Device state estimation under pedestrian motion with swinging limb

• US 10,345,426 B2
• Filed: 09/02/2015
• Issued: 07/09/2019
• Est. Priority Date: 09/02/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Miller, Isaac Thomas
• Primary Examiner(s): Williams, Jamel E
• Application Number:
  US14/843,894
• Publication Number:
  US 20170059602A1
• Time in Patent Office: 1,406 Days
• Field of Search: 7350402
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems
• CPC Class Codes: G01C 22/006 Pedometers
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering

Abstract

Systems, methods, devices and computer-readable storage mediums are disclosed for device state estimation under pedestrian motion with swinging limb. In some implementations, a method comprises: determining, by a device, that the device is attached to a swinging limb based on a sensor signal; determining, by the device, a rotational velocity component due to the swinging limb based on the sensor signal and limb parameters; estimating, by the device, device velocity; and determining, by the device, user velocity based on the device velocity and the rotational velocity component.

Claims

1. A method comprising:

determining, by a device, that the device is attached to a swinging limb based on a sensor signal;

determining, by the device, a rotational velocity component of device velocity due to the swinging limb based on the sensor signal and a limb position vector;

estimating, by the device, device velocity using a global navigation satellite (GNSS) velocity or velocity determined from wireless signals transmitted by a wireless network; and

determining, by the device, a user velocity by excluding the rotational velocity component from the device velocity.

2. The method of claim 1, wherein determining that the device is attached to a swinging limb based on the sensor signal, further comprises:

detecting periodicity in the sensor signal; and

determining that the device is attached to the swinging limb based on the detected periodicity in the sensor signal.

3. The method of claim 1, wherein determining that the device is attached to a swinging limb based on the sensor signal, further comprises:

detecting a first periodicity in device acceleration data;

detecting a second periodicity in device orientation data; and

determining that the device is attached to the swinging limb based on a relative strength of the first or second periodicities.

4. The method of claim 1, wherein determining a rotational velocity component due to the swinging limb based on the sensor signal and limb parameters, further comprises:

determining a limb rotation rate vector in a reference coordinate frame;

determining a swinging limb position vector in the reference coordinate frame; and

determining the rotational velocity component based on a cross product of the limb rotation rate vector and the swinging limb position vector.

5. The method of claim 4, wherein one or more of the swinging limb parameters are estimated by a device state estimator.

6. The method of claim 4, wherein determining a swinging limb position vector in the reference coordinate frame further comprises:

determining terminus points of a swing path of the limb; and

interpolating between the terminus points to determine the swinging limb position vector.

7. The method of claim 1, wherein one of the swinging limb parameters is a limb length that is obtained from user input.

8. The method of claim 1, wherein determining user velocity based on the velocity of the device and the rotational velocity component uses the formula,

_user=_device−

_rotation=_device−

(_L×

),

where _user is the user velocity, _device is the device velocity, _L is a limb rotation rate vector and is a limb position vector.

9. The method of claim 1, wherein the user velocity is used to update a device state estimator between measurement time epochs.

10. The method of claim 9, where the update occurs at time indicated by a trigger signal or schedule based on a periodicity feature detected in the sensor signal.

11. A device comprising:

one or more sensors;

one or more processors;

memory coupled to the one or more processors and configured to store instructions, which, when executed by the one or more processors, causes the one or more processors to perform operations comprising;

determining that the device is attached to a swinging limb based on a sensor signal;

determining a rotational velocity component of device velocity due to the swinging limb based on the sensor signal and a limb position vector;

estimating device velocity using a global navigation satellite (GNSS) velocity or velocity determined from wireless signals transmitted by a wireless network; and

determining a user velocity by excluding the rotational velocity component from the device velocity.

12. The device of claim 11, wherein determining that the device is attached to a swinging limb based on the sensor signal, further comprises:

detecting periodicity in the sensor signal; and

determining that the device is attached to the swinging limb based on the detected periodicity in the sensor signal.

13. The device of claim 11, wherein determining that the device is attached to a swinging limb based on the sensor signal, further comprises:

detecting a first periodicity in device acceleration data;

detecting a second periodicity in device orientation data; and

determining that device is attached to the swinging limb based on a relative strength of the first and second periodicities.

14. The device of claim 11, wherein determining a rotational velocity component due to the swinging limb based on the sensor signal and limb parameters, further comprises:

determining a limb rotation rate vector in a reference coordinate frame;

determining a swinging limb position vector in the reference coordinate frame; and

determining the rotational velocity component based on a cross product of the limb rotation rate vector and the swinging limb position vector.

15. The device of claim 14, wherein one or more of the swinging limb parameters are estimated by a device state estimator.

16. The device of claim 14, wherein determining a swinging limb position vector in the reference coordinate frame further comprises:

determining terminus points of a swing path of the limb; and

interpolating between the terminus points to determine the swinging limb position vector.

17. The device of claim 11, wherein one of the swinging limb parameters is a limb length that is obtained from user input.

18. The device of claim 11, wherein determining user velocity based on the velocity of the device and the rotational velocity component uses the formula,

_user=_device−

_rotation=_device−

(_L×

),

where _user is the user velocity, _device is the device velocity, _L is a limb rotation rate vector and is a limb position vector.

19. The device of claim 11, wherein the user velocity is used to update a device state estimator between measurement time epochs.

20. The device of claim 19, where the update occurs at time indicated by a trigger signal or schedule based on a periodicity feature detected in the sensor signal.