RADIONAVIGATION FOR SWIMMERS

• US 20170357007A1
• Filed: 06/10/2016
• Published: 12/14/2017
• Est. Priority Date: 06/10/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Miller, Isaac Thomas, MacGougan, Glenn Donald, Xiao, Xiao
• Granted Patent: US 10,261,192 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 19/19 Sporting applications
• CPC Class Codes: G01S 19/40 Correcting position, velocity or attitude
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 2205/04 Nautical
• CPC Class Codes: G01S 2205/08 Sport
• CPC Class Codes: G01S 2205/09 for tracking people
• CPC Class Codes: G01S 5/0246 involving frequency difference of arrival or Doppler measurements G01S5/02685 takes precedence

Abstract

Methods, systems and computer program products for radionavigation for swimmers are described. A mobile device configured to estimate a location using radio frequency signals can estimate a position of the swimmer when the mobile device is worn on a limb of the swimmer and periodically submerged. The mobile device can supply auxiliary information to a radionavigation subsystem to correct a navigation solution affected by limb motion of the swimmer and affected by the periodic submersion of the mobile device.

Claims

1. A method comprising:

receiving, by a mobile device and from a radionavigation subsystem of the mobile device, a velocity estimate, the velocity estimate being determined based on radio frequency (RF) signals;

determining a stroke rate of a swimmer wearing the mobile device on a limb;

determining a relative velocity based on the stroke rate, an estimated length of the limb, and a direction of travel of the mobile device, the relative velocity being a velocity of the mobile device relative to a torso of the swimmer; and

correcting the velocity of the mobile device based on the relative velocity.

2. The method of claim 1, wherein determining the stroke rate is based at least in part on readings of sensors of the mobile device measuring linear and angular acceleration.

3. The method of claim 1, wherein determining the stroke rate is based at least in part on readings of sensors of the mobile device measuring magnetic field and acceleration.

4. The method of claim 1, wherein determining the stroke rate is based at least in part on readings of a barometer of the mobile device indicating periods that the mobile device is above water.

5. The method of claim 1, wherein the length of the limb is estimated based on a user input indicating a height of the swimmer.

6. The method of claim 1, wherein the length of the limb is estimated by learning during a current swim or based on stroke data collected from one or more previous swims.

7. The method of claim 1, wherein the direction of travel is determined based on the velocity estimate.

8. The method of claim 1, wherein the direction of travel is determined based on an output from an inertial navigation subsystem of the mobile device.

9. The method of claim 1, wherein the direction of travel is determined based on geographic data indicating an orientation of a body of water.

10. The method of claim 1, wherein correcting the velocity of the mobile device based on the relative velocity comprises instructing the radionavigation subsystem to determine a travel distance of the swimmer by integrating a torso velocity over time.

11. The method of claim 1, wherein correcting the velocity of the mobile device based on the relative velocity comprises instructing the radionavigation subsystem to correct one or more radionavigation observables of the RF signals according to the relative velocity.

12. The method of claim 11, wherein the one or more radionavigation observables include at least one of a Doppler shift or a carrier phase.

13. A mobile device comprising:

one or more processors; and

a non-transitory computer-readable medium storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising;

receiving, by the mobile device and from a radionavigation subsystem of the mobile device, a velocity estimate, the velocity estimate being determined based on radio frequency (RF) signals;

determining a stroke rate of a swimmer wearing the mobile device on a limb;

determining a relative velocity based on the stroke rate, an estimated length of the limb, and a direction of travel of the mobile device, the relative velocity being a velocity of the mobile device relative to a torso of the swimmer; and

correcting the velocity of the mobile device based on the relative velocity.

14. The mobile device of claim 13, wherein determining the stroke rate is based at least in part on readings of sensors of the mobile device measuring linear and angular acceleration.

15. The mobile device of claim 13, wherein the length of the limb is estimated based on a user input indicating a height of the swimmer.

16. The mobile device of claim 13, wherein the length of the limb is estimated by learning during a current swim or based on stroke data collected from one or more previous swims.

17. The mobile device of claim 13, wherein the direction of travel is determined based on the velocity estimate.

18. The mobile device of claim 13, wherein the direction of travel is determined based on an output from an inertial navigation subsystem of the mobile device.

19. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

receiving, by a mobile device and from a radionavigation subsystem of the mobile device, a velocity estimate, the velocity estimate being determined based on radio frequency (RF) signals;

determining a stroke rate of a swimmer wearing the mobile device on a limb;

determining a relative velocity based on the stroke rate, an estimated length of the limb, and a direction of travel of the mobile device, the relative velocity being a velocity of the mobile device relative to a torso of the swimmer; and

correcting the velocity of the mobile device based on the relative velocity.

20. The non-transitory computer-readable medium of claim 19, wherein determining the stroke rate is based at least in part on readings of sensors of the mobile device measuring linear and angular acceleration.