System and method for tracking and locating a person, animal, or machine

• US 9,091,549 B2
• Filed: 12/16/2013
• Issued: 07/28/2015
• Est. Priority Date: 01/22/2013
• Status: Active Grant

• Current Assignee: ENSCO, Incorporated (Teris LLC)
• Original Assignee: ENSCO, Incorporated (Teris LLC)
• Inventors: Taylor, David W. A. Jr., Farnsworth, Bradley David, Faulkner, William Todd, Foster, Christopher Matthew, Alwood, Robert Barlow
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): PAIGE, TYLER D
• Application Number:
  US14/107,287
• Publication Number:
  US 20140203971A1
• Time in Patent Office: 589 Days
• Field of Search: 701/469, 701/470, 702/150, 702/160
• US Class Current: 1/1
• CPC Class Codes: G01C 21/1652 with ranging devices, e.g. LIDAR or RADAR
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects
• CPC Class Codes: G01C 21/185 for gravity
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 13/84 for distance determination by phase measurement
• CPC Class Codes: G01S 19/14 specially adapted for specific applications

Abstract

A system and method for estimating the position of an object, such as a person, animal, or machine. The system includes first and second inertial measurement units, a first and second originator antennas, and a first and second transponder antennas. The system uses data from the inertial measurement units to estimate a position of the object. The system also calculates a range measurement between the first originator antenna and first transponder antenna. The system calculates a first CPD measurement between the second transponder antenna and the first originator antenna, and a second CPD measurement between the second originator antenna and the first transponder antenna. The range measurement and at least one CPD measurement are used to update a Kalman filter for estimating the position of the object. The system determines also updates the Kalman filter when one of the inertial measurement units is in a zero-velocity condition.

Claims

1. A navigation system device comprising:

a first antenna;

a second antenna,

wherein said first antenna and said second antenna are configured to receive a first wireless signal from a transmitting device,

a memory; and

a processor configured to communicate with said memory and to use said first wireless signal to update an estimate of a position of said navigation system device by calculating a differential distance between said first antenna and said second antenna from said transmitting device.

2. The device according to claim 1, wherein said navigation system device is mounted to an article of footwear.

3. The device according to claim 1, wherein said first antenna is rigidly coupled to said second antenna.

4. The device according to claim 1, wherein said navigation system device is attached to a vehicle.

5. The device according to claim 1, further comprising:

an inertial measurement unit configured to output IMU data, and

where said processor is further configured to use said IMU data to update said estimate of said position of said navigation system device.

6. The device according to claim 1, wherein said processor is further configured to calculate a range measurement between said first antenna and said transmitting device.

7. The device according to claim 1, wherein said processor is further configured to calculate a carrier phase difference measurement between said second antenna and said first antenna, and

to use said carrier phase difference measurement to update said estimate of said position of said navigation system device.

8. The device according to claim 7, wherein said processor is further configured to calculate said carrier phase difference measurement by computing the difference between a first carrier phase received at said first antenna and a second carrier phase received at said second antenna.

9. The device according to claim 8, wherein said processor is further configured to calculate said first carrier phase by computing a first in-phase channel signal and a first quadrature channel signal based on said first wireless signal received by said first antenna, and

calculate said second carrier phase by computing a second in-phase channel signal and a second quadrature channel signal based on said first wireless signal received by said second antenna.

10. The device according to claim 9, wherein said processor is further configured to calculate said first carrier signal by calculating the arctangent of said first quadrature signal over said first in-phase channel signal, and

to calculate said second carrier signal by calculating the arctangent of said second quadrature signal over said second in-phase channel signal.

11. The device according to claim 7, wherein said processor is further configured to calculate said carrier phase difference measurement by subtracting a first carrier phase of said first wireless signal received at said first antenna and a second carrier phase of said first wireless signal received at said second antenna.

12. The device according to claim 5, wherein said processor is further configured to determine whether said inertial measurement unit is in a zero-velocity condition.

13. The device according to claim 12, wherein said processor is further configured to determine whether said inertial measurement unit is in said zero-velocity condition by

rotating said IMU data to a level frame;

applying a first time-based window to said rotated data;

calculating a first rotated standard deviation for said rotated data within said first time-based window;

determining whether said first rotated standard deviation is less than a first window threshold value; and

performing a zero-velocity-based update to a Kalman filter when said first rotated standard deviation is less than said first window threshold value.

14. The device according to claim 13, wherein said processor is further configured to determine whether said inertial measurement unit is in said zero-velocity condition by

determining a second time-based window and a second window threshold value, if said first rotated standard deviation is not less than said first window threshold value;

applying said second time-based window to said rotated data;

calculating a second rotated standard deviation for said rotated data within said second time-based window;

determining whether said second rotated standard deviation is less than said second window threshold value; and

performing a zero-velocity-based update to a Kalman filter when said second rotated standard deviation is less than said second window threshold value.

15. The device according to claim 14, wherein said second time-based window length is less than said first time-based window.

16. The device according to claim 15, wherein said second window threshold value is greater than said first window threshold value.

17. The device according to claim 13, wherein said IMU data comprises gyroscopic data, accelerometer data, gyroscopic deviation data, and accelerometer deviation data.

18. The device according to claim 17, wherein said processor is configured to, before rotating said IMU data to said level frame:

calculate a gyroscopic magnitude residual, wherein said gyroscopic magnitude residual comprises the difference between the magnitude of said gyroscopic data and a magnitude of the Earth'"'"'s rotation,

calculate an accelerometer magnitude residual, wherein said accelerometer magnitude residual comprises the difference between the magnitude of said accelerometer data and the magnitude of gravity; and

wherein said processor is configured to rotate said first IMU data to said level frame when

said gyroscopic magnitude residual is less than a predetermined gyroscopic magnitude threshold,

said accelerometer magnitude residual is less than a predetermined accelerometer magnitude threshold, and

at least one of said gyroscopic deviation data is not less than a gyroscopic deviation threshold and said accelerometer deviation data is not less than an accelerometer deviation threshold.

19. The device according to claim 1, wherein said processor is configured to update said estimate of said position using a Kalman filer and said differential distance.

20. The device according to claim 19 wherein said processor is configured to calculate said distance between said navigation system device and said transmitting device.

21. The device according to claim 1, wherein said processor is further configured to update said estimate of said position using said differential distance and a distance between said navigation system device and said transmitting device.