space sciences and exploration
Farshad Somayehee; Amir Ali Nikkhah; Jafar Roshanian
Volume 14, Issue 2 , June 2021, , Pages 103-110
Abstract
In this paper, a new algorithm for determining the density of scattered data at the surface of the sphere is presented and then the proposed algorithm along with Geodesic Weighted K-Means clustering and Deluany triangulation are used to make uniform star catalogs. Comparison of the results with the results ...
Read More
In this paper, a new algorithm for determining the density of scattered data at the surface of the sphere is presented and then the proposed algorithm along with Geodesic Weighted K-Means clustering and Deluany triangulation are used to make uniform star catalogs. Comparison of the results with the results of other related articles shows that the proposed algorithm resulted in a significant decrease in the probability of observing a large number of stars in all simulated star sensor fields of view. This improvement is due to the uniformity of the star catalog, especially in the celestial sphere poles due to the proposed density determination algorithm. On the other hand, the use of a proper data density algorithm has increased the likelihood of observing a few stars (such as 3 or 5) in all fields of view used in the Monte Carlo simulation.
Javad Shams; Jafar Roshanian
Volume 12, Issue 4 , December 2019, , Pages 19-33
Abstract
In this paper, the hybrid control of the formation flying of spacecrafts has been investigated. The trajectory deflection of space asteroids, which are potentially life-threatening on Earth, are being actively pursued in recent scientific researches. To accomplish this mission, several methods have been ...
Read More
In this paper, the hybrid control of the formation flying of spacecrafts has been investigated. The trajectory deflection of space asteroids, which are potentially life-threatening on Earth, are being actively pursued in recent scientific researches. To accomplish this mission, several methods have been proposed to date, in which case the use of gravity tractor is an indicator and hence the method is used in this paper. The formation flight of spacecrafts technology is a function of the relative dynamic equations, which are also used for its active control. In this way, the PID controller, which is widely used in various industries and inherently has robust properties, has been used as a base controller, and the fuzzy control has been used to improve its adjustment, which results in the results obtained. From simulation, the performance of the combined controller performance is effective.
Amie ali Nikkhah; farsahd somayehee; Jafar Roshanian
Volume 11, Issue 3 , December 2018, , Pages 21-32
Abstract
In this paper, the aim is to simulate night-sky images for use in star-sensor designing software. For this purpose, a comprehensive and precise algorithm was developed to simulate night sky images based on the ideal pinhole method and the use of Gaussian distribution functions. Then, in order to create ...
Read More
In this paper, the aim is to simulate night-sky images for use in star-sensor designing software. For this purpose, a comprehensive and precise algorithm was developed to simulate night sky images based on the ideal pinhole method and the use of Gaussian distribution functions. Then, in order to create more realism, sources of random and systematic errors, the elongated images due to the high dynamics of the platform, as well as the asymmetric back-lighting of the moon, the sun, and the planets of the solar system have been simulated. Finally, considering the importance of realism in the problem-solving simulation approach, the use of precision ray tracking method as an alternative to the ideal pinhole method is suggested.
Javad Shams; Jafar Roshanian
Volume 11, Issue 4 , December 2018, , Pages 31-42
Abstract
In this paper, an analytical solution to deflection mission of asteroid as potentially hazardous spatial mass that threat humanity in future is investigated . The mission of deflecting potentially hazardous asteroids in recently years with possibility of their collision with Earth and the priority to ...
Read More
In this paper, an analytical solution to deflection mission of asteroid as potentially hazardous spatial mass that threat humanity in future is investigated . The mission of deflecting potentially hazardous asteroids in recently years with possibility of their collision with Earth and the priority to carry out the mission of mitigate risk of these objects from its original space trajectory in recent years has been studied with interest in scientific research. Different methods have been proposed for execute the deflecting these celestial objects, among which the use of gravity tractor technology has become more widely used. In addition, the increasing use of formation flying technology in space missions is increasingly increasing, which has led to the use of this technology in this survey.
Mojtaba Alavi pour; Amir Ali Nikkhah; Jafar Roshanian
Volume 9, Issue 4 , April 2017, , Pages 13-25
Abstract
In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch ...
Read More
In this research, the problem of optimal trajectory design of an upper stage is considered for satellite injection into Geostationary orbit in 3-Dimensional space. The optimal multi-burn trajectory is obtained based on Euler-Lagrange theory with minimum fuel consumption criteria. Instead of using switch function for obtaining the switching times, which complicates the numerical solution of the optimal control problem, the presented algorithm uses a simple and optimal process to find the burn and coast times. To solve the tow point boundary value problem, an improved indirect shooting method with high performance is used which in addition to having higher precision, converges very fast to the desired condition.
A.A Nikkhah; J. Tayebi; J. Roshanian
Volume 7, Issue 2 , July 2014, , Pages 1-9
Abstract
In this paper attitude control system of nanosatellite based on Single Gimbal Control Moment Gyroscope (SGCMG) is presented. A LQR/LQG method is developed for stability of satellite and a feedback quaternion strategy is used for maneuvering mode. In the stabilization mode LQR/LQG controllers ...
