Device and method for determining a rough component of a latitude or longitude position of a moving craft

• US 9,971,734 B2
• Filed: 11/19/2015
• Issued: 05/15/2018
• Est. Priority Date: 11/25/2014
• Status: Active Grant

• Current Assignee: Airbus Operations SAS (Airbus SE)
• Original Assignee: Airbus Operations SAS (Airbus SE)
• Inventors: Fabas, Nicolas
• Primary Examiner(s): Khatib, Rami
• Assistant Examiner(s): Wiltey, Nicholas K
• Application Number:
  US14/945,994
• Publication Number:
  US 20160147711A1
• Time in Patent Office: 908 Days
• Field of Search: None
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G06F 17/10 Complex mathematical operations function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 2012/4028 the transportation system being an aircraft

Abstract

A device and a method for determining a rough component of a latitude or longitude position of a moving craft. The position is reconstructed cyclically by combining the rough component with a corresponding fine component. The device determines the sign of a difference between the fine component for an acquisition cycle and the fine component for a preceding acquisition cycle. The device then computes the rough component corresponding to the given acquisition cycle of the fine component, as a function of the sign of the difference and of the sign and of the value of the speed of the craft. The device and the corresponding method make it possible to extrapolate an unrefreshed rough component as a function of the trend of the fine component and of the sign of the speed of the moving craft to reduce error associated with the computation of the latitude or longitude position.

Claims

1. A device for determining a coarse component of a position datum of a moving craft, said position datum representing one of a latitude of the moving craft or a longitude of the moving craft, said position datum being reconstructed cyclically in accordance with cycles of reconstruction of the position datum, by combining said coarse component acquired cyclically in accordance with cycles of acquisition of the coarse component, with a corresponding fine component acquired cyclically in accordance with cycles of acquisition of the fine component, comprising:

an acquisition module configured to acquire said fine component in accordance with cycles of acquisition of the fine component and to acquire the coarse component in accordance with cycles of acquisition of the coarse component, wherein the cycles of acquisition of the fine component are executed at a first frequency, and wherein the cycles of acquisition of the coarse component are executed at a second frequency lower than the first frequency;

a first determination module configured to determine a sign of a difference between the fine component for a given one of the cycles of acquisition of the fine component and the fine component for the preceding one of the cycles of acquisition of the fine component;

a second determination module configured to determine a sign and a value of the speed of the moving craft based on speed data from a computation system;

a computer configured to compute the coarse component corresponding to said given one of the cycles of acquisition of the fine component, as a function of said sign of the difference between the fine component for said given one of the cycles of acquisition of the fine component and the fine component for said preceding one of the cycles of acquisition of the fine component, and as a function of said sign and said value of the speed of the moving craft.

2. The device as claimed in claim 1, wherein the computer is configured to compute the coarse component corresponding to said given one of the cycles of acquisition of the fine component, also as a function of the value of the speed of the moving craft.

3. The device as claimed in claim 1, wherein, for the determination by said device of the coarse component of a latitude position, said second determination module is configured to determine the sign of the speed of the moving craft along the south-north axis.

4. The device as claimed in claim 1, wherein, for the determination by said device of the coarse component of a longitude position, said second determination module is configured to determine the sign of the speed of the moving craft along the west-east axis.

5. The device as claimed in claim 1, wherein the computer is configured to compute the coarse component corresponding to said given one of the cycles of acquisition of the fine component, denoted N+1, N being a positive integer, in accordance with a first algorithm comprising the following computations:

6. The device as claimed in claim 5, wherein the device includes a third determination module configured to determine the value A as a function of the value of the speed of the moving craft.

7. The device as claimed in claim 1, wherein said device includes a computer configured to compute a corrected coarse component of the position datum corresponding to said given reconstruction cycle, as a function of the difference between the position datum reconstructed for said given reconstruction cycle and the corrected reconstructed position for said preceding reconstruction cycle, and as a function of said sign of the speed of the moving craft.

8. The device as claimed in claim 7, wherein the computer is configured to compute the corrected coarse component of the position corresponding to said given reconstruction cycle, denoted N+1, N being a positive integer, in accordance with a second algorithm comprising the following computations:

9. The device as claimed in claim 8, wherein the device includes a determination module configured to determine the value A as a function of the value of the speed of the moving craft.

10. A system for a moving craft comprising:

a computation system configured to compute cyclically a coarse component of a position datum of the moving craft, and to compute cyclically a corresponding fine component of the position datum, said position datum being one of a latitude position or a longitude position of the moving craft, and,

a determination device for determining the coarse component of the position datum of the moving craft, said position datum being reconstructed cyclically in accordance with cycles of reconstruction of the position datum, by combining said coarse component acquired cyclically in accordance with cycles of acquisition of the coarse component, with a corresponding fine component acquired cyclically in accordance with cycles of acquisition of the fine component, said determination device comprising;

an acquisition module configured to acquire said fine component from said computation system in accordance with cycles of acquisition of the fine component and to acquire said coarse component from said computation system in accordance with cycles of acquisition of the coarse component, wherein the cycles of acquisition of the fine component are executed at a first frequency, and wherein the cycles of acquisition of the coarse component are executed at a second frequency lower than the first frequency;

a first determination module configured to determine a sign of a difference between the fine component for a given one of the cycles of acquisition of the fine component and the fine component for the preceding one of the cycles of acquisition of the fine component;

a second determination module configured to determine a sign and a value of the speed of the moving craft based on speed data from the computation system;

a computer configured to compute the coarse component corresponding to said given cycle of acquisition of the fine component, as a function of said sign of the difference between the fine component for said given one of the cycles of acquisition of the fine component and the fine component for said preceding one of the cycles of acquisition of the fine component, and as a function of said sign and said value of the speed of the moving craft.

11. The system as claimed in claim 10, wherein the computation system is configured to encode the coarse and fine components in a binary format, so that the fine component evolves between zero and the least significant bit of the coarse component.

12. A method performed by a processor for determining a coarse component of a position datum of a moving craft, said position datum being one of a latitude position or a longitude position of the moving craft, comprising the steps:

reconstructing said position datum cyclically in accordance with cycles of construction of the position datum by combining said coarse component acquired cyclically in accordance with cycles of acquisition of the coarse component, with a corresponding fine component acquired cyclically in accordance with cycles of acquisition of the fine component,

acquiring said fine component in accordance with cycles of acquisition of the fine component and acquiring the coarse component in accordance with cycles of acquisition of the coarse component, wherein the cycles of acquisition of the fine component are executed at a first frequency, and wherein the cycles of acquisition of the coarse component are executed at a second frequency lower than the first frequency;

determining a sign of a difference between the fine component for a given one of the cycles of acquisition of the fine component and the fine component for a preceding one of the cycles of acquisition of the fine component;

determining the sign and of the value of the speed of the moving craft based on speed data from a computation system; and

computing the coarse component corresponding to said given one of the cycles of acquisition of the fine component, as a function of said sign of said difference, and as a function of said sign and of said value of the speed of the moving craft.

13. The method as claimed in claim 12, wherein, for the correction of a coarse component of a position datum corresponding to a given reconstruction cycle, said method further includes the computation of said corrected coarse component, as a function of the difference between the position datum reconstructed for said given reconstruction cycle and the reconstructed position corrected for said preceding reconstruction cycle, and as a function of said sign and of the value of the speed of the moving craft.