More accurate asset tag locating of radio frequency devices

• US 10,422,848 B1
• Filed: 03/09/2018
• Issued: 09/24/2019
• Est. Priority Date: 03/09/2018
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Inventors: Li, Xiangrong, Abou-Rizk, Mitri J.
• Primary Examiner(s): Ho, Huy C
• Application Number:
  US15/916,893
• Publication Number:
  US 20190277937A1
• Time in Patent Office: 564 Days
• Field of Search: 4554561
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: G01S 5/0295 Proximity-based methods, e.g. position inferred from reception of particular signals
• CPC Class Codes: G01S 5/02955 by computing a weighted average of the positions of the signal transmitters
• CPC Class Codes: G01S 5/08 Position of single direction-finder fixed by determining direction of a plurality of spaced sources of known location
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

Disclosed are examples of a method, system and asset tag that enables general, coarse and fine estimates of a location of the asset tag. The asset tag receives a signal transmitted from radio frequency (RF)-enabled nodes within a space. Each respective received signal includes a unique node identifier of the respective RF node that transmitted the respective received radio signal. Each RF node has a physical node location in the space that is associated with the unique node identifier. The tag measures the received signal strength of each respective received signal that is associated with the node identifier of the RF node that transmitted the respective received signal. The strongest measured received signal strengths are selected, and a tuple containing the node identifiers for the selected strongest signal strengths is forwarded for estimating a location of the asset tag by a computing device.

Claims

1. A method, comprising:

receiving, by an asset tag, a radio signal transmitted from each of three or more radio frequency-enabled nodes within a space, each respective received radio signal including a unique node identifier of the respective radio frequency-enabled node that transmitted the respective received radio signal, wherein each unique node identifier is associated with a specific node location in the space of the respective radio frequency-enabled node;

measuring a received signal strength of each respective received radio signal;

obtaining a respective transmitting node identifier from each of at least three of the respective received radio signals whose measured received signal strengths are strongest;

generating a tuple containing an ordered list of at least three transmitting obtained node identifiers sorted by the respective measured received signal strengths;

forwarding the tuple and the respective measured signal strengths to a tag location estimating application; and

estimating, by the tag location estimating application, based on the generated tuple and the specific node locations associated with the obtained transmitting node identifiers, a location of the asset tag with respect to the specific node locations of the nodes associated with the obtained node identifiers, wherein the estimating includes;

for each pair of the respective measured signal strengths, calculating a respective delta value ratio; and

decreasing or increasing a respective area of a respective region of a set of regions that segment a triangle or other polygon area of the space that the asset tag is located based on the respective delta value ratio.

2. The method of claim 1, wherein the estimating of a location, further comprises:

retrieving, using the three node identifiers provided in the generated tuple, data indicating the specific node locations of the three or more transmitting nodes within the space from a memory; and

determining where within a triangular region of the space the asset tag is located, wherein the vertices of the triangular region are the specific node locations of the obtained transmitting node identifiers.

3. The method of claim 1, further comprising:

generating a data packet including information related to the estimated location of the asset tag within the space; and

forwarding the data packet to a computing device for output of an indicator of the estimated location of the asset tag on a display device coupled to the computing device.

4. The method of claim 1, wherein:

the three obtained transmitting node identifiers are ordered within the generated tuple according to a ranking of a strongest received signal strength value to a lowest received signal strength value of the respective received signal strengths of the three selected transmitted node identifiers.

5. The method of claim 1, wherein the generated tuple comprises:

a first ordinal representing the obtained transmitting node identifier associated with the strongest received signal strength value of the measured received signal strengths of the three obtained transmitting node identifiers,

a second ordinal representing the selected node identifier associated with an intermediary received signal strength value of the measured received signal strengths of the three obtained node identifiers, and

a third ordinal representing the obtained transmitting node identifier associated with a lowest received signal strength value of the measured received signal strengths of the three obtained transmitting node identifiers.

6. The method of claim 1, wherein generated tuple comprises:

a first ordinal representing the obtained transmitting node identifier associated with the lowest received signal strength value measured received signal strength of the three obtained transmitting node identifiers,

a second ordinal representing the obtained transmitting node identifier associated with an intermediary received signal strength value measured received signal strength of the three obtained transmitting node identifiers, and

a third ordinal representing a strongest of the three obtained transmitting node identifiers.

