scholarly journals A Star Identification Method for Star Sensor Attitude Determination Systems by using Structual Pattern Recognition

1987 ◽  
Vol 107 (4) ◽  
pp. 365-372
Author(s):  
Toshiro Sasaki ◽  
Michitaka Kosaka
Keyword(s):  
Pattern Recognition ◽  
Attitude Determination ◽  
Star Sensor ◽  
Identification Method ◽  
Star Identification

scholarly journals Efficient Star Identification Using a Neural Network

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3684
Author(s):  
David Rijlaarsdam ◽  
Hamza Yous ◽  
Jonathan Byrne ◽  
Davide Oddenino ◽  
Gianluca Furano ◽  
...  
Keyword(s):  
Neural Network ◽  
Attitude Determination ◽  
Lightweight Design ◽  
A Priori ◽  
Search Time ◽  
Identification Algorithm ◽  
Star Sensor ◽  
Feature Extraction Method ◽  
Star Identification ◽  
Space Star

The required precision for attitude determination in spacecraft is increasing, providing a need for more accurate attitude determination sensors. The star sensor or star tracker provides unmatched arc-second precision and with the rise of micro satellites these sensors are becoming smaller, faster and more efficient. The most critical component in the star sensor system is the lost-in-space star identification algorithm which identifies stars in a scene without a priori attitude information. In this paper, we present an efficient lost-in-space star identification algorithm using a neural network and a robust and novel feature extraction method. Since a neural network implicitly stores the patterns associated with a guide star, a database lookup is eliminated from the matching process. The search time is therefore not influenced by the number of patterns stored in the network, making it constant (O(1)). This search time is unrivalled by other star identification algorithms. The presented algorithm provides excellent performance in a simple and lightweight design, making neural networks the preferred choice for star identification algorithms.

Spinor-Based Attitude Determination with Star Sensor Considering Depth

2021 ◽  
Vol 87 (8) ◽  
pp. 551-556
Author(s):  
Qinghong Sheng ◽  
Rui Ren ◽  
Weilan Xu ◽  
Hui Xiao ◽  
Bo Wang ◽  
...  
Keyword(s):  
Attitude Determination ◽  
Geometric Condition ◽  
Depth Information ◽  
Star Sensor ◽  
Imaging Geometry ◽  
Straight Line Passing ◽  
Geometry Model ◽  
Straight Line ◽  
Order Of Magnitude ◽  
Line Passing

A star sensor is a high-precision satellite attitude measurement device. Since its observation information has only two-dimensional direction vectors, when a star sensor is used for attitude determination the dimension of the observation information is less than the number of attitude angles determined, so mainstream algorithms usually only guarantee the accuracy of the pitch angle and the roll angle. In view of the lack of depth information in the observation's imaging geometric condition, this article proposes a spinor-based attitude determination model, which describes a straight line passing through two stars with the spinor and maps the depth information of the straight line with the pitch, to establish an imaging geometry model of the spinor coplanar condition. Experiments show that the yaw-angle attitude accuracy of the method is an order of magnitude better than that of mainstream algorithms, and the accuracy of the three attitude angles reaches the arc-second level.

scholarly journals Star Image Prediction and Restoration under Dynamic Conditions

Sensors ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 1890 ◽  
Author(s):  
Liu ◽  
Chen ◽  
Liu ◽  
Shi
Keyword(s):  
Attitude Control ◽  
Attitude Determination ◽  
Back Propagation ◽  
Prediction Method ◽  
Back Propagation Neural Network ◽  
Attitude Measurement ◽  
Star Sensor ◽  
Dynamic Conditions ◽  
Star Image ◽  
Image Prediction

The star sensor is widely used in attitude control systems of spacecraft for attitude measurement. However, under high dynamic conditions, frame loss and smearing of the star image may appear and result in decreased accuracy or even failure of the star centroid extraction and attitude determination. To improve the performance of the star sensor under dynamic conditions, a gyroscope-assisted star image prediction method and an improved Richardson-Lucy (RL) algorithm based on the ensemble back-propagation neural network (EBPNN) are proposed. First, for the frame loss problem of the star sensor, considering the distortion of the star sensor lens, a prediction model of the star spot position is obtained by the angular rates of the gyroscope. Second, to restore the smearing star image, the point spread function (PSF) is calculated by the angular velocity of the gyroscope. Then, we use the EBPNN to predict the number of iterations required by the RL algorithm to complete the star image deblurring. Finally, simulation experiments are performed to verify the effectiveness and real-time of the proposed algorithm.

A Correction Algorithm of Aberration of Light for Spacecraft Attitude Determination System

2012 ◽  
Vol 166-169 ◽  
pp. 3197-3201
Author(s):  
Bao Hua Li ◽  
Xi Jun Chen ◽  
Yang Pang ◽  
Bo Qi Xi
Keyword(s):  
Mathematical Models ◽  
Coordinate System ◽  
Attitude Determination ◽  
Spacecraft Attitude ◽  
Star Sensor ◽  
Correction Algorithm ◽  
Attitude Error ◽  
Determination System ◽  
Space Coordinate ◽  
Celestial Sphere

There is the long periodicity attitude error between true attitude and measurement attitude using star sensor for spacecraft attitude determination system because of aberration of light. Aberration of light occurs because the spacecraft’s velocity has a component that is perpendicular to the line traveled by the light incoming from the star. The type of aberration is analyzed and their constants of aberration are calculated in this paper. According to the constants the aberration, the correction mathematical models of parallax of aberration of light of these types of aberration are derived. The parallax of aberration of light of the recognized stars in the FOV of star sensor is calculated with the mathematical models. Then the true vectors of recognized stars at image space coordinate system of star sensor are calculated. The measurement attitude of star sensor is calculated with the true vectors of recognized stars and their vectors at celestial sphere coordinate system. The simulations show the long periodicity attitude error is corrected with the method in this paper. At last the correction of aberration of light was successfully demonstrated using two star sensors with real sky experiment in 2011.

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