Method and system of three-dimensional positional finding

• US 7,760,132 B1
• Filed: 08/04/2008
• Issued: 07/20/2010
• Est. Priority Date: 03/14/2006
• Status: Active Grant

• Current Assignee: Qualcomm Technologies Incorporated (Qualcomm, Inc.)
• Original Assignee: InvisiTrack, Inc.
• Inventors: Markhovsky, Russ, Mikhienko, Evgenii, Vityaev, Evgenii
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US12/185,767
• Time in Patent Office: 715 Days
• Field of Search: 342/42, 342/46, 342/47, 342/50, 342/52, 342 56- 58, 342/118, 342/125, 342/126, 342/146, 340/539.13, 340/573.4, 340/572.1, 340/539.32, 455/456.1, 455/550.1
• US Class Current: 342/126
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar

Abstract

The present invention is an RF system and methods for finding a target T in three dimensional space configured to have a transponder disposed on the target T, a monitoring unit configured as a transceiver for determining or monitoring the location of the target T and an RF wireless communication system configured with a processor to repeatedly determine position, communication and other values between the transponder and monitoring unit and so as to generate a measured distance between units in three dimensional space by determining the measured distance of the target T by a spherical virtual triangulation relationship when successive values of said position information has a predetermined logical relationship relative to said previous values between said monitoring unit and transponder and/or slave unit disposed on the target T.

Claims

1. An RF system for finding a target in three dimensional space, comprising:

a slave unit configured as a transponder;

a monitoring unit configured as a transceiver for monitoring a location of the slave unit;

a Radio Frequency (RF) communication system for communication between the slave unit and the monitoring unit and configured to transmit a ranging signal to the slave unit, the slave unit responding to the ranging signal by transmitting a reply ranging signal, the RF communication system further comprising a processor configured to repeatedly determine values for the position information of the slave unit based on

(a) a transmission interval between the monitoring unit and the slave unit being an elapsed time between transmitting the ranging signal and receiving the reply ranging signal,

(b) a calibration interval between each of the monitoring unit and the slave unit and being a time interval of a period to normalize circuitry of the monitoring unit and the slave unit,

(c) an antenna propagation interval of the monitoring unit and the slave unit being an elapsed time of a signal measured as it passes through antennas of the monitoring and slave units, and

(b) a measured distance between the monitoring unit and the slave unit in three dimensional space, determined by a spherical virtual triangulation relationship when successive values of the position information have a logical relationship relative to the previous values between the monitoring unit and slave unit.

2. The system of claim 1, wherein the processor determines the spherical virtual triangulation relationship based on the position information values from at least three points P1, P2 and P3 determined for the slave unit respective of the monitoring unit, the slave unit is located utilizing the point of intersection of at least three spheres based on values of the position information relating to the points P1, P2 and P3, wherein the points P1, P2 and P3 have spheres with radii R1, R2 and R3 respective of the monitoring unit to the slave unit.

3. The system of claim 2, wherein the processor determines the spherical virtual triangulation relationship by measuring the value of each of the points P1, P2 and P3 not in a straight line, but on the same plane relative to the monitoring unit to reduce ambiguity, each measurement of the value of the radii R1, R2 and or R3 to locate the slave unit utilizing a position of the monitoring unit.

4. The system of claim 1, wherein the system transmits, receives and displays the position information of other monitoring units and slave units.

5. The system of claim 1, further comprising at least two additional monitoring units.

6. The system of claim 5, further comprising at least one additional slave unit.

7. The system of claim 6, wherein:

(a) each monitoring unit includes an altimeter, a compass and a pedometer for determining a distance the monitoring unit traveled, its relative height and direction of travel, and

(b) all monitoring units are mobile.

8. The system of claim 6, wherein the slave units are mobile.

9. The system of claim 6, wherein each slave unit includes an altimeter.

10. The system of claim 6, wherein at least two monitoring units are stationary.

11. The system of claim 10, wherein the two stationary units are positioned vertically, one above the other.

12. A method for finding a target in three dimensional space, comprising the steps of:

(a) establishing a system of coordinates on plane referenced to four compass directions and selecting one of the compass directions as a reference axis;

(b) determining a height by using an altimeter;

(c) establishing a natural system of coordinates based on steps (a) and (b);

(d) establishing an origin for all monitoring units relative to each other (initial reference points) in the natural system of coordinates;

(e) representing positions of the monitoring units and slave units as points in three dimensional space using the natural system of coordinates,

(f) projecting all positions of the monitoring units and the slave units onto a plane in the natural coordinate system;

(g) calculating target coordinates plane in the natural coordinate system;

(h) determining a bearing of movement of the monitoring units toward the slave unit relative to the selected reference axis; and

(i) using the height to reduce impact of a landscape profile on accuracy of position determination.

13. The method of claim 12, further comprising:

periodically measuring and storing a distance the monitoring unit travels and the bearing of its movement relative to the reference axis of the natural system coordinates,

periodically measuring and storing the height of the monitoring unit; and

repeating the calculations of steps (b) through (i).

14. The method of claim 12, further comprising periodically measuring and storing the height of the slave unit.

15. The method of claim 12, wherein N monitoring units are searching for positions of M slave units, and M<

N.

16. The method of claim 12, wherein N monitoring units are searching for positions of K monitoring units and L slave units, wherein K+L=N.

17. The method of claim 12, further comprising at least one additional monitoring unit and one additional slave unit.

18. A method for finding a target in three dimensional space, comprising the steps of:

a. establishing a system of coordinates on plane referenced to four compass directions and selecting one of the compass directions as a reference axis;

b. determining a height by using an altimeter;

c. establishing a natural system of coordinates based on steps (a) and (b);

d. establishing an origin for all monitoring units relative to each other (initial reference points) in the natural system of coordinates;

e. calculating target coordinates in the natural coordinate system;

f. calculating monitoring units coordinates in the natural coordinate system;

g. determining a bearing of movement of the monitoring unit toward the slave unit relative to the selected reference axis.

19. The method of claim 18, further comprising:

periodically measuring and storing a distance the monitoring unit travels and the bearing of its movement relative to the reference axis of the natural system coordinates,

periodically measuring calculating and storing coordinates of the monitoring unit; and

repeating the calculations of steps (b) through (g).

20. The method of claim 18, wherein N mobile monitoring units are searching for positions of N slave units.

21. A method for finding a target in three dimensional space, comprising the steps of:

determining three spheres between multiple readings using a transponder and a transceiver, both operating using radio frequency (RF), the spheres determined by readings each having centers that do not lie on one straight line, but belonging to the same plane;

defining separate points of an intersection of the spheres;

the number of such points can be equal either to zero or one, or two;

determining a single valid point; and

calculating a position of the transponder from this one point.

22. A method for finding a target in three dimensional space, comprising the steps of:

a. establishing a system of coordinates on plane referenced to four compass directions and selecting one of the compass directions as a reference axis;

b. establishing a natural system of coordinates;

c. establishing an origin for all monitoring units relative to each other in the natural system of coordinates;

d. calculating all three coordinates for every mobile monitoring unit and slave unit in the natural coordinate system using Spherical Virtual Triangulation; and

e. determining a bearing of movement of the mobile monitoring unit toward the slave unit relative to the selected reference axis.