Step Detection Methods and Apparatus

• US 20150362520A1
• Filed: 06/17/2014
• Published: 12/17/2015
• 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
• Granted Patent: US 10,724,864 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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:

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.

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

3. The method of claim 2 wherein the indicating comprises indicating the at least one cycle as corresponding to the user taking the footstep as a result of the period of the individual cycle being less than the period of the typical footstep cycle.

4. The method of claim 2 wherein the analyzing identifies an other of the cycles as not corresponding to the user taking the footstep as a result of the period of the other of the cycles being greater than the period of the typical footstep cycle.

5. The method of claim 1 wherein the analyzing an individual one of the cycles comprises analyzing less than the entirety of the individual cycle.

6. The method of claim 5 wherein the analyzing the individual one of the cycles comprises comparing only a portion of the individual cycle with a predefined length of time.

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

8. The method of claim 1 wherein the indicating the at least one cycle as corresponding to the user taking a footstep comprises indicating as a result of the accelerometer data of the at least one cycle either one of:

decreasing while crossing a low threshold;

increasing while crossing a high threshold; and

the crossings of the low and high thresholds occur within a cutoff period of time;

or

decreasing while crossing the high threshold;

increasing while crossing the low threshold; and

the crossings of the low and high thresholds occur within the cutoff period of time.

9. The method of claim 8 further comprising adjusting the low and high thresholds using an amplitude of the accelerometer data.

10. The method of claim 8 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.

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

12. The method of claim 11 wherein the digital Finite Impulse Response Filter employs a 16-element coefficient vector to perform the filtering.

13. The method of claim 12 wherein the filtering the accelerometer data comprises low passing frequencies below 4 Hz.

14. The method of claim 13 wherein the analyzing the accelerometer data comprises high pass filtering the accelerometer data.

15. The method of claim 14 where the high pass filtering comprises filtering with a high pass filter having an infinitely small transition zone.

16. The method of claim 15 wherein the filtering and analyzing band pass filter the accelerometer data about the typical stepping frequency range of 1-4 Hz.

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

18. The method of claim 17 wherein the transforming provides the acceleration data only comprising acceleration information regarding the stepping of the user in a Z axis of the global coordinate reference frame.

19. The method of claim 17 wherein the analyzing comprises analyzing using only the accelerometer data in a Z axis of the global coordinate reference frame.

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

21. The method of claim 20 further comprising determining the amplitude of the at least one cycle while the accelerometer data is decreasing and prior to the increasing of the accelerometer data.

22. The method of claim 21 wherein the determining comprises determining an absolute value of a minimum acceleration since the accelerometer data last crossed 0.0 g while decreasing.

23. 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.

24. 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 indicating.

25. The method of claim 1 further comprising moving a virtual camera within a virtual scene of a virtual model as a result of the indicating the at least one footstep which is a single footstep.

26. The method of claim 25 wherein the moving comprises initiating the moving prior to indication of another footstep after the indicating of the single footstep.