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A composite rigid body algorithm for modeling and simulation of an underwater vehicle equipped with manipulator arms
, Article 23rd International Conference on Offshore Mechanics and Arctic Engineering, Vancouver, BC, 20 June 2004 through 25 June 2004 ; Volume 3 , 2004 , Pages 839-853 ; Banae, M ; Meghdari, A ; Sharif University of Technology
2004
Abstract
In this paper modeling and simulation of an underwater vehicle equipped with manipulator arms, using Composite Rigid Body (CRB) algorithm will be discussed. Because of increasing need to Unmanned Underwater Vehicles (UUVs) in oil and gas projects in Persian Gulf, for doing operations such as inspection of offshore jackets, subsea pipelines and submarine cables and also pre installation survey and post laid survey of submarine pipelines and cables, design and construction of "SROV" was developed in Sharif University of Technology, and at design stage behavior of underwater vehicles was studied. In this paper, an efficient dynamic simulation algorithm is developed for an UUV equipped with m...
An articulated body algorithm for modelling and simulation of an underwater vehicle equipped with manipulator arm
, Article 2003 ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Chicago, IL, 2 September 2003 through 6 September 2003 ; Volume 2 B , 2003 , Pages 1259-1270 ; Vossoughi, G. R ; Hosseini, M. A ; Sharif University of Technology
American Society of Mechanical Engineers
2003
Abstract
In this paper, an efficient dynamic simulation algorithm is developed for an Unmanned Underwater Vehicle (UUV) with a N degrees of freedom manipulator. In addition to the effects of mobile base, the various hydrodynamic forces exerted on these systems in an underwater environment are also incorporated into the simulation. The effects modeled in this work are added mass, viscous drag, fluid acceleration, and buoyancy forces. Also the dynamics of thrusters are developed, and an appropriate mapping matrix dependent on the position and orientation of the thrusters on the vehicle, is used to calculate resultant forces and moments of the thrusters on the center of gravity of the vehicle. It should...
Numerical Study of Film Cooling in a Space Thruster
, M.Sc. Thesis Sharif University of Technology ; Mardani, Amir (Supervisor)
Abstract
In high-performance liquid fuel motors and space thrusters, the combustion chamber and nozzle walls are in contact with the gases caused by high temperature and pressure combustion, making severe thermal loads on the walls. Therefore, these systems require cooling mechanisms. The most common way of cooling in space thrusters is film cooling. This study is a numerical simulation of film cooling in the liquid fuel space thrusters. Numerical and empirical studies have been reviewed in this area and evaluated while conducting studies and results to select an appropriate model for ongoing project studies. Along this path, various fuel and oxidizing thrusters, including oxygen and hydrogen,...
Effect of power on PPT discharge current
, Article Aircraft Engineering and Aerospace Technology ; Volume 85, Issue 3 , 2013 , Pages 207-214 ; 00022667 (ISSN) ; Sharif University of Technology
2013
Abstract
Purpose - The purpose of this paper is to investigate the effect of power on pulsed plasma thruster (PPT) discharge current with respect to its peak, duration, and behavior while the power elevates in a low power range. Design/methodology/approach - A rectangular parallel-plate breech-fed PPT has been developed with a self-inductor coupling element connecting the PPT cathode to the ignitor plug cathode. The PPT has been operated in vacuum chamber at 10-6mbar and its discharge current has been recorded using a Rogowski coil while input power has been changed by means of varying the capacitor voltage at given capacitance and frequency. Findings - The analysis leads to elucidate the effects of...
Design and Development a Prototype Pulsed Plasma Thruster (PPT)
, M.Sc. Thesis Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Although Pulsed Plasma Thruster (PPT) has first been utilized in a space mission in 1964 but after more than four decades, it is still a space rated technology which has performed various propulsion tasks from stationkeeping tasks to three-axis attitude control for a variety of former missions. With respect to the rapid growth in the small satellite community and the growing interest for smaller satellites in recent years, PPT is one of the promising electric propulsion devices for small satellites (e.g. CubeSats) as the following advantages: simplicity, lightweight, robustness, low power consumptions, low production costs and small dimensions. In spite of the fact that the issues relating...
