High-precision 3D position-finding system

• US 20030220092A1
• Filed: 02/21/2003
• Published: 11/27/2003
• Est. Priority Date: 02/22/2002
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Hethuin, Serge, Giraudo, Michel, Eumurian, Gregoire
• Granted Patent: US 6,895,333 B2
• Time in Patent Office: Days
• US Class Current: 455/404.2
• CPC Class Codes: G01S 2205/02 Indoor
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers

Abstract

A precise 3D position-finding system and method comprises at least the following elements: a set of beacons working on the basis of differential global positioning satellites (DGPS), the beacons being connected to one another and temporally synchronized, spread-spectrum radio means between the members of the network whose position is to be located and said beacons, and a computation station. The computation station is provided with a processor adapted to finding the position of one or more elements from a list of direct paths and/or multiple paths with the time and direction of arrival of each of the direct paths and/or multiple paths, and from the position of the beacons and in taking account of data that represents obstacles.

Claims

1. A precise 3D position-finding system comprising at least the following elements:

a set of beacons working on the basis of differential global positioning satellites (DGPS), the beacons being connected to one another and temporally synchronized, spread-spectrum radio means between the members of the network whose position is to be located and said beacons, and a computation station, wherein the computation station is provided with a processor adapted to finding the position of one or more elements from a list of direct paths and/or multiple paths with the time and direction of arrival of each of the direct paths and/or multiple paths, and from the position of the beacons and in taking account of data that represents obstacles.

2. A system according to claim 1, wherein the number of beacons is at least equal to four, three of them being positioned in the same plane and the fourth having a given altitude relative to this plane.

3. A system according to one of the claims 1 and 2, wherein the means of communication between the beacons and the members of the network whose position is to be located are identical or appreciably identical to the standard means that constitute the communications network and accept sound, video and fixed images.

4. A system according to claim 1, wherein the spread-spectrum radio means, between the members of the network whose position is to be located and the beacons, are of different natures, such as direct sequence waveforms (PN code), UWB, FHSS (Frequency Hopping Spread Spectrum), chirp type frequency ramp, etc.

5. A method for the 3D positioning of an element in a system comprising at least four beacons working on the basis of the differential global positioning system (DGPS), the beacons being temporally synchronized, wherein the system comprises at least the following steps:

the transmission, by a beacon, of its DGPS position and of a list of multiple paths with the time and direction of arrival of each of the direct paths and/or the multiple paths sent by the element whose position is to be located,

temporal readjustment, if necessary in the event of a detected shift, of one or more beacons,

the computation of the estimated positions of the element for the context of information received from each beacon,

a processing of the data using a mapping or a topology of the environment in which the element whose position is to be located is placed to reconstruct the different direct paths and/or multiple paths and select the multiple paths to achieve a precise 3D determining of the element whose position is to be located.

6. A method according to claim 5, wherein the data-processing comprises a step to compare the readjusted data and a step to eliminate information from the beacon or beacons that diverge excessively from the value indicated by the greatest number of beacons.

7. A method according to claim 5, wherein the processing of the data comprises the taking into account of information on the multiple paths by comparing the readjusted data with a mapping database.

8. A method according to claim 5, wherein one of the beacons sends a request in order to locate the position of the element.

9. A method according to claim 5, wherein the position-finding is done by examining the communications signals sent in the course of time by the element or elements to whose position is to be located.

10. A method according to one of the claims 5 to 9 wherein the signals exchanged between the beacons and the members of the network whose position is to be located are identical or appreciably identical to the standard means that constitute the communications network and accept sound, video and fixed images.

11. A method according to one of the claims 5 to 9, using spread-spectrum radio means, between the members of the network whose position is to be located and the beacons, that are of different natures, such as direct sequence waveforms (PN code), UWB, FHSS (Frequency Hopping Spread Spectrum), chirp type frequency ramp, etc.