Device state estimation under periodic motion

• US 10,359,289 B2
• Filed: 09/02/2015
• Issued: 07/23/2019
• Est. Priority Date: 09/02/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Miller, Isaac Thomas
• Primary Examiner(s): Yi, Changhyun
• Application Number:
  US14/843,849
• Publication Number:
  US 20170059327A1
• Time in Patent Office: 1,420 Days
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• 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 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 5/0264 at least one of the systems being a non-radio wave positioning system
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering

Abstract

Systems, methods, apparatuses and computer-readable storage mediums are disclosed for device state estimation under periodic motion. In some implementations, a method comprises: detecting, by a device, periodic motion from a sensor signal generated by a sensor of the device; generating, by the device, a trigger signal or schedule based on the detecting; generating, by the device, a periodic motion constraint update in response to the detecting; and updating, by the device and in response to the trigger signal or schedule, an estimated state of the device using the periodic motion constraint update.

Claims

1. A method comprising:

detecting, by a location processor of a device, periodic motion from a sensor signal generated by a sensor of the device;

generating, by the location processor of the device, a trigger signal or schedule based on the detecting;

generating, by the location processor of the device, a periodic motion constraint update in response to the detecting; and

updating, by the location processor of the device and in response to the trigger signal or schedule, a predicted position or velocity of the device.

2. The method of claim 1, wherein detecting periodic motion from the sensor signal further comprises:

applying a sliding window frequency transform to the sensor signal to determine a fundamental motion frequency.

3. The method of claim 2, wherein generating the trigger signal or schedule based on the detecting further comprises:

extracting, by the location processor of the device, a periodicity feature from the sensor signal based on the fundamental motion frequency; and

generating the trigger signal or schedule based on the extracted periodicity feature.

4. The method of claim 3, wherein the sensor signal is acceleration magnitude and the periodicity feature is a local acceleration magnitude minimum.

5. The method of claim 1, wherein applying the update to a predicted position or velocity of the device in response to the trigger signal or schedule includes updating a Kalman filter prediction with the update.

6. The method of claim 1, wherein the periodic motion constraint update includes a change in device horizontal position across a time period.

7. The method of claim 1, wherein the periodic motion constraint update includes a change in device altitude across a time period.

8. The method of claim 1, wherein the periodic motion constraint update includes a change of device velocity across a time period.

9. The method of claim 1, wherein the periodic motion constraint update includes a primary direction of device motion across a time period.

10. A device comprising:

one or more sensors;

a location processor;

memory coupled to the location processor and configured to store instructions that when executed by the location processor cause the location processor to perform operations comprising;

detecting, by the location processor, periodic motion from a sensor signal generated by the one or more sensors;

generating, by the location processor, a trigger signal or schedule based on the detecting;

generating, by the location processor, a periodic motion constraint update in response to the detecting; and

responsive to the trigger signal or schedule, updating, by the location processor, a predicted position or velocity of the device.

11. The device of claim 10, wherein detecting periodic motion from the sensor signal further comprises:

applying a sliding window frequency transform to the sensor signal to determine a fundamental motion frequency.

12. The device of claim 11, wherein generating the trigger signal or schedule based on the detecting further comprises:

extracting a periodicity feature from the sensor signal based on the fundamental motion frequency; and

generating the signal or schedule based on the extracted periodicity feature.

13. The device of claim 12, wherein the sensor signal is acceleration magnitude and the periodicity feature is a local acceleration magnitude minimum.

14. The device of claim 10, wherein applying the update to a predicted position or velocity of the device in response to the trigger signal or schedule includes updating a Kalman filter prediction with the update.

15. The device of claim 10, wherein the periodic motion constraint update includes a change in device horizontal position across a time period.

16. The device of claim 10, wherein the periodic motion constraint update includes a change in device altitude across a last time period.

17. The device of claim 10, wherein the periodic motion constraint update includes a change of device velocity across a last time period.

18. The device of claim 10, wherein the periodic motion constraint update includes a primary direction of device motion across a last time period.