Seyed Hamid Jalali Naini
Volume 7, Issue 4 , January 2015, Pages 1-9
Abstract
In this paper, implicit guidance equations are derived in polar coordinates. Depending on applications, implicit guidance equations in polar coordinates may be preferred over cartesian coordinates. Moreover, depending on the type of guidance problem, analytical solutions for sensitivity matrices may ...
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In this paper, implicit guidance equations are derived in polar coordinates. Depending on applications, implicit guidance equations in polar coordinates may be preferred over cartesian coordinates. Moreover, depending on the type of guidance problem, analytical solutions for sensitivity matrices may be simplified using polar coordinates. Therefore, transformation of implicit guidance equation into polar coordinates can be useful in guidance problems. In addition, the resulting equations are extended to cylindrical coordinates.
Seyed Hossein Mortazavi
Volume 7, Issue 4 , January 2015, Pages 11-21
Abstract
Satellite formation flying is one of the most recent research topics in space field owing to various operational projects. The first and the most important step in facing with this concept is studying and modeling of dynamics of the problem. In this paper, the relative dynamics of a satellite formation ...
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Satellite formation flying is one of the most recent research topics in space field owing to various operational projects. The first and the most important step in facing with this concept is studying and modeling of dynamics of the problem. In this paper, the relative dynamics of a satellite formation flying including the leader-follower satellites based on the concept of control for geostationary vehicles, has been examined. As a consequence, an analytical solution for determination of relative position and velocity of the formation in local horizontal coordinate system which is set on leader-follower satellites has been derived. Dynamics modeling of the problem is done based on parameters which are normally used for control of geostationary maneuvers like station keeping. The advantages of utilizing these parameters are non singularity of equations and having physical sensation to these parameters. The analytical solution has been resulted from two supposes: the relative orbit is semi circular and the leader-follower satellites are close to each other in the formation.Â
Mehran Nosrat Elahi; Ali Reza Basohbat Novinzadeh; Mostafa Zakeri; Vali Bemani; Yazdan Emadi Noori
Volume 7, Issue 4 , January 2015, Pages 23-37
Abstract
The design method presented in this paper is for utilizing, fast and easy system designing of orbital transfer block for transferring satellite from park orbit to destination orbit. The main purpose of this paper is system designing liquid propellant orbital transfer block with a new approach for ideal ...
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The design method presented in this paper is for utilizing, fast and easy system designing of orbital transfer block for transferring satellite from park orbit to destination orbit. The main purpose of this paper is system designing liquid propellant orbital transfer block with a new approach for ideal orbital transfer and presenting a simple interfered systematic method for designing aerospace products. Designing orbital transfer block consists of designing all subsystems and integrating all parts of design. Designing all subsystems can be achieved with a meaningful connection between all system and subsystem constraints. In addition to systematic design approach to each of the design sub- algorithms, creating subsystem optimization environment according to physical performance of subsystem and also general integration of orbital transfer block system design in an optimized environment have been carried out. Final result of orbital transfer block design for a specific mission is through mass-dimension convergence of equations in integrated design. Design integration according to design matrix and optimizations and convergences of the design is discussed in the paper. According to presented method, which is scientific, functional and extensible to final design of the product, parametric process of results is briefly validated. So in this paper new method is provided for integrating the design in an optimized and collaborative convergence environment maintaining all systemic constraints and limitations to specify specifications of orbital transfer block systems and subsystems.
M. Navabi; M. Tavana; H.R. Mirzaei
Volume 7, Issue 4 , January 2015, Pages 39-49
Abstract
Attitude control of spacecraft in order to nonlinear and high order dynamics is fundamental and challenging issue. With respect to these nonlinearities, linear control theories are not suitable choices and spacecraft may be unstable or lose performance. In this paper, State Dependent Riccati Equation ...
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Attitude control of spacecraft in order to nonlinear and high order dynamics is fundamental and challenging issue. With respect to these nonlinearities, linear control theories are not suitable choices and spacecraft may be unstable or lose performance. In this paper, State Dependent Riccati Equation (SDRE) method is utilized to 3-axis stabilization using four reaction wheels. State dependent Riccati equation method is systematic approach for optimal control of nonlinear systems which satisfies constraints of systems. In order to solve time consuming problem of this method in practical systems, Theta-D method is used. Results demonstrate the effectiveness of Theta-D in compare with Riccati method.
