Method and system for determining the position marine vessels and similar objects

• US 20060044179A1
• Filed: 03/15/2005
• Published: 03/02/2006
• Est. Priority Date: 03/15/2004
• Status: Active Grant

• Current Assignee: Kongsberg Discovery As
• Original Assignee: Kongsberg Seatex AS (Government of Norway)
• Inventors: Fossum, Bjorn A
• Granted Patent: US 7,315,274 B2
• Time in Patent Office: Days
• US Class Current: 342/46
• CPC Class Codes: G01S 13/82 wherein continuous-type signals are transmitted
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 7/4056 specially adapted to FMCW
• CPC Class Codes: G01S 7/4091 during normal radar operation

Abstract

A method for determining the relative position between two or more objects in a marine environment, including waterways, of which at least one object can be maneuvered relative to one or more other objects. At least one interrogator is arranged on one or more of the objects and sends a radio wave signal to at least one transponder arranged on one or more of the other objects. The novel method is the use of a FMCW radar in the interrogator, the use of the transponders for including identity tags into the signals to be reflected to the interrogator, and attitude determination. A system for this determination is also described.

Claims

1. A method for determining the relative position between two or more objects in a marine environment, including waterways, of which at least one object can be maneuvered relative to one or more other objects, where at least one interrogator is arranged on one or more of the objects and sends a radio wave signal to at least one transponder arranged on one or more of the other objects, comprising the steps of:

using a FMCW radar in the interrogator,

using the transponders for bringing identity tags into the signals to be reflected to the interrogator, and

using attitude determination.

2. A method according to claim 1, wherein:

at least one interrogator sends a radio signal to at least one transponder arranged on an object for relative positioning,

one or more transponders modulates an identifier frequency into the signal from the interrogator prior to the signal being reflected to the interrogator,

the signals from the transponders are received by a series of antenna elements in the interrogator,

that the combination of the signals received on different antenna elements is used to determine the angles to the transponders in two planes relative to the antenna elements geometry, and

the signals from the transponders are processed to determine the beat frequencies and the Doppler frequencies for each transponder, and

this is used for determining the distance and the relative velocity between the interrogator and each of the transponders, which from the frequency of the carrier signal, can determine the identity of the signal and on this basis determine the position data.

3. Method according to claim 2, wherein one or more interrogators are simultaneously interrogating multiple transponders.

4. Method according to claim 2, wherein an interrogator is operated autonomously towards any transponder.

5. Method according to claim 3, wherein the interrogator illuminates all the transponders simultaneously.

6. Method according to claim 2, comprising combining the distance and angles in two planes, for positioning of one or more transponders in 3 dimensions.

7. Method according to claim 2, comprising combining the relative distance and angles with attitude determination systems, to provide an absolute determination of transponders or interrogators.

8. Method according to claim 2, wherein a fixed transponder at the same object as the interrogator, is used for continuous self calibration and integrity monitoring.

9. Method according to claim 2, wherein a differential positioning between two or more transponders is carried out.

10. Method according to claim 2, wherein a position determination of the interrogator from ranges is obtained, when the relative or absolute position of the transponders is known.

11. System for carrying out the method of claim 1, for determining the relative position between two or more objects (10, 12) in a marine environment, including waterways, of which at least one object (10) can be maneuvered relative to one or more other objects (12), where at least one interrogator (20) is arranged on one of the objects (10) and provided to transmit a radio wave signal to at least one transponder (Tr) arranged on one or more of the other objects (12), comprising:

a FMCW radar in the at least one interrogator (12) and

at least one transponder (Tr) is provided to generate a different sideband frequency to introduce an identity tag into a signal to be reflected to the interrogator, and

a signal processing unit with software containing algorithms for determination of ranges, velocities and angles to transponders.

12. System according to claim 11, wherein the interrogator (20) is implemented with non-moving elements.

13. System according to claim 11, wherein a fixed transponder is provided on the same object as the interrogator, for continuous self calibration and integrity monitoring.