Ultrasonic locating system

• US 7,362,656 B2
• Filed: 12/02/2003
• Issued: 04/22/2008
• Est. Priority Date: 12/04/2002
• Status: Active Grant

• Current Assignee: Sonitor Technologies AS
• Original Assignee: Sonitor Technologies AS
• Inventors: Holm, Sverre
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US10/534,485
• Publication Number:
  US 20060077759A1
• Time in Patent Office: 1,603 Days
• Field of Search: 367/128, 367/127
• US Class Current: 367/128
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence

Abstract

The invention relates to a method and a system for monitoring and position determination of objects and/or living beings within an area, such as, e.g. a room in a building or a road tunnel. The system comprises a plurality of identification tags equipped with an ultrasonic receiver and radio transmitter which is attached to the objects that have to be monitored. The identification tags receive ultrasonic signals whose arrival time they measure. This information together with the identification tags'"'"'ID code are transmitted by radio waves to a central unit which calculates the position of each of the identification tags.

Claims

1. An identification tag for use in a location system for determining the identification tag'"'"'s location in a room in a building or areas to be monitored, wherein the identification tag comprises an ultrasonic transducer connected to a receiver adapted to receive ultrasonic signals, together with a radio transmitter connected to an antenna adapted to transmit an identity radio signals with information containing the identity of the identification tag, and wherein the tag further comprises a calculating unit connected to a control unit arranged to calculate transit time differences for the received ultrasonic pulses.

2. An identification tag according to claim 1, wherein the ultrasonic transducer is connected to the receiver unit in order to detect ultrasonic pulses with different frequencies or codes that are transmitted from one or more master units and slave units which transmit the different frequencies or codes.

3. An identification tag according to claim 1, characterised in that the receiver unit is connected to a control unit.

4. An identification tag according to claim 3, wherein the control unit is arranged to cause the radio transmitter to transmit a radio signals in response to the identification tag'"'"'s calculating unit having calculated transit time differences for the received ultrasonic pulses.

5. An identification tag according to claim 4, further comprising a sabotage unit connected with the control unit for detecting any attempt to remove and/or open the identification tag, and where, after such detection, the control unit is adapted to add such additional information to a radio signal transmitted from the identification tag.

6. An identification tag according to claim 3, characterised in that it further comprises a radio receiver connected to the control unit for receiving information on which room or area it is located in, with the result that the identification tag does not need to listen continuously for ultrasonic signals.

7. A system for position determination of at least one identification tag, comprising:

a central processing unit,

at least one stationary master unit, with an ultrasonic transducer for transmitting ultrasonic signals in the form of ultrasonic pulses and a receiver unit for receiving instructions from the central processing unit,

at least one identification tag according to claim 1 for transmitting the identification tag'"'"'s identity, as well as measured transit time differences for received ultrasonic pulses, together with any additional information,

a network interconnecting the at least one stationary master unit with the central processing unit for transfer of instructions,

means in the central processing unit for calling up identification tags as well as detecting, collecting and interpreting received radio signals from the identification tags, and

processing means in the central processing unit for determining the position of the identification tags.

8. A system according to claim 7, further comprising at least one stationary slave unit with an ultrasonic transducer for transmitting ultrasonic signals in the form of ultrasonic pulses.

9. A system according to claim 8, wherein the number of stationary master units is one, and the number of stationary slave units is at least three.

10. A system according to claim 8, wherein a network interconnects the stationary master unit and the stationary slave unit for transferring a synchronisation message from the master unit.

11. A system according to claim 8, wherein the stationary master unit and the stationary slave unit each transmits ultrasonic waves on its own frequency or with its own coding.

12. A system according to claim 7, wherein the stationary master unit comprises means for transmitting a synchronisation message to all stationary slave units with which it is connected.

13. A system according to claim 7, wherein characterised in that the network interconnecting the stationary master unit and the central processing unit is based on radio waves.

14. A system according to claim 7, wherein the network interconnecting the stationary master unit and the central processing unit is wire-based.

15. A system according to claim 7, wherein the stationary slave unit comprises means for receiving a synchronisation message from a stationary master unit with which it is in network connection.

16. A system according to claim 8, wherein the network interconnecting the stationary master unit and the stationary slave unit is radio-based.

17. A system according to claim 8, wherein the network interconnecting the stationary master unit and the stationary slave unit is wire-based.

25. An identification tag as in claim 1 wherein the radio transmitter is further arranged to transmit a transit time radio signal comprising information about one of said calculated transit time differences.

26. An identification tag as in claim 1 further comprising a radio receiver wherein the tag is arranged to listen for ultrasonic pulses only for a predetermined period after receiving a radio signal transmitted in the room or area in which it is located.

18. A method for position determination of one or more identification tags in a room in a building or areas to be monitored, comprising the steps of:

a) transmitting a message from a central processing unit to at least one stationary master unit,

b) transmitting a synchronisation message from the stationary master unit to at least one stationary slave unit,

c) transmitting ultrasonic pulses synchronously from the stationary master unit and the stationary slave unit,

d) receiving the ultrasonic pulses at an identification tag,

e) calculating arrival times for received ultrasonic pulses in the identification tag,

f) transmitting radio signals containing information concerning arrival times for received ultrasonic pulses together with identification of the identification tag to a central processing unit,

g) calculating the position of the specific identification tag in the central processing unit on the basis of received identification and transit time differences transmitted from the identification tag, together with knowledge of the position of each individual stationary master unit and stationary slave unit in every room or area.

19. A method according to claim 18, wherein the synchronisation message contains information on which frequency or code has to be employed.

20. A method according to claim 18, comprising the step of the stationary master unit and stationary slave unit each transmitting on its own code.

21. A method according to claim 18, comprising the step of initiating the message from the central processing unit to the stationary master unit by a user requesting an update of positions via a user interface on the central processing unit.

22. A method according to claim 18, comprising the step of initiating the message from the central processing unit to the stationary master unit by an identification tag transmitting a request via signals to the central processing unit.

23. A method according to claim 18, wherein each identification tag that contains a radio receiver in addition to an ultrasonic receiver listens to radio signals transmitted from the central processing unit to the master unit and switches on its ultrasonic receiver only when it determines that the master unit and the slave unit are to transmit ultrasonic pulses in an area where the tag is located.

24. A method according to claim 18, wherein the identification tag transmits a request for initiation of a position determination update to the central processing unit when an attempt is made to open or move it.

27. A method as in claim 18 wherein a master unit is located in each of a plurality of rooms and wherein the steps of the method are repeated for each one of said plurality of rooms in turn until the position of the tag is determined.

28. A central processing unit for use in a tag-position determination system arranged to receive ultrasound transit time difference information from a tag and to determine the tag'"'"'s position therefrom.