Method of estimating the motion of a carrier with respect to an environment and calculation device for navigation system

Patent metadata

Field	Value
Publication number	US-10565715-B2
Application number	US-201515532447-A
Country	US
Kind code	B2
Filing date	Dec 2, 2015
Priority date	Dec 3, 2014
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

A method for estimating the motion of a carrier with respect to an environment in relation to which the carrier is moving. The carrier bearing a navigation sensor and a vision sensor producing images of the environment. In the images acquired by the vision sensor, the characteristic elements of the images representing characteristic elements of the environment are identified. At least one condensed measurement is calculated as a function of characteristic elements of at least two images acquired at different instants. The motion of the carrier by a navigation filter is estimated, as a function of navigation measurements carried out and as a function of the condensed measurement. The condensed measurement is calculated as a function furthermore of a priori estimation of the motion, as provided by the navigation filter.

First claim

The invention claimed is:

1. A method for estimating a motion of a carrier with respect to an environment in relation to which the carrier is moving, the carrier bearing on board at least one navigation sensor and at least one vision sensor producing images of the environment, the method comprising the steps, performed by a calculation device, of:
identifying, in the images acquired by said at least one vision sensor, characteristic elements of the images representing characteristic elements of the environment;
calculating at least one condensed measurement as a function of the characteristic elements of at least two images acquired at different times, said at least one condensed measurement being representative of characteristics of the motion of the carrier during acquisition of said at least two images;
estimating the motion of the carrier by a navigation filter performed as a function of navigation measurements performed by said at least one navigation sensor and as a function of said at least one condensed measurement;
wherein said at least one condensed measurement is calculated as a function furthermore of an a priori estimation of the motion of the carrier provided by the navigation filter; and
estimating an error made in said at least one condensed measurement; estimating a relation between an error made in the a priori estimation of the motion of the carrier and the error made in said at least one condensed measurement; and wherein the navigation filter estimates the motion of the carrier as a function furthermore of the error made in said at least one condensed measurement, and as a function of the relation between the error made in the a priori estimation of the motion of the carrier and the error made in said at least one condensed measurement.

2. The method as claimed in claim 1 , wherein the navigation filter estimating the motion of the carrier is a Kalman filter.

3. The method as claimed in claim 1 , wherein the calculation device determines, during the calculation step, a condensed measurement representative of a ratio of distances traveled by the carrier between times of acquisition of two pairs of images of a triplet of images, as a function of characteristic elements of the images of the triplet representing the characteristic elements of the environment which are visible in each of the images of the triplet.

4. A method for estimating a motion of a carrier with respect to an environment in relation to which the carrier is moving, the carrier bearing on board at least one navigation sensor and at least one vision sensor producing images of the environment, the method comprising the steps, performed by a calculation device, of:
identifying, in the images acquired by said at least one vision sensor, characteristic elements of the images representing characteristic elements of the environment;
calculating at least one condensed measurement as a function of the characteristic elements of at least two images acquired at different times, said at least one condensed measurement being representative of characteristics of the motion of the carrier during acquisition of said at least two images;
estimating the motion of the carrier by a navigation filter performed as a function of navigation measurements performed by said at least one navigation sensor and as a function of said at least one condensed measurement;
wherein said at least one condensed measurement is calculated as a function furthermore of an a priori estimation of the motion of the carrier provided by the navigation filter; and
estimating an error made in the a priori estimation of the motion of the carrier; and calculating said at least one condensed measurement as a function furthermore of the error made in the a priori estimation of the motion.

5. The method as claimed in claim 4 , wherein the navigation filter estimating the motion of the carrier is a Kalman filter.

6. The method as claimed in claim 4 , wherein the calculation device determines, during the calculation step, a condensed measurement representative of a ratio of distances traveled by the carrier between times of acquisition of two pairs of images of a triplet of images, as a function of characteristic elements of the images of the triplet representing the characteristic elements of the environment which are visible in each of the images of the triplet.

7. A method for estimating a motion of a carrier with respect to an environment in relation to which the carrier is moving, the carrier bearing on board at least one navigation sensor and at least one vision sensor producing images of the environment, the method comprising the steps, performed by a calculation device, of:
identifying, in the images acquired by said at least one vision sensor, characteristic elements of the images representing characteristic elements of the environment;
calculating at least one condensed measurement as a function of the characteristic elements of at least two images acquired at different times, said at least one condensed measurement being representative of characteristics of the motion of the carrier during acquisition of said at least two images;
estimating the motion of the carrier by a navigation filter performed as a function of navigation measurements performed by said at least one navigation sensor and as a function of said at least one condensed measurement;
wherein said at least one condensed measurement is calculated as a function furthermore of an a priori estimation of the motion of the carrier provided by the navigation filter; and
wherein the a priori estimation of the motion of the carrier comprises estimating a rotation of the carrier.

8. The method as claimed in claim 7 , wherein the navigation filter estimating the motion of the carrier is a Kalman filter.

9. The method as claimed in claim 7 , wherein the calculation device determines, during the calculation step, a condensed measurement representative of a ratio of distances traveled by the carrier between times of acquisition of two pairs of images of a triplet of images, as a function of characteristic elements of the images of the triplet representing the characteristic elements of the environment which are visible in each of the images of the triplet.

10. A method for estimating a motion of a carrier with respect to an environment in relation to which the carrier is moving, the carrier bearing on board at least one navigation sensor and at least one vision sensor producing images of the environment, the method comprising the steps, performed by a calculation device, of:
identifying, in the images acquired by said at least one vision sensor, characteristic elements of the images representing characteristic elements of the environment;
calculating at least one condensed measurement as a function of the characteristic elements of at least two images acquired at different times, said at least one condensed measurement being representative of characteristics of the motion of the carrier during acquisition of said at least two images;
estimating the motion of the carrier by a navigation filter performed as a function of navigation measurements performed by said at least one navigation sensor and as a function of said at least one condensed measurement;
wherein said at least one condensed measurement is calculated as a function furthermore of an a priori estimation of the motion of the carrier provided by the navigation filter; and
wherein the a priori estimation of the motion of the carrier comprises estimating a translation of the carrier between times of acquisition of the images.

11. The method as claimed in claim 10 , wherein the navigation filter estimating the motion of the carrier is a Kalman

Assignees

• Airbus Defence & Space Sas

Inventors

• Polle Bernard

Classifications

• G01C21/005

  with correlation of navigation data from several sources, e.g. map or contour matching (G01C21/30 takes precedence) · CPC title

• G06T2207/30244

  Camera pose · CPC title

• G06T7/277 Primary

  involving stochastic approaches, e.g. using Kalman filters · CPC title

• G06T2207/30241

  Trajectory · CPC title