Space systems design (spacecraft, satellites, space stations and their equipment)
Abbas Saeidi; Nasser Rahbar; Mohammad Ali Alirezapouri
Volume 14, Issue 3 , September 2021, , Pages 65-73
Abstract
In recent years, according to progress of aerospace industries particularly satellites it has been paying much attention to attitude determination of satellite. Attitude determination of satellite in various ways, such as: radio, radar, optical methods and using GPS, q and kalman filter is done, that ...
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In recent years, according to progress of aerospace industries particularly satellites it has been paying much attention to attitude determination of satellite. Attitude determination of satellite in various ways, such as: radio, radar, optical methods and using GPS, q and kalman filter is done, that each of these methods has advantages and disadvantages. Due to disturbance in space, high accuracy in attitude determination, various algorithms to obtain properly accurately attitude, desirable access to position, velocity and time of satellite to achieve desired attitude determination satellite are considered a top priority. However in this Paper, first we review the various methods for attitude determination satellite and then examine of operation and relations of algorithms discussed. This Paper focus on the advantages and disadvantages of qEKF algorithm in compare to other methods are available.
amirhossein tavakoli; ali faghihi; S.Mohammad Mehdi Dehghan
Volume 10, Issue 1 , June 2017, , Pages 47-53
Abstract
Simulating environmental conditions for the satellite attitude sensors is a fundamental requirement of hardware in the loop tests of attitude determination and control subsystem. In this paper, a new design for simulating sun vector and magnetic vector is presented. The operating environment for attitude ...
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Simulating environmental conditions for the satellite attitude sensors is a fundamental requirement of hardware in the loop tests of attitude determination and control subsystem. In this paper, a new design for simulating sun vector and magnetic vector is presented. The operating environment for attitude sensors is simulated using a sun simulator, a two-degree-of-freedom table for changing the attitude of the sun sensor, and a three-axis Helmholtz coil. The sensors measurements showed that with this setup, the sun and magnetic vectors can be created with an acceptable accuracy using the orbital position and the attitude of the satellite. So, the test bed can be used for attitude determination of hardware in the loop tests.
Malihe Hashemi; Seyed Kamaleddin Mosavi Mashhadi; Seyed Majid Esmaeilzadeh; Mohammad Fiuzy
Volume 9, Issue 2 , September 2016, , Pages 85-90
Abstract
Attitude Determining is one of the major and critical satellites space missions. In this study, a new method to Attitude determination of satellites is presented. Such that, based on the proposed method search space will be more limited then accuracy and speed of attitude determination in the proposed ...
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Attitude Determining is one of the major and critical satellites space missions. In this study, a new method to Attitude determination of satellites is presented. Such that, based on the proposed method search space will be more limited then accuracy and speed of attitude determination in the proposed method has risen. At first in this method, implementation and the test algorithms will be discussed, after these some algorithms, such as navigation, pattern recognition and ultimately attitude determination will be reviewed. In order to implement these algorithm. High quality images of stars which must provided by the star tracker camera requires to implement. Really these images to perform the necessary processing sent to the processor so the processor based on designed algorithms, determines the attitude of camera and satellite in all three axes. This means that some features considered for star tracker and based on them begins the designing process. The range of accurately determination for star tracker is one of these features. In this article, the ranges of two axes of Yao and Pitch less than 20 seconds on the scale of degree are considered and in the roll axis less than 100 seconds is intended. Can show in the results, much better accuracy and less than initial assumptions have been achieved. It also carried out by an adaptive identified algorithm so that the brighter stars are identified and based on their attitude determination, the sensor accuracy have increased. Because of according research, the clearer stars, have more accurate in calculation. The other important feature is the speed of attitude detection which performed by 1 GHz processor, and correct identification of pyramidal algorithm where have reached less than 15 milliseconds. Due to the duration, the desire update rate gained. Other important parameters which influence the accuracy of the attitude determination is knowing the exact coordinates of the intersection point vector of focal length lens with image sensors. By Land calibration for camera with a good accuracy, these parameters were estimated.
Ahmad Reza Sadeghi; Mohammad Farzan Sabahi; Sayed Mohamad Saberali
Volume 9, Issue 1 , May 2016, , Pages 37-46
Abstract
Automatic control of satellites and spacecrafts, has been extensively paid attention. Attitude determination is one of the most important procedures to control a spacecraft. Star trackers are widely used for attitude determining. A star tracker provides images from the around space and try to identify ...
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Automatic control of satellites and spacecrafts, has been extensively paid attention. Attitude determination is one of the most important procedures to control a spacecraft. Star trackers are widely used for attitude determining. A star tracker provides images from the around space and try to identify the stars in the images. Several algorithms are proposed to this end. However, most of these algorithms use the raw measurements to star identification and attitude determination. As the measurements are often affected by various types of noise, the performance of such algorithms is degraded. Here, we employ tracking algorithms to improve the performance of existing methods for attitude determining. The Kalman filter-based tracking algorithms are shown to have satisfactory results for object tracking. We use the JPDAF to build an algorithm for accurate tracking of stars locations in successive images and, consequently, determining the attitude of spacecraft. The presented algorithm is compared with the well known algorithm for attitude determining called SNA.
Amir Hosein Tavakkoli; Masoud Yazdanian; Yarollah Koolivand; Morteza Shahravi; Morad Momeni; S. Mohammad Mahdi Dehghan
Volume 5, Issue 4 , January 2013, , Pages 69-78
Abstract
Evaluation of the satellite attitude determination system is very complicate because of need to simulate space environment on the ground. In this paper a laboratory Implementation of attitude estimation using sun sensor and magnetometer is reported. The test setup includes a sun simulator installed in ...
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Evaluation of the satellite attitude determination system is very complicate because of need to simulate space environment on the ground. In this paper a laboratory Implementation of attitude estimation using sun sensor and magnetometer is reported. The test setup includes a sun simulator installed in a dark room. The magnetometer measures the local magnetic field. Sensors are rotated using a 2 DOF table. The reference models are adapted with the test setup. Attitude determination using classic and extended kalman filter methods is implemented by sensors data fusion. The test results verify the controlled motion of sensors in the limits of setup accuracy order.
