Location determination system having mesh infrastructure to reduce power consumption

Patent metadata

Field	Value
Publication number	US-10368216-B2
Application number	US-201715858632-A
Country	US
Kind code	B2
Filing date	Dec 29, 2017
Priority date	Dec 29, 2017
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

The present disclosure relates to a location determination system that includes acoustic transmitting devices, location tags, and a wireless mesh network, where the wireless mesh network uses battery-powered devices. A location tag receives acoustic signals (e.g., ultrasound signals) from an acoustic transmitting device. Clocks from members of the wireless mesh network are synchronized by observation of clock pairings, each clock pair formed by respective clocks in a transmitting device that transmits a message and a receiving device that receives the message. By analyzing the observed clock pairings, a best fit between the clock pairings may be determined. After selecting a reference clock, an acoustic transmission schedule may be propagated to the respective acoustic transmitting device.

First claim

What is claimed is:

1. A real-time location system in an environment, comprising:
a location tag having a location ID, wherein the location tag is configured to transmit the location ID and a received acoustic ID from an acoustic transmitting device to a central server via a wireless mesh network;
the wireless mesh network comprising a first mesh network member and a second mesh network member, the first mesh network member and the second mesh network member being battery-powered devices, the first mesh network member having a first clock and the second mesh network member having a second clock, wherein the first mesh network member transmits a first timestamp of the first clock to the second mesh network member, and the second mesh network member generates a message for propagation to the central server, the message including identification of the first mesh network member and the second mesh network member, and the first timestamp and a second timestamp of the second clock; and
a central server configured to select a reference clock within the wireless mesh network, further configured to determine a time offset between the first clock and the reference clock based on the message; and further configured to propagate an acoustic transmission schedule to the first mesh network member,
wherein the first mesh network member and the location tag communicate acoustically based on the acoustic transmission schedule.

2. The real-time location system of claim 1 , wherein the time offset is determined using statistical analysis.

3. The real-time location system of claim 1 , wherein the time offset is determined using linear regression analysis with outlier rejection.

4. The real-time location system of claim 1 , wherein the central server is further configured to update the acoustic transmission schedule.

5. The real-time location system of claim 1 , wherein the central server is further configured to select a replacement reference clock.

6. The real-time location system of claim 1 , wherein the wireless mesh network uses a Zigbee protocol.

7. The real-time location system of claim 1 , wherein the wireless mesh network communicates within a radio frequency range of 2.4 to 2.5 GHz, or within an 433 MHz, 868 MHz or 915 MHz ISM band.

8. The real-time location system of claim 1 , wherein the location tag receives a firmware upgrade via the wireless mesh network.

9. The real-time location system of claim 1 , wherein the wireless mesh network facilitates propagation of the acoustic transmission schedule via intermediate connections based on wireless signal strength.

10. The real-time location system of claim 1 , wherein the reference clock is a part of the central server.

11. A method for utilizing a wireless mesh network, comprising:
receiving, by a location tag, an acoustic ID from an acoustic transmitting device;
transmitting, by the location tag having a location ID, the location ID and the received acoustic ID to a central server via a wireless mesh network, the wireless mesh network comprising a first mesh network member and a second mesh network member, the first mesh network member and the second mesh network member being battery-powered devices, the first mesh network member having a first clock and the second mesh network member having a second clock;
transmitting by the first mesh network member a first timestamp of the first clock to the second mesh network member;
generating a message by the second mesh network member for propagation to the central server, the message including identification of the first mesh network member and the second mesh network member, and the first timestamp and a second timestamp of the second clock;
determining by the central server a reference clock within the wireless mesh network, and determining a time offset between the first clock and a reference clock based on the message; and
propagating an acoustic transmission schedule to the first mesh network member,
wherein the first mesh network member and the location tag communicate acoustically based on the acoustic transmission schedule.

12. The method of claim 11 , wherein the determining uses statistical analysis.

13. The method of claim 11 , wherein the determining uses linear regression analysis with outlier rejection.

14. The method of claim 11 , further comprising:
updating the acoustic transmission schedule.

15. The method of claim 11 , further comprising:
selecting a replacement reference clock.

16. The method of claim 11 , wherein the wireless mesh network uses a Zigbee protocol.

17. The method of claim 11 , wherein the wireless mesh network communicates within a radio frequency range of 2.4 to 2.5 GHz, or within an 433 MHz, 868 MHz or 915 MHz ISM band.

18. The method of claim 11 , further comprising:
receiving, by the location tag, a firmware upgrade via the wireless mesh network.

19. The method of claim 11 , wherein the propagating the acoustic transmission schedule to the first mesh network member includes:
propagating the acoustic transmission schedule via intermediate connections based on wireless signal strength.

20. The method of claim 11 , wherein the reference clock is a part of the central server.

Assignees

• Sonitor Technologies As

Inventors

• Booij Wilfred Edwin
• Bakka Endre

Classifications

• G01S1/76

  Systems for determining direction or position line · CPC title

• G01S1/751 Primary

  Mounting or deployment thereof · CPC title

• G01S5/0081

  Transmission between base stations · CPC title

• G01S5/0036

  of measured values, i.e. measurement on mobile and position calculation on base station · CPC title

• G01S1/725

  Marker, boundary, call-sign or like beacons transmitting signals not carrying directional information · CPC title