Step Detection Methods and Apparatus

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.

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 - 26 . (canceled)