Star map simulation and platform influence of airborne star sensor based on J-band data of 2MASS catalog

doi:10.1016/j.infrared.2020.103541

Infrared Physics & Technology

Volume 111, December 2020, 103541

https://doi.org/10.1016/j.infrared.2020.103541 Get rights and content

Highlights

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The radiation transfer model, the star sensor imaging model and the influence model of platform motion on the imaging of star sensor is constructed.
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The star map considering daytime and platform motion environment is simulated.
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The influence of the platform motion on the image quality is discussed.
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According to the comparison between the simulated and measured star map, the accuracy of the simulation result is evaluated.

Abstract

In order to solve the problem of insufficient star map data for airborne star sensor algorithm testing and the difficulty in characterizing the effect of airborne platform motion on image quality of airborne star sensor, this paper carries out star map simulation and platform influence research on airborne star sensor based on J-band data of 2MASS catalog. Based on the analysis of the star target characteristics in the J-band of the 2MASS catalog, the imaging link model of the star sensor and the analysis model of the influence of platform motion on the imaging are constructed. According to the input simulation conditions, the simulation of sequence star map is realized. Based on the features of star map recognition algorithm, the quality evaluation index of star map is constructed, and the influence of platform motion on the quality of star map is analyzed. The star map simulation results show that the minimum SNR of the simulated star map is 8.45 dB for −1~6 magnitude stars, which can meet the requirements of star point extraction, star pattern recognition and attitude solution algorithm performance evaluation for daytime airborne star sensors in short wave infrared band. The result of platform impact analysis shows that when the rotation speed of the platform around the non-optical axis reaches 0.35 rad/s, or the rotation speed around the optical axis reaches 0.10 rad/s, or the vibration amplitude reaches about 5 μm, the SNR of the star map will decline to about 6 dB, which reaches the limit of star detection. The analysis of the influence of platform motion on image quality can provide theoretical support for the design and implementation of image stabilization algorithm for star sensors.

Introduction

Star sensor is a kind of attitude measurement instrument widely used in aerospace field. By recording the distribution of stars in the field of view of the optical lens of the star sensor, the direction of the sky area indicated by the optical axis of the star sensor can be calculated and the attitude of the spacecraft can be measured [1]. The precondition of star map matching and attitude determination is to extract and locate the centers of the star points. When the conditions are limited and it is impossible to obtain the real star maps, the simulation method is generally used to generate the star maps [2].

Compared with the spaceborne star sensor, the airborne star sensor will be interfered by many factors when imaging. Besides the noise of the detector itself, the background noise caused by the stray light and the attenuation of the atmospheric transmittance, the influence of the motion factors of the airborne platform on the image quality cannot be ignored. These factors will reduce the star observation ability of the airborne star sensor working in the visible light band. The short wave infrared optical detection method is one of important technologies to improve the star measurement ability of the airborne star sensor in the daytime. In Ref. [3], the influence of noise on the simulated star map is analyzed. In Ref. [4], the coordinate system conversion formula of astronomical navigation is given and the influence of atmospheric refraction on the image shift of stars is analyzed. On the basis of Refs. [3], [4], this paper constructs the imaging link simulation model of star sensor in short wave infrared band, carries out the star map simulation of star sensor in short wave infrared airborne based on the J-band data of 2MASS star catalog, and analyzes the influence of platform motion on star map degradation. Others works mainly focused on the imaging model construction of star sensor on motion platform and placed emphasis on the influence of algorithm performance, especially the location error of the star point, instead of the image quality. This paper analyzes math model of the motion factors and their influences on the image, which provides a reference for optimization system design. The star map obtained by simulation will provide a reliable data input for star point extraction, star pattern recognition and attitude solution algorithm test and evaluation. And an experiment device is also designed to demonstrate the daytime star detection capacity based on J-band. The analysis of the influence of platform motion on image quality will also provide important technical support for on-orbit control of star sensor platform.

Section snippets

The working principle of star sensor

The working principle of star sensor is shown in Fig. 1. Star sensors take pictures of stars in the sky, extract the centroids of star points in the obtained star map, and obtain the coordinates of stars on the image surface; then compare the navigation star database data for star pattern recognition, and obtain the direction of the optical axis sky area corresponding to the coordinates of stars; finally, use the attitude solution algorithm to convert the optical axis direction into the

The implementation process of star map simulation

The flow chart of star map simulation is shown in Fig. 6. Taking the J-band data of 2MASS catalog as the data source, the simulation conditions are input, including detector parameters and optical system parameters, as well as the motion parameters of the platform. For the given input system parameters and catalog data, the processing of star point data is carried out, including the coordinate transformation from celestial coordinate system to star sensor image plane coordinate system,

The image quality evaluation index construction

The gray level information on the image surface can reflect the distribution and energy characteristics of stars. Combined with the characteristics of simulated star map, the quality of star map is evaluated by using SNR, image shift and gray-scale concentration as evaluation indexes. SNR determines the error rate and detection rate of the star point extraction algorithm. Image shift is relevant to the accuracy of positioning of star point. Gray-scale concentration reflects the dispersion

Conclusion

Based on the J-band data of 2MASS catalog, the star map simulation of star sensor working on the airborne motion platform is carried out in this paper. The transmission link model of star sensor, the star sensor imaging model and the influence model of platform motion on the imaging are constructed respectively. Under the given system parameters, the simulation of star map in the working environment of the moving platform is realized. The evaluation indexes of star map SNR, image shift and

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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Citation Excerpt :
C. Sun et al. proposed a star map simulation method of ship-borne star sensor based on INS data [18], which considered the coordinate transformation and star point's Gaussian dispersion, and concentrated on the influence of ship movement on stellar imaging but did not pay attention to atmospheric disturbance. Z. Wei et al. constructed the SWIR star sensor imaging link model [19], analyzed the effect of platform jitter on the star map quality, and completed the star map simulation based on the J-band data of the 2MASS point source catalog. The existing star simulation theories and methods of near-earth space SWIR star sensors consider stellar signal radiation transmission, sky background radiation transmission, coordinate rotation transformation, and detector noise superposition.
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View full text

Regular articleStar map simulation and platform influence of airborne star sensor based on J-band data of 2MASS catalog

Highlights

Abstract

Introduction

Section snippets

The working principle of star sensor

The implementation process of star map simulation

The image quality evaluation index construction

Conclusion

Declaration of Competing Interest

Realization of simulated star map with noise

Chinese J. Opt.

The algorithm research of ground celestial sphere and dynamic star simulator

J. Syst. Simulat.

One method on star image simulation of airborne astronomical navigation

Optoelectron. Technol.

Simulation technology of airborne star sensor imaging

Optoelectron. Technol.

Research status and development tendency of star tracker technique

Chinese J. Optics

Three-axis attitude accuracy of better than 5 arcseconds obtained for the star sensor in a long-term on-ship dynamic experiment

Appl. Opt.

Simulation Analysis of Dynamic Working Performance for Star Trackers

Opt. Soc. Am. A

Dynamic imaging model and parameter optimization for a star tracker

Opt. Exp.

Parameter selection and optical design of all-day star sensor

Acta Photonica Sinica.

Regular article
Star map simulation and platform influence of airborne star sensor based on J-band data of 2MASS catalog