Method and system for assessing human movements
One embodiment provides a system for analyzing a motion. During operation, the system obtains acceleration data associated with the motion. The acceleration data can include three components corresponding to three spatially orthogonal directions. For each orthogonal direction, the system computes an amount of oscillatory energy included in the motion in the orthogonal direction based on a corresponding acceleration component. For at least one orthogonal direction, the system obtains an energy fraction factor by computing a ratio between the amount of the oscillatory energy in the orthogonal direction and a total amount of the oscillator energy. The system generates a motion-analysis output based at least on the energy fraction factor.
1 . A method for assessing a risk of falling based on gaits of a human user, the method comprising:
attaching a motion sensor to a belt at a location directly behind a lumbosacral joint of the human user;
monitoring, by the motion sensor, a walking or running motion of the human user, wherein monitoring the motion comprises determining a sampling rate of the motion sensor based on a stride frequency of the walking or running motion, obtaining acceleration data associated with the walking or running motion, and applying one or more filters to remove sensor noise and the stride frequency from the acceleration data, and wherein the acceleration data comprises three components corresponding to three spatially orthogonal directions;
for each orthogonal direction of the three spatially orthogonal directions, determining, by a computer, an amount of oscillatory energy included in the walking or running motion in the orthogonal direction based on a corresponding acceleration component, wherein determining the amount of oscillatory energy comprises performing frequency-domain analysis on the acceleration data and removing a fundamental frequency component to remove non-oscillatory energy included in the walking or running motion;
for at least one orthogonal direction of the three spatially orthogonal directions, obtaining an energy fraction factor by computing a ratio between the amount of the oscillatory energy in the at least one orthogonal direction and a total amount of the oscillator energy;
generating one or more gait-analysis results based on the energy fraction factor associated with each orthogonal direction, wherein the gait-analysis results comprise at least a stability factor and a symmetry index associated with the human user's gaits; and
configuring a graphic user interface (GUI) to display the gait-analysis results to the human user, wherein the GUI comprises at least a first region for displaying the symmetry index and a second region for displaying the energy fraction factor corresponding to each orthogonal direction, and wherein the energy fraction factor corresponding to a vertical direction indicates the risk of falling associated with the human user.
2 . The method of claim 1 , wherein the walking or running motion is along a horizontal plane, wherein the three spatially orthogonal directions comprise: a medial lateral (ML) direction, a vertical (VT) direction, and an anterior posterior (AP) direction.
3 . The method of claim 1 , wherein the gait-analysis results further comprise an efficiency factor.
4 . The method of claim 1 , wherein performing the frequency-domain analysis comprises:
performing a Fourier transform (FT) on the acceleration data to obtain a plurality of frequency components of the acceleration;
computing, for each frequency of a predetermined set of frequencies, a frequency component of the oscillatory energy at that frequency; and
summing the computed frequency components of the oscillatory energy.
5 . The method of claim 1 , wherein the motion sensor comprises at least one of: a three-axis accelerometer, a gyroscope, and a magnetometer.
6 . The method of claim 1 , wherein the computer comprises a mobile computing device, and wherein the motion sensor is integrated into the mobile computing device.
7 . The method of claim 6 , further comprising:
forwarding, by the mobile computing device, output of the motion sensor to a remote server; and
receiving, from the remote server, the gait-analysis results.
8 . A non-transitory computer-readable storage device storing instructions that when executed by a computer cause the computer to perform a method for assessing a risk of falling based on gaits of a human user, the method comprising:
obtaining acceleration data associated with a walking or running motion of the human user, wherein obtaining the acceleration data comprises determining a sampling rate of the motion sensor based on a stride frequency of the walking or running motion wherein the acceleration data is collected by a motion sensor attached to a belt at a location directly behind a lumbosacral joint of the human user and comprises three components corresponding to three spatially orthogonal directions, and wherein the motion sensor is coupled to the computer via a wired or wireless link;
applying one or more filters to remove sensor noise and the stride frequency from the acceleration data;
for each orthogonal direction of the three spatially orthogonal directions, determining an amount of oscillatory energy included in the walking or running motion in the orthogonal direction based on a corresponding acceleration component, wherein determining the amount of oscillatory energy comprises performing frequency-domain analysis on the acceleration data and removing a fundamental frequency component to remove non-oscillatory energy included in the walking or running motion; and
for at least one orthogonal direction of the three spatially orthogonal directions, obtaining an energy fraction factor by computing a ratio between the amount of the oscillatory energy in the at least one orthogonal direction and a total amount of the oscillator energy;
generating one or more gait-analysis results based on the energy fraction factor associated with each orthogonal direction, wherein the gait-analysis results comprise at least a stability factor and a symmetry index associated with the human user's gaits; and
configuring a graphic user interface (GUI) to display the gait-analysis results to the human user, wherein the GUI comprises at least a first region for displaying the symmetry index and a second region for displaying the energy fraction factor corresponding to each orthogonal direction, and wherein the energy fraction factor corresponding to a vertical direction indicates the risk of falling associated with the human user.
9 . The non-transitory computer-readable storage device of claim 8 ,
wherein the walking or running motion is along a horizontal plane, wherein the three spatially orthogonal directions comprise: a medial lateral (ML) direction, a vertical (VT) direction, and an anterior posterior (AP) direction.
10 . The non-transitory computer-readable storage device of claim 8 , wherein the gait-analysis results further comprise an efficiency factor.
11 . The non-transitory computer-readable storage device of claim 8 , wherein performing the frequency-domain analysis comprises:
performing a Fourier transform (FT) on the acceleration data to obtain a plurality of frequency components of the acceleration;
computing, for each frequency of a predetermined set of frequencies, a frequency component of the oscillatory energy at that frequency; and
summing the computed frequency components of the oscillatory energy.
12 . The non-transitory computer-readable storage device of claim 8 , wherein the motion sensor comprises at least one of: a three-axis accelerometer, a gyroscope, and a magnetometer.