DEVICE STATE ESTIMATION UNDER PERIODIC MOTION

• US 20170059327A1
• Filed: 09/02/2015
• Published: 03/02/2017
• Est. Priority Date: 09/02/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Miller, Isaac Thomas
• Granted Patent: US 10,359,289 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 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.

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 a trigger signal or schedule based on the detecting further comprises:

extracting, by 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 1, wherein the sensor signal is acceleration magnitude and the periodicity feature is a local acceleration magnitude minimum.

5. The method of claim 1, wherein updating an estimated state of the device using the periodic motion constraint update includes applying the update to a predicted position or velocity of the device in response to the trigger signal or schedule.

6. The method of claim 5, 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.

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

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

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

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

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;

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

generating a trigger signal or schedule based on the detecting;

generating a periodic motion constraint update in response to the detecting; and

responsive to the trigger signal or schedule, updating an estimated state of the device using the periodic motion constraint update.

12. The device of claim 11, 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.

13. The device of claim 12, wherein generating a 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.

14. The device of claim 11, wherein the sensor signal is acceleration magnitude and the periodicity feature is a local acceleration magnitude minimum.

15. The device of claim 11, wherein updating an estimated state of the device using the periodic motion constraint update includes applying the update to a predicted position or velocity of the device in response to the trigger signal or schedule.

16. The device of claim 15, 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.

17. The device of claim 11, wherein the periodic motion constraint update includes a change in device horizontal position across a time period.

18. The device of claim 11, wherein the periodic motion constraint update includes a change in device altitude across a last time period.

19. The device of claim 11, wherein the periodic motion constraint update includes a change of device velocity across a last time period.

20. The device of claim 11, wherein the periodic motion constraint update includes a primary direction of device motion across a last time period.