Hybrid inertial/stellar navigation method with harmonization performance indicator

Patent metadata

Field	Value
Publication number	US-12566066-B2
Application number	US-202218708081-A
Country	US
Kind code	B2
Filing date	Nov 9, 2022
Priority date	Nov 9, 2021
Publication date	Mar 3, 2026
Grant date	Mar 3, 2026

Abstract

A navigation method of a vehicle equipped with a star tracking device, a first inertial measurement device and a satellite positioning device, the star tracking device and the first inertial measurement device being connected to a single support. The method includes controlling movements of the support; simultaneously with these movements, calculating, in a horizontal plane, first positions of the vehicle, and second positions of the vehicle; calculating first deviations between the first positions and the second positions corresponding to each tracking heading and depicting them in a polar reference frame as a function of the corresponding heading and the values of the first deviations; carrying out a circular regression on said first deviations to determine, in this polar reference frame, a first circle; and determining a radius of the circle and a second deviation between a centre of the first circle and an origin of the polar reference frame.

First claim

The invention claimed is:

1 . A navigation method of a vehicle equipped with a star tracking device, a first inertial measurement device and a satellite positioning device, the star tracking device and the first inertial measurement device being rigidly connected to a single support, comprising the steps of:
controlling movements of the support according to different tracking headings of the star tracking device, simultaneously with these movements, calculating in a horizontal plane, first positions of the vehicle on the basis of a first navigation algorithm using stellar measurements, and second positions of the vehicle on the basis of a second navigation algorithm using first inertial measurements coming from the first inertial measurement device coupled with satellite measurements, calculating first deviations between the first positions and the second positions corresponding to each tracking heading and depicting them in a polar reference frame as a function of the corresponding heading and values of the first deviations, carrying out a circular regression on said first deviations to determine, in this polar reference frame, a first circle representative of all of the first deviations, determining a radius of the first circle, this radius being representative of a harmonisation error between the inertial measurement device and the star tracking device, and a second deviation between a centre of the first circle and an origin of the polar reference frame, the second deviation being representative of an attitude error of the horizontal plane of the inertial measurement device, monitoring the harmonisation error and the attitude error of the horizontal plane.

2 . The navigation method according to claim 1 , wherein the first deviations are depicted in the polar reference frame in the form of an average of the values of the first deviations per heading.

3 . The navigation method according to claim 1 , comprising the steps of:
returning all the first deviations to a single heading to obtain third deviations, carrying out a linear regression on the third deviations to obtain a straight line representative of all of the third deviations, deducing from this, an attitude error of the horizontal plane and a harmonisation error between the star tracking device and the inertial measurement device, defining in the polar reference frame, a second circle having a radius equal to the harmonisation error and a centre separated from an origin of the polar reference frame according to a vector corresponding to the attitude error of the horizontal plane as a function of the heading, verifying a coherence between the first circle and the second circle.

4 . The navigation method according to claim 1 , comprising the step of determining an indicator representative of the coherence between the first circle and the second circle.

5 . The navigation method according to claim 1 , wherein the first deviations are calculated and placed in the polar reference frame in real time.

6 . The navigation method according to claim 1 , wherein the heading movements of the support are obtained by controlling corresponding movements of the vehicle.

7 . The method according to claim 1 , wherein the heading movements of the support are obtained by making the support pivot with respect to the vehicle.

8 . The navigation method according to claim 1 , wherein:
the first inertial measurement device is associated with the star tracking device and the first inertial measurements are used to determine an orientation of the star tracking device on which the stellar measurements depend; the vehicle comprises a second inertial measurement device providing second inertial measurements which are used coupled with the satellite measurements to develop third positions by means of a third navigation algorithm, the third positions being used to direct the vehicle.

9 . The navigation method according to claim 1 , implemented to carry out a verification of a harmonisation of the star tracking device, while the vehicle is immobile.

10 . A navigation system for a vehicle, comprising a star tracking device, an inertial measurement device, a satellite positioning device, and an electronic navigation calculation unit connected to these, the star tracking device and the inertial measurement device being rigidly connected to a single support and the electronic navigation calculation unit being programmed to implement the navigation method according to claim 1 .

11 . A vehicle equipped with the navigation system according to claim 10 .

Assignees

• Safran Electronics & Defense

Inventors

• Elie Philippe

Classifications

• G01C21/025 Primary

  with the use of startrackers · CPC title

• G01C21/1656

  with passive imaging devices, e.g. cameras · CPC title

• G01C21/188 Primary

  for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems · CPC title