System for determining the position of an object

• US 20040012524A1
• Filed: 06/24/2003
• Published: 01/22/2004
• Est. Priority Date: 11/08/2000
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Koehler, Stefan, Gerhaeuser, Heinz, Rohmer, Guenter, Couronne, Sylvie, Von Der Gruen, Thomas, Bretz, Ingmar
• Granted Patent: US 7,039,421 B2
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system for determining the position of an object, comprising a reference transmitter device (202) disposed in a fixed position, the reference transmitter device (202) having a reference time supplying means for supplying a reference time signal that indicates a reference time, at least two transmitter/receiver devices (302) disposed in fixed positions with respect to each other and to the reference transmitter device (202), each transmitter/receiver device (302) having a time supplying means for supplying a time signal indicating a time, a receiver means for receiving the reference time signal from the reference transmitter device (202) and a synchronization means for processing the time signal and the reference time signal, as well as a position determining device (502) on the object for determining the position of the object.

Claims

1. A system (100) for determining the position of an object, comprising:

a reference transmitter device (202) arranged in a fixed position, said reference transmitter device (202) including;

a) a reference time supplying means (204) for supplying a reference time signal indicating a reference time;

b) a first signal generating means (206) for generating a first information signal containing at least the transmission time of the first information signal that is determined from the reference time signal; and

c) a first transmitter means (208) for transmitting the first information signal and/or the reference time signal, said first transmitter means (208) including;

c1) a first code supplying means (210) for supplying a first code associated with the reference transmitter device (202); and

c2) a first coding means (212) for coding the first information signal with the first code;

two or more transmitter/receiver devices (302) arranged in fixed positions with respect to each other and to the reference transmitter device (202), each transmitter/receiver device (302) including;

d) a first time supplying means (304) for supplying a first time signal indicating a first time;

e) a first receiver means (306) for receiving the reference time signal from the reference transmitter device (202);

f) a synchronization means (308) for processing the first time signal and the reference time signal and for synchronizing the first time with the reference time in consideration of the transit times of the reference time signal from the reference transmitter device (202) to the transmitter/receiver device (302);

g) a second signal processing means (310) for generating a second information signal containing at least the transmission time of the second information signal that is determined from the first time signal; and

h) a second transmitter means (312) for transmitting the second information signal, said second transmitter means (312) including;

h1) a second code supplying means (314) for supplying a second code associated with the transmitter/receiver device (302) and differing from the first code of the reference transmitter device (202) and the second codes of the other transmitter/receiver devices (302); and

h2) a second coding means (316) for coding the second information signal with the second code; and

a position determining device (502) for determining the position of the object, said object including the position determining device (502) and said position determining device (502) including;

i) a second time supplying means (504) for supplying a second time signal indicating a second time;

j) a second receiver means (506) for receiving a reception signal containing the first information signal and the second information signals, said second receiver means (506) including;

j1) a third code supplying means (512) for supplying the first code and the second codes;

j2) a decoding means (514) for decoding the reception signal using the first code supplied from the third code supplying means (522) and the second codes supplied from the third code supplying means (522) in order to obtain reception information signals corresponding to the first information signal and the second information signals; and

j3) a reception time determining means (510) for determining the reception time of each reception information signal with the second time signal of the second time supplying means (504); and

k) a processing means (508) for processing the reception information signals, said processing means (508) including;

k1) an extraction means (536) for extracting the transmission times of the first information signal and the second information signals from the reception information signals;

k2) a transit time determining means (538) for determining the transmit times of the first information signal and the second information signals from the reference transmitter device (202) and the transmitter/receiver devices (302), respectively, to the position determining device (540) on the basis of the transmission times of the first information signal and the second information signals and the reception times of the reception information signals; and

k3) a calculating means (520) for calculating the position of the object using the transit times of the first information signal and the second information signals and the positions of the reference transmitter device (202) and the transmitter/receiver devices (302).

2. A system (100) for determining the position of an object according to claim 1, with said first transmitter means (208) and said second transmitter means (312) further comprising:

c3) a modulation means (214, 318) for modulating the first and, respectively, the second information signals onto a carrier signal having a carrier frequency.

3. A system (100) for determining the position of an object according to claim 2, with said processing means (508) of the position determining device (502) further comprising:

k4) a multipath signal filtering and data recovering means (542) for demodulating and decoding the reception information signals, so as to synchronize to a reception information format and, possibly, for passing the information data on to the extraction means (536).

4. A system (100) for determining the position of an object according to claim 2 or 3, with said second receiver means (506) of the position determining device (502) further comprising:

j4) a mixing means (544) for mixing the reception signal containing the first and second information signals modulated upon the carrier signal, into an intermediate signal having an intermediate frequency.

5. A system (100) for determining the position of an object according to any of the preceding claims, with said decoding means (514) of the second receiver means (506) of the position determining device (502) comprising furthermore:

at least one correlation means (544) for each reference transmitter device (202) and each transmitter/receiver device (302) of the system (100) for correlating the reception signal with the first and second codes, respectively, associated with the respective reference transmitter device (202) or transmitter/receiver device (302) in order to obtain a correlated reception signal;

one integration means (518) each associated with each correlation means (516) for integrating the correlated reception signal over time so as to obtain a reception information signal associated with the respective reference transmitter device (202) or transmitter/receiver device (302).

