WIRELESS LOCALISATION SYSTEM

• US 20160370455A1
• Filed: 09/01/2016
• Published: 12/22/2016
• Est. Priority Date: 07/04/2008
• Status: Active Grant

• Current Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Original Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Inventors: HEDLEY, Mark, HUMPHREY, David Eric
• Granted Patent: US 10,338,194 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/017 Detecting state or type of motion
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Disclosed is method of computing a round trip delay between a pair of nodes, the method comprising transmitting at least one beacon at a known transmit time from each of the nodes; measuring the times-of-arrival of the beacons at other of the nodes; and estimating a round trip delay between the nodes from the measured times-of-arrival and the transmit times; and correcting the round trip delay for either or both of a frequency offset between the nodes and relative motion between the nodes.

Claims

1. A method of estimating the location of a mobile object using a plurality of anchor nodes, the method comprising:

synchronising said plurality of anchor nodes;

measuring a plurality of times-of-arrival of beacons transmitted from said object to respective said anchor nodes; and

estimating the location of said object relative to said anchor nodes using said measured times-of-arrival, corrected for a propagation delay at each said anchor node.

2. The method according to claim 1, wherein the step of synchronising said plurality of anchor nodes comprises the sub-steps of:

measuring a plurality of trip delays of beacons transmitted between said anchor nodes;

correcting said trip delays for propagation delays at said anchor nodes and frequency offsets between local clocks at respective said anchor nodes; and

determining a time offset of each said local clock from said corrected trip delays.

3. The method according to claim 1, wherein the step of estimating the location of said object relative to said anchor nodes comprises the sub-steps of:

subtracting respective propagation delays from each of said plurality of measured times-of-arrival to give respective pseudo-ranges;

wherein the step of estimating the location of said object relative to said anchor nodes comprises the sub-steps of;

estimating, for a current said range, the location of said object and an error in said location estimate from said range excluding said current range;

discarding the range whose exclusion gave the lowest error estimate, if said lowest error estimate is less than a threshold;

repeating said estimating and said discarding until said lowest error estimate is not less than said threshold or the number of undiscarded ranges reaches a minimum number; and

estimating the location of said object from the undiscarded ranges;

estimating an offset common to all said ranges.