US 12,705,793 B2Granted

Imaging system and method for attitude determination

AssigneeUrugus S.A.

InventorsFlorian Pignol, Manuel Díaz Ramos, Matias Graña

Life of this patent

Estimating the term…

Loading patent…

Abstract

The subject matter disclosed herein is generally directed towards systems and methods for estimating vehicle attitude information using position data of stars and astronomical objects in the sky. Considerable advantages may be realized by equipping vehicles with low-cost star trackers adequate for filtering images based on statistical-based techniques, which could provide a robust and reliable attitude determination. The methods described herein provide algorithms to reduce the amount of processing capacity and memory for finding stars and astronomical objects. In some instances, the provided systems and methods allow the prediction of the next location of the stars and/or other astronomical objects to enhance the search by looking for them at the predicted location. The algorithms may be applied in real-time and are suitable for movable platforms with limited resources such as satellites and spacecraft.

Claims16

Dependent claims

An imaging system for attitude determination, the imaging system comprising:

one or more imaging sensors comprising a plurality of pixel sensors and configured to capture at least one image having a plurality of pixels;
and
one or more processors configured to:
instruct the one or more imaging sensors to capture the at least one image having a plurality of pixels;
filter the at least one image, based at least in part on statistical-based techniques, to detect one or more centroid candidates, by filtering some or all the pixels of the plurality of pixels of the at least one image based at least in part on a hypothesis test;
identify, based at least in part on the one or more centroid candidates, one or more stars;
generate a mapping between the one or more stars and the one or more centroid candidates;
and
estimate an attitude, based on the mapping;
wherein the hypothesis test comprises computing statistical values in a window of the at least one image to test one or more hypotheses to determine the one or more centroid candidates, the window having a size of one or more pixels, and determining whether a likelihood metric is above, equal or below a threshold value;
and
wherein the threshold value is a variable threshold value adjusted based on a priori information;
wherein the window is slid over the at least one image to compute the statistical values in selected one or more sub-regions of the at least one image;
wherein the one or more sub-regions are determined based at least in part on a hint, the hint including an attitude hint or a centroid hint;
and
wherein the attitude hint is determined by the steps comprising:
before capturing the at least one image, capturing a plurality of subsequent images;
determining, based at least in part on a first image and a second image of the plurality of subsequent images, a first order angular velocity estimate;
and
determining, based at least in part upon the first order angular velocity estimate, an attitude estimate associated to the at least one image, to obtain the attitude hint.

17 more elements

A method for attitude determination of a vehicle, the method comprising:

detecting one or more centroid candidates in at least one image by filtering the at least one image based at least in part on statistical-based techniques, wherein the filtering comprises filtering some or all of the pixels of a plurality of pixels of the at least one image based at least in part on a hypothesis test;
matching the one or more centroid candidates to astronomical objects to obtain matches;
determining, based on the matches, a transformation factor;
and
determining, based on the transformation factor, the attitude of the vehicle;
wherein the hypothesis test comprises computing statistical values in a window of the at least one image to test one or more hypotheses to determine the one or more centroid candidates, the window having a size of one or more pixels, and determining whether a likelihood metric is above, equal or below a threshold value;
wherein the threshold value is a variable threshold value adjusted based on a priori information;
wherein the window is slid over the at least one image to compute the statistical values in selected one or more sub-regions of the at least one image;
wherein the one or more sub-regions are determined based at least in part on a hint, the hint including an attitude hint or a centroid hint;
and
wherein the attitude hint is determined by the steps comprising:
before capturing the at least one image, capturing a plurality of subsequent images;
determining, based at least in part on a first image and a second image of the plurality of subsequent images, a first order angular velocity estimate;
and
determining, based at least in part upon the first order angular velocity estimate, an attitude estimate associated to the at least one image, to obtain the attitude hint.

12 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/090,382Filed 28 Dec 2022
Priority: EP 2121838430 Dec 2021
Published: US 2023/0215039 A16 Jul 2023
Granted: 11 Aug 2026
Term ends: Not estimatedThe source records don’t support an estimate.