Mohammad Tahaye Abadi; Mehdi AlizadehYazdi; Mohammad Ali Farsi; Mohammad Ebrahimi
Volume 7, Issue 4 , January 2015, Pages 51-62
Abstract
The paper concerns with the experimental analysis of the pyroshock wave propagation in the structure of Kavoshgar's payloadon the ground. The source of waves is the explosion of pyrotechnic materialacting as the actuator of separation mechanism for the payload subsystems. The shock sensors are attached ...
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The paper concerns with the experimental analysis of the pyroshock wave propagation in the structure of Kavoshgar's payloadon the ground. The source of waves is the explosion of pyrotechnic materialacting as the actuator of separation mechanism for the payload subsystems. The shock sensors are attached in different locations of structure to measure the acceleration amplitude along three orthogonal directions after the activation of pyrotechnic material.The experimental setup is used for measurement of the acceleration history as well as the evaluation of the shock response spectrum at specific locations during two-stage separation of payload subsystems. The experimental acceleration record is evaluated to eliminate the noise signals and incorrect data. The variations of shock  response at different payload locations are evaluated to determine the amplitude attenuation of the wave passing through the structure body and joints. The measured data are also employed to determine the working condition and design criteria for the equipment of Kavoshgar payload.
Seyed Mohammad Reza Mosavi; Narjes Rahemi; Satar Mirza Kuchaki
Volume 7, Issue 4 , January 2015, Pages 63-72
Abstract
GPS is a satellite-based navigation system that is able to determine the exact position of objects on the Earth, sky, or space. By increasing the velocity of a moving object, the accuracy of positioning decreases; meanwhile, the calculation of the exact position in the movement by high velocities like ...
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GPS is a satellite-based navigation system that is able to determine the exact position of objects on the Earth, sky, or space. By increasing the velocity of a moving object, the accuracy of positioning decreases; meanwhile, the calculation of the exact position in the movement by high velocities like airplane movement or very high velocities like satellite movement is so important. In this paper, two methods for positioning in very high velocities based on recursive least squares method and its combination with fuzzy logic are presented. Simulations on different data with different velocities show that proposed method can improve the accuracy of positioning more than 50%. In previous methods, the algorithm is quite dependent on the initial point, whereas in proposed method, this dependency is resolved.
Mohsen Bahrami; Behzad Parsi
Volume 7, Issue 4 , January 2015, Pages 73-79
Abstract
In this paper a low cost calibration method which can calibrate with measuring the sensor displacement is suggested. To verify this calibration method a two-axis table, which is expensive, with artificial neural network (ANN) for mapping non-linear relationships between the inputs and outputs is used. ...
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In this paper a low cost calibration method which can calibrate with measuring the sensor displacement is suggested. To verify this calibration method a two-axis table, which is expensive, with artificial neural network (ANN) for mapping non-linear relationships between the inputs and outputs is used. The result illustrates the efficiency of this calibration method. In order to design the artificial neural network the MATLAB software is used.
Kamal Jahani; Hossein Farajollahi
Volume 7, Issue 4 , January 2015, Pages 81-91
Abstract
During launching and deploying to orbit, satellites experience vibration loads from launch vehicle especially in longitudinal direction. Even though the aim of the adapter between satellite and launcher is to isolate the satellite from the launcher's dynamic loads, however, still enough harsh vibration ...
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During launching and deploying to orbit, satellites experience vibration loads from launch vehicle especially in longitudinal direction. Even though the aim of the adapter between satellite and launcher is to isolate the satellite from the launcher's dynamic loads, however, still enough harsh vibration loads that can affect the operation of satellite's delicate systems transmit to the structure of the satellite. Therefore, there is need to isolate the delicate systems from vibrations of the satellite's structure. In this paper, the performance of a new material namely Silicone Gel in isolating delicate equipments (such as electronic board and its components) of satellite from longitudinal vibrations is investigated using finite element method. The results of modeling of an isolator containing Silicone Gel are verified by the available experimental results from the literature. Besides having frequency dependent behavior and dissipation characteristic, Silicone Gel shows hyper-elastic behavior that these characteristic are considered in modeling and analysis. Also an electronic board that overlays on Silicon Gel type mounts is modeled and the amount of transmitted vibration to lead wire of a resistor on it is investigated. The obtained results show that the Silicone Gel has good performance in isolating of delicate equipments of satellite from incoming longitudinal vibrations.Â
