Portable integrated indoor and outdoor positioning system and method

• US 6,459,989 B1
• Filed: 03/03/2000
• Issued: 10/01/2002
• Est. Priority Date: 03/03/2000
• Status: Expired due to Fees

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Gellrich, Christian, Cutter, Michael, Binnion, James, Kirkpatrick, Michael, Casper, Jeffrey, Ross, Clay, Seaton, D. Scott
• Primary Examiner(s): Beaulieu, Yonel
• Assistant Examiner(s): MANCHO, RONNIE M
• Application Number:
  US09/517,897
• Time in Patent Office: 942 Days
• Field of Search: 701/215, 701/213, 701/214, 701/207, 455/465, 455/452, 455/62, 455/509, 340/988, 340/426, 342/457, 342/357.06, 342/450, 342/357.09, 342/45, 342/357.17, 379/200, 379/16, 379/199, 379/230, 379/231, 370/316, 370/329, 370/320, 370/431
• US Class Current: 701/215
• CPC Class Codes: G01S 1/725 Marker, boundary, call-sign or like beacons transmitting signals not carrying directional information
• CPC Class Codes: G01S 15/74 Systems using reradiation of acoustic waves, e.g. IFF, i.e. identification of friend or foe
• CPC Class Codes: G01S 19/10 providing dedicated supplementary positioning signals
• CPC Class Codes: G01S 19/14 specially adapted for specific applications
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile

Abstract

An integrated indoor and outdoor positioning system and method. A first communication unit aperiodically emits an ultrasonic signal. A second communication unit receives the ultrasonic signal and transmits an identification signal in response to receiving the ultrasonic signal. One of the two communication units is placed at a predetermined position and the other of the two communication units is placed with an object. Identification information obtained from the identification signal is used to determine position information indicating that the object is at the predetermined position. The first communication unit is placed at the predetermined position and the second communication unit accompanies the object. Alternatively, the first communication unit accompanies the object and the second communication unit is placed at the predetermined position. One of the two communication units may also include a GPS receiver for receiving GPS signals from a plurality of satellites or pseudolites and computing position information therefrom. The GPS receiver applies differential GPS corrections computed by a GPS reference receiver to improve the accuracy of the position information. Position information is transmitted to a base station over an assigned radio frequency and during a time slot allocated to the communication unit that is transmitting the position information.

Claims

1. A system for determining a position of an object, comprising:

a first communication unit having a transmitter that emits a sound signal; and

a second communication unit having a receiver to receive the sound signal and a transmitter to transmit a responsive identification signal,

wherein one of the two communication units is placed at a predetermined position and the other of the two communication units is placed with an object, and

wherein the object is identified as being located at the predetermined position if the two communication units establish communications by exchanging the sound and identification signals.

2. The system of claim 1 further comprising:

a timer producing a window of time;

a receiver in the first communication unit in communication with the timer, the receiver accepting any identification signal that arrives within the window of time and ignoring any identification signal that arrives outside of the window of time.

3. The system of claim 2 wherein the timer opens the window of time a predetermined period of time after the transmitter of the first communication unit emits the sound signal.

4. The system of claim 3 wherein the predetermined period of time approximates a period of time required for the sound signal to propagate to the second communication unit.

5. The system of claim 1 wherein the first communication unit is placed at the predetermined position and the second communication unit accompanies the object.

6. The system of claim 1 wherein the first communication unit accompanies the object and the second communication unit is placed at the predetermined position.

7. The system of claim 1 wherein the identification signal is a radio frequency (RF) signal.

8. The system of claim 1 wherein the identification signal includes information that leads to identifying the predetermined position.

9. The system of claim 1 wherein the identification signal includes information that leads to identifying the object.

10. The system of claim 1 wherein the identification signal includes information related to an identity of the object and further comprising a processor in communication with one of the communication units to receive the identification signal and use the identification information in the identification signal to produce position information indicating that the object is at the predetermined position.

11. The system of claim 10 further comprising a differential global positioning system (DGPS), in communication with the processor, capable of computing a position of the object from GPS signals received from remote signal transmitters.

12. The system of claim 10 wherein one of the two communication units includes a second transmitter in communication with the processor, the second transmitter transmitting the position information to a base station.

