Ultrasound zone location system with high capacity

• US 8,779,895 B2
• Filed: 11/12/2008
• Issued: 07/15/2014
• Est. Priority Date: 11/13/2007
• Status: Active Grant

• Current Assignee: Universitetet I Oslo (Kunnskapsdepartementet)
• Original Assignee: Universitetet I Oslo (Kunnskapsdepartementet)
• Inventors: Holm, Sverre
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): OBINIYI, PAULSON IDOWU
• Application Number:
  US12/742,619
• Publication Number:
  US 20110018687A1
• Time in Patent Office: 2,071 Days
• Field of Search: 340/5.61, 340/8.1, 340/10.1, 340/539.1, 340/539.22, 340/539.26
• US Class Current: 340/10.1
• CPC Class Codes: G01S 1/72 using ultrasonic, sonic or infrasonic waves
• CPC Class Codes: G01S 11/14 using ultrasonic, sonic, or infrasonic waves

Abstract

A zone location system with ultrasound US transmitters S1, S2, S3 located in respective zones Z1, Z2, Z3 such as rooms of a building B. Preferably, the US transmitters are time-multiplexed so that each of them in turn transmits a US signal US with a unique ID code USID represented therein. The portable tag PT includes an ultrasound receiver USR arranged to receive the US signal. Based on the received US signal, the portable tag PT measures a strength of the received US signal. The portable tag PT also measures a parameter related to a movement of the portable tag PT, e.g. a Doppler shift based on the received US signal. Further, the portable tag extracts the USID. Then it transmits a wireless Radio Frequency signal RFS with its own ID PTID, the USID and first and second data values D1, D2 representing the signal strength and the movement related parameters. A processor P connected to a Radio Frequency receiver RFR receives the data from the portable tag PT and determines a connection between PTID and the zone Z2 in which it is present based on the USID. Further, the processor utilizes data D1 and D2 to calculate an estimated position POS within the zone Z2. Especially, estimated distance between US transmitter S2 and portable tag PT and velocity of the portable tag may be estimated based on D1 and D2, thus assisting in estimating the position POS of the portable tag PT. The system may further be combined with a Radio Frequency based positioning system, e.g. an RF signal strength based system, thereby enhancing the resolution of the estimated position POS of the portable tag PT. Further, such combined system help location in complicated and changing environments and in situations where the portable tag PT may be out of reach for US signals, e.g. when attached to a paper file enclosed in a box.

Claims

1. A zone location system arranged to determine in which zone of a predetermined set of zones a portable tag is present, the system comprising:

a set of ultrasound transmitters located in respective zones of the predetermined set of zones, wherein the ultrasound transmitters are arranged to generate an ultrasound signal;

a portable tag with an associated identification code, the portable tag comprising;

an ultrasound receiver arranged to receive the ultrasound signal,

a signal processing means arranged to;

measure a strength of the received ultrasound signal and to generate a first data value accordingly, and

measure a Doppler shift parameter based on the received ultrasound signal, and generate a second data value accordingly; and

a Radio Frequency transmitter arranged to transmit a Radio Frequency signal with data representing the identification code, and the first and second data values;

a Radio Frequency station arranged to receive the Radio Frequency signal from the portable tag; and

a processor operationally connected to the Radio Frequency station, the processor being arranged to;

identify the portable tag based on the identification code,

determine in which zone the portable tag is present, based on detecting which of the set of ultrasound transmitters is/are capable of establishing ultrasound communication with the portable tag,

use the second data value to determine a relative movement between the portable tag and one of the ultrasound transmitters, and

determine a position within said zone, based on the first data value and the determined relative movement.

2. The zone location system according to claim 1, wherein the processor is arranged to determine a distance between the ultrasound transmitter and the portable tag based on the first data value, and to determine said position within said zone based on said distance and the determined relative movement.

3. The zone location system according to claim 1, wherein the ultrasound signal transmitted from one of the ultrasound transmitters includes a code identifying said ultrasound transmitter.

4. The zone location system according to claim 3, wherein the portable tag transmits data received in the ultrasound signal in a Radio Frequency signal.

