resultant effects on the arm flexible motions. Lagrange's equations and some appropriate shape functions in the series approximation method are employed to study the arm lateral elastic displacements. Finally a system of ordinary differential equations with time varying... 

This work investigates the application of Dependency Structure Matrix (DSM) to problems with fast dynamics, such as airspace sectorization. The aim of this paper is to use a powerful mathematical tool to distinguish relevant agents in a busy airspace with a logical and meaningful distribution of the workload among air traffic controllers. This approach will help prevent controllers from getting exhausted in busy airspaces and increase the overall capacity of the airspace. It could also serve as a logical interface to simulate the chance of human error in a controlled aerodrome. Different case-studies by the authors reveal that adding real-time capabilities to the existing platform can be... 

The dynamics of the flexible robot arm subjected to tip mass during an actual deployment is studied. The Euler-Bernoulli beam theory and the real deployment are considered in the simulation. A new real axial velocity profile is developed. This new suggested profile simulates the actual deployment such that the arm movement starts from immovability and after attaining the final required length comes back again to the static state. Using Lagrange's equation, the equations of motion of the system are derived to study the system dynamics in this suggested deployment profile. A series approximation is used to represent the lateral elastic displacements. Using variables separation and also some... 

This work aims to propose a new technique that considerably helps enhance time and precision needed to identify "Inertia Parameters (IPs)" of a typical Autonomous Space-Robot (ASR). Operations might include, capturing an unknown Target Space-Object (TSO), "active space-debris removal" or "automated in-orbit assemblies". In these operations generating precise successive commands are essential to the success of the mission. We show how a generalized, repeatable estimation-process could play an effective role to manage the operation. With the help of the well-known Force-Based approach, a new "modular formulation" has been developed to simultaneously identify IPs of an ASR while it captures a... 

This study deals with the problem of track-to-track fusion in a sensor network when the correlation terms between the estimates of the agents are unknown. The proposed method offers an upper bound for the optimal minimum variance fusion rule through construction of the correlation terms according to an optimisation scheme. In general, the upper bound filter provides an estimate that is more conservative than the optimal estimate generated by the minimum variance fusion rule, while at the same time is less conservative than one obtained by the widely used covariance intersection method. From the geometrical viewpoint, the upper bound filter results in the inscribed largest volume ellipsoid... 

This work describes an efficient technique to sequentially combine estimates resulting from individual sets of measurements provided by a network of satellites. The prescribed method is especially effective to estimate motion states of an uncooperative space object using range image data. The technique, which is fast and suitable for on-line applications, could also be effective to capture stray objects or those satellites that require periodic servicing. Such missions call for high degree of precision and reliable estimation methods. In fact, the proposed estimation architecture consists of a network of synchronized platforms, i.e., Observer Satellites (OS), each with processing power and... 

This work describes a new formulation to study the identifiability characteristics of Serially Linked Multi-body Space Systems (SLMBSS). The process exploits the so called “Lagrange Formulation” to develop a linear form of Equations of Motion w.r.t the system Inertia Parameters (IPs). Having developed a specific form of regressor matrix, we aim to expedite the identification process. The new approach allows analytical as well as numerical identification and identifiability analysis for different SLMBSSs' configurations. Moreover, the explicit forms of SLMBSSs identifiable parameters are derived by analyzing the identifiability characteristics of the robot. We further show that any SLMBSS... 

Increasing competition in the transport commercial market has resulted in many changes in the aircraft design process. There is a great tendency to include economic factors such as "affordability" In the design process. On the other hand, the so-called market dynamics are also getting complicated and a design team has to deal with many uncertainties as far as the business environment is concerned. This leads to the need for new decision-making tools in the early stages of the design process. This paper introduces a decision-making algorithm based on fuzzy logic systems which provides a structured approach to deal with uncertainties in the aircraft preliminary design. The developed tool leads... 

Purpose - The purpose of this paper is to present research into reducing the aircraft design cycle period, by reducing the necessary number of design cycle iterations. The design cycle period is one of the main characteristics of the design process and design cycle iterations play a major role in the design cycle period. Design/methodology/approach - Toachieve the above-mentioned goal, the paper presents a mathematical model of iterations for the aircraft design process. This model describes the design coupled tasks as a discrete-linear time invariant dynamic system. This model also helps identify tasks which are the most important for generating iterations. This new method basically helps... 

A novel approach in Terrain Following/Terrain Avoidance (TF/TA) flight is proposed. Due to existing unknown terrain during flight, an intelligent approach is used. Intelligence is implemented using the fuzzy approach. This method can be used in off-line design in trajectory planning which has wide applications in TF/TA maneuvers in unmanned aerial vehicles. A relationship between slope of terrain and aircraft height with speed of aircraft is constructed by fuzzy approach. This work is performed for a two dimensional Terrain Following Flight. This method is state of the art in literature. © 2007 IEEE  

A novel approach in minimum time trajectory planning in Terrain Following/Terrain Avoidance (TF/TA) flight is proposed. In this research, terrain is understood based on fuzzy logic and small changes in terrain are omitted. Another novelty is constructing a relationship between slope of terrain and aircraft height with speed of aircraft by fuzzy approach. Finally after a decision making process and based on governing dynamics and cost function, trajectory is constructed by a polynomial. This method is state of the art in literature