7. A system, comprising:

a plurality of radio frequency-enabled nodes located within a space, each of the plurality of nodes being configured to emit a node-unique radio frequency signal including a unique node identifier of the radio frequency-enabled node, wherein each unique node identifier is associated with a specific node location in the space;

an asset tag within the space, the asset tag comprising;

logic circuitry,

a memory coupled to the logic circuitry,

radio frequency receiver circuitry, and

radio frequency transmitter circuitry; and

a server coupled via a radio frequency communication data link provided by one of the plurality of nodes to the asset tag,

wherein the logic circuitry configures the asset tag to perform functions, including functions to;

receive, via the radio frequency receiver circuitry, a node-unique radio signal transmitted from at least three of the radio frequency-enabled nodes of the plurality of nodes within a space;

measure a received signal strength of each respective received node-unique signal;

obtain a respective transmitting node identifier whose measured received signal strength is from the measured received signal strengths that are strongest;

generate a tuple containing at least three of the obtained transmitting node identifiers; and

forward the generated tuple and the respective measured signal strengths to the server,

wherein the server is configured to;

receive the generated tuple forwarded and the respective measured signal strengths from the asset tag; and

estimate, based on the generated tuple and the specific node locations associated with the obtained transmitting node identifiers, a location of the asset tag with respect to a respective specific node location of each of the obtained transmitting node identifiers in the generated tuple, wherein the estimating includes;

for each pair of the respective measured signal strengths, calculating a respective delta value ratio; and

decreasing or increasing a respective area of a respective region of a set of regions that segment a triangle or other polygon area of the space that the asset tag is located based on the respective delta value ratio.

8. The system of claim 7, wherein when obtaining a respective transmitting node identifier, the logic circuit is configured to perform the function to:

extract a node identifier from each received node-unique signal; and

associate the node identifier extracted from each respective received node-unique signal with the measured received signal strength of the same respective received node-unique signal.

9. The system of claim 7, wherein the server is further configured to perform functions, including functions to:

output of an indicator of the estimated location of the asset tag to a user device.

10. The system of claim 7, wherein:

the obtained node identifiers are ordered in the generated tuple according to a ranking of a strongest received signal strength value to a lowest received signal strength value of the respective received signal strengths of the obtained transmitting node identifiers.

11. The system of claim 7, wherein generated tuple comprises:

a first ordinal representing the obtained node identifier associated with the strongest received signal strength value measured received signal strength of the three obtained node identifiers,

a second ordinal representing the selected node identifier associated with an intermediary received signal strength value measured received signal strength of the three obtained node identifiers, and

a third ordinal representing a lowest of the three obtained node identifiers.

12. The system of claim 7, wherein each obtained node identifier is further associated with a specific node location of the selected node in the space.

13. A method, comprising:

receiving, from an asset tag coupled to a data communication network, a tuple containing at least three wireless node identifiers;

retrieving data indicating a node location for the wireless nodes identified by the at least three wireless node identifiers included in the received tuple, the retrieved data including measured signal strengths; and

estimating a location of the asset tag with respect to the node locations of the at least three node identifiers based on the order of the at least three wireless node identifiers in the received tuple and the retrieved data indicating the node location for each wireless node associated with the at least three node identifiers, wherein the estimating includes;

for each pair of the respective measured signal strengths, calculating a respective delta value ratio; and

decreasing or increasing a respective area of a respective region of a set of regions that segment a triangle or other polygon area of the space that the asset tag is located based on the respective delta value ratio; and

forwarding the estimated asset tag location to an output device for presentation to a user.

14. The method of claim 13, wherein each node identifier of the at least three node identifiers is further associated with a respective physical location within the space.

15. The method of claim 13, wherein the signal attribute is a received signal strength.

16. The method of claim 13, wherein the at least three wireless node identifiers are ordered in the tuple according to a strongest ranked signal attribute to a lowest ranked signal attribute of signals received from wireless nodes associated with each of the at least three wireless node identifiers.