5. The zone location system according to claim 4, wherein the portable tag transmits the code identifying the ultrasound transmitter in the Radio Frequency signal, and wherein the processor determines in which zone the portable tag is present, based on the code identifying the ultrasound transmitter received in the Radio Frequency signal.

6. The zone location system according to claim 1, wherein the portable tag includes a Radio Frequency receiver arranged to receive a Radio Frequency signal from an external Radio Frequency transmitter.

7. The zone location system according to claim 6, wherein the portable tag is arranged to receive a request for location in said Radio Frequency signal from the external Radio Frequency transmitter.

8. The zone location system according to claim 7, wherein the portable tag is arranged to activate the ultrasound receiver in response to said request.

9. The zone location system according to claim 1, wherein the Radio Frequency receiver and the ultrasound transmitters are stationary components, and wherein the processor is operationally connected to the Radio Frequency receiver by means of a wireless Radio Frequency connection.

10. The zone location system according to claim 1, further comprising a plurality of portable tags each with an associated unique identification code.

11. The zone location system according to claim 1, wherein the predetermined set of zones corresponds to rooms of a building.

12. The zone location system according to claim 1, wherein at least first and second spatially separated ultrasound transmitters are located in at least one of the predetermined set of zones, and wherein the portable tag is arranged to receive a first ultrasound signal from the first ultrasound transmitter and a second ultrasound signal from the second ultrasound transmitter.

13. The zone location system according to claim 1, further comprising a Radio Frequency based positioning system so as to supplement the zone location and position determination provided by ultrasound communication.

14. The zone location system according to claim 13, further comprising one or more stationary Radio Frequency transmitters, wherein the portable tag includes a Radio Frequency receiver arranged to receive a Radio Frequency signal from at least one of the stationary Radio Frequency transmitters, and wherein the portable tag is arranged to determine at least one of:

a strength of the received Radio Frequency signal, and a time of arrival of the received Radio Frequency signal.

15. The zone location system according to claim 1, wherein the portable tag comprises a microphone arranged to receive said ultrasound signal and further arranged to receive an acoustic signal at audio frequencies, and wherein the portable tag is arranged to transmit a representation of the received acoustic signal at audio frequencies in a Radio Frequency signal upon receipt of a user input.

19. The zone location system according to claim 1, wherein the processor is further arranged to use a model for object behavior when using the determined relative movement to determine a position within the zone.

20. The zone location system according to claim 1, wherein the processor is further arranged to create a history of Doppler-shift data for the portable tag, and use said history to track the portable tag.

21. The zone location system according to claim 20, wherein the processor is further arranged to determine a position within said zone by integrating velocity data, derived from said history, over time.

16. A method for determining in which zone of a predetermined set of zones a portable tag is present comprising:

transmitting an ultrasound signal on an ultrasound channel from a set of ultrasound stations of which at least one is positioned in each of the predetermined set of zones;

receiving the ultrasound signal in the portable tag;

determining a strength of the received ultrasound signal, and generating a first data value accordingly;

determining a Doppler shift parameter based on the received ultrasound signal, and generating a second data value accordingly;

transmitting from the portable tag a Radio Frequency signal including a code identifying the portable tag, and the first and second data values;

receiving the Radio Frequency signal from the portable tag;

identifying the portable tag based on the identification code;

determining in which zone the portable tag is present by detecting which of the set of ultrasound stations is/are capable of establishing a communication with the portable tag on the ultrasound channel;

using the second data value to determine a relative movement between the portable tag and one of the ultrasound transmitters; and

determining a position within said zone, based on the first data value and the determined relative movement.

17. The method according to claim 16, wherein the portable tag is located on an object.

18. The method according to claim 16, wherein the portable tag is located on a person.

22. The method according to claim 16, further comprising using a model for object behavior to determine a position within the zone based on the determined relative movement.

23. The method according to claim 16, further comprising creating a history of Doppler-shift data for the portable tag, and using said history to track the portable tag.

24. The method of claim 23, further comprising determining a position within said zone by integrating velocity data, derived from said history, over time.