Analysis of effective parameters on ablative PPT performance
, Article Aircraft Engineering and Aerospace Technology ; Volume 84, Issue 4 , 2012 , Pages 231-243 ; 00022667 (ISSN) ; Schönherr, T ; Sharif University of Technology
2012
Abstract
Purpose - The purpose of this paper is to comprehensively review most of the significant works ever done worldwide to study the effects of essential parameters on pulsed plasma thruster (PPT) performance and to analyze the effects of each parameter on PPT performance. Design/methodology/approach - All the important works studying PPT performance are categorized by the parameter they have studied and its effect on the thruster performance, and their works have been reviewed to analyze the influence of each parameter. Findings - The analysis leads to elucidation of the effects of different geometrical parameters including aspect ratio, electrode width, electrode spacing, electrode shape,...
Robust Control of Flexible Satellite in Rendezvous and Docking with Thruster Actuators
, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
The primary purpose of this research is to model, control and simulate a flexible and fully actuated satellite, equipped with twelve on-off thruster actuators, in rendezvous and docking maneuver. Flexibility of the satellite is modeled by considering two flexible and asymmetrical multi section solar panels with rotational springs and dampers in joints, attached to a central rigid body. Solar panel sections have been modeled in the form of Euler-Bernoulli beam by using assumed mode method and taking into account finite bending mode-shapes. The governing differential equations are obtained using Lagrange method. Then, the dynamic model is validated by comparing the simulation results of the...
Simulation of Mixing Rarefied Gas in Micro/Nano Thrusters Using DSMC Method
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Progress of technology and the ability of construction of devices in micro and nano scales, have developed a new field of science that the classical laws of fluid dynamics can not be analyzed in by the well known Navier-Stokes Model. So, research fields in micro and nano scales have been paid attention more. In micro and nano scales, due to small size of characteristic length, the fluid is rarefied and the behavior of the fluid and its interaction with surfaces and walls in such scales is very different from those in large-scale systems. So, the particle-based-methods like Direct Simulation Monte-Carlo (DSMC) method have been considered one of the most interesting fields of researches for...
Experimental Investigation of a Monopropellant Thruster Using Hydrogen Peroxide
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
Monopropellant thrusters are one of the most common types of propulsion systems that are used extensively in space applications. Especially thrusters with a capacity of less than 50N, they are used on space satellites and are developing rapidly. Problems such as contamination, toxicity of the propellant, difficulty in storing and custody, as well as price, led to the removal of the hydrazine from the focus of attention and focus on green propulsion. One of these, is the green propellant of hydrogen peroxide, which is decomposed in the proper catalytic vicinity, and the only chemical decomposition products are oxygen and water vapour. The present study aims to design and construct mono...
Review of worldwide activities in liquid-fed pulsed plasma thruster
, Article Journal of Propulsion and Power ; Volume 30, Issue 2 , March-April , 2014 , Pages 253-264 ; ISSN: 07484658 ; Schonherr, T ; Sharif University of Technology
Abstract
A review of worldwide activities in liquid-fed pulsed plasma thruster (LPPT) is discussed. Pulsed plasma thruster are extensively recognized as one of the most promising electric space propulsion systems to perform propulsive tasks on micro- and nanosatellites, including cubesats, because they offer many advantages compared with other electric space propulsion systems. The low plasma exhaust velocity measured by a Langmuir probe showed that thrust is mainly produced by 0.3 μg mass ionized by the first trigger and a much greater quantity of propellant introduced by the main discharge remained neutral at low speed. Various propellant feeding and discharge initiation methods have been applied...
