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maneuvering
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Evaluation of planing craft maneuverability using mathematical modelling
, Article Brodogradnja ; Volume 67, Issue 1 , 2016 , Pages 85-100 ; 0007215X (ISSN) ; Seif, M.S ; Mehdigholi, H ; Sharif University of Technology
Brodarski Institute
2016
Abstract
Ship transportation is increasing globally as is the risk of collision especially in congested areas. Numerical modeling method is a major simulation method to predict ship maneuverability. Ship maneuvering in calm water is an important topic to avoid collisions and leads to safe navigation. Therefore, reliable ship maneuvering simulations are required for incident analysis and prevention. In recent time within the research community orientated towards ship hydrodynamics an increasing attention has been paid to simultaneous solution of the planing ship maneuvering problem. The maneuverability of planing craft has been the subject of many research projects during the last few decades. To...
Hydrodynamic analysis of trimaran vessels
, Article Polish Maritime Research ; Volume 15, Issue 1 , June , 2008 , Pages 11-18 ; 12332585 (ISSN) ; Jahanbakhsh, E ; Seif, M ; Sayyaadi, H ; Sharif University of Technology
2008
Abstract
Trimaran vessels are developed for different applications and hydrodynamic behavior of such vessels is different than usual mono-hulls. In this paper hydrodynamic resistance and maneuvering of a trimaran with Wigley body form are investigated. The effects of outriggers position in four different longitudinal and two transverse locations are studied. For hydrodynamic simulations a CFD code has been developed and used. This code is capable for simulating three dimensional, time dependent, two phases, viscous flow coupled with rigid body motion. Formulation and solution algorithm are described in detail. Different case studies have been performance and numerical results have shown good...
A hybrid fuzzy adaptive tracking algorithm for maneuvering targets
, Article 2008 IEEE International Conference on Fuzzy Systems, FUZZ 2008, Hong Kong, 1 June 2008 through 6 June 2008 ; 2008 , Pages 1869-1873 ; 10987584 (ISSN) ; 9781424418190 (ISBN) ; Sadati, N ; Sharif University of Technology
2008
Abstract
A new hybrid fuzzy adaptive algorithm for tracking maneuvering targets is proposed in this paper. The algorithm is implemented with fuzzy inference system (FIS) and current statistical model and adaptive Altering (CSMAF). The CSMAF algorithm is one of most effective methods for tracking the maneuvering targets. It has a higher precision in tracking the maneuvering targets with larger accelerations while it has a lower precision in tracking the maneuvering targets with smaller acceleration. In the proposed algorithm, to overcome the disadvantage of the CSMAF algorithm, the covariance of process noise CSMAF is adjusted adaptively by the output of a FIS. The input of the FIS is discrepancy of...
Optimal Trajectory Shaping of Orbital Maneuver in Presence of Uncertainties
, M.Sc. Thesis Sharif University of Technology ; Pourtakdoust, Hossein (Supervisor) ; Kiani, Maryam (Supervisor)
Abstract
Traditionally, orbital maneuvers are obtained according to mission cost, time and several constraints. This thesis considers the use of covariance as a measure of uncertainties in the design of orbit maneuvers. The ideal solution in the proposed method is the maneuver that obtains the minimum uncertainty at the desired times in presence of the mission constraints. In this thesis two impulsive orbit maneuver schemes, based on shaping method and sequential lambert solutions, are developed and has been analyzed under uncertainties. Moreover, a novel rendezvous design methodology is proposed in order to minimize the covariace trace at the impulse locations, considering several constraints...
Multiple-impulse orbital maneuver with limited observation window
, Article Advances in Space Research ; Volume 66, Issue 4 , 2020 , Pages 992-1000 ; Pourtakdoust, S. H ; Sayanjali, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper proposes a solution for multiple-impulse orbital maneuvers near circular orbits for special cases where orbital observations are not globally available and the spacecraft is being observed through a limited window from a ground or a space-based station. The current study is particularly useful for small private launching companies with limited access to global observations around the Earth and for orbital maneuvers around other planets for which the orbital observations are limited to the in situ equipment. An appropriate cost function is introduced for the sake of minimizing the total control/impulse effort as well as the orbital uncertainty. It is subsequently proved that for a...
