Step detection methods and apparatus

• US 10,724,864 B2
• Filed: 06/17/2014
• Issued: 07/28/2020
• Est. Priority Date: 06/17/2014
• Status: Active Grant

• Current Assignee: Chief Architect Incorporated
• Original Assignee: Chief Architect Incorporated
• Inventors: Wells, Greg, Tenbrink, Chris, Wieland, Carl
• Primary Examiner(s): Nghiem, Michael P
• Assistant Examiner(s): Ngo, Dacthang P
• Application Number:
  US14/307,268
• Publication Number:
  US 20150362520A1
• Time in Patent Office: 2,233 Days
• Field of Search: 702141
• CPC Class Codes: G01C 19/00 Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06T 19/003 Navigation within 3D models or images

Abstract

Step detection methods and apparatus are described. According to one aspect, a footstep detection method includes obtaining accelerometer data regarding movements of a user device, filtering the accelerometer data to remove frequencies above a typical stepping frequency range of a user, after the filtering, analyzing individual ones of a plurality of cycles of the accelerometer data to determine whether any of the individual cycles corresponds to a user taking a footstep with the user device, and as a result of the analyzing, indicating at least one of the individual cycles as corresponding to the user taking a footstep.

Claims

1. A footstep detection method comprising:

using an accelerometer sensor, generating accelerometer data regarding movements of a user device;

using a filter, filtering the accelerometer data to remove frequencies above a typical stepping frequency range of a user;

using processing circuitry, analyzing an individual one of a plurality of cycles of the accelerometer data to determine whether the one cycle corresponds to the user taking a footstep with the user device after the filtering;

using the processing circuitry, determining that the one cycle corresponds to the user taking the footstep as a result of the analyzing; and

wherein the determining comprises;

determining the one cycle as corresponding to the user taking the footstep as a result of the accelerometer data of the one cycle decreasing while first crossing a low threshold and increasing while second crossing a high threshold, and the first and second crossings occur within a cutoff period of time;

or

determining the one cycle as corresponding to the user taking the footstep as a result of the accelerometer data of the one cycle decreasing while third crossing the high threshold and increasing while fourth crossing the low threshold, and the third and fourth crossings occur within the cutoff period of time.

2. The method of claim 1 wherein the analyzing comprises analyzing less than the entirety of the one cycle.

3. The method of claim 2 wherein the analyzing comprises comparing only a portion of the one cycle with a predefined length of time.

4. The method of claim 1 wherein the analyzing filters cycles having frequencies less than the typical stepping frequency range.

5. The method of claim 1 wherein the cutoff period of time is longer than half the period of a typical footstep cycle of the user and less than the period of a typical footstep cycle which corresponds to a footstep of the user.

6. The method of claim 1 wherein the filtering comprises filtering using a digital Finite Impulse Response filter.

7. The method of claim 6 wherein the digital Finite Impulse Response Filter employs a 16-element coefficient vector to perform the filtering.

8. The method of claim 7 wherein the filtering the accelerometer data comprises low passing frequencies below 4 Hz.

9. The method of claim 8 wherein the analyzing the accelerometer data comprises high pass filtering the accelerometer data.

10. The method of claim 9 where the high pass filtering comprises filtering with a high pass filter having an infinitely small transition zone.

11. The method of claim 10 wherein the filtering and analyzing band pass filter the accelerometer data about the typical stepping frequency range of 1-4 Hz.

12. The method of claim 1 wherein the accelerometer sensor is configured to provide the accelerometer data from one of a plurality of axes of a device coordinate reference frame of the user device.

13. The method of claim 12 wherein the acceleration data only comprises acceleration information regarding the stepping of the user in a Z axis of a global coordinate reference frame.

14. The method of claim 12 wherein the analyzing comprises analyzing using only the accelerometer data in a Z axis of a global coordinate reference frame.

15. The method of claim 1 wherein the analyzing identifies the one cycle as corresponding to the user taking a footstep as a result of the accelerometer data of the one cycle having an amplitude which is less than a threshold amplitude which is indicative of a typical footstep.

16. The method of claim 15 further comprising determining the amplitude of the one cycle while the accelerometer data is decreasing and prior to the increasing of the accelerometer data.

17. The method of claim 16 wherein the determining comprises determining an absolute value of a minimum acceleration since the accelerometer data last crossed 0.0 g while decreasing.

18. The method of claim 1 wherein the analyzing identifies an other of the cycles as not corresponding to the user taking a footstep as a result of the accelerometer data of the other cycle having an amplitude which is larger than a threshold amplitude which is indicative of a typical footstep.

19. The method of claim 1 further comprising determining a distance a virtual camera is to be moved within a virtual scene of a virtual model as a result of the determining that the one cycle corresponds to the user taking the footstep.

20. The method of claim 1 further comprising moving a virtual camera within a virtual scene of a virtual model as a result of the determining that the one cycle corresponds to the user taking the footstep.

21. The method of claim 20 wherein the moving comprises initiating the moving after the determining and prior to determining that an other cycle of the accelerometer data corresponds to the user taking another footstep.

22. The method of claim 1 further comprising generating an indication that the one cycle corresponds to the user taking the footstep.

23. The method of claim 1 further comprising initiating an operation of a user computer device as a result of the determining that the one cycle corresponds to the user taking the footstep.

24. The method of claim 1 wherein the analyzing and determining occur in real-time as the user takes the footstep.

25. The method of claim 1 wherein the filtering comprises first filtering and the analyzing comprises second filtering the accelerometer data.

26. The method of claim 1 wherein the analyzing comprises analyzing a period of the one cycle with respect to a period of a typical footstep cycle which corresponds to a typical footstep.

27. The method of claim 26 wherein the determining comprises determining the one cycle as corresponding to the user taking the footstep as a result of the period of the one cycle being less than the period of the typical footstep cycle.

28. The method of claim 26 further comprising identifying an other of the cycles as not corresponding to the user taking the footstep as a result of a period of the other of the cycles being greater than the period of the typical footstep cycle.

29. A user computer device configured to perform the footstep detection method of claim 1.

30. An article of manufacture comprising programming configured to cause the processing circuitry to perform the method of claim 1.