Positioning system using ultrasonic waves and method for operating the same

• US 7,764,574 B2
• Filed: 07/11/2008
• Issued: 07/27/2010
• Est. Priority Date: 03/08/2004
• Status: Active Grant

• Current Assignee: KT Corporation
• Original Assignee: KT Corporation
• Inventors: Lee, Dong Hwal
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US12/171,491
• Publication Number:
  US 20090016165A1
• Time in Patent Office: 746 Days
• Field of Search: 367/127, 367/128
• US Class Current: 367/128
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location

Abstract

Provided is a method for controlling a positioning system using ultrasonic waves. The method installs a plurality of ultrasonic satellites generating ultrasonic signals to position a mobile. The method sequentially gives satellite identification numbers to the plurality of ultrasonic satellites, generates a synchronization signal, provides it to the plurality of ultrasonic satellites, and allows the mobile to receive ultrasonic signals, which are generated by the plurality of ultrasonic satellites in the order of the satellite identification numbers when the ultrasonic satellites receive the synchronization signal, to measure distances between the mobile and the ultrasonic satellites. The positioning system includes ultrasonic satellites, a mobile that receives ultrasonic signals from the ultrasonic satellites to recognize its current position, a reference time broadcaster for providing a synchronization signal to ultrasonic satellites and the mobile, and a server for providing the coordinates of the ultrasonic satellites to the mobile.

Claims

1. A method for operating a mobile device positioning system, wherein a positioning system comprises a plurality of ultrasonic signal transmitters, the method comprising:

assigning an identification number to each of the plurality of ultrasonic signal transmitters; and

transmitting an ultrasonic signal from each of the plurality of ultrasonic signal transmitters in a predetermined order of the plurality of ultrasonic signal transmitters for transmitting the ultrasonic signals, in order to allow the mobile device to compute a distance between the mobile device and each of the plurality of ultrasonic signal transmitters based on the ultrasonic signal and to determine the mobile device'"'"'s position using the distance between the mobile device and each of the plurality of ultrasonic signal transmitters, wherein each of the plurality of ultrasonic signal transmitters transmits the ultrasonic signal with a time delay after a synchronization signal, wherein the delay time for each of the plurality of ultrasonic signal transmitters is predetermined according to the predetermined order.

2. The method of claim 1, wherein each of the plurality of ultrasonic signal transmitters is configured to transmit its ultrasonic signal in the delay time after its receipt of the synchronization signal.

3. A method of determining a position of a mobile device, the method comprising:

receiving, by a mobile device, a synchronization signal;

synchronizing the mobile device based on the synchronization signal;

receiving, by the mobile device, a first ultrasonic signal transmitted from a first source located at a first source location at a first transmission time, which is after a first predetermined interval from the first source'"'"'s receipt of the synchronization signal, wherein the first ultrasonic signal does not comprises information indicative of the first transmission time; and

computing a first distance between the mobile device and the first source location using the first predetermined interval and further using a first transmission time difference between receipt of the first ultrasonic signal and receipt of the synchronization signal by the mobile device;

receiving, by the mobile device, a second ultrasonic signal transmitted from a second source located at a second source location at a second transmission time, which is after a second predetermined interval from the second source'"'"'s receipt of the synchronization signal, wherein the second ultrasonic signal does not comprises information indicative of the second transmission time; and

computing a second distance between the mobile device and the second source location using the second predetermined interval and further using second transmission time difference between receipt of the second ultrasonic signal and receipt of the synchronization signal by the mobile device; and

determining the mobile device'"'"'s position using the first distance and the second distance.

4. The method of claim 3, further comprising:

receiving, by the mobile device, a third ultrasonic signal transmitted from a third source located at a third source location at a third transmission time, which is after a third predetermined interval from the third source'"'"'s receipt of the synchronization signal, wherein the third ultrasonic signal does not comprises information indicative of the third transmission time; and

computing a third distance between the mobile device and the third source location using the third predetermined interval and further using a third time difference between receipt of the third ultrasonic signal and receipt of the synchronization signal by the mobile device,

wherein determining further uses the third distance.

5. The method of claim 3, wherein the first predetermined interval is different from the second predetermined interval.

6. The method of claim 3, further comprising receiving, by the mobile device, the information of the first predetermined interval.

7. The method of claim 6, wherein the information of the first predetermined interval is pre-stored in the mobile device.

8. The method of claim 3, further comprising receiving, by the mobile device, the information of the first source location.

9. The method of claim 8, wherein the information of the first source location is pre-stored in the mobile device.

10. The method of claim 3, wherein computing the first distance further uses the transmission speed of the ultrasonic signal.

14. The method of claim 3, wherein the mobile device comprises at least one memory storing locational information of at least three ultrasonic signal transmitters and further storing a predetermined order of transmission of ultrasonic signals from the at least three ultrasonic signal transmitters.

15. The method of claim 3, wherein determining the mobile device'"'"'s position further comprises using the locational information pre-stored in the at least one memory.

11. A mobile device for determining a position based on an ultrasonic signal, comprising:

an ultrasonic receiver configured to receive a synchronization signal and to further receive ultrasonic signals that are transmitted from a plurality of ultrasonic signal transmitters in a predetermined order at a predetermined time interval from receipt of the synchronization signal by the transmitters; and

at least one processor configured to compute a distance between the mobile device and each of the plurality of ultrasonic signal transmitters, using the predetermined time interval and a time difference between receipt of the synchronization signal and receipt of each of the ultrasonic signals,

wherein the at least one processor is further configured to determine the mobile device'"'"'s position based on location information of the ultrasonic signal transmitters and the computed distances between the mobile device and the ultrasonic signal transmitters.

12. The mobile device of claim 11, further comprising:

a storage unit configured to store the predetermined order of the ultrasonic signal transmitters, the predetermined time interval and the location information of the ultrasonic signal transmitters.

13. A ultrasonic signal transmitter for a mobile device positioning system including a plurality of ultrasonic signal transmitters and a mobile device, the ultrasonic signal transmitter comprising:

a unit configured to receive a synchronization signal; and

a unit configured to transmit a ultrasonic signal after a predetermined time interval from receipt of the synchronization signal to the mobile device,

wherein each of the ultrasonic signal transmitters transmits the ultrasonic signal at a predetermined order, in order to allow the mobile device to compute a distance between the mobile device and each of the plurality of ultrasonic signal transmitters based on the ultrasonic signal and to determine the mobile device'"'"'s position using the distance between the mobile device and each of the plurality of ultrasonic signal transmitters.