LOCALIZATION METHOD AND SYSTEM USING NON-REGENERATIVE UWB RELAYS

• US 20130154836A1
• Filed: 12/13/2012
• Published: 06/20/2013
• Est. Priority Date: 12/15/2011
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Consorzio Nazi Interuniv Per Le Telecomunicazioni
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: DERRICO, Raffaele, Conti, Andrea, Dardari, Davide, Sibille, Alain
• Granted Patent: US 9,311,798 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00

Abstract

The present invention relates to a method and a system for determining the position of an object which can be a passive or an active tag (140). The system comprises a plurality of anchor nodes (111,112) and a plurality of non-regenerative relays (121,122,123) of known positions. In case of an active tag, a UWB pulse signal is emitted by the tag and received by the anchor nodes either directly or via a relay. In case of a passive tag, UWB pulse signals are sent by the anchors nodes and reflected back, either way being either a LOS path or a relayed path. A processing node (130) collects the signals received by the anchor nodes (111,112) to estimate the position of the tag.

Claims

1. A method for determining the position of an active tag with a radio locating system comprising a plurality of nodes in known positions, referred to as anchor nodes, and a plurality of non-regenerative relays in known positions, each said relay being adapted to relay a UWB pulse signal emitted by said tag to an anchor node, wherein the signals received by said anchor nodes, either directly from said tag through a LOS path or relayed by a relay through a relayed path, are collected at a processing node, said processing node processing the thus collected signals to estimate the position of the tag.

2. A method according to claim 1, wherein the non-regenerative relays are passive.

3. A method according to claim 1, wherein the non-regenerative relays are active.

4. A method according to claim 1, wherein the processing node estimates the position of the node together with the time of emission of the UWB pulse signal by maximizing a log maximum likelihood function depending upon the collected signals.

5. A method according to claim 4, wherein the log maximum likelihood function is calculated as:

6. A method according to claim 1, wherein the UWB pulse signal is modulated with a time-hopping code and/or a bipolar code.

7. A method for determining the position of an object with a radio locating system comprising a plurality of nodes of known positions, referred to as anchor nodes, and a plurality of non-regenerative relays of known positions, each said relay being adapted to relay an interrogating UWB pulse signal emitted from an anchor node to said object and a UWB pulse signal reflected by said object back to said anchor node, wherein the signals received by said anchor nodes after reflection on said object, either through a LOS path or relayed by a relay through a relayed path, are collected at a processing node, said processing node processing the thus collected signals to estimate the position of the object.

8. A method according to claim 7, wherein the object is a passive tag.

9. A method according to claim 8, wherein the passive tag is adapted to backscatter an incoming signal according to code of binary symbols, a first binary state corresponding to a reflection of the incoming signal as it is and a second binary state corresponding to a reflection of the incoming signal with a reverse polarity.

10. A method according to claim 7, wherein the non-regenerative relays are passive.

11. A method according to claim 7, wherein the non-regenerative relays are active.

12. A method according to claim 8, wherein the processing node estimates the position of the node by maximizing a log maximum likelihood function depending upon the collected signals.

13. A method according to claim 12, wherein the log maximum likelihood function is calculated as:

14. A method according to claim 7, wherein each anchor node emits a UWB pulse signal which is modulated according to a unique time-hopping and/or bipolar code.

15. A radio locating system for estimating the position of an active tag, said radio locating system comprising:

a plurality of nodes of known positions, referred to as anchor nodes;

a plurality of non-regenerative relays of known positions, each said relay being adapted to relay a UWB pulse signal emitted by said tag to an anchor node;

a processing node for collecting the signals received by said anchor nodes, either directly from said tag through a LOS path or relayed by a relay through a relayed path, said processing node being adapted to process the thus collected signals to estimate the position of the tag.

17. A radio locating system according to claim 15, wherein each non-regenerative relay comprises a first antenna and a second antenna, a first switch connected to said first antenna and being adapted to switch between the input of a first amplifier and the output of a second amplifier, a second switch connected to said second antenna and being adapted to switch between the input of the second amplifier and the output of the first amplifier, the first switch and second switch being either simultaneously switched to the respective input and output of the first amplifier, or simultaneously switched to the respective output and input of the second amplifier.

16. A radio locating system for estimating the position of an active tag, said radio locating system comprising:

a plurality of nodes of known positions, referred to as anchor nodes, each anchor node being adapted to emit an interrogating UWB pulse signal;

a plurality of non-regenerative relays of known positions, each said relay being adapted to relay an interrogating UWB pulse signal emitted from an anchor node to said object and a UWB pulse signal reflected by said object back to said anchor node;

a processing node adapted to collect the signals received by said anchor nodes after reflection on said object, either through a LOS path or relayed by a relay through a relayed path, said processing node being further adapted to process the thus collected signals to estimate the position of the object.