7 results about "Angular distance" patented technology

The invention discloses a star map registration method based on a remote optical image, relates to the technical field of image processing, and solves the problems that the existing method is multi-oriented to a single telescope, most of the single telescope is aligned at a star point level, and the robustness is insufficient when parallax, distortion, optical difference and background pollution exist in remote multi-station imaging. The method comprises the following steps: acquiring a remote star map and extracting a star point centroid; angular distance calculation and triangle construction; registering the centroids of the star points in the whole image; performing similarity transformation and homography estimation; and carrying out sub-pixel refinement and full image registration. According to the invention, dual registration of star point centroids and pixel coordinates can be realized for star maps shot by a plurality of telescopes in different places, and meanwhile, a high-quality registration reference can be provided for subsequent three-dimensional information acquisition of a space target and identification and positioning of the space target.

The invention discloses an optical observation correlation method based on mixed multi-hour ephemeris, and belongs to the technical field of space target monitoring. Aiming at the problem that the correlation performance is reduced when the ephemeris quality is unstable due to dependence on a single ephemeris in the prior art, the method comprises the following steps of: firstly, constructing a mixed set containing multi-source ephemeris; secondly, intelligently selecting a leading ephemeris and a lagging ephemeris which are closest in time for each observation arc section and each target; then, the two ephemeris are used for association respectively, and union sets of results are obtained, so that an initial association set is expanded; and for the generated fuzzy correlation, performing primary disambiguation based on the comprehensive confidence, and performing secondary accurate disambiguation on the residual fuzzy condition by comparing the weighted angular distance residual error root-mean-square value of the whole arc section. According to the method, the dependence on single-term and single-source ephemeris precision is effectively reduced, available information is fully utilized, and the correlation robustness and accuracy of optical observation data under the complex ephemeris condition are remarkably improved.

A kind of relative navigation reference deviation calibration method of star and pulsar information fusion is disclosed, which comprises the following steps: configuring a star angular distance measuring sensor and an X-ray detector on a spacecraft; observing stars by the star angular distance measuring sensor to extract navigation information contained in two kinds of relativistic effects, i.e., star aberration caused by the movement of the spacecraft and light deflection caused by celestial gravitational field; observing pulsars by the X-ray detector to obtain pulse arrival time difference observations; combining spacecraft and earth orbit dynamics model to predict the state; processing star angular distance and pulse arrival time difference observations by an extended Kalman filter to correct the state prediction value, and obtaining the estimation of the spacecraft position and velocity, the geocenter position and velocity, and the sensor system error parameters, so as to realize the calibration of two kinds of reference deviations, i.e., earth ephemeris error and sensor system error. The present application provides a new way to improve the performance of relativistic navigation system.

The invention relates to the technical field of remote sensing satellite ground data processing, in particular to a multi-probe star camera internal and external parameter joint calibration method, which comprises the following steps: constructing an initial light pointing model, and resolving initial attitude parameters; calculating a theoretical image space coordinate of a fixed star control point based on the initial attitude parameter, calculating an attitude parameter again by using the star point data after gross error elimination, and determining a relative installation relation initial value among the multi-probe star cameras; based on the angular distance constraint between star points in a single-frame image, constructing a single-probe internal parameter calibration model and a combined calibration model with internal parameters and relative installation relations as unknown numbers; the observation equation is weighted according to the weighting model, the internal and external parameters are updated based on the resolving result, iterative optimization is carried out until the convergence condition is met, the accurate internal and external parameters of the star camera are obtained, the influence of observation errors on parameter resolving is effectively restrained, and the calibration precision and the reliability of parameter estimation are further improved.

This invention discloses a star map recognition method, apparatus, and related equipment based on an improved K-vector. The method includes calculating the elevation angle of the current observation position relative to each star in the star catalog, filtering the stars in the catalog based on the elevation angle to establish a temporary navigation star database; taking any two stars within a preset angular distance range in the temporary navigation star database as a pair, calculating the angular distance of each pair, and constructing an angular distance table based on the cosine value of the calculated angular distance; dividing the angular distance table into equal regions, connecting the beginning and end of each region with straight lines to obtain multiple segmented straight lines; constructing a K-vector lookup table; obtaining the target angular distance between the target navigation star pairs to be identified, and calculating the matching range of the target navigation star pairs in the angular distance table based on the target angular distance, a preset measurement error, and the K-vector lookup table. This method effectively improves the star map recognition speed.

The present application relates to remote sensing satellite ground data processing technical field, especially to a kind of multi-probe star camera internal and external parameter joint calibration method, the method, including constructing initial light direction model, and solving initial attitude parameter;Based on initial attitude parameter, the theoretical image coordinate of star control point is solved, and the relative installation relationship initial value between multi-probe star camera is determined after solving attitude parameter using star point data after gross error elimination;Based on the angular distance constraint between the star points in single frame image, a single-probe internal parameter calibration model and a joint calibration model with internal parameters and relative installation relationship as unknowns are constructed;According to the weighting model, the observation equation is weighted, the internal and external parameters are updated based on the solution, and the star camera accurate internal and external parameters are obtained by iterative optimization until the convergence condition is met.The present application effectively suppresses the influence of observation error on parameter solution, and further improves the calibration accuracy and the reliability of parameter estimation.

The invention discloses a low-orbit target association evaluation method based on optical observation, and belongs to the technical field of space target monitoring. In order to solve the problems of high false alarm rate and poor robustness caused by neglecting a distance factor in a traditional fixed angular distance correlation method, the method comprises the following steps: firstly, setting a nominal detection distance and a corresponding nominal angular distance residual error threshold; secondly, aiming at potential associated targets of different distances, dynamically calculating an exclusive associated threshold value according to a formula that an angular distance residual error threshold value = a nominal threshold value * (nominal distance / target distance), and reflecting a principle that an angular distance residual error caused by an ephemeris forecast error is inversely proportional to the distance; and finally, in order to prevent the correlation threshold of the extremely close distance target from being too wide, setting a maximum angular distance threshold for constraint. According to the method, the association confidence of different distance targets is unified through the distance self-adaptive dynamic threshold, the association false alarm rate is remarkably reduced, the tolerance to ephemeris forecast errors is improved, and the accuracy and robustness of optical observation data association are effectively improved.