Tracking control of an underwater vehicle using adaptive back-stepping with tuning function
, Article DETC2005: ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Long Beach, CA, 24 September 2005 through 28 September 2005 ; Volume 4 , 2005 , Pages 131-138 ; 0791847411 (ISBN); 9780791847411 (ISBN) ; Saghafi, M. M ; Sharif University of Technology
American Society of Mechanical Engineers
2005
Abstract
In this article the design and simulation of a velocity and position control for an underwater Remotely Operated Vehicle (ROV) is addressed. The system has a nonlinear dynamic with parametric uncertainties making it a reasonable test-bed for investigating the effectiveness of robust nonlinear control algorithms. The studied ROV can be actively controlled along the 3 Cartesian coordinate directions and rotated about the vertical axis using 4 thrusters positioned on the ROV. The dynamics of the actuator system, consisting of thrusters, is assumed to be a first order linear system with an unknown parameter. To control this system adaptive back-stepping, as a robust adaptive nonlinear control...
Optimal apogee burn time for low thrust spinning satellite in low altitude
, Article European Journal of Operational Research ; Volume 222, Issue 2 , 2012 , Pages 386-391 ; 03772217 (ISSN) ; Assadian, N ; Sharif University of Technology
2012
Abstract
In this study, the optimal burn time for low-thrust impulsive propulsion systems is investigated to raise the perigee altitude of a low-Earth orbit. The maneuver is done using spin-stabilized attitude control and impulsive thrusting system for a time interval centered about apogee point. On the one hand, the low value of the thrust level causes more burn time needed to accomplish the transfer. This, in turn, will cause more thrust loss due to the deviation between the thrust axis (spin axis) and the velocity vector of the satellite. On the other hand, for small thrust duration, the transfer needs more revolutions around the Earth and more travel in lower altitudes with dense atmosphere and...
Actuator failure-tolerant control of an all-thruster satellite in coupled translational and rotational motion using neural networks
, Article International Journal of Adaptive Control and Signal Processing ; 2018 ; 08906327 (ISSN) ; Assadian, N ; Sharif University of Technology
John Wiley and Sons Ltd
2018
Abstract
The nonlinear model predictive control (MPC) approach is used to control the coupled translational-rotational motion of an all-thruster spacecraft when one of the actuators fails. In order to model the dynamical response of the spacecraft in MPC, instead of direct integration, a neural network (NN) model is utilized. This model is built of a static NN, followed by a dynamic NN. The static NN is used to find the changes of the mapping of “the demanded forces to the thrusters” and “the real torques/forces produced by the remaining thrusters” after the failure occurrence through online training. In this manner, the effect of failed thruster on the dynamics can be found and the need for...
Numerical Study of Unsteady Swirl Injector Spray
,
M.Sc. Thesis
Sharif University of Technology
;
Morad, Mohammad Reza
(Supervisor)
;
Kebriaee, Azadeh
(Co-Supervisor)
;
Jahan Nama, Mohammad Reza
(Co-Supervisor)
Abstract
Iin this thesis, evaporation of droplets of a spray from a pressure-swirl injector in a sub-atmospheric combustion chamber is studied. The liquid used in this sudy is a hypergolic oxidizer, Dinitrogen Tetroxide, also known as NTO. The significance of this thesis is its application during the cold startup of a satellite thruster when only oxidizer is injected into the combustion chamber. The most important phenomemon in this stage which is also the focal point for this study, is the ‘Flashing’. In this phenomenon a liquid having a temperature above the boiling point of its own species (for the surrounding gas pressure) is present in the solution field. This state is a non-equilibrium state....
Design and Fabrication of a Vacuum Chamber Exhaust for a Thruster Testing in High Altitude Simulation
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
High-altitude simulation lab of chemical thrusters is one of the most important infrastructures for the development of space thrusters technology. In these laboratories, different sections are designed according to the requirements for simulation of the thrusters at specific pressure and temperature. The purpose of this research is to design a subset of the creation and preservation of vacuum for the purpose of ground testing of chemical thrusters. Vacuum preservation is more comprehensive than the vacuum creation and is usually the bottleneck of design, so the design of this subset is intended in the present study. To illustrate this, after introducing the basic concepts required, two...