Read More
In this paper attitude control system of nanosatellite based on Single Gimbal Control Moment Gyroscope (SGCMG) is presented. A LQR/LQG method is developed for stability of satellite and a feedback quaternion strategy is used for maneuvering mode. In the stabilization mode LQR/LQG controllers are designed with linearization of nonlinear dynamic equation of satellite and control moment gyroscope, so that in other reseach didn’t use this controller in the stabilization mode of this system. In the maneuvering mode a feedback quaternion controller applyed for nonlinear system. Numerical simulations are provided to show the efficiency of the proposed controller for a nanosatellite with four single gimbal control moment gyroscope pyramid cluster. Results of simulations shown that LQR/LQG method is more accurate in compared with feedback quaternion controller.
Jafar Roshanian; Shabnam Yazdani; S. Mehdi Hasani; Masoud Ebrahimi Kachouie
Volume 5, Issue 2 , July 2012, , Pages 15-23
Abstract
Star trackers are one of the most accurate attitude determination devices of a spacecraft. Star trackers are able to determine the spacecraft attitude with the use of recognizing the stars within their field of view. One of the major subsystems of star tracker software is the star pattern recognition ...
Read More
Star trackers are one of the most accurate attitude determination devices of a spacecraft. Star trackers are able to determine the spacecraft attitude with the use of recognizing the stars within their field of view. One of the major subsystems of star tracker software is the star pattern recognition algorithm. In this research a novel star pattern recognition algorithm called Non-Dimensional is considered. This algorithm can recognize the stars within its field of view without using the information of camera calibration. In order to fulfill this goal, the algorithm requires a database which contains the star inertial information. Afterwards a fast search method is used to compare the combinations on the image with database. Eventually there has been a tradeoff between database volume and the update frequency for a better performance.
J. Roshanian; M. Ebrahimi; A. Bataleblu
Volume 4, Issue 2 , January 2012, , Pages 23-34
Abstract
The purpose of this paper is introducing the concept of nondeterministic optimal design or optimal design in the presence of uncertainty based on researches done in the past two decades. Therefore, after an introduction about uncertainty, the uncertainty and uncertainty modeling techniques are described. ...
Read More
The purpose of this paper is introducing the concept of nondeterministic optimal design or optimal design in the presence of uncertainty based on researches done in the past two decades. Therefore, after an introduction about uncertainty, the uncertainty and uncertainty modeling techniques are described. After that, thetraditionalmethodof dealingwith uncertaintyin thedesignis described. The importance of paying attention to the uncertainty and its benefits for different projects and companies is described. The third section is dedicated to introducing the methods of interval analysis, fuzzy logic and probability analysis, which are used in the analysis of uncertainty.The two general categories of nondeterministic design problems, the robust optimal design and reliability-based optimal design are reviewed. The next section introduces the application of nondeterministic design methods in the different disciplines and recent researches in the world on this topic. Finally, future aspects and challenges of the nondeterministic design are addressed.
E. Amani; M. Ebrahimi; J. Roshanian
Volume 3, Issue 2 , January 2011, , Pages 59-67
Abstract
در این مقاله، معادلات کوپلشده جسم صلب- تلاطم سیال- الاستیسیته برای پرواز شش درجه آزادی ماهوارهبرها توسعه داده شده است. معادلات حرکت به کمک معادلات لاگرانژ در دستگاه ...
Read More
در این مقاله، معادلات کوپلشده جسم صلب- تلاطم سیال- الاستیسیته برای پرواز شش درجه آزادی ماهوارهبرها توسعه داده شده است. معادلات حرکت به کمک معادلات لاگرانژ در دستگاه شبه مختصات و همچنین در دستگاه مختصات اینرسی استخراج شدهاند. مدل پاندول ساده برای حرکت صفحهای به منظور مدل کردن دینامیک تلاطم سیال در پرواز شش درجه آزادی گسترش داده شده و تغییر شکلهای الاستیک بر اساس مختصات مودال نسبت به مختصات میانی ارائه شدند و نیز نشان داده شده است که این مدل با مدل سادهتر حرکت صفحهای که در مطالعات پیشین توسعه یافته است، سازگاری دارد. مدل دینامیکی پیشنهاد شده در کنار مدلهای لازم برای سایر زیرسیستمها در برنامة متلب/ سیمولینک با موفقیت برای شبیهسازی حرکت شش درجه آزادی ماهوارهبرها به کار گرفته شده است.
M. Sayanjali; J. Roshanian; A. Ghafari
Volume 1, Issue 2 , December 2008, , Pages 51-56
Abstract
In this paper, based on the Lagrange method, attitude motion equations for a flexible spacecraft have been derived. Flexible appendages are modeled by Euler-Bernoulli beam. Hybrid control scheme ofand sliding mode are used for attitude regulation. Switching between these to algorithm is determined using ...
Read More
In this paper, based on the Lagrange method, attitude motion equations for a flexible spacecraft have been derived. Flexible appendages are modeled by Euler-Bernoulli beam. Hybrid control scheme ofand sliding mode are used for attitude regulation. Switching between these to algorithm is determined using absolute error parameter, so that when this parameter is large (i.e. the attitude is far from its desired conditions) the sliding mode control is used. in contrast, when the spacecraft is close to the desired attitude, the control is based onmethod. This hybrid scheme leads to a fast response and also robustness against uncertainty. Switching surface has been designed so that a certain cost function is minimized. Incontroller design, the first three vibration modes of the flexible spacecraft are considered as well as the Euler angles and their rates.
