Method for automatically selecting radionavigation beacons

• US 7,652,621 B2
• Filed: 10/18/2006
• Issued: 01/26/2010
• Est. Priority Date: 11/04/2005
• Status: Expired due to Fees

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Jacotot, Gregoire
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Brainard; Timothy A
• Application Number:
  US12/066,503
• Publication Number:
  US 20080252511A1
• Time in Patent Office: 1,196 Days
• Field of Search: 342/29, 342/36, 342/47
• US Class Current: 342/357.48
• CPC Class Codes: G01S 13/785 Distance Measuring Equipment [DME] systems

Abstract

A method for selecting radionavigation beacons using an onboard navigation system aboard an aircraft from a list of eligible beacons, includes a step for formulating a criterion for selecting a pair of beacons (B_X, B_Y) from among beacons forming part of a list of eligible beacons, and the selection criterion is based on a search for a maximum duration of membership, for instants subsequent to the instant t₁, for which the 2D terrestrial position of the aircraft belongs to the zones of employment of all the pairs of beacons achievable from among the eligible beacons, on the basis of a given predictive trajectory of the aircraft.

Claims

1. A method of selecting radionavigation beacons implemented in an onboard navigation system aboard an aircraft from a list of

eligible beacons at an instant t₂,

a position A(t₁) taken by the aircraft in a reference frame tied to the Earth at an instant t₁ prior to t₂ being known,

a projection of the position of the aircraft onto the 2D terrestrial globe according to the vertical to the aircraft being dubbed the 2D terrestrial position of the aircraft,

the eligible beacons being arranged on the terrestrial surface at known positions which are stored in a database with which the aircraft is equipped,

a domain of employment of an eligible beacon B_i defining a set of 2D terrestrial positions of the aircraft corresponding to positions of the aircraft for which a distance measurement separating the aircraft and the beacon B_i is relevant,

an employment zone Z_X,Y(θ

, t₁) of a pair of eligible beacons being defined by an intersection between the employment domains of the beacons B_X and B_Y and a geometric locus that groups together 2D terrestrial positions of the aircraft for which an angle formed by axes connecting the 2D terrestrial position of the aircraft and the positions of the beacons B_X and B_Y is greater than a predefined value θ

,

the employment zone Z_X,Y(θ

, t₁) being delimited by a boundary, said method comprising;

formulating a criterion for selecting a pair of beacons (B_X, B_Y) from among the beacons forming part of the list of the eligible beacons,

wherein the selection criterion is based on a search for a maximum duration of membership, for instants subsequent to the instant t₁, for which the 2D terrestrial position of the aircraft belongs to the zones of employment of all the pairs of beacons achievable from among the eligible beacons, on the basis of a given predefined trajectory of the aircraft.

2. The method for selecting beacons as claimed in claim 1 further comprising a step for selecting a pair of beacons according to the selection criterion.

3. The method for selecting beacons as claimed in claim 1, a 2D terrestrial position of the aircraft at the instant t₁ being known, a pair of beacons (B_X, B_Y) being selected, at the instant t₁, an employment zone Z_X,Y(θ

, t₁) being defined by the pair of selected beacons (B_X, B_Y) and a value θ

predefined, a duration of membership T_X,Y(θ

, t₁) of the aircraft in the employment zone Z_X,Y(θ

, t₁), on the basis of the position by following the predictive trajectory of the aircraft, the method further comprising

a step for formulating a criterion for modifying the selection of the pair of beacons (B_X, B_Y), wherein the modification criterion is based on a comparison of the value of T(t₁) and of the product k.T_X,Y(θ

, t₁), when T(t₁) is the maximum duration of membership in the zones of employment of all possible pairs from among the eligible beacons except for the pair (B_X, B_Y), on the basis of the 2D terrestrial position of the aircraft at the instant t₁, by following the predictive trajectory of the aircraft, and k is a parameter whose value is predefined.

4. The method for selecting beacons as claimed in claim 3 further comprising:

evaluating, according to the modification criterion, the modification of the pair of beacons (B_X, B_Y); and

making a new selection of a beacon pair according to the selection criterion when the value of k.T_X,Y(θ

, t₁) is less than the value of T(t₁).

5. The method for selecting beacons as claimed in claim 3, wherein the definition of the domain of employment of a beacon depends on the technical characteristics of the beacon and in that the technical characteristics are stored in the database.

6. The method for selecting beacons as claimed in claim 5, wherein the database meets the ARINC 424 standard.

7. The method for selecting beacons as claimed in claim 6, wherein the values of k and of θ

are adapted, over time, as a function of the flight phases of the aircraft.

8. The method for selecting a beacon as claimed in claim 7, wherein the values of k and of θ

are adapted, over time, as a function of the value of the “

Required Navigation Performance”

(RNP) of the trajectory followed by the aircraft.

11. The method for selecting beacons as claimed in claim 3 wherein the predefined trajectory consists of a rectilinear motion of predefined nonzero speed V, from the 2D terrestrial position A(t₁) taken by the aircraft at the date t₁ to a position of a point B belonging to the boundary of the employment zone Z_X,Y(θ

, t₁), the position of the point B on the boundary minimizing the distance separating A(t₁) and positions of the points of the boundary of the employment zone Z_X,Y(θ

, t₁).

12. The method for selecting beacons as claimed in claim 3 wherein a definition of a domain of employment of a beacon depends on an aircraft position.

15. The method for selecting beacons as claimed in claim 1 wherein the predefined trajectory consists of a rectilinear motion of predefined nonzero speed V, from the 2D terrestrial position A(t₁) taken by the aircraft at the date t₁ to a position of a point B belonging to the boundary of the employment zone Z_X,Y(θ

, t₁), the position of the point B on the boundary minimizing the distance separating A(t₁) and positions of the points of the boundary of the employment zone Z_X,Y(θ

, t₁).

16. The method for selecting beacons as claimed in claim 1 wherein a definition of a domain of employment of a beacon depends on an aircraft position.

17. The method for selecting beacons as claimed in claim 1 wherein the definition of the domain of employment of a beacon depends on the technical characteristics of the beacon and in that the technical characteristics are stored in the database.

18. The method for selecting beacons as claimed in claim 17 wherein the database meets the ARINC 424 standard.

19. The method for selecting beacons as claimed in claim 18, wherein the values of k and of θ

are adapted, over time, as a function of the flight phases of the aircraft.

20. The method for selecting a beacon as claimed in claim 19, wherein the values of k and of θ

are adapted, over time, as a function of the value of the “

Required Navigation Performance”

(RNP) of the trajectory followed by the aircraft.

9. The method for selecting beacons as claimed in 3 wherein the predefined trajectory consists in prolonging the motion of the aircraft at the instant t₁ by a uniform rectilinear motion.

10. The method for selecting beacons as claimed in 3 wherein the predefined trajectory is determined on the basis of data featuring in a flight plan onboard the aircraft.

13. The method for selecting beacons as claimed in 1 wherein the predefined trajectory consists in prolonging the motion of the aircraft at the instant t₁ by a uniform rectilinear motion.

14. The method for selecting beacons as claimed in 1 wherein the predefined trajectory is determined on the basis of data featuring in a flight plan onboard the aircraft.