13. The system of claim 12 wherein the first communication unit includes the second transmitter that transmits the position information to the base station.

14. The system of claim 1 further comprising a base station in communication with one of the communication units to receive the position information obtained by that communication unit.

15. The system of claim 1 wherein the sound signal is an ultrasonic signal.

16. The system of claim 1 wherein the transmitter transmits sound signals aperiodically.

17. A method for tracking an object in a system having a first communication unit placed at a predetermined position and a second communication unit placed with the object, the method comprising:

(a) emitting a sound signal from one of the communication units;

(b) opening a window of time having a limited duration for receiving a response to the sound signal from the other of the communication units;

(c) accepting the response to the sound signal if the response arrives within the opened window of time; and

(d) associating the predetermined position with the object based on information provided with the response.

18. The method of claim 17 further comprising:

waiting a predetermined period of time before opening the window of time to allow for the sound signal to propagate to the other of the communication units.

19. The method of claim 17 further comprising:

computing position information of the object from GPS signals received from a plurality of remote signal transmitters using a differential global positioning system (DGPS).

20. The method of claim 17 further comprising:

assigning a frequency to one of the communication units for communicating with a base station; and

allocating a time slot within the assigned frequency during which that one communication unit can transmit position information to the base station.

21. The method of claim 17 further comprising:

detecting the sound signal at more than one position; and

calculating an approximate position of the object based in part on when the sound signal was detected at each position.

22. The method of claim 17 further comprising receiving a radio frequency (RF) signal as the response to the sound signal.

23. The method of claim 17 further comprising repeating the emitting, the opening, and the accepting before associating the predetermined position with the object.

24. The method of claim 17 wherein the emitting of the sound signal occurs aperiodically.

25. A method for tracking a plurality of objects in a system having a first communication unit placed at a predetermined position and a plurality of second communication units each accompanying a respective object from the plurality of objects, the method comprising:

(a) emitting a sound signal from each of the second communication units;

(b) opening a window of time having limited duration by each of the second communication units in response to emitting the sound signal; and

(c) accepting by each second communication unit a response to the sound signal emitted by such second communication unit if that response arrives within the window of time opened by that second communication unit and ignoring any response that arrives outside of that window of time.

26. The method of claim 25, further comprising:

determining position information by each of the second communication units; and

assigning one of a plurality of frequencies to each of the second communication units for transmitting the position information determined by that second communication unit; and

allocating a time slot to each of the second communication units within the frequency assigned to that second communication unit during which that second communication unit can transmit the determined position information.

27. The method of claim 25 wherein the emitting of the sound signal occurs aperiodically.

28. A system for tracking a position of an object, comprising:

a global positioning system accompanying the object, the global positioning system computing position information about the object when the global positioning system is able to receive signals from a signal transmitter; and

an indoor tracking system including a communication unit placed at a predetermined position, the indoor tracking system determining position information about the object when the object enters within a predetermined range of the communication unit by communicating with a communication unit located with the object using sound signaling.

29. The system of claim 28 further comprising a processor in communication with the global positioning and the indoor tracking systems to receive position information about the object.

30. In a system including a transceiver placed at a predetermined location, a portable apparatus accompanying an object used for determining a position of the object, comprising:

a global positioning system (GPS) receiver computing the position of the object from signals concurrently received from a plurality of signal transmitters; and

a communication unit exchanging sound and radio frequency signals with the transceiver to determine the position of the object when the object is within range of the transceiver.

31. The portable apparatus of claim 30 wherein the communication unit comprises:

an ultrasonic transmitter aperiodically emitting an ultrasonic signal; and

a radio frequency (RF) modem receiving an identification signal from the transceiver in response to the emitted ultrasonic signal.

32. The portable apparatus of claim 30 wherein the communication unit comprises:

a receiver receiving an ultrasonic signal emitted by the transceiver; and

a radio frequency (RF) modem transmitting an identification signal in response to the received sound signal.

33. The portable apparatus of claim 30 further comprising a radio frequency (RF) modem exchanging signals with a second transceiver.

34. The portable apparatus of claim 30 wherein the exchanged signals represent voice data.