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Imaging method and imaging system for performing in-orbit geometric calibration through star observation

A technology of geometric calibration and imaging method, which is applied in the direction of navigation, measuring devices, instruments, etc. through velocity/acceleration measurement, to overcome the problem of weak geometric strength, improve the geometric strength of measurement, and achieve the effect of high signal-to-noise ratio

Active Publication Date: 2020-04-07
CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0004] In order to solve the existing problem of how to combine space optical imaging and electronic technology to ensure the internal orientation element calibration of the high-precision imaging system on-orbit, the present invention provides an imaging method and imaging system for on-orbit geometric calibration through stargazing

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  • Imaging method and imaging system for performing in-orbit geometric calibration through star observation
  • Imaging method and imaging system for performing in-orbit geometric calibration through star observation
  • Imaging method and imaging system for performing in-orbit geometric calibration through star observation

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specific Embodiment approach 1

[0024] Specific implementation mode 1. Combination figure 1 To illustrate this embodiment, the system for on-orbit geometric calibration through stargazing mainly includes satellite platforms, star sensors, line array cameras and gyroscopes. The star sensor, line array camera and gyroscope are all installed on the satellite platform. The star sensor measures the on-orbit attitude of the satellite, and the gyroscope outputs the angular velocity output by the satellite.

[0025] m V The illuminance produced by the magnitude outside the atmosphere is:

[0026]

[0027] where E 0 =2.54×10 -6 lux, is the illuminance of a zero-magnitude star outside the atmosphere, and lux is the unit of illuminance; MV Represents the star magnitude.

[0028] require M V The magnitude of the light at the detector integration time t int The number of starlight charges that may be generated on a single pixel cannot reach the full well charge of the detector, and the signal-to-noise ratio can...

specific Embodiment approach 2

[0046] Specific embodiment 2. This embodiment is the imaging method of the on-orbit geometric calibration system through stargazing described in specific embodiment 1. This method adopts the combined stargazing mode of star sensitivity + gyroscope. First, the imaging method of the line array camera The selection of parameters requires that the focal ratio of the optical system of the line scan camera and 2.44 times the central wavelength be greater than the pixel size, expressed as:

[0047] 2.44λF>a

[0048] Where λ is the average light wavelength.

[0049] Secondly, according to the magnitude of the predicted star and the spectral range of the detector, set an appropriate integration time to ensure that the linear array detector is not saturated and the signal-to-noise ratio is greater than or equal to 2; namely:

[0050] set M V The magnitude of the light at the detector integration time t int The number of starlight charges that may be generated on a single pixel cannot...

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Abstract

The invention discloses an imaging method and an imaging system for performing in-orbit geometric calibration through star observation, relates to an imaging system for in-orbit geometric calibrationin a satellite observation technology, and solves the problem of how to combine space optical imaging with an electronic technology to ensure interior orientation element calibration of a high-precision imaging system in orbit. The system comprises a satellite platform, a star sensor, a line-scan digital camera and a gyroscope. The star sensor, the line-scan digital camera and the gyroscope are all installed on the satellite platform, the star sensor measures the on-orbit attitude of a satellite, and the gyroscope outputs the angular velocity of the satellite. According to the invention, a star sensor and gyroscope combined star observation mode is adopted, and proper integral time is set according to imaging parameters of the line-scan digital camera and pre-observed star magnitude; the uniform swinging speed of the satellite is set according to the set integral time and an allowable image motion amount, a proper gyroscope is selected according to flutter characteristics of the satellite, and combined extension of Kalman filtering between the gyroscope and the star sensor is performed, so that the attitude variation between linear array rows is accurately obtained, and the geometric strength of measurement is improved.

Description

technical field [0001] The invention relates to an imaging system for on-orbit geometric calibration in satellite observation technology, in particular to a method for on-orbit geometric calibration through stargazing and an imaging system. Background technique [0002] Most of today's on-orbit calibrations are based on the true coordinates of the control points of the calibration field. Due to the influence of various factors such as the satellite's orbital return period and weather, the calibration efficiency is low, and it is time-consuming and laborious. The relative angular distance between star points in the sky is constant, which is a natural source of geometric calibration. If you use an area array detector for stargazing to calibrate, it is relatively easy to implement and has high geometric strength; however, most detectors used in earth observation are linear array detectors, which need to synthesize a stargazing image through multiple swing imaging, and the geome...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01C21/02G01C21/16G01C25/00
CPCG01C21/025G01C21/165G01C25/00
Inventor 余达刘金国吴国栋姜肖楠王钢裴君妍张雨
Owner CHANGCHUN INST OF OPTICS FINE MECHANICS & PHYSICS CHINESE ACAD OF SCI