6. A system (100) for determining the position of an object according to claim 5, wherein the correlation means (516) comprises a correlator (520) for correlating the first and second codes, respectively, with the reception signal in order to obtain a correlated reception signal, and wherein the integration means (518) comprises an integrator (526) associated with the correlator (520) for integrating the correlated reception signal over time, so as to obtain the reception information signal associated with the first and second codes, respectively.

7. A system (100) for determining the position of an object according to claim 6, wherein the correlation means (516) comprises furthermore an additional correlator (522) for correlating the time-shifted first and second codes, respectively, with the reception signal, so as to obtain a correlated reception signal, and wherein the integration means (518) comprises furthermore an additional integrator (528) associated with said additional correlator (522) for integrating the correlated reception signal over time, so as to obtain a time-shifted reception information signal associated with the first and second codes, respectively, and differing from the reception information signal reaching the position determining device (502) on a direct path.

8. A system (100) for determining the position of an object according to claim 7, comprising at least three additional correlators (522, 524) and associated integrators (528, 530) for each correlation means (516) associated with a first and second code, respectively.

9. A system (100) for determining the position of an object according to any of claims 1 to 8, further comprising:

a connecting means for connecting the reference transmitter device (202) with each transmitter/receiver device (302) and for transmitting the reference time signal to the transmitter/receiver devices (302) in order to synchronize the first time of each transmitter/receiver device (302) with the reference time of the reference transmitter device (202) by means of the synchronization means (308) of each transmitter/receiver device (302).

10. A system (100) for determining the position of an object according to any of claims 1 to 9, wherein the first code supplying means (210), the second code supplying means (314) and the third code supplying means (512) have a memory and/or fed-back shift registers supplying pseudo noise codes (PN codes).

11. A system (100) for determining the position of an object according to any of claims 2 to 10, wherein the carrier signal of the modulation means (214, 318) is a radio-frequency carrier signal.

12. A system (100) for determining the position of an object according to any of claims 1 to 11, wherein the first information signal of the first signal generating means (206) of the reference transmitter device (202) further comprises the position of the reference transmitter device (202), wherein the second information signal of the second signal generating means (310) of each transmitter/receiver device (302) further comprises the position of the transmitter/receiver device (302), and wherein the extraction means (536) of the processing means (514) of the position determining device (502) furthermore extracts the positions of the reference transmitter device (202) and of the transmitter/receiver devices (302) from the reception information signals.

13. A system (100) for determining the position of an object according to any of claims 1 to 12, wherein the position determining device (502) further comprises:

l) a memory (546) for storing the positions of the reference transmitter device (202) and of the transmitter/receiver devices (302).

14. A system (100) for determining the position of an object according to any of claims 2 to 13, wherein the modulation means (214, 318) of the first transmitter means (208) and the second transmitter means (312) as well as the multipath signal filtering and data recovering means (542) of the processing means (508) of the position determining device (502) employ phase shift keying modulation (PSK modulation) for modulating the first and, respectively, second information signal and/or the reference time signal onto the carrier signal and for demodulating the first and, respectively, second information signal and/or the reference time signal form the carrier signal.

15. A system (100) for determining the position of an object according to any of claims 9 to 14, wherein the connecting means is an electrical or optical cable.

16. A system (100) for determining the position of an object according to any of claims 1 to 15, wherein the reference time supplying means (204) of the reference transmitter device (202), the first time supplying means (304) of the transmitter/receiver devices (302) and/or the second time supplying means (504) of the position determining device (502) comprise:

a clock for supplying the reference time and/or the first and second times, respectively.

17. A system (100) for determining the position of an object according to claim 16, wherein the synchronization means (308) of each transmitter/receiver device (302) comprises:

f1) a time correction means for correcting the first time of the clock of the first time supplying means (304) using a time correction value representing the difference in time between the reference time of the reference time supplying means (204) of the reference transmitter device (202) and the first time of the first time supplying means (304) of the transmitter/receiver device (302).

18. A system (100) for determining the position of an object according to any of claims 12 to 17, wherein the first information signal and the second information signals further comprise local information, local messages, specific system parameters, synchronization data, a map of the surroundings or a building plan and/or directories of reference transmitter devices (202) and/or radio beacons.

19. A system (100) for determining the position of an object according to any of claims 13 to 18, wherein the memory (546) of the position determining device (502) further has a building plan or a map of the surroundings stored therein in order to indicate the position of the object in a building or in surroundings.

20. A system (100) for determining the position of an object according to claim 19, wherein the position determining device (502) further comprises:

m) an information outputting unit for outputting information on the position determined by the calculating means (540) of the processing means (508) of the position determining device (502), the building plan and/or the map of the surroundings stored in the memory (546) of the position determining device (502), and/or optical and acoustical orientation aids and/or orientation instructions.

21. A system (100) for determining the position of an object according to any of claims 3 to 20, wherein the processing means (508) of the position determining device (502) further comprises:

k5) a multipath module filter for filtering the reception information signals in order to separate multipath signals superimposed on the reception information signals from each other.

22. A system (100) for determining the position of an object according to any of claims 1 to 21, wherein the reference transmitter device (202) is an additional transmitter/receiver device (302).