A gaussian sum method to analyze bounded acceleration guidance systems
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 53, Issue 4 , 2017 , Pages 2060-2076 ; 00189251 (ISSN) ; Nobahari, H ; Sharif University of Technology
Abstract
To analyze a highly nonlinear dynamical system, it is necessary to evaluate the time evolution of the probability density function (pdf) of the states. In this paper, a novel Gaussian sum method is proposed to approximate the non-Gaussian pdf of a dynamical system whose nonlinear elements depend only on a single state variable. Using the Chapman-Kolmogorov equation, a set of recursive equations is derived to propagate the mean, covariance, and weight of the Gaussian sum components. There are several multiple integrals in the recursive equations which are analytically reduced to single integrals. As an application, the proposed approach is applied to statistically analyze the engagement of...
Studying crash avoidance maneuvers prior to an impact considering different types of driver's distractions
, Article 21st EURO Working Group on Transportation Meeting, EWGT 2018, 17 September 2018 through 19 September 2018 ; Volume 37 , 2019 , Pages 203-210 ; 23521457 (ISSN) ; Razi Ardakani, H ; Kermanshah, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Performing maneuvers such as braking and lane changing can hinder the occurrence of a crash. The driver tends to escape from the crash occurrence or reduce its severity by doing the maneuver, so finding the factors affecting this type of maneuver can help the driver to react better. This work aims to discover the effect of distraction-related factors on the performance of a crash avoidance maneuver. In order to pave the way for a more thorough comprehension of this matter, variables related to the characteristics of the driver, road, crash, vehicle, and environmental properties are also considered in the analysis. The used data is based on General Estimate System 2010 dataset, a dataset...
Adaptive passive sensor selection for maneuvering target localization and tracking using a multisensor surveillance system
, Article Cogent Engineering ; Volume 7, Issue 1 , 2020 ; Haeri, M ; Khaloozadeh, H ; Sharif University of Technology
Cogent OA
2020
Abstract
This paper investigates maneuvering-target tracking problem based on a multisensor system and interacting multiple model (IMM). The estimation is performed by a novel particle filter (PF) with a capability to deal with the state-dependent noises and interference of the sensors’ coverage environment. An adaptive sensor selection algorithm, where some sensors are selected in each stage based on the signal-to-interference pulse noise ratio (SINR) and participate in the state estimation, is proposed. To deal with the effect of interference, we focus on designing and implementing the sensor selection algorithm, where a multisensor system with nonuniform arrays is derived by solving a convex...
Fatigue life analysis of automotive cast iron knuckle under constant and variable amplitude loading conditions
, Article Applied Mechanics ; Volume 3, Issue 2 , 2022 , Pages 517-532 ; 26733161 (ISSN) ; Souri, K ; Bayat, A. G ; Jabalbarez, R. S ; Ahmad, M ; Sharif University of Technology
MDPI
2022
Abstract
The main aim of the present paper is to assess the fatigue lifetime of ductile cast iron knuckles as one of the critical components of an automotive steering system. To this end, a real driving path, including various maneuvers, such as acceleration, braking, cornering, and moving on various types of road roughness, was considered. Different load histories, which are applied on various joints of the component (i.e., lower control arm, steering linkage, and Macpherson strut), were extracted through Multi-Body Dynamics (MBD) analysis of a full vehicle model. The achievements of previous studies have proved that the steering knuckle fails from the steering linkage and due to the rotational...