Translational and Rotational Dynamics and Control Of an All-Thruster Satellite Considering Fuel Slosh
, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima (Supervisor)
Abstract
The purpose of the present study is to model and control a 6DOF satellite dynamics with a rigid body in the Earth’s orbit including the fuel slosh. The satellite manages and controls its attitude and position by twelve ON-OFF thrusters installed alongside the principal body axes. Moreover, due to using the liquid fuel to feed these thrusters, fuel slosh may have a strong dynamical effect on the satellite translational and rotational dynamics and control. The thrusters’ activation may result in fuel slosh and the impact of their frequent switching ON-OFF on fuel is considered in this study. The thrusters force magnitude, switching intervals, and their frequencies can affect the magnitude of...
Fault-Tolerant Attitude Control of Satellite with Thrusters Using μ-synthesis
, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima (Supervisor)
Abstract
In this project, a fault-tolerant attitude control system is developed for thruster-driven satellites. The proposed method has the advantage over current state-of-the-art approaches in that it does not require a fault detection and isolation system. Generalized moments are generated by a robust controller that is designed using mixed sensitivity H_∞ and μ-synthesis by DK-iteration. Moreover, a pulse-width modulation technique with quadratic programming optimization is tuned to map the controller outputs to thruster on-off commands as efficiently as possible. The controller is designed to tolerate up to ±30% perturbations in inertia properties and thrust degradations up to 90% of the nominal...
Applying a hybrid DSMC/Navier-Stokes frame to explore the effect of splitter catalyst plates in micro/nanopropulsion systems
, Article Sensors and Actuators, A: Physical ; Volume 189 , January , 2013 , Pages 409-419 ; 09244247 (ISSN) ; Roohi, E ; Sharif University of Technology
2013
Abstract
In this study, we apply a hybrid direct simulation Monte Carlo (DSMC)/Navier-Stokes (NS) frame to simulate the effects of catalyst or splitter plates in propulsive efficiency of micro/nanopropulsion systems. Our hybrid frame uses the local Knudsen number based on the gradient of the flow properties (KnGLL) to distinct the continuum and molecular regions. This frame also uses the state-based coupling (Dirichlet-Dirichlet boundary-condition coupling) to transfer the information between the two regions. We simulate typical micro/nanopropulsion systems consisting of channels, catalyst or splitter plates, and convergent-divergent nozzles. According to the Kn GLL, we apply the NS solver to the...
Dynamic-programming-based failure-tolerant control for satellite with thrusters in 6-DOF motion
, Article Advances in Space Research ; Volume 65, Issue 12 , 2020 , Pages 2857-2877 ; Assadian, N ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, a dynamic-programming approach to the coupled translational and rotational control of thruster-driven spacecraft is studied. To reduce the complexity of the problem, dynamic-programming-based optimal policies are calculated using decoupled position and attitude dynamics with generalized forces and torques as controls. A quadratic-programming-based control allocation is then used to map the controls to actuator commands. To control the spacecraft in the event of thruster failure, both the dynamic programming policies and control allocation are reconfigured to cope with the losses in controls. The control allocation parameters are adjusted dynamically to ensure the satellite...
Actuator Failure-Tolerant Predictive Control of an All-Thruster Satellite in Coupled Translational and Rotational Motion using Neural Networks
, Ph.D. Dissertation Sharif University of Technology ; Asadian, Nima (Supervisor)
Abstract
In this thesis, the problem of failure-tolerant control of the satellite in coupled orbital and rotational motion is investigated. All of the actuators of the satellite are thrusters and only the failure of the actuators is considered. At first, the equations of coupled relative translational-rotational motion of the satellite are derived. Then, the required specifications of the approapriate control method for the problem is explored with the conclution that the controller must be able to predict the behavior or planning the future trajectory of the satellite. In the next step, model predictive control, which has the required specifications, is used to control the coupled...