Adaptive Maneuvers for Aircraft Conflict Resolution Using Learning Theory
, M.Sc. Thesis Sharif University of Technology ; Malaek, Mohammad Bagher (Supervisor)
Abstract
The problem of detection and resolution of aircraft collisions is very important due to the increasing demand for flights. Many algorithms have been developed in the past to increase automation in air traffic management and reduce the workload of air traffic controllers. These algorithms either have difficulty in generalizing to real problems or have high computational costs and do not correspond to the reality of the actual maneuvering characteristics of the aircraft performance. The aim of present study is to obtain dynamic maneuvers that are adaptive with reality and also optimal in terms of utilizing the capacity of flight sectors, so we propose Deep Reinforcement Learning(DRL) based on...
A new shape-based multiple-impulse strategy for coplanar orbital maneuvers
, Article Acta Astronautica ; Volume 161 , 2019 , Pages 200-208 ; 00945765 (ISSN) ; Kiani, M ; Pourtakdoust, S. H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A new shape-based geometric method (SBGM) is proposed for generation of multi-impulse transfer trajectories between arbitrary coplanar oblique orbits via a heuristic algorithm. The key advantage of the proposed SBGM includes a significant reduction in the number of design variables for an N-impulse orbital maneuver leading to a lower computational effort and energy requirement. The SBGM generates a smooth transfer trajectory by joining a number of confocal elliptic arcs such that the intersections share common tangent directions. It is proven that the well-known classic Hohmann transfer and its bi-elliptic counterpart between circular orbits are special cases of the proposed SBGM. The...
Impedance control of a flexible link robot for constrained and unconstrained maneuvers using Sliding Mode Control (SMC) method
, Article Scientia Iranica ; Volume 14, Issue 1 , 2007 , Pages 33-45 ; 10263098 (ISSN) ; Karimzadeh, A ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
In this paper, the modeling and impedance-control of a one link flexible robot is presented. The concept of impedance control of flexible link robots is rather new and is being addressed for the first time. The control algorithm is valid for both constrained and unconstrained maneuvers. First, equations of motion and the associated boundary conditions are derived using Hamilton's principle. A linear finite dimensional model is, then, generated in the Cartesian coordinates, using the assumed mode method and by introduction of a proper coordinate transformation. The target impedance is, then, introduced in the Cartesian coordinate system and a control law is designed to realize the proposed...
Novel command to line of sight guidance with practical limitations
, Article Asian Journal of Control ; Volume 24, Issue 3 , 2022 , Pages 1426-1436 ; 15618625 (ISSN) ; Haeri, M ; Sharif University of Technology
John Wiley and Sons Inc
2022
Abstract
In this paper, a novel scheme of command to line-of-sight guidance law regarding the outstanding practical limitations is proposed. With the aid of formulating problem in pursuer's line of sight frame, the exact feed-forward acceleration commands are derived for a general target motion in three-dimensional engagement geometry. Then, a nonlinear control scheme constructed from feed-forward terms along with a nested saturated feedback strategy is suggested. Two momentous practical limitations are considered. The first is related to existence of pursuer's acceleration saturation which is ignored in all existing solutions. The required conditions to insure the global stability are derived...
A Correction Algorithm for Intersecting Trajectories of Two Flying Robots
, M.Sc. Thesis Sharif University of Technology ; Banazade, Afshin (Supervisor)
Abstract
The main interest of this study is designing a correction algorithm for intersecting trajectories of two flying robots. For this purpose, path planning algorithms were studied and Rapidly-exploring random tree (RRT) was chosen as a proper algorithm for flying robots in urban environments which is modified for the problem. It should be considered that this project focuses on path correction therefore initial path could be produced by any suitable algorithm. In addition, new paths were designed with flying robots’ performance equations. The correction was done so the paths differ as little as possible in comparison to the original path. Since there are no flight regulations available for...
Dynamic based cost functions for TF/TA flights
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 48, Issue 1 , 2012 , Pages 44-63 ; 00189251 (ISSN) ; Kosari, A. R ; Sharif University of Technology
Abstract
In this work we present a systematic approach to incorporating the dynamic capabilities of an aircraft via suitable cost functions while planning for terrain following-terrain avoidance trajectories. We further show that use of nondimensional parameters related to the dynamics of an aircraft within the cost function provides a better understanding of how they could affect the resulting trajectories. Different case studies for arbitrary three-dimensional flights show that the current approach provides more realistic trajectories and so helps alleviate the design process of relevant controllers as well as tracking systems over the desired terrain. We further introduce two new parameters of...
On the impulsive formation control of spacecraft under path constraints
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 55, Issue 6 , 2019 , Pages 3292-3302 ; 00189251 (ISSN) ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper deals with the impulsive formation control of spacecraft in the presence of constraints on the position vector and time. Determining a set of path constraints can increase the safety and reliability in an impulsive relative motion of spacecraft. Specially, the feasibility problem of the position norm constraints is considered in this paper. Under assumptions, it is proved that if a position vector be reachable, then the reach time and the corresponding time of impulses are unique. The trajectory boundedness of the spacecraft between adjacent impulses are analyzed using the Gerschgorin and the Rayleigh-Ritz theorems as well as a finite form of the Jensen's inequality. Some...
An algorithm to estimate parameters and states of a nonlinear maneuvering target
, Article Cogent Engineering ; Volume 7, Issue 1 , 2020 ; Haeri, M ; Khaloozadeh, H ; Sharif University of Technology
Cogent OA
2020
Abstract
This paper investigates the problem of unknown input estimation such as acceleration, target class, and maneuvering target tracking using a hybrid algorithm. One of the challenges of unknown input estimation is that no effective method has been presented so far that could be applied to general cases. The available methods are ineffective when the range of variation of the unknown input parameter is large. Also, the issue of determining the system class could improve the performance of the tracking algorithms in many applications. Using the Bayesian theory, the posterior distribution functions of state and parameter could be obtained concurrently. In the proposed algorithm, Liu and West and...
Intelligent operation using terrain following flight in unmanned aerial vehicles
, Article 2007 IEEE Aerospace Conference, Big Sky, MT, 3 March 2007 through 10 March 2007 ; 2007 ; 1095323X (ISSN) ; 1424405254 (ISBN); 9781424405251 (ISBN) ; Malaek, S. M. B ; Sharif University of Technology
2007
Abstract
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 neural network aided adaptive second-order gaussian filter for tracking maneuvering targets
, Article ICTAI 2005: 17th IEEE International Conference on Tools with Artificial Intelligence, ICTAI'05, Hong Kong, 14 November 2005 through 16 November 2005 ; Volume 2005 , 2005 , Pages 439-446 ; 10823409 (ISSN); 0769524885 (ISBN); 9780769524887 (ISBN) ; Langary, D ; Sharif University of Technology
2005
Abstract
The adaptive capability of filters is known to be increased by incorporating a neural network into the filtering procedure. In this paper, an adaptive algorithm for tracking maneuvering targets based on neural networks is proposed. This algorithm is implemented with two filters based on the current statistical model and a multilayer feedforward neural network. The two filters track the same maneuvering target in parallel and the neural network automatically considers all the state information of the two filters and adaptively adjusts the process variance of one of them to achieve better performance in different target maneuver tracking. Simulations results show that the proposed adaptive...
Maneuver Modeling and Nonlinear Analysis of a High Speed Ship Considering Thrusting and Propulsive Systems
, M.Sc. Thesis Sharif University of Technology ; Sayyadi, Hassan (Supervisor) ; Mehdigholi, Hamid (Co-Advisor)
Abstract
Ship maneuverability is so important from different aspects. According to the regulations of International Maritime Organization (IMO), every vessel has to meet the minimum requirements of mentioned rules. Consequently, prediction of ship maneuverability in early stages of the ship design has become to one of the most necessary steps for shipbuilding and design companies. In this research work maneuvering of a high speed ship has been investigated using three different propulsive modes, considering propeller and rudder systems, azipod propeller and waterjet systems. First of all, hydrodynamics equations of each cases while considering different motion modes such as surge, sway